Business Combinations (eRx Network Holdings, Inc. - Summary of Information Related to Acquisition) (Details) - USD ($) $ in Thousands	May 01, 2020	Sep. 30, 2020	Mar. 31, 2020
Business Acquisition [Line Items]
Goodwill		$ 4,126,481	$ 3,795,325
eRx Network Holdings, Inc. [Member]
Business Acquisition [Line Items]
Cash paid at closing	$ 249,359
Fair value of eRx purchase option	140,200
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	400,547
Cash	54,108
Accounts receivable, net of allowance for doubtful accounts	12,747
Prepaid expenses and other current assets	609
Goodwill	224,452
Other noncurrent assets	20
Accounts payable	(2,543)
Accrued expenses and other current liabilities	(10,976)
Deferred income tax liabilities	(38,770)
Total consideration transferred	400,547
Accounts receivable, allownace for doubtful accounts	326
Customer Relationships [Member] | eRx Network Holdings, Inc. [Member]
Business Acquisition [Line Items]
Identified intangible assets	$ 131,200
Useful life	17 years
Internally Developed Technology [Member] | eRx Network Holdings, Inc. [Member]
Business Acquisition [Line Items]
Identified intangible assets	$ 29,700
Internally Developed Technology [Member] | eRx Network Holdings, Inc. [Member] | Minimum [Member]
Business Acquisition [Line Items]
Useful life	9 years
Internally Developed Technology [Member] | eRx Network Holdings, Inc. [Member] | Maximum [Member]
Business Acquisition [Line Items]
Useful life	12 years