Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Income tax provision	$ 18,189	$ 13,595	$ 29,046	$ 20,105
Increase in income tax provision	4,600		8,900
Tax benefit associated with the settlement of equity awards			500
Unrecognized tax benefits	10,200		10,200			$ 10,500
Tax benefits that, if recognized, would affect the effective tax rate	$ 1,900		$ 1,900			$ 2,200
Scenario, Forecast [Member]
Income Taxes [Line Items]
Effective tax rate estimate					37.00%