Interest and Debt Expense - Details of Interest and Debt Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest And Debt Expense [Abstract]
Interest and debt expense	$ 132,574	$ 146,334	$ 165,801
Amortization of deferred financing costs	11,188	6,804	2,565
Total interest and debt expense	$ 143,762	$ 153,138	$ 168,366