Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Taxes
Provisional income tax expense	$ 20,531	$ 8,866	$ 65,600	$ 44,689
Effective tax rate (as a percent)			16.90%	17.00%