Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income	$ 231.4	$ 238.2
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	107.4	104.9
Depreciation, amortization, and accretion	98.6	89.0
Restructuring and non-cash acquisition charges (benefits)	5.2	(0.5)
Deferred income taxes	42.7	23.9
Loss (gain) on investments, net	1.8	(0.8)
Excess tax benefits from share-based compensation	(5.6)	(4.3)
Loss on disposal of fixed assets	0.0	(0.4)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	39.5	29.0
Prepaid expenses and other assets	(58.0)	(41.7)
Accounts payable	62.9	(13.8)
Accrued compensation	(67.2)	3.6
Income taxes payable	(23.6)	56.7
Other accrued liabilities	(24.7)	(30.7)
Deferred revenue	116.4	28.6
Net cash provided by operating activities	526.8	482.5
Cash flows from investing activities:
Purchases of property and equipment	(116.9)	(83.8)
Purchases of available-for-sale investments	(794.9)	(841.3)
Proceeds from sales of available-for-sale investments	665.8	450.9
Proceeds from maturities of available-for-sale investments	152.8	115.9
Purchases of trading investments	(3.2)	(2.5)
Proceeds from sales of privately-held investments	2.8	0.0
Purchases of privately-held investments	(10.5)	(3.2)
Payments for business acquisitions, net of cash and cash equivalents acquired	22.8	0.0
Changes in restricted cash	(0.5)	0.0
Net cash used in investing activities	(126.4)	(364.0)
Cash flows from financing activities:
Proceeds from issuance of common stock	32.2	63.0
Purchases and retirement of common stock	(210.1)	(1,004.7)
Issuance of long-term debt, net	494.0	594.6
Payment of long-term debt	(300.0)	0.0
Payment under lease obligations	(0.9)	0.4
Payment of assumed debt	(15.5)	0.0
Excess tax benefits from share-based compensation	5.6	4.3
Payment of cash dividends	(76.4)	(79.5)
Net cash used in financing activities	(71.1)	(421.9)
Effect of foreign currency exchange rates on cash and cash equivalents	6.7	(5.9)
Net increase (decrease) in cash and cash equivalents	336.0	(309.3)
Cash and cash equivalents at beginning of period	1,420.9	1,639.6
Cash and cash equivalents at end of period	$ 1,756.9	$ 1,330.3