Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	600	$ 1,200	$ (900)
Deferred Tax Assets, Gross, Noncurrent	(24,633)	(12,187)
Deferred tax assets:
Deferred compensation	22,325	38,602
Deferred income	2,015	9,830
Accrued expenses	11,652	24,663
Deferred Tax Assets, Operating Loss Carryforwards	222,065	14,140
Other	2,203	46,745
Gross deferred tax assets	260,260	133,980
Valuation allowance	(206,586)	(4,200)
Total deferred tax assets	53,674	129,780
Deferred tax liabilities:
Property and equipment	65,366	86,237
Unremitted foreign earnings	0	257,414
Basis difference in equity investments	5,715	10,055
Deferred Tax Liabilities, Gross	71,081	353,706
Deferred Tax Assets (Liabilities), Net [Abstract]
Deferred tax liabilities	42,040	236,113
Deferred Tax Assets, Gross, Noncurrent	(24,633)	(12,187)
Total deferred tax liabilities	$ 17,407	$ 223,926