Revision of prior period financial statements and out-of-period adjustments (Details) - Effect of the error correction (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 31, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Inventory	$ 24,216,000				$ 23,901,000				$ 24,216,000	$ 23,901,000
Total assets	59,707,000				95,485,000				59,707,000	95,485,000
Accounts payable	6,425,000				7,059,000				6,425,000	7,059,000
Total current liabilities	9,693,000				14,710,000				9,693,000	14,710,000
Deferred compensation, long-term portion					4,503,000					4,503,000
Total liabilities	18,728,000				24,495,000				18,728,000	24,495,000
Retained earnings	26,683,000				56,575,000				26,683,000	56,575,000		39,431,000
Accumulated other comprehensive loss	(2,697,000)				(1,600,000)				(2,697,000)	(1,600,000)		(1,528,000)
Total stockholders’ equity	40,979,000				70,990,000				40,979,000	70,990,000	82,405,000	53,088,000
Net sales	16,020,000	13,928,000	16,033,000	14,642,000	13,264,000	14,661,000	14,465,000	16,169,000	60,623,000	58,559,000	61,260,000
Total expenses										62,236,000	63,026,000
Operating loss		(670,000)	(1,458,000)	(1,340,000)	(1,916,000)	(232,000)	(1,558,000)	29,000	(2,869,000)	(3,677,000)	(1,766,000)
Net (loss) income from continuing operations	(2,528,000)	(1,438,000)	(2,197,000)	(1,725,000)	(2,600,000)	(770,000)	(2,159,000)	(593,000)	(7,888,000)	(6,122,000)	34,697,000
Net (loss) from discontinued operations	(682,000)	(1,118,000)	(17,303,000)	(2,901,000)	(2,141,000)	(1,700,000)	(1,370,000)	(1,501,000)	(22,004,000)	(6,712,000)	(4,719,000)
Net (loss) income	(3,210,000)	(2,556,000)	(19,500,000)	(4,626,000)	(4,741,000)	(2,470,000)	(3,529,000)	(2,094,000)	(29,892,000)	(12,834,000)	29,978,000
Actuarial (gain) loss										(762,000)	681,000
Amortization of actuarial loss									(70,000)	(111,000)	(80,000)
Adjustments to net periodic benefit										(706,000)	778,000
Comprehensive (loss) income									(30,989,000)	(12,128,000)	29,200,000
Scenario, Previously Reported [Member]
Inventory					23,640,000					23,640,000
Total assets					95,224,000					95,224,000
Accounts payable					5,989,000					5,989,000
Total current liabilities					13,640,000					13,640,000
Deferred compensation, long-term portion					661,000					661,000
Total liabilities					19,583,000					19,583,000
Retained earnings					59,784,000					59,784,000		42,037,000
Accumulated other comprehensive loss					(158,000)					(158,000)		(182,000)
Total stockholders’ equity					75,641,000					75,641,000
Net sales		13,928,000	24,038,000	21,891,000	22,744,000	14,661,000	24,166,000	26,052,000		58,559,000	61,260,000
Total expenses										61,991,000	62,544,000
Operating loss		(378,000)	(18,321,000)	(4,025,000)	(3,860,000)	(232,000)	(2,928,000)	(1,472,000)		(3,432,000)	(1,284,000)
Net (loss) income from continuing operations		(1,146,000)				(770,000)				(5,877,000)	35,179,000
Net (loss) from discontinued operations		(1,118,000)				(1,700,000)				(6,760,000)	(4,795,000)
Net (loss) income		(2,264,000)	(19,060,000)	(4,410,000)	(4,544,000)	(2,470,000)	(3,529,000)	(2,094,000)		(12,637,000)	30,384,000
Actuarial (gain) loss										(460,000)	157,000
Amortization of actuarial loss										(33,000)	(32,000)
Adjustments to net periodic benefit										(326,000)	302,000
Comprehensive (loss) income										(12,311,000)	30,082,000
Restatement Adjustment [Member]
Inventory					261,000					261,000
Total assets					261,000					261,000
Accounts payable					1,070,000					1,070,000
Total current liabilities					1,070,000					1,070,000
Deferred compensation, long-term portion					3,842,000					3,842,000
Total liabilities					4,912,000					4,912,000
Retained earnings					(3,209,000)					(3,209,000)
Accumulated other comprehensive loss					(1,442,000)					(1,442,000)
Total stockholders’ equity					(4,651,000)					(4,651,000)
Net sales		13,928,000	16,033,000	14,642,000	13,264,000	14,661,000	14,465,000	16,169,000
Total expenses										245,000	482,000
Operating loss		(378,000)	(1,018,000)	(1,124,000)	(1,671,000)	(232,000)	(1,558,000)	29,000		245,000	482,000
Net (loss) income from continuing operations		(1,146,000)	(1,757,000)	(1,509,000)	(2,355,000)	(770,000)	(2,159,000)	(593,000)		245,000	482,000
Net (loss) from discontinued operations		(1,118,000)	(17,303,000)	(2,901,000)	(2,189,000)	(1,700,000)	(1,370,000)	(1,501,000)		(48,000)	(76,000)
Net (loss) income		(2,264,000)	(19,060,000)	(4,410,000)	(4,544,000)	(2,470,000)	(3,529,000)	(2,094,000)		197,000	406,000
Actuarial (gain) loss										(302,000)	524,000
Amortization of actuarial loss										(78,000)	(48,000)
Adjustments to net periodic benefit										(380,000)	476,000
Comprehensive (loss) income										$ (183,000)	$ (882,000)