Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate	27.10%	37.00%	26.10%	34.00%
Provision for income taxes	$ 16,473	$ 16,581	$ 40,202	$ 40,972
Change in enacted tax rate	$ (100)		800
Change in Enacted Tax Rate, Percent	36.00%	28.00%
Net income	$ 44,361	$ 28,197	$ 113,876	$ 79,532	$ 13,085