Income Taxes - Income Tax Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income tax contingency disclosures
Unrecognized tax benefits: Changes due to lapses of statutes of limitations	$ 1,826	$ 3,177	$ 2,906
Unrecognized tax benefits, could be reversed in following year	1,300
Unrecognized tax benefits, could be reversed in following year, income tax expense, decrease	1,100
Unrecognized tax benefits, could be reversed in following year, deferred tax assets, decrease	200
Accrued interest and penalties related to unrecognized tax benefits	300	300
Interest and penalties recorded	0	100	100
Tax Year 2016
Income tax contingency disclosures
Unrecognized tax benefits: Changes due to lapses of statutes of limitations	1,800
Unrecognized tax benefits: Changes due to lapses of statutes of limitations, income tax expense, decrease	1,400
Unrecognized tax benefits: Changes due to lapses of statutes of limitations, deferred tax assets, decrease	400
Accrued interest reversed	$ 100
Tax Year 2015
Income tax contingency disclosures
Unrecognized tax benefits: Changes due to lapses of statutes of limitations		3,200
Unrecognized tax benefits: Changes due to lapses of statutes of limitations, income tax expense, decrease		2,500
Unrecognized tax benefits: Changes due to lapses of statutes of limitations, deferred tax assets, decrease		700
Accrued interest reversed		$ 300
Tax Year 2014
Income tax contingency disclosures
Unrecognized tax benefits: Changes due to lapses of statutes of limitations			2,900
Unrecognized tax benefits: Changes due to lapses of statutes of limitations, income tax expense, decrease			2,300
Unrecognized tax benefits: Changes due to lapses of statutes of limitations, deferred tax assets, decrease			600
Accrued interest reversed			$ 200