Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Debt Disclosure [Abstract]
Interest expense	$ 24,878	$ 25,257	$ 53,443	$ 50,394
Non-cash interest expense:
Amortization of deferred financing costs	971	852	3,038	1,727
Amortization of debt discount	1,726	1,634	3,429	3,634
Total interest expense	$ 27,575	$ 27,743	$ 59,910	$ 55,755