Stockholders' Equity - Capital Stock (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Nov. 18, 2020	Sep. 30, 2020
Common Class B
Capital Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares issued	19,720,381	19,720,381
Common stock, shares outstanding	19,720,381
Common Class A
Capital Stock
Common stock, par value	$ 0.0001	$ 0.0001		$ 0.0001
Common stock, shares issued excluding treasury shares	20,550,862
Common stock, shares issued	25,992,774	25,457,709
Number of shares repurchased	129,735
Aggregate purchase price	$ 1.3
Share repurchased	200,000
Total aggregate purchase price	$ 1.7
Remaining authorization for future repurchases	$ 18.3
Common Class A | Maximum
Capital Stock
Authorized repurchase amount			$ 20.0