Earnings Per Share (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Class A common stock
Income available to stockholders (Basic EPS:)
Allocated net income (numerator) | $	$ 295,421	$ 290,902	$ 314,227
Weighted shares (denominator) (in shares) | shares	46,188,806	46,188,659	46,188,836
Per- share amount (in dollars per share) | $ / shares	$ 6.40	$ 6.30	$ 6.80
Dilutive effect of stock-based awards
Allocated net income (numerator) | $	$ 0	$ 0	$ 0
Weighted shares (denominator) (in shares) | shares	17,696	23,901	30,224
Assumed conversion of Class B shares
Allocated net income (numerator) | $	$ 2,439	$ 2,402	$ 2,594
Weighted shares (denominator) (in shares) | shares	6,100,800	6,100,800	6,100,800
Income available to stockholders on equivalent shares (Diluted EPS:)
Allocated net income (numerator) | $	$ 297,860	$ 293,304	$ 316,821
Weighted shares (denominator) (in shares) | shares	52,307,302	52,313,360	52,319,860
Per- share amount (in dollars per share) | $ / shares	$ 5.69	$ 5.61	$ 6.06
Class B common stock
Reconciliation of the numerators and denominators used in the basic and diluted per-share computations
Ratio for converting shares of Class B common stock into shares of Class A common stock	2,400	2,400
Income available to stockholders (Basic EPS:)
Allocated net income (numerator) | $	$ 2,439	$ 2,402	$ 2,594
Weighted shares (denominator) (in shares) | shares	2,542	2,542	2,542
Per- share amount (in dollars per share) | $ / shares	$ 959	$ 945	$ 1,020
Income available to stockholders on equivalent shares (Diluted EPS:)
Allocated net income (numerator) | $	$ 2,438	$ 2,401	$ 2,593
Weighted shares (denominator) (in shares) | shares	2,542	2,542	2,542
Per- share amount (in dollars per share) | $ / shares	$ 959	$ 945	$ 1,020