Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Current tax expense (benefit):
Income tax provision	$ 15,420	$ 12,993
Current income tax expense (benefit)	$ 1,800
Effective tax rate	28.20%	23.40%
Deferred tax expense (benefit):
Deferred income taxes	$ 4,574	$ 192
Deferred Income Tax Expense (Benefit), Excluding Discontinued Operations	$ 65,200
Effective tax rate	28.20%	23.40%