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 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 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 attributable to redeemable noncontrolling interests	126
As of at Mar. 31, 2020	5,781
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 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