Summary of Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Costs relating to construction included in accounts payable and accrued expenses	$ 22,908	$ 28,665	$ 23,033
Interest paid, net of interest capitalized	$ 50,270	49,542	$ 55,379
Dividend Declared [Member]
Special Dividend		$ 21,200