Business Combinations (eRx Network Holdings, Inc. - Summary of Information Related to Acquisition) (Details) - USD ($) $ in Thousands	May 01, 2020	Sep. 30, 2021	Mar. 31, 2021
Business Acquisition [Line Items]
Goodwill		$ 4,110,823	$ 4,108,792
eRx Network Holdings, Inc. [Member]
Business Acquisition [Line Items]
Cash paid at closing	$ 249,359
Fair value of eRx purchase option	140,500
Fair value of vested stock appreciation rights	5,097
Cash paid for canceled eRx equity awards	5,891
Total Consideration Fair Value at Acquisition Date	400,847
Cash	54,108
Accounts receivable	12,747
Prepaid expenses and other current assets	609
Goodwill	225,156
Other noncurrent assets	20
Accounts payable	(2,543)
Accrued expenses and other current liabilities	(10,933)
Deferred income tax liabilities	(39,217)
Total consideration transferred	400,847
Customer Relationships [Member] | eRx Network Holdings, Inc. [Member]
Business Acquisition [Line Items]
Identified intangible assets	$ 131,200
Useful life	17 years
Technology-Based Intangible Assets [Member] | eRx Network Holdings, Inc. [Member]
Business Acquisition [Line Items]
Identified intangible assets	$ 29,700
Technology-Based Intangible Assets [Member] | eRx Network Holdings, Inc. [Member] | Minimum [Member]
Business Acquisition [Line Items]
Useful life	9 years
Technology-Based Intangible Assets [Member] | eRx Network Holdings, Inc. [Member] | Maximum [Member]
Business Acquisition [Line Items]
Useful life	12 years