Interest and Debt Expense - Details of Interest and Debt Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest And Debt Expense [Abstract]
Interest expense	$ 33,321	$ 34,288
Amortization of deferred financing costs	2,761	2,730
Total interest and debt expense	$ 36,082	$ 37,018