Notes Payable - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Interest Expense
Interest expense on debt and finance lease obligations	$ 11,484	$ 11,479	$ 22,993	$ 22,745
Noncash interest on derivatives and finance lease obligations, net	3,634	(1,040)	5,753	(4,177)
Amortization of deferred financing costs	698	745	1,396	1,492
Total interest expense	$ 15,816	$ 11,184	$ 30,142	$ 20,060