Income Taxes - Components of Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Deferred tax assets	$ 326,023	$ 191,349
Less: Valuation allowance	128,159	130,641
Net deferred tax assets	197,864	60,708
Net deferred tax liability	101,831	247,121
Deferred tax assets:
Federal net operating loss carryforwards	115,168	12,615
State net operating loss carryforwards	118,063	107,303
Deferred compensation	9,307	8,240
Foreign tax credits	21,367	20,469
Alternative minimum tax credits		3,296
Accrued insurance, pension liability and other	62,118	39,426
Total deferred tax assets	326,023	191,349
Deferred tax liabilities:
Property and equipment	220,927	226,872
Intangible assets and other	78,768	80,957
Deferred tax liabilities	$ 299,695	$ 307,829