Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income taxes currently payable	$ 12,757	$ 15,652	$ 23,074	$ 25,697
Deferred income taxes	2,859	(1,869)	4,940	2,052
Provision for income taxes	$ 15,616	$ 13,783	$ 28,014	$ 27,749

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration