Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Taxes.
Unrecognized tax benefits that would affect the effective tax rate	$ 1,094,000		$ 1,145,000
Deferred tax assets valuation allowance	$ 143,000		$ 135,000
Effective tax rate (as a percent)	16.40%	17.50%
Decrease in effective income tax rate from prior reporting period to current reporting period (as a percent)	(1.10%)