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]
Income before provision for income taxes	$ 50,373	$ 46,340	$ 43,366	$ 82,096
Income tax expense using estimated annual effective income tax rate	19,152	18,793	16,457	33,317
Changes in effective tax rates	(56)	210	0	0
Impact of discrete items, net	(269)	0	(412)	49
Income tax expense	$ 18,827	$ 19,003	$ 16,045	$ 33,366