Debt - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Components of interest expense
Contractual coupon interest	$ 29,176	$ 7,716
Non-cash interest expense (including amortization of discounts and deferred financing costs)	9,151	1,128
Total interest expense	$ 38,327	$ 8,844