Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Current tax expense (benefit):
Income tax provision	$ 12,127	$ 14,485	$ 25,120	$ 68,980
Current income tax expense (benefit)			$ 43,400
Effective tax rate	19.10%	24.20%	21.10%	59.70%
Deferred tax expense (benefit):
Deferred income taxes			$ (150)	$ (372)
Deferred Income Tax Expense (Benefit), Excluding Discontinued Operations			$ 58,500
Effective tax rate	19.10%	24.20%	21.10%	59.70%