Income Taxes - Schedule of Composition of Net Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets
Net operating losses	$ 22,360	$ 56,769
Alternative minimum tax credits	22,120	114,149
Foreign tax credits	0	3,473
Other business credits	0	3,380
Incentive compensation	17,776	17,378
Deferred compensation	5,463	5,690
Post-retirement benefits	7,847	6,799
Equity method investments	21,454	20,746
Capital loss carryforward	0	8,877
Other	1,336	2,957
Less: valuation allowance	(31,763)	(14,943)
Total	66,593	225,275
Deferred Tax Liabilities
Properties and equipment	768,692	670,704
Derivative instruments	5	13,168
Total	768,697	683,872
Net deferred tax liabilities	$ 702,104	$ 458,597