Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Contingency [Line Items]
Provision (benefit) for income taxes	$ 28,802	$ (50,470)	$ 5,518	$ (38,406)
(Loss) income before income taxes	$ 75,072	$ (142,751)	$ 32,201	$ (94,254)
Effective income tax rate	38.40%	35.40%	17.10%	40.70%
Tax Cuts and Jobs Act of 2017, incomplete accounting, provisional income tax benefit					$ 123,200
Tax Cuts and Jobs Act of 2017, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense					63,600
Unrecognized tax benefits	$ 60,300		$ 60,300		$ 60,300
Decrease in unrecognized tax benefits is reasonably possible	5,200		$ 5,200
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Tax Cuts and Jobs Act of 2017, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense	$ 700