Income Taxes - Net Deferred Income Tax Liabilities (Details 3) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Net deferred income tax liabilities
Deferred income tax assets	$ 77,270	$ 77,201
Deferred income tax liabilities	(42,576)	(55,045)
Valuation allowance	(17,414)	(20,507)
Net deferred income tax assets	$ 17,280	$ 1,649