Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Interest	$ 40,048	$ 30,262
Employee related costs	84,200	117,850
Income taxes payable	13,799	19,558
Other accrued expenses	102,845	95,406
Total accrued liabilities	$ 240,892	$ 263,076