Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 345.0	$ 566.9	$ 306.2
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	202.2	217.1	187.5
Depreciation, amortization, and accretion	210.3	210.5	225.6
Operating lease assets expense	42.0	0.0	0.0
Loss on extinguishment of debt	15.3	0.0	0.0
Deferred income taxes	2.9	42.6	(139.6)
Other	3.5	9.6	(14.5)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	(118.1)	96.3	203.8
Prepaid expenses and other assets	(100.7)	(70.9)	43.0
Accounts payable	6.4	3.5	(10.1)
Accrued compensation	6.5	41.4	(42.8)
Income taxes payable	(40.5)	(269.2)	447.3
Other accrued liabilities	(46.8)	(11.4)	(2.1)
Deferred revenue	0.9	24.7	55.0
Net cash provided by operating activities	528.9	861.1	1,259.3
Cash flows from investing activities:
Purchases of property and equipment	(109.6)	(147.4)	(151.2)
Purchases of available-for-sale debt securities	(3,209.8)	(1,228.5)	(1,882.9)
Proceeds from sales of available-for-sale debt securities	1,520.0	1,070.2	944.0
Proceeds from maturities and redemptions of available-for-sale debt securities	1,642.3	910.2	741.6
Purchases of equity securities	(107.1)	(17.5)	(14.9)
Proceeds from sales of equity securities	14.2	36.9	12.4
Proceeds from Pulse note receivable	0.0	0.0	75.0
Payments for business acquisitions, net of cash and cash equivalents acquired	(270.9)	(16.4)	(27.0)
Subsequent payments related to acquisitions in prior years	(7.3)	(42.7)	0.0
Net cash (used in) provided by investing activities	(528.2)	564.8	(303.0)
Cash flows from financing activities:
Repurchase and retirement of common stock	(554.9)	(756.6)	(725.8)
Proceeds from issuance of common stock	55.6	56.9	64.5
Payment of dividends	(260.1)	(249.3)	(150.4)
Payment of debt	(950.0)	0.0	0.0
Issuance of debt, net	495.2	0.0	0.0
Payment for debt extinguishment costs	(14.6)	0.0	0.0
Change in customer financing arrangement	0.0	(16.9)	16.9
Other	0.0	(2.7)	0.0
Net cash used in financing activities	(1,228.8)	(968.6)	(794.8)
Effect of foreign currency exchange rates on cash, cash equivalents, and restricted cash	(1.2)	(10.6)	17.0
Net increase in cash, cash equivalents, and restricted cash	(1,229.3)	446.7	178.5
Cash, cash equivalents, and restricted cash at beginning of period	1,276.5	2,505.8	2,059.1
Cash, cash equivalents, and restricted cash at end of period	2,505.8	2,059.1	1,880.6
Supplemental disclosures of cash flow information:
Cash paid for interest, net of amounts capitalized	90.6	94.0	93.9
Cash paid for income taxes, net	$ 98.8	$ 181.0	$ 193.5