Accounting Policies - VIE Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Current assets	$ 34,047	$ 51,354
Non-current assets	24,447	25,607
Current liabilities	11,191	29,324
Non-current liabilities	$ 23,365	$ 28,849