Restricted Cash - Reconciliation of Cash and Cash Equivalents, and Restricted Cash to the Total Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 6,485	$ 6,042	$ 9,647	$ 7,747
Restricted cash	1,251	1,843	1,327	1,362
Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows	$ 7,736	$ 7,885	$ 10,974	$ 9,109