Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 81.6	$ 77.3
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	86.0	89.6
Depreciation, amortization, and accretion	106.0	101.7
Operating lease assets expense	21.0	21.3
Other	3.8	0.4
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	124.7	102.3
Prepaid expenses and other assets	(38.7)	(55.2)
Accounts payable	20.6	(28.1)
Accrued compensation	(11.7)	(15.8)
Income taxes payable	0.9	(3.8)
Other accrued liabilities	(14.2)	(20.1)
Deferred revenue	(10.2)	(21.4)
Net cash provided by operating activities	369.8	248.2
Cash flows from investing activities:
Purchases of property and equipment	(43.8)	(55.2)
Purchases of available-for-sale debt securities	(546.2)	(1,760.0)
Proceeds from sales of available-for-sale debt securities	156.9	628.5
Proceeds from maturities and redemptions of available-for-sale debt securities	622.7	906.0
Purchases of equity securities	(3.6)	(9.4)
Proceeds from sales of equity securities	3.7	4.1
Payments for business acquisitions, net of cash and cash equivalents acquired	0.0	(270.9)
Subsequent payments related to acquisitions in prior years	(0.2)	0.0
Net cash provided by (used in) investing activities	189.5	(556.9)
Cash flows from financing activities:
Repurchase and retirement of common stock	(205.3)	(303.8)
Proceeds from issuance of common stock	27.6	29.7
Payment of dividends	(131.8)	(131.7)
Payment of debt	0.0	(350.0)
Customer financing arrangement	4.8	0.0
Net cash used in financing activities	(304.7)	(755.8)
Effect of foreign currency exchange rates on cash, cash equivalents, and restricted cash	(9.9)	2.1
Net increase (decrease) in cash, cash equivalents, and restricted cash	244.7	(1,062.4)
Cash, cash equivalents, and restricted cash at beginning of period	1,276.5	2,505.8
Cash, cash equivalents, and restricted cash at end of period	$ 1,521.2	$ 1,443.4