Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Voting Common Stock [Member] Common Stock [Member]	Non-Voting Common Stock [Member] Common Stock [Member]	Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Dec. 31, 2018	$ 216	$ 95	$ 1,019,988	$ (9,592)	$ (695,521)	$ (17,620)	$ 297,566
Balance, shares at Dec. 31, 2018	21,582	9,506		154
Net (loss) income					38,516
Other comprehensive income (loss)						(6,406)
Comprehensive (loss) income							32,110
Balance at Mar. 31, 2019	$ 216	$ 95	1,019,988	$ (9,592)	(657,005)	(24,026)	329,676
Balance, shares at Mar. 31, 2019	21,582	9,506		154
Balance at Dec. 31, 2018	$ 216	$ 95	1,019,988	$ (9,592)	(695,521)	(17,620)	297,566
Balance, shares at Dec. 31, 2018	21,582	9,506		154
Net (loss) income							76,743
Other comprehensive income (loss)							(13,052)
Comprehensive (loss) income							63,691
Balance at Jun. 30, 2019	$ 216	$ 95	1,019,988	$ (9,592)	(618,778)	(30,672)	361,257
Balance, shares at Jun. 30, 2019	21,582	9,506		154
Balance at Dec. 31, 2018	$ 216	$ 95	1,019,988	$ (9,592)	(695,521)	(17,620)	297,566
Balance, shares at Dec. 31, 2018	21,582	9,506		154
Other comprehensive income (loss)						(37,294)
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	9,506		154
Balance at Mar. 31, 2019	$ 216	$ 95	1,019,988	$ (9,592)	(657,005)	(24,026)	329,676
Balance, shares at Mar. 31, 2019	21,582	9,506		154
Net (loss) income					38,227		38,227
Other comprehensive income (loss)						(6,646)	(6,646)
Comprehensive (loss) income							31,581
Balance at Jun. 30, 2019	$ 216	$ 95	1,019,988	$ (9,592)	(618,778)	(30,672)	361,257
Balance, shares at Jun. 30, 2019	21,582	9,506		154
Net (loss) income					13,012
Other comprehensive income (loss)						(24,242)
Comprehensive (loss) income							(11,230)
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	9,506		154
Net (loss) income					(121,343)
Other comprehensive income (loss)						31,290
Comprehensive (loss) income							(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	9,506		154
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	9,506		154
Net (loss) income							(47,777)
Other comprehensive income (loss)						14,111	14,111
Comprehensive (loss) income							(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	9,506		154
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	9,506		154
Net (loss) income					73,566		73,566
Other comprehensive income (loss)						(17,179)	(17,179)
Comprehensive (loss) income							56,387
Common dividends paid ($5.50 per share)					(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	9,506		154