Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Voting Common Stock [Member] Common Stock [Member]	Voting Common Stock [Member]	Nonvoting Common Stock [Member] Common Stock [Member]	Nonvoting Common Stock [Member]	Paid-In Capital [Member]	Treasury Stock Voting [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Dec. 31, 2019	$ 216		$ 95		$ 1,019,988	$ (9,592)	$ (605,766)	$ (54,914)	$ 350,027
Balance, shares at Dec. 31, 2019	21,582,000		9,506,000			154,000
Net income (loss)							(121,343)
Other comprehensive income (loss)								31,290
Comprehensive income (loss)									(90,053)
Balance at Mar. 31, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(727,109)	(23,624)	259,974
Balance, shares at Mar. 31, 2020	21,582,000		9,506,000			154,000
Balance at Dec. 31, 2019	$ 216		$ 95		1,019,988	$ (9,592)	(605,766)	(54,914)	350,027
Balance, shares at Dec. 31, 2019	21,582,000		9,506,000			154,000
Net income (loss)									(47,777)
Other comprehensive income (loss)									14,111
Comprehensive income (loss)									(33,666)
Balance at Jun. 30, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(823,673)	(40,803)	146,231
Balance, shares at Jun. 30, 2020	21,582,000		9,506,000			154,000
Balance at Dec. 31, 2019	$ 216		$ 95		1,019,988	$ (9,592)	(605,766)	(54,914)	350,027
Balance, shares at Dec. 31, 2019	21,582,000		9,506,000			154,000
Other comprehensive income (loss)								(17,058)
Balance at Dec. 31, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(729,202)	(71,972)	209,533
Balance, shares at Dec. 31, 2020	21,582,000	21,581,572	9,506,000	9,505,673		154,000
Balance at Mar. 31, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(727,109)	(23,624)	259,974
Balance, shares at Mar. 31, 2020	21,582,000		9,506,000			154,000
Net income (loss)							73,566		73,566
Other comprehensive income (loss)								(17,179)	(17,179)
Comprehensive income (loss)									56,387
Common dividend paid							(170,130)		(170,130)
Balance at Jun. 30, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(823,673)	(40,803)	146,231
Balance, shares at Jun. 30, 2020	21,582,000		9,506,000			154,000
Net income (loss)							140,870
Other comprehensive income (loss)								(31,169)
Comprehensive income (loss)									109,701
Common dividend paid							(46,399)		(46,399)
Balance at Dec. 31, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(729,202)	(71,972)	209,533
Balance, shares at Dec. 31, 2020	21,582,000	21,581,572	9,506,000	9,505,673		154,000
Net income (loss)							30,716
Other comprehensive income (loss)								(1,816)
Comprehensive income (loss)									28,900
Balance at Mar. 31, 2021	$ 216		$ 95		1,019,988	$ (9,592)	(698,486)	(73,788)	238,433
Balance, shares at Mar. 31, 2021	21,582,000		9,506,000			154,000
Balance at Dec. 31, 2020	$ 216		$ 95		1,019,988	$ (9,592)	(729,202)	(71,972)	209,533
Balance, shares at Dec. 31, 2020	21,582,000	21,581,572	9,506,000	9,505,673		154,000
Net income (loss)									52,207
Other comprehensive income (loss)								(3,601)	(3,601)
Comprehensive income (loss)									48,606
Balance at Jun. 30, 2021	$ 216		$ 95		1,019,988	$ (9,592)	(676,995)	(75,573)	258,139
Balance, shares at Jun. 30, 2021	21,582,000	21,581,572	9,506,000	9,505,673		154,000
Balance at Mar. 31, 2021	$ 216		$ 95		1,019,988	$ (9,592)	(698,486)	(73,788)	238,433
Balance, shares at Mar. 31, 2021	21,582,000		9,506,000			154,000
Net income (loss)							21,491		21,491
Other comprehensive income (loss)								(1,785)	(1,785)
Comprehensive income (loss)									19,706
Balance at Jun. 30, 2021	$ 216		$ 95		$ 1,019,988	$ (9,592)	$ (676,995)	$ (75,573)	$ 258,139
Balance, shares at Jun. 30, 2021	21,582,000	21,581,572	9,506,000	9,505,673		154,000