Corporate Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of unrecognized tax benefits excluding amounts pertaining to examined tax returns RollForward
Beginning balance	$ 1,187	$ 1,187	$ 13,830
Gross decreases for tax positions taken in prior years	0	0	(12,675)
Gross increases for tax positions taken in prior years	0	0	32
Ending balance	$ 1,187	$ 1,187	$ 1,187