Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets:
Insurance liabilities	$ 42,425	$ 62,473
Pension liability	6,900	8,950
Deferred compensation	27,742	35,649
Other (including liabilities and reserves)	28,534	32,350
Total deferred income tax assets	105,601	139,422
Valuation allowance for deferred tax assets	(3,825)	(3,531)
Net deferred income tax assets	101,776	135,891
Deferred income tax liabilities:
Goodwill and identifiable intangible assets	(150,900)	(229,347)
Depreciation of property, plant and equipment	(11,781)	(18,145)
Other	(3,792)	(5,761)
Total deferred income tax liabilities	(166,473)	(253,253)
Net deferred income tax liabilities	$ (64,697)	$ (117,362)