Employee Stock Plans (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	[1]	4 years 9 months 18 days	5 years 3 months 18 days	5 years 4 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		21,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Additional Registered Shares		5,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		7,553,173	3,228,748
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value		$ 10,400	$ 15,360	$ 16,345
Proceeds from exercise of stock options		14,900	21,788	36,014
Tax benefits related to stock-based compensation awards		$ 16,593	$ 18,718	$ 21,882
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 19.10	$ 20.32	$ 15.83
Non-employee director award		$ 130

[1] The expected term represents the weighted-average period the option is expected to be outstanding and is based primarily on the historical exercise behavior of employees.