Quarterly Results of Operations (Unaudited) (Restated Condensed Consolidated Statements of Equity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance, beginning of period	$ 42,544	$ 49,189	$ 52,958	$ 56,818	$ 46,935	$ 39,753	$ 41,147	$ 42,026	$ 56,818	$ 42,026	$ 56,818	$ 42,026	$ 56,818	$ 42,026	$ 62,948
Net income (loss)	(7,304)	(2,200)	(618)	(3,385)	13,861	7,141	(1,121)	(2,183)	(4,003)	(3,304)	(6,203)	3,837	(13,507)	17,698	15,884
Issuance of common stock, net of conversions	(1)			1	(444)	246	198	324					0	324	0
Purchase of treasury stock	0	(3,626)	(2,334)										(5,960)	0
Share-based compensation expense	367	801	822	807	792	399	1,472	955					2,797	3,618
Cash dividends	(1,217)	(1,215)	(1,242)	(1,177)	(1,166)	(1,165)	(1,165)	(1,162)					(4,851)	(4,658)	(38,000)
Other comprehensive loss	1,761	(654)	(643)	(192)	(3,349)	548	(961)	863					272	(2,899)	1,409
Reclassification adjustment to net income	116	249	246	86	189	13	183	324					697	709	947
Balance, end of period	$ 36,266	$ 42,544	$ 49,189	$ 52,958	$ 56,818	$ 46,935	$ 39,753	$ 41,147	49,189	39,753	42,544	46,935	$ 36,266	$ 56,818	$ 42,026
Common stock dividends (in dollars per share)	$ 0.9	$ 0.9	$ 0.9	$ 0.085	$ 0.085	$ 0.085	$ 0.085	$ 0.085					$ 0.355	$ 0.34	$ 0.085
Capital in Excess of Par Value (1)
Balance, beginning of period	$ 54,143	$ 53,342	$ 52,520	$ 51,714	$ 51,366	$ 50,721	$ 49,051	$ 47,773	51,714	47,773	51,714	47,773	$ 51,714	$ 47,773	$ 75,031
Issuance of common stock, net of conversions	(1)			(1)	(444)	246	198	323					(2)	323	(136)
Share-based compensation expense	367	801	822	807	792	399	1,472	955					2,797	3,618
Cash dividends	0	0	0	0											(27,122)
Balance, end of period	54,509	54,143	53,342	52,520	51,714	51,366	50,721	49,051	53,342	50,721	54,143	51,366	54,509	51,714	47,773
Retained Earnings (1)
Balance, beginning of period	12,231	15,646	17,506	22,068	9,373	3,397	5,683	7,860	22,068	7,860	22,068	7,860	22,068	7,860	4,016
Net income (loss)	(7,304)	(2,200)	(618)	(3,385)	13,861	7,141	(1,121)	(2,183)					(13,507)	17,698	15,884
Cash dividends	(1,217)	(1,215)	(1,242)	(1,177)	(1,166)	(1,165)	(1,165)	(1,162)					(4,851)	(4,658)	(10,878)
Reclassification due to adoption of ASU 2018-02															1,168
Reclassification adjustment to net income														0
Balance, end of period	3,710	12,231	15,646	17,506	22,068	9,373	3,397	5,683	15,646	3,397	12,231	9,373	3,710	22,068	7,860
Accumulated Other Comprehensive Income (Loss)
Balance, beginning of period	(18,009)	(17,604)	(17,207)	(17,101)	(13,941)	(14,502)	(13,724)	(13,743)	(17,101)	(13,743)	(17,101)	(13,743)	(17,101)	(13,743)	(16,099)
Reclassification due to adoption of ASU 2018-02															(1,168)
Other comprehensive loss	1,761	(654)	(643)	(192)	(3,349)	548	(961)	863					272	(2,899)	1,409
Reclassification adjustment to net income	116	249	246	86	189	13	183	324					697	709	947
Balance, end of period	(16,132)	(18,009)	(17,604)	(17,207)	(17,101)	(13,941)	(14,502)	(13,724)	(17,604)	(14,502)	(18,009)	(13,941)	(16,132)	(17,101)	(13,743)
Treasury Stock
Balance, beginning of period	(5,960)	(2,334)	0	0				0	0	0	0	0	0	0	0
Purchase of treasury stock	0	(3,626)	(2,334)										(5,960)
Balance, end of period	(5,960)	(5,960)	(2,334)	0	0				(2,334)		(5,960)		(5,960)	0	0
Class A Common Stock | Common Stock
Balance, beginning of period	95	95	95	93	92	92	92	88	93	88	93	88	93	88	0
Issuance of common stock, net of conversions	3			2	1			4					5	5	88
Balance, end of period	98	95	95	95	93	92	92	92	95	92	95	92	98	93	88
Class B Common Stock | Common Stock
Balance, beginning of period	44	44	44	44	45	45	45	48	44	48	44	48	44	48	0
Issuance of common stock, net of conversions	(3)				(1)			(3)					(3)	(4)	48
Balance, end of period	41	44	44	44	44	45	45	45	44	45	44	45	41	44	48
Restatement Impacts
Balance, beginning of period				(8,620)				(4,382)	(8,620)	(4,382)	(8,620)	(4,382)	(8,620)	(4,382)	(2,320)
Net income (loss)	(6,090)	$ (2,597)	$ 326	(1,624)	(1,171)	$ (903)	$ (247)	(1,765)	(1,298)	(2,012)	(3,895)	(2,915)	(9,985)	(4,086)	(2,021)
Share-based compensation expense													165
Other comprehensive loss													(447)	(58)	(41)
Reclassification adjustment to net income				100									94	(94)
Balance, end of period	(18,793)				(8,620)								$ (18,793)	$ (8,620)	$ (4,382)
Common stock dividends (in dollars per share)													$ 0.355	$ 0.34	$ 0.085
Restatement Impacts | Capital in Excess of Par Value (1)
Balance, beginning of period				0				0	0	0	0	0	$ 0	$ 0	$ 0
Share-based compensation expense													165
Balance, end of period	165				0								165	0	0
Restatement Impacts | Retained Earnings (1)
Balance, beginning of period				(8,829)				(4,743)	(8,829)	(4,743)	(8,829)	(4,743)	(8,829)	(4,743)	(2,722)
Net income (loss)													(9,985)	(4,086)	(2,021)
Balance, end of period	(18,814)				(8,829)								(18,814)	(8,829)	(4,743)
Restatement Impacts | Accumulated Other Comprehensive Income (Loss)
Balance, beginning of period				209				361	209	361	209	361	209	361	402
Other comprehensive loss													(447)	(58)	(41)
Reclassification adjustment to net income													94	(94)
Balance, end of period	(144)				209								(144)	209	361
Restatement Impacts | Treasury Stock
Balance, beginning of period				0				0	0	0	0	0	0	0	0
Balance, end of period	0				0								0	0	0
Restatement Impacts | Class A Common Stock | Common Stock
Balance, beginning of period				0				0	0	0	0	0	0	0	0
Balance, end of period	0				0								0	0	0
Restatement Impacts | Class B Common Stock | Common Stock
Balance, beginning of period				$ 0				$ 0	$ 0	$ 0	$ 0	$ 0	0	0	0
Balance, end of period	$ 0				$ 0								$ 0	$ 0	$ 0