Organization and Basis of Presentation - Cash, Cash Equivalents and Restricted Cash And Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents-unrestricted	$ 121,954	$ 44,620	$ 84,344	$ 64,921
Cash and cash equivalents-restricted	17,124	16,506	15,908	105,381
Total unrestricted and restricted cash and cash equivalents shown in the condensed consolidated statement of cash flows	$ 139,078	$ 61,126	$ 100,252	$ 170,302