Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Components of Earnings Per Share, Basic and Diluted [Line Items]
Distributed earnings	$ 16,751	$ 15,396
Undistributed earnings	14,590	16,932
Net income	31,341	32,328
Class A common stock
Components of Earnings Per Share, Basic and Diluted [Line Items]
Basic net income available to common stockholders	$ 21,617	$ 21,809
Basic weighted average common shares outstanding	28,150	27,317
Basic earnings per share	$ 0.77	$ 0.80
Diluted net income available to common stockholders	$ 21,682	$ 21,912
Effect of potential exercise of stock options	273	401
Diluted weighted average common shares outstanding	28,423	27,718
Diluted earnings per share	$ 0.76	$ 0.79
Class B common stock
Components of Earnings Per Share, Basic and Diluted [Line Items]
Basic net income available to common stockholders	$ 9,724	$ 10,519
Basic weighted average common shares outstanding	12,662	13,177
Basic earnings per share	$ 0.77	$ 0.80
Diluted net income available to common stockholders	$ 9,659	$ 10,416
Diluted weighted average common shares outstanding	12,662	13,177
Diluted earnings per share	$ 0.76	$ 0.79