Summary of Significant Accounting Policies (Cash and Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Total cash and cash equivalents	$ 146,103	$ 75,452	$ 135,583	$ 119,923
Restricted cash	50,504	45,853
Company's Share Of Joint Venture [Member]
Total cash and cash equivalents	96,564	57,043
Corporate Cash And Cash Equivalents [Member]
Total cash and cash equivalents	$ 49,539	$ 18,409