Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 8,545,000	$ 11,668,000	$ 13,757,000	$ 39,682,000
Excess tax benefit	23,800,000		71,700,000
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits	$ 34,400,000		34,400,000
Income tax benefit resulting from unrecognized tax benefits recognized in future periods			21,300,000
Minimum
Income Tax Contingency [Line Items]
Reduction in unrecognized tax benefit recorded			0
Maximum
Income Tax Contingency [Line Items]
Reduction in unrecognized tax benefit recorded			$ 2,200,000