CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 583.6	$ 569.5	$ 494.9
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	81.9	71.2	65.8
Stock-based compensation (Notes 2 and 13)	61.6	56.9	49.9
Excess tax benefit from stock plans (Notes 2 and 13)	0.0	(64.3)	(41.3)
Impairment charges (Note 4)	31.0	0.0	0.0
Change in fair value of contingent consideration liabilities	(9.9)	1.1	0.2
Deferred income taxes	17.8	(37.4)	(95.0)
Purchased in-process research and development	6.7	34.5	0.0
Other	(6.2)	7.9	11.0
Changes in operating assets and liabilities:
Accounts and other receivables, net	(3.9)	(56.7)	(38.3)
Inventories	(124.0)	(65.6)	(67.7)
Accounts payable and accrued liabilities	85.2	74.0	29.4
Income taxes	278.4	105.1	134.5
Prepaid expenses and other current assets	(9.9)	(12.6)	(0.2)
Other	8.4	20.8	6.5
Net cash provided by operating activities	1,000.7	704.4	549.7
Cash flows from investing activities
Capital expenditures	(168.1)	(176.1)	(102.7)
Deposit of cash in escrow	(25.0)	0.0	0.0
Purchases of held-to-maturity investments (Note 6)	(804.9)	(594.7)	(928.5)
Proceeds from held-to-maturity investments (Note 6)	654.7	852.5	1,260.1
Purchases of available-for-sale investments (Note 6)	(529.8)	(470.4)	(380.3)
Proceeds from available-for-sale investments (Note 6)	448.7	232.6	179.6
Investments in unconsolidated affiliates (Note 6)	0.0	(7.6)	(5.1)
Proceeds from unconsolidated affiliates (Note 6)	8.3	1.9	3.0
Investments in trading securities, net	(12.7)	(9.8)	(9.2)
Acquisitions (Notes 7 and 8)	(192.9)	0.0	(331.6)
Issuances of notes receivable	(18.9)	0.0	0.0
Investments in intangible assets and in-process research and development	(7.4)	(41.3)	(3.8)
Other	0.8	1.2	2.4
Net cash used in investing activities	(647.2)	(211.7)	(316.1)
Cash flows from financing activities
Proceeds from issuance of debt	994.7	253.5	31.4
Payments on debt and capital lease obligations	(818.4)	(31.4)	(29.5)
Purchases of treasury stock	(763.3)	(662.3)	(280.1)
Proceeds from stock plans	113.8	103.3	87.2
Excess tax benefit from stock plans (Notes 2 and 13)	0.0	64.3	41.3
Other	0.0	4.1	(8.9)
Net cash used in financing activities	(473.2)	(268.5)	(158.6)
Effect of currency exchange rate changes on cash and cash equivalents	7.9	(12.5)	(10.4)
Net (decrease) increase in cash and cash equivalents	(111.8)	211.7	64.6
Cash and cash equivalents at beginning of year	930.1	718.4	653.8
Cash and cash equivalents at end of year	818.3	930.1	718.4
Cash paid during the year for:
Interest	19.9	16.1	14.1
Income taxes	143.7	99.9	86.9
Non-cash investing and financing transactions:
Fair value of shares issued in connection with business combinations (Note 7)	266.5	0.0	0.0
Capital expenditures accruals	21.6	22.7	15.1
Retirement of treasury stock	0.0
Treasury Stock
Non-cash investing and financing transactions:
Fair value of shares issued in connection with business combinations (Note 7)	264.3
Retirement of treasury stock	$ 2,746.2	$ 0.0	$ 0.0