Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of income before provision for income taxes and noncontrolling interest
Domestic									$ 466.2	$ 456.3	$ (509.7)
Foreign									361.2	395.9	423.4
Income (loss) before income taxes	$ 272.1	$ 236.6	$ 192.2	$ 126.5	$ 260.6	$ 249.6	$ 226.0	$ 116.0	827.4	852.2	(86.3)
Current provision:
Federal									121.4	181.4	180.1
States									10.3	15.9	15.2
Foreign									46.0	43.3	33.7
Total current provision									177.7	240.6	229.0
Deferred provision (benefit):
Federal									57.2	(16.7)	17.3
States									4.3	(0.4)	1.2
Foreign									(4.5)	(5.0)	0.5
Total deferred provision (benefit)									57.0	(22.1)	19.0
Total provision for income taxes									$ 234.7	218.5	248.0
Income tax reconciliation
Federal statutory rate									35.00%
Expected provision at 35% rate									$ 289.6	298.3	(30.2)
State taxes, net of federal benefit									8.9	8.9	9.5
Foreign income at different tax rates									(53.4)	(68.9)	(90.2)
R&D tax credits									(16.8)	(12.7)	(17.1)
Share-based compensation									10.5	13.2	25.3
Non-deductible goodwill impairment									0.0	0.0	297.5
Gain on sale of Junos Pulse									0.0	0.0	75.6
Release of valuation allowance									(0.7)	0.0	(22.8)
Domestic production activities									(9.5)	(15.1)	(6.8)
Non-deductible compensation									2.4	3.7	3.2
Cost sharing adjustment									0.0	(13.2)	0.0
Other									3.7	4.3	4.0
Total provision for income taxes									$ 234.7	218.5	$ 248.0
Tax benefit related to cost sharing agreement										$ 70.3