Income Taxes - Net Deferred Income Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Net deferred income tax liabilities
Deferred income tax assets	$ 59,895	$ 71,343
Deferred income tax liabilities	(33,099)	(48,411)
Valuation allowance	(21,700)	(19,916)
Net deferred income tax assets	$ 5,096	$ 3,016