Income Taxes - Net Deferred Income Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Net deferred income tax liabilities
Deferred income tax assets	$ 71,343	$ 51,533
Deferred income tax liabilities	(48,411)	(28,837)
Valuation allowance	(19,916)	(19,814)
Net deferred income tax assets	$ 3,016	$ 2,882