Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member] Class A [Member]	Additional Paid-in Capital [Member]	Treasury Stock, at Cost [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Total	Cumulative Effect Adjustment [Member] Common Stock [Member] Class A [Member]	Cumulative Effect Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect Adjustment [Member] Treasury Stock, at Cost [Member]	Cumulative Effect Adjustment [Member] Accumulated Other Comprehensive Loss [Member]	Cumulative Effect Adjustment [Member] Retained Earnings [Member]	Cumulative Effect Adjustment [Member]
Balance at beginning of period at Dec. 31, 2018	$ 91	$ 552,564	$ (1,326,605)	$ (79,934)	$ 1,635,751	$ 781,867
Balance at beginning of period (ASC 842 [Member]) at Dec. 31, 2018							$ 0	$ 0	$ 0	$ 0	$ 657	$ 657
Stockholders' Equity [Roll Forward]
Net income	0	0	0	0	173,553	173,553
Other comprehensive (loss) income, net of tax	0	0	0	(5,358)	0	(5,358)
Repurchase of Class A common stock (Note 8)	0	0	(825)	0	0	(825)
Exercise of employee stock options/vesting of stock awards	0	(4,929)	2,604	0	0	(2,325)
Stock-based compensation	0	9,909	0	0	0	9,909
Cash dividends	0	0	0	0	(82,189)	(82,189)
Balance at end of period at Dec. 31, 2019	91	557,544	(1,324,826)	(85,292)	1,727,772	875,289
Stockholders' Equity [Roll Forward]
Net income	0	0	0	0	191,355	191,355
Other comprehensive (loss) income, net of tax	0	0	0	20,524	0	20,524
Repurchase of Class A common stock (Note 8)	0	0	(144,334)	0	0	(144,334)
Exercise of employee stock options/vesting of stock awards	0	(1,803)	7,567	0	0	5,764
Stock-based compensation	0	24,060	0	0	0	24,060
Cash dividends	0	0	0	0	(78,387)	(78,387)
Balance at end of period at Dec. 31, 2020	91	579,801	(1,461,593)	(64,768)	1,840,740	894,271
Stockholders' Equity [Roll Forward]
Net income	0	0	0	0	147,266	147,266
Other comprehensive (loss) income, net of tax	0	0	0	(9,128)	0	(9,128)
Repurchase of Class A common stock (Note 8)	0	0	(80,420)	0	0	(80,420)
Exercise of employee stock options/vesting of stock awards	0	(1,292)	15,153	0	0	13,861
Stock-based compensation	0	23,194	0	0	0	23,194
Cash dividends	0	0	0	0	(76,272)	(76,272)
Balance at end of period at Dec. 31, 2021	$ 91	$ 601,703	$ (1,526,860)	$ (73,896)	$ 1,911,734	$ 912,772