Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Class A and B	Total Stockholders' Equity	Total Stockholders' Equity Common Class A and B	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Capital in Excess of Par Value (1)	Treasury Stock	Retained Earnings (1)	Retained Earnings (1) Common Class A and B	Accumulated Other Comprehensive Income (Loss)	As Previously Reported	As Previously Reported Common Class A and B	As Previously Reported Total Stockholders' Equity	As Previously Reported Common Stock Class A Common Stock	As Previously Reported Common Stock Class B Common Stock	As Previously Reported Capital in Excess of Par Value (1)	As Previously Reported Treasury Stock	As Previously Reported Retained Earnings (1)	As Previously Reported Retained Earnings (1) Common Class A and B	As Previously Reported Accumulated Other Comprehensive Income (Loss)	Restatement Impacts	Restatement Impacts Total Stockholders' Equity	Restatement Impacts Common Stock Class A Common Stock	Restatement Impacts Common Stock Class B Common Stock	Restatement Impacts Capital in Excess of Par Value (1)	Restatement Impacts Treasury Stock	Restatement Impacts Retained Earnings (1)	Restatement Impacts Accumulated Other Comprehensive Income (Loss)
Balance, beginning of period at Dec. 31, 2016	$ 62,948		$ 62,948		$ 0	$ 0	$ 75,031	$ 0	$ 4,016		$ (16,099)	$ 65,268		$ 65,268	$ 0	$ 0	$ 75,031	$ 0	$ 6,738		$ (16,501)	$ (2,320)	$ (2,320)	$ 0	$ 0	$ 0	$ 0	$ (2,722)	$ 402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,884		15,884						15,884			17,905							17,905			(2,021)						(2,021)
Issuance of common stock, net of conversions	0				88	48	(136)					0			88	48	(136)
Cash dividends	(38,000)	$ (1,162)	(38,000)	$ (1,162)			(27,122)		(10,878)	$ (1,162)		(38,000)	$ (1,162)				(27,122)		(10,878)	$ (1,162)
Other comprehensive loss	1,409		1,409								1,409	1,450									1,450	(41)							(41)
Reclassification adjustment to net income	947		947								947	947									947
Balance, end of period at Dec. 31, 2017	42,026		42,026		88	48	47,773	0	7,860		(13,743)	46,408			88	48	47,773	0	12,603		(14,104)	(4,382)		0	0	0	0	(4,743)	361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(2,183)								(2,183)			(418)										(1,765)
Issuance of common stock, net of conversions	324				4	(3)	323
Stock compensation expense	955						955
Cash dividends	(1,162)								(1,162)
Other comprehensive loss	863										863
Reclassification adjustment to net income	324										324
Balance, end of period at Mar. 31, 2018	41,147				92	45	49,051		5,683		(13,724)
Balance, beginning of period at Dec. 31, 2017	42,026		42,026		88	48	47,773	0	7,860		(13,743)	46,408			88	48	47,773	0	12,603		(14,104)	(4,382)		0	0	0	0	(4,743)	361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(3,304)											(1,292)										(2,012)
Balance, end of period at Jun. 30, 2018	39,753				92	45	50,721		3,397		(14,502)
Balance, beginning of period at Dec. 31, 2017	42,026		42,026		88	48	47,773	0	7,860		(13,743)	46,408			88	48	47,773	0	12,603		(14,104)	(4,382)		0	0	0	0	(4,743)	361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,837											6,752										(2,915)
Balance, end of period at Sep. 30, 2018	46,935				92	45	51,366		9,373		(13,941)
Balance, beginning of period at Dec. 31, 2017	42,026		42,026		88	48	47,773	0	7,860		(13,743)	46,408			88	48	47,773	0	12,603		(14,104)	(4,382)		0	0	0	0	(4,743)	361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,698		17,698						17,698			21,784							21,784			(4,086)						(4,086)
Issuance of common stock, net of conversions	324				5	(4)	323					324			5	(4)	323
Purchase of treasury stock	0											0
Stock compensation expense	3,618						3,618					3,618					3,618
Cash dividends	(4,658)	$ (4,658)							(4,658)	(4,658)		(4,658)							(4,658)
Reclassification due to adoption of ASU 2018-02	0								1,168		(1,168)
Other comprehensive loss	(2,899)		(2,899)								(2,899)	(2,841)									(2,841)	(58)							(58)
Reclassification adjustment to net income	709		709						0		709	803							0		803	(94)							(94)
Balance, end of period at Dec. 31, 2018	56,818		56,818		93	44	51,714	0	22,068		(17,101)	65,438			93	44	51,714	0	30,897		(17,310)	(8,620)		0	0	0	0	(8,829)	209
Balance, beginning of period at Mar. 31, 2018	41,147				92	45	49,051		5,683		(13,724)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(1,121)								(1,121)			(874)										(247)
Issuance of common stock, net of conversions	198						198
Stock compensation expense	1,472						1,472
Cash dividends	(1,165)								(1,165)
Other comprehensive loss	(961)										(961)
Reclassification adjustment to net income	183										183
Balance, end of period at Jun. 30, 2018	39,753				92	45	50,721		3,397		(14,502)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,141								7,141			8,044										(903)
Issuance of common stock, net of conversions	246						246
Stock compensation expense	399						399
Cash dividends	(1,165)								(1,165)
Other comprehensive loss	548										548
Reclassification adjustment to net income	13										13
Balance, end of period at Sep. 30, 2018	46,935				92	45	51,366		9,373		(13,941)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,861								13,861			15,032										(1,171)
Issuance of common stock, net of conversions	(444)				1	(1)	(444)
Stock compensation expense	792						792
Cash dividends	(1,166)								(1,166)
Other comprehensive loss	(3,349)										(3,349)
Reclassification adjustment to net income	189										189
Balance, end of period at Dec. 31, 2018	56,818		56,818		93	44	51,714	0	22,068		(17,101)	65,438			93	44	51,714	0	30,897		(17,310)	(8,620)		0	0	0	0	(8,829)	209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(3,385)								(3,385)			(1,761)										(1,624)
Issuance of common stock, net of conversions	1				2		(1)
Stock compensation expense	807						807
Cash dividends	(1,177)						0		(1,177)
Other comprehensive loss	(192)										(192)
Reclassification adjustment to net income	86										86											100
Balance, end of period at Mar. 31, 2019	52,958				95	44	52,520	0	17,506		(17,207)
Balance, beginning of period at Dec. 31, 2018	56,818		56,818		93	44	51,714	0	22,068		(17,101)	65,438			93	44	51,714	0	30,897		(17,310)	(8,620)		0	0	0	0	(8,829)	209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(4,003)											(2,705)										(1,298)
Balance, end of period at Jun. 30, 2019	49,189				95	44	53,342	(2,334)	15,646		(17,604)
Balance, beginning of period at Dec. 31, 2018	56,818		56,818		93	44	51,714	0	22,068		(17,101)	65,438			93	44	51,714	0	30,897		(17,310)	(8,620)		0	0	0	0	(8,829)	209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(6,203)											(2,308)										(3,895)
Balance, end of period at Sep. 30, 2019	42,544				95	44	54,143	(5,960)	12,231		(18,009)
Balance, beginning of period at Dec. 31, 2018	56,818		56,818		93	44	51,714	0	22,068		(17,101)	65,438			93	44	51,714	0	30,897		(17,310)	(8,620)		0	0	0	0	(8,829)	209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(13,507)		(13,507)						(13,507)			(3,522)							(3,522)			(9,985)						(9,985)
Issuance of common stock, net of conversions	0				5	(3)	(2)					0			5	(3)	(2)
Purchase of treasury stock	(5,960)							(5,960)				(5,960)						(5,960)
Stock compensation expense	2,797						2,797					2,632					2,632					165				165
Cash dividends	(4,851)			$ (4,851)					(4,851)	$ (4,851)		(4,851)							(4,851)
Other comprehensive loss	272		272								272	719									719	(447)							(447)
Reclassification adjustment to net income	697		697								697	603									603	94							94
Balance, end of period at Dec. 31, 2019	36,266		36,266		98	41	54,509	(5,960)	3,710		(16,132)	55,059			98	41	54,344	(5,960)	22,524		(15,988)	(18,793)		0	0	165	0	(18,814)	(144)
Balance, beginning of period at Mar. 31, 2019	52,958				95	44	52,520	0	17,506		(17,207)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(618)								(618)			(944)										326
Purchase of treasury stock	(2,334)							(2,334)
Stock compensation expense	822						822
Cash dividends	(1,242)						0		(1,242)
Other comprehensive loss	(643)										(643)
Reclassification adjustment to net income	246										246
Balance, end of period at Jun. 30, 2019	49,189				95	44	53,342	(2,334)	15,646		(17,604)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(2,200)								(2,200)			397										(2,597)
Purchase of treasury stock	(3,626)							(3,626)
Stock compensation expense	801						801
Cash dividends	(1,215)						0		(1,215)
Other comprehensive loss	(654)										(654)
Reclassification adjustment to net income	249										249
Balance, end of period at Sep. 30, 2019	42,544				95	44	54,143	(5,960)	12,231		(18,009)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(7,304)								(7,304)			(1,214)										(6,090)
Issuance of common stock, net of conversions	(1)				3	(3)	(1)
Purchase of treasury stock	0							0
Stock compensation expense	367						367
Cash dividends	(1,217)						0		(1,217)
Other comprehensive loss	1,761										1,761
Reclassification adjustment to net income	116										116
Balance, end of period at Dec. 31, 2019	$ 36,266		$ 36,266		$ 98	$ 41	$ 54,509	$ (5,960)	$ 3,710		$ (16,132)	$ 55,059			$ 98	$ 41	$ 54,344	$ (5,960)	$ 22,524		$ (15,988)	$ (18,793)		$ 0	$ 0	$ 165	$ 0	$ (18,814)	$ (144)