Income Taxes - Deferred tax (liabilities) assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Temporary differences [Abstract]
Property and equipment	$ (35,904)	$ (36,926)
Goodwill and other intangible assets	(96,773)	(82,607)
Investments, primarily gains and losses not yet recognized for tax purposes	5,218	5,997
Accrued expenses not deductible until paid	8,883	11,329
Deferred compensation and retiree benefits not deductible until paid	97,470	96,463
Other temporary differences, net	3,799	3,410
Total temporary differences	(17,307)	(2,334)
Federal and state net operating loss carryforwards	9,597	17,005
Valuation allowance for state deferred tax assets	(955)	(1,031)
Net deferred tax liability	(8,665)
Deferred Tax Assets, Net	$ 9,000	$ 13,640