Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Provision for Income Taxes	$ 22,459	$ 30,676	$ 40,751	$ 40,410
Effective Income Tax Rate Reconciliation, Percent	46.00%	48.00%	25.00%	49.00%
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount			$ (23,172)
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Percent			14.00%
Increase (Decrease) in Deferred Tax Assets, Changes in Unrealized Gain (Loss) on Marketable Securities			$ (205)	$ 290
Increase (Decrease) in Deferred Tax Assets, Changes in Foreign Currency Translation Adjustments			$ (629)	$ 4,549