Valuation and Qualifying Accounts (Details) - Tax valuation allowance - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Balance at beginning of fiscal period	$ 117,725	$ 115,313
Charges to costs and expenses	0
Charges to other accounts	0	0
Deductions	(3,318)	0
Balance at end of fiscal period	$ 114,407	$ 117,725