Summary of Significant Accounting Policies (Restricted Cash) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Cash and cash equivalents in balance sheet	$ 12,306	$ 12,620	$ 7,138	$ 15,256
Restricted cash, current portion in balance sheet	5,612	59	764	1,092
Restricted cash in other assets in balance sheet	342	342	342	342
Total cash, cash equivalents and restricted cash in statements of cash flows	$ 18,260	$ 13,021	8,244	16,690
Accounting Standards Update 2016-18
Total cash, cash equivalents and restricted cash in statements of cash flows			$ 1,106	$ 1,434