Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member] Class A [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Total
Balance at beginning 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 (loss)	0	0	0	0	156,497	156,497
Other comprehensive income (loss), net of tax	0	0	0	(10,890)	0	(10,890)
Repurchase of Class A common stock (Note 6)	0	0	(70,415)	0	0	(70,415)
Exercise of employee stock options/vesting of stock awards	0	(5,599)	13,473	0	0	7,874
Stock-based compensation	0	16,476	0	0	0	16,476
Cash dividends	0	0	0	0	(57,336)	(57,336)
Balance at end of period at Sep. 30, 2021	91	590,678	(1,518,535)	(75,658)	1,939,901	936,477
Balance at beginning of period at Jun. 30, 2021	91	586,976	(1,509,867)	(68,553)	1,909,179	917,826
Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	0	0	49,729	49,729
Other comprehensive income (loss), net of tax	0	0	0	(7,105)	0	(7,105)
Repurchase of Class A common stock (Note 6)	0	0	(10,005)	0	0	(10,005)
Exercise of employee stock options/vesting of stock awards	0	609	1,337	0	0	1,946
Stock-based compensation	0	3,093	0	0	0	3,093
Cash dividends	0	0	0	0	(19,007)	(19,007)
Balance at end of period at Sep. 30, 2021	91	590,678	(1,518,535)	(75,658)	1,939,901	936,477
Balance at beginning of period at Dec. 31, 2021	91	601,703	(1,526,860)	(73,896)	1,911,734	912,772
Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	0	0	47,563	47,563
Other comprehensive income (loss), net of tax	0	0	0	(35,489)	0	(35,489)
Repurchase of Class A common stock (Note 6)	0	0	(60,038)	0	0	(60,038)
Exercise of employee stock options/vesting of stock awards	0	(1,137)	26,931	0	0	25,794
Stock-based compensation	0	9,320	0	0	0	9,320
Cash dividends	0	0	0	0	(57,988)	(57,988)
Balance at end of period at Sep. 30, 2022	91	609,886	(1,559,967)	(109,385)	1,901,309	841,934
Balance at beginning of period at Jun. 30, 2022	91	606,349	(1,520,769)	(90,638)	1,946,002	941,035
Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	0	0	(25,390)	(25,390)
Other comprehensive income (loss), net of tax	0	0	0	(18,747)	0	(18,747)
Repurchase of Class A common stock (Note 6)	0	0	(40,028)	0	0	(40,028)
Exercise of employee stock options/vesting of stock awards	0	366	830	0	0	1,196
Stock-based compensation	0	3,171	0	0	0	3,171
Cash dividends	0	0	0	0	(19,303)	(19,303)
Balance at end of period at Sep. 30, 2022	$ 91	$ 609,886	$ (1,559,967)	$ (109,385)	$ 1,901,309	$ 841,934