Divestiture-related activities - schedule of operating results of operations treated as discontinued operations (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Divestiture-Related Activities [Abstract]
Costs and other expenses									$ 1,730	$ 3,407	$ 2,205
Taxes (benefit) on income (loss) from discontinued operations									(10,635)	(698)	(1,770)
Gain (loss) on discontinued operations	$ 10,517	$ (719)	$ (190)	$ (703)	$ (1,188)	$ (271)	$ (1,125)	$ (125)	$ 8,905	$ (2,709)	$ (435)

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
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