Income Taxes - Summary of Provision for Income Taxes and U.S. Federal Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount [Abstract]
Computed tax expense at the U.S. federal tax rate	$ 114,626	$ 59,571
Foreign income tax differential	(9,247)	(4,265)
Excess tax benefits related to stock-based compensation	(4,360)	(8,247)
State taxes net of federal benefits	5,926	1,678
Foreign-sourced nontaxable income	1,558	(6,691)
Valuation allowance on investment loss	16,718	960
Other	(542)	(2,420)
Provision for income taxes	$ 124,679	$ 40,586	$ 227,756	$ 132,503
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Computed tax expense at the U.S. federal tax rate	35.00%	35.00%
Foreign income tax differential	(2.80%)	(2.50%)
Excess tax benefits related to stock-based compensation	(1.30%)	(4.90%)
State taxes net of federal benefits	1.80%	1.00%
Foreign-sourced nontaxable income	0.50%	(3.90%)
Valuation allowance on investment loss	5.10%	0.60%
Other	(0.20%)	(1.40%)
Provision for income taxes	38.10%	23.90%