Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accrued Liabilities, Current [Abstract]
Interest	$ 29,936	$ 30,018
Employee related costs	71,839	100,729
Income taxes payable	9,992	1,527
Other accrued expenses	120,092	132,644
Total accrued liabilities	$ 231,859	$ 264,918