Condensed Consolidated Statements of Changes in Common Stockholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
As of at Dec. 31, 2019	$ 3,326,796	$ 20,000	$ 381,669	$ 6,534,427	$ 303,295	$ (3,920,152)	$ 7,557
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	(33,891)			(33,891)
Net (income) loss attributable to noncontrolling interest	0			772			(772)
Net income (loss) attributable to redeemable noncontrolling interests	(126)			(126)
Dividends on common stock	(15,289)			(15,289)
Repurchase of Class B Common Stock	(33,610)					(33,610)
Issuance of Class B common stock, net of restricted stock award forfeitures	5,335					5,335
Amortization of unearned stock compensation and stock option expense	1,568		1,568
Other comprehensive income (loss), net of income taxes	(37,943)				(37,943)
As of at Mar. 31, 2020	3,212,840	20,000	383,237	6,485,893	265,352	(3,948,427)	6,785
As of at Dec. 31, 2019	5,655
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interests	126
As of at Mar. 31, 2020	5,781
As of at Dec. 31, 2019	3,326,796	20,000	381,669	6,534,427	303,295	(3,920,152)	7,557
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	63,025
Other comprehensive income (loss), net of income taxes	388
As of at Sep. 30, 2020	3,246,658	20,000	386,506	6,567,676	303,683	(4,038,052)	6,845
As of at Dec. 31, 2019	5,655
As of at Sep. 30, 2020	11,897
As of at Mar. 31, 2020	3,212,840	20,000	383,237	6,485,893	265,352	(3,948,427)	6,785
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	18,862			18,862
Net (income) loss attributable to noncontrolling interest	0			37			(37)
Acquisition of redeemable noncontrolling interest	0
Net income (loss) attributable to redeemable noncontrolling interests	(45)			(45)
Dividends on common stock	(7,581)			(7,581)
Repurchase of Class B Common Stock	(29,295)					(29,295)
Amortization of unearned stock compensation and stock option expense	1,567		1,567
Other comprehensive income (loss), net of income taxes	17,068				17,068
As of at Jun. 30, 2020	3,213,416	20,000	384,804	6,497,166	282,420	(3,977,722)	6,748
As of at Mar. 31, 2020	5,781
Increase (Decrease) in Temporary Equity [Roll Forward]
Acquisition of redeemable noncontrolling interest	6,005
Net income (loss) attributable to redeemable noncontrolling interests	45
As of at Jun. 30, 2020	11,831
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	78,054			78,054
Net (income) loss attributable to noncontrolling interest	0			(373)			373
Net income (loss) attributable to redeemable noncontrolling interests	(66)			(66)
Distribution to noncontrolling interest	(276)						(276)
Dividends on common stock	(7,100)			(7,100)
Repurchase of Class B Common Stock	(60,250)					(60,250)
Issuance of Class B common stock, net of restricted stock award forfeitures	(146)		(66)			(80)
Amortization of unearned stock compensation and stock option expense	1,768		1,768
Other comprehensive income (loss), net of income taxes	21,263				21,263
Other	(5)			(5)
As of at Sep. 30, 2020	3,246,658	20,000	386,506	6,567,676	303,683	(4,038,052)	6,845
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interests	66
As of at Sep. 30, 2020	11,897
As of at Dec. 31, 2020	3,766,393	20,000	388,159	6,804,822	603,314	(4,056,993)	7,091
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	112,635			112,635
Net (income) loss attributable to noncontrolling interest	0			(185)			185
Change in redemption value of redeemable noncontrolling interest	761		697				64
Distribution to noncontrolling interest	(126)						(126)
Dividends on common stock	(15,106)			(15,106)
Issuance of Class B common stock, net of restricted stock award forfeitures	(104)		(5,188)			5,084
Amortization of unearned stock compensation and stock option expense	1,589		1,589
Other comprehensive income (loss), net of income taxes	(1,203)				(1,203)
Purchase of redeemable noncontrolling interest	0
As of at Mar. 31, 2021	3,864,839	20,000	385,257	6,902,166	602,111	(4,051,909)	7,214
As of at Dec. 31, 2020	11,928
Increase (Decrease) in Temporary Equity [Roll Forward]
Change in redemption value of redeemable noncontrolling interests	(634)
Purchase of redeemable noncontrolling interest	(3,508)
As of at Mar. 31, 2021	7,786
As of at Dec. 31, 2020	3,766,393	20,000	388,159	6,804,822	603,314	(4,056,993)	7,091
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	268,244
Other comprehensive income (loss), net of income taxes	(16,249)
As of at Sep. 30, 2021	3,973,738	20,000	388,386	7,042,061	587,065	(4,073,677)	9,903
As of at Dec. 31, 2020	11,928
As of at Sep. 30, 2021	7,412
As of at Mar. 31, 2021	3,864,839	20,000	385,257	6,902,166	602,111	(4,051,909)	7,214
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	115,926			115,926
Net (income) loss attributable to noncontrolling interest	0			(699)			699
Net income (loss) attributable to redeemable noncontrolling interests	131			131
Change in redemption value of redeemable noncontrolling interest	65						65
Distribution to noncontrolling interest	(152)						(152)
Dividends on common stock	(7,553)			(7,553)
Issuance of Class B common stock, net of restricted stock award forfeitures	(96)		(47)			(49)
Amortization of unearned stock compensation and stock option expense	1,672		1,672
Other comprehensive income (loss), net of income taxes	1,080				1,080
As of at Jun. 30, 2021	3,975,912	20,000	386,882	7,009,971	603,191	(4,051,958)	7,826
As of at Mar. 31, 2021	7,786
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interests	(131)
Change in redemption value of redeemable noncontrolling interests	65
As of at Jun. 30, 2021	7,720
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	39,683			39,683
Noncontrolling interest capital contribution	1,750						1,750
Net (income) loss attributable to noncontrolling interest	0			(469)			469
Net income (loss) attributable to redeemable noncontrolling interests	372			372
Change in redemption value of redeemable noncontrolling interest	64						64
Distribution to noncontrolling interest	(206)						(206)
Dividends on common stock	(7,496)			(7,496)
Repurchase of Class B Common Stock	(21,840)					(21,840)
Issuance of Class B common stock, net of restricted stock award forfeitures	(67)		(188)			121
Amortization of unearned stock compensation and stock option expense	1,692		1,692
Other comprehensive income (loss), net of income taxes	(16,126)				(16,126)
As of at Sep. 30, 2021	3,973,738	$ 20,000	$ 388,386	$ 7,042,061	$ 587,065	$ (4,073,677)	$ 9,903
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interests	(372)
Change in redemption value of redeemable noncontrolling interests	64
As of at Sep. 30, 2021	$ 7,412