CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 197,200,000	$ 159,600,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	578,600,000	604,700,000
Deferred income taxes	(48,100,000)	(110,900,000)
Share-based compensation expense related to equity incentive plans	92,100,000	86,000,000.0
Loss on settlement of debt	71,900,000	2,000,000.0
Amortization of debt discount	43,100,000	60,200,000
Amortization of debt issuance costs	9,000,000.0	8,500,000
Gains on sale of assets	(900,000)	0
Impairment of intangible assets	0	500,000
Gains on available-for-sale investments and marketable equity securities, net	(200,000)	(1,000,000.0)
Other non-cash adjustment	900,000	0
Changes in operating assets and liabilities, excluding impact of acquisitions:
Decrease in accounts receivable	30,300,000	32,100,000
Decrease (increase) in inventories	21,400,000	(20,200,000)
Decrease in accounts payable and accrued liabilities	(34,600,000)	(8,400,000)
Change in other assets and liabilities	18,600,000	(900,000)
Change in income tax payable	(21,700,000)	(35,600,000)
Net cash provided by operating activities	957,600,000	776,600,000
Cash flows from investing activities:
Investments in other assets	(43,000,000.0)	(13,600,000)
Proceeds from sale of assets	200,000	500,000
Capital expenditures	(15,800,000)	(41,600,000)
Net cash used in investing activities	(58,600,000)	(54,700,000)
Cash flows from financing activities:
Payments on settlement of convertible debt	(1,823,300,000)	0
Proceeds from issuance of senior notes	2,182,000,000.0	0
Repayment of bridge loan facility	(615,000,000.0)	0
Deferred financing costs	(6,800,000)	(1,800,000)
Payment of cash dividends	(185,700,000)	(174,400,000)
Proceeds from sale of common stock	29,600,000	27,500,000
Tax payments related to shares withheld for vested restricted stock units	(25,400,000)	(26,600,000)
Capital lease payments	(400,000)	(400,000)
Net cash used in financing activities	(931,700,000)	(748,700,000)
Net decrease in cash and cash equivalents	(32,700,000)	(26,800,000)
Cash and cash equivalents, and restricted cash at beginning of period	401,000,000.0	428,600,000
Cash and cash equivalents, and restricted cash at end of period	368,300,000	401,800,000
Supplemental disclosure of cash flow information
Restricted Cash	0	37,300,000
Term Loan Facility
Cash flows from financing activities:
Repayments of loan facility	(17,800,000)	(188,000,000.0)
Revolving Credit Facility
Cash flows from financing activities:
Repayments of loan facility	(2,672,900,000)	(812,000,000.0)
Proceeds from borrowings on revolving loan under credit facility	$ 2,204,000,000.0	$ 427,000,000.0