Basis of Condensed Consolidated Financial Statements (Cash, Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 85,031	$ 118,804	$ 89,422
Restricted cash included in other assets	9,756		17,435
Restricted cash included in prepaid expenses and other current assets	1,070		0
Total cash, cash equivalents and restricted cash	$ 95,857	$ 132,154	$ 106,857	$ 89,974