Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of income before income taxes:
Increase (Decrease) in income tax expense	$ (3,700)		$ 2,000
Income Tax Expense (Benefit)	$ 18,207	$ 21,941	$ 40,692	$ 38,710
Effective Income Tax Rate Reconciliation, Percent	34.90%	44.40%	35.60%	42.40%