Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets:
Insurance liabilities	$ 44,192	$ 42,425
Pension liability	3,204	6,900
Deferred compensation	29,300	27,742
Other (including liabilities and reserves)	27,400	28,534
Total deferred income tax assets	104,096	105,601
Valuation allowance for deferred tax assets	(3,855)	(3,825)
Net deferred income tax assets	100,241	101,776
Deferred income tax liabilities:
Goodwill and identifiable intangible assets	(152,761)	(150,900)
Depreciation of property, plant and equipment	(14,904)	(11,781)
Other	(3,424)	(3,792)
Total deferred income tax liabilities	(171,089)	(166,473)
Net deferred income tax liabilities	$ (70,848)	$ (64,697)