Divestiture-related activities - schedule of operating results of operations treated as discontinued operations (Detail) (USD $)	0 Months Ended	3 Months Ended								12 Months Ended
	Aug. 26, 2012	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Divestiture-Related Activities [Abstract]
Retained liability income expenses on divested business										$ 3,400,000		$ (2,200,000)		$ (2,700,000)
Proceeds from divestiture of businesses	45,200,000									5,251,000		0		66,660,000
Loss on Disposition of Business	39,000
Net revenues										0		0		16,616,000
Disposal Group, Including Discontinued Operation, Other Expense										3,407,000		2,205,000		18,328,000
Goodwill impairment										0	[1]	0	[1]	9,700,000	[1]
Gain on disposition										0	[2]	0	[2]	2,205,000	[2]
Loss from discontinued operations before income taxes										(3,407,000)		(2,205,000)		(9,207,000)
Taxes (benefit) on income (loss) from discontinued operations										(698,000)		(1,770,000)		(1,887,000)
Loss from discontinued operations		$ (1,188,000)	$ (271,000)	$ (1,125,000)	$ (125,000)	$ (236,000)	$ 1,029,000	$ (766,000)	$ (462,000)	$ (2,709,000)		$ (435,000)		$ (7,320,000)

[1] During 2012, the Company recognized a non-cash goodwill impairment charge of $9.7 million to adjust the carrying value of its former orthopedic business to its estimated fair value.

[2] The $2.2 million pre-tax gain on disposition during 2012 primarily reflects the gain recognized on the working capital adjustment related to the sale of the Company's former cargo systems and cargo container businesses.