Consolidated Statements of Shareholders' Equity - USD ($)	Common Stock [Member] Series A	Common Stock [Member] Series B	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock Series A	Treasury Stock	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Total
Beginning Balance at Dec. 31, 2017			$ 232,000	$ 494,989,000		$ (11,302,000)	$ (24,932,000)	$ (361,288,000)	$ 97,699,000
Beginning Balance, Shares Common Stock at Dec. 31, 2017	20,700,292	2,469,755
Beginning Balance, Treasury Stock at Dec. 31, 2017					(1,430,961)
Net income (loss)								(5,584,000)	(5,584,000)
Other comprehensive income							473,000		473,000
Shares repurchased, shares					(210,964)
Shares repurchased						(1,056,000)			(1,056,000)
Issuance of shares for restricted stock units, shares	151,236
Issuance of shares for restricted stock units			1,000	(1,000)
Share-based compensation				854,000					854,000
Conversion of Series B to Series A, shares	200	(200)
Dividends declared								(5,345,000)	(5,345,000)
Ending Balance at Sep. 30, 2018			233,000	495,842,000		(12,358,000)	(24,459,000)	(372,217,000)	87,041,000
Ending Balance, Shares Common Stock at Sep. 30, 2018	20,851,728	2,469,555
Ending Balance, Shares Treasury Stock at Sep. 30, 2018					(1,641,925)
Beginning Balance at Jun. 30, 2018			233,000	495,708,000		(12,127,000)	(24,617,000)	(369,400,000)	89,797,000
Beginning Balance, Shares Common Stock at Jun. 30, 2018	20,851,648	2,469,635
Beginning Balance, Treasury Stock at Jun. 30, 2018					(1,591,141)
Net income (loss)								(1,036,000)	(1,036,000)
Other comprehensive income							158,000		158,000
Shares repurchased, shares					(50,784)
Shares repurchased						(231,000)			(231,000)
Share-based compensation				134,000					134,000
Conversion of Series B to Series A, shares	80	(80)
Dividends declared								(1,781,000)	(1,781,000)
Ending Balance at Sep. 30, 2018			233,000	495,842,000		(12,358,000)	(24,459,000)	(372,217,000)	87,041,000
Ending Balance, Shares Common Stock at Sep. 30, 2018	20,851,728	2,469,555
Ending Balance, Shares Treasury Stock at Sep. 30, 2018					(1,641,925)
Beginning Balance at Dec. 31, 2018			233,000	494,389,000		(12,601,000)	(37,641,000)	(393,582,000)	50,798,000
Beginning Balance, Shares Common Stock at Dec. 31, 2018	20,854,728	2,469,555
Beginning Balance, Treasury Stock at Dec. 31, 2018					(1,697,370)
Net income (loss)								10,388,000	10,388,000
Other comprehensive income							188,000		188,000
Shares repurchased, shares					(183,458)
Shares repurchased						(719,000)			(719,000)
Conversion of Series B to Series A, shares	207	(207)
Dividends declared								(5,148,000)	(5,148,000)
Ending Balance at Sep. 30, 2019			233,000	494,389,000	$ (1,880,828)	(13,320,000)	(37,453,000)	(388,342,000)	55,507,000
Ending Balance, Shares Common Stock at Sep. 30, 2019	20,854,935	2,469,348
Ending Balance, Shares Treasury Stock at Sep. 30, 2019					(1,880,828)
Beginning Balance at Jun. 30, 2019			233,000	494,389,000		(13,128,000)	(37,516,000)	(382,625,000)	61,353,000
Beginning Balance, Shares Common Stock at Jun. 30, 2019	20,854,771	2,469,512
Beginning Balance, Treasury Stock at Jun. 30, 2019					(1,828,983)
Net income (loss)								(4,005,000)	(4,005,000)
Other comprehensive income							63,000		63,000
Shares repurchased, shares					(51,845)
Shares repurchased						(192,000)			(192,000)
Conversion of Series B to Series A, shares	164	(164)
Dividends declared								(1,712,000)	(1,712,000)
Ending Balance at Sep. 30, 2019			$ 233,000	$ 494,389,000	$ (1,880,828)	$ (13,320,000)	$ (37,453,000)	$ (388,342,000)	$ 55,507,000
Ending Balance, Shares Common Stock at Sep. 30, 2019	20,854,935	2,469,348
Ending Balance, Shares Treasury Stock at Sep. 30, 2019					(1,880,828)