Goodwill and changes in goodwill as of and for the years ended May 31, 2020 and May 31, 2019 were as follows:

Goodwill acquired in fiscal 2019 related to the December 2018 acquisition of Oasis. Refer to Note D of this Item 8 for further details.

The Company had certain intangible assets on its Consolidated Balance Sheets. The components of intangible assets, at cost, consisted of the following:

During fiscal 2020, the Company acquired customer lists with a weighted-average amortization of 7.7 years. Amortization expense relating to intangible assets was $81.9 million, $55.8 million, and $21.1 million for fiscal years 2020, 2019, and 2018, respectively.

The Company did not recognize an impairment loss as it relates to its goodwill or intangible assets during the fiscal years 2020, 2019, or 2018.

The estimated amortization expense for the next five fiscal years relating to intangible asset balances is as follows: