Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Interest	$ 40,093	$ 30,262
Employee related costs	55,181	117,850
Income taxes payable	35,025	19,558
Other accrued expenses	105,002	95,406
Total accrued liabilities	$ 235,301	$ 263,076