Income Taxes - Reconciliations of the Reported Income Tax Expense by Applying United States federal Statutory Rate (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax (expense) benefit at the United States statutory rate		$ (9,380)	$ (150,885)	$ 70,213
Permanent differences		(14,927)	(29,345)	(23,483)
State income tax benefit, net of federal tax effect		(702)	654	312
Tax effect of foreign income taxed at lower rate		46,956	87,161	29,267
Change in valuation allowance		(114,119)	(52,758)	(148,912)
Effect of tax contingencies		9,066	28,536	(34,572)
Tax credits		19,833	19,414	25,557
Withholding taxes		(6,355)	(33,791)	(35,332)
U.S. tax on repatriated earnings		(875)	(64,316)	(1,451)
Impairments		0	(8,230)	(36)
Sale of subsidiaries		0	139,335	0
Transition tax on unremitted earnings		(149,800)	0	0
Tax effect of rate changes	$ 66,900	66,943	0	0
Change in valuation allowance		213,609	0	0
State income tax benefit, net of federal tax effect		6,848	0	0
Other		(284)	(776)	707
Total income tax benefit (expense)		$ 66,813	$ (65,001)	$ (117,730)