Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Current tax expense (benefit):
Income tax provision	$ 12,267	$ 21,004	$ 39,077	$ 46,124
Current income tax expense (benefit)			$ 46,700
Effective tax rate	14.40%	24.80%	17.50%	22.60%
Deferred tax expense (benefit):
Deferred income taxes			$ 1,919	$ (2,337)
Deferred Income Tax Expense (Benefit), Excluding Discontinued Operations			$ 63,100
Effective tax rate	14.40%	24.80%	17.50%	22.60%