Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Stockholders Equity [Abstract]
Class A common stock dividends	$ 0.47	$ 0.47	$ 1.41	$ 1.88
Tax expense (benefit) related to delivery of Class A Common Stock in connection with share-based incentive compensation	$ 5	$ (61)	$ (978)	$ (4,419)