Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued capital expenditures	$ 96,439	$ 71,769
Accounts payable and accrued expenses	27,655	32,509
Interest rate swap agreements liability	0	436
Accrued interest payable	5,161	5,687
Due to affiliated companies	689	448
Total accounts payable and accrued expenses	$ 129,944	$ 110,849