Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 20.4	$ 31.1
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	42.0	33.9
Depreciation, amortization, and accretion	54.0	48.7
Operating lease assets expense	10.5	9.6
Other	10.3	(2.2)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	202.6	108.6
Prepaid expenses and other assets	(37.1)	(9.1)
Accounts payable	18.4	10.1
Accrued compensation	(59.8)	(54.9)
Income taxes payable	5.1	(5.7)
Other accrued liabilities	(27.0)	(27.9)
Deferred revenue	32.8	17.2
Net cash provided by operating activities	272.2	159.4
Cash flows from investing activities:
Purchases of property and equipment	(21.8)	(27.9)
Purchases of available-for-sale debt securities	(257.1)	(884.4)
Proceeds from sales of available-for-sale debt securities	94.0	232.8
Proceeds from maturities and redemptions of available-for-sale debt securities	354.0	578.3
Purchases of equity securities	(3.1)	(5.1)
Proceeds from sales of equity securities	3.1	2.2
Subsequent payments related to acquisitions in prior years	(0.2)	0.0
Net cash provided by (used in) investing activities	168.9	(104.1)
Cash flows from financing activities:
Repurchase and retirement of common stock	(203.2)	(2.9)
Proceeds from issuance of common stock	27.1	29.5
Payment of dividends	(65.5)	(66.2)
Payment of debt	0.0	(350.0)
Net cash used in financing activities	(241.6)	(389.6)
Effect of foreign currency exchange rates on cash, cash equivalents, and restricted cash	(16.2)	1.6
Net increase (decrease) in cash, cash equivalents, and restricted cash	183.3	(332.7)
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	$ 1,459.8	$ 2,173.1