Funds Held for Clients and Corporate Investments (Amortized Cost and Fair Value of Available-for-Sale Securities by Contractual Maturity) (Details) - USD ($) $ in Millions |
Feb. 28, 2026 |
May 31, 2025 |
|---|---|---|
| Funds Held for Clients and Corporate Investments [Abstract] | ||
| Due in one year or less, Amortized cost | $ 774.4 | |
| Due after one year through three years, Amortized cost | 1,690.2 | |
| Due after three years through five years, Amortized cost | 508.1 | |
| Due after five years, Amortized cost | 1,500.9 | |
| AFS securities, Amortized cost | 4,473.6 | $ 3,809.1 |
| Due in one year or less, Fair value | 769.0 | |
| Due after one year through three years, Fair value | 1,678.8 | |
| Due after three years through five years, Fair value | 517.6 | |
| Due after five years, Fair value | 1,515.4 | |
| AFS securities, Fair value | $ 4,480.8 | $ 3,755.5 |
| X | ||||||||||
- Definition Amount after adjustments of available-for-sale debt securities at cost, maturing after the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. No definition available.
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| X | ||||||||||
- Definition Fair value of available-for-sale debt securities maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. No definition available.
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| X | ||||||||||
- Definition Amount after adjustments of available-for-sale debt securities at cost, maturing after the first fiscal year through the third fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. No definition available.
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| X | ||||||||||
- Definition Fair value of available-for-sale debt securities maturing after the first fiscal year through the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. No definition available.
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| X | ||||||||||
- Definition Amount after adjustments of available-for-sale debt securities at cost, maturing after the third fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. No definition available.
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| X | ||||||||||
- Definition Fair value of available-for-sale debt securities maturing after the third fiscal year through the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. No definition available.
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- Definition Funds held for clients and corporate investments. No definition available.
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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