Income taxes (Details) (USD $)	12 Months Ended
	Dec. 30, 2011	Dec. 31, 2010	Dec. 25, 2009
Income taxes [Abstract]
Discontinued operations income tax expense (benefit)	$ 300,000	$ 800,000	$ 1,900,000
Total unrecognized tax benefits	17,300,000	17,686,000	23,237,000
Unrecognized tax benefits in other long-term liabilities	8,000,000	7,500,000	21,100,000
Unrecognized tax benefits that would impact effective tax rate	17,300,000
Domestic	(14,242,000)	1,293,000	(13,638,000)
Non-U.S.	(10,413,000)	(26,339,000)	(57,342,000)
Total	(24,655,000)	(25,046,000)	(70,980,000)
Current [Abstract]
Federal	655,000	0	267,000
State and local	36,000	88,000	(432,000)
Non-U.S.	(1,971,000)	3,765,000	8,927,000
Total current income tax expense	(1,280,000)	3,853,000	8,762,000
Deferred [Abstract]
Federal	16,460,000	(245,000)	(4,169,000)
State and local	5,777,000	(37,000)	(464,000)
Non-U.S.	7,834,000	(880,000)	(2,250,000)
Total deferred income tax expense	30,071,000	(1,162,000)	(6,883,000)
Net tax expense (benefit)	28,791,000	2,691,000	1,879,000
Effective Income Tax Rate Reconciliation [Abstract]
U.S. statutory federal income tax rate (in hundredths)	35.00%	35.00%	35.00%
Decrease (increase) resulting from [Abstract]
State and local income taxes, net of federal tax effect (in hundredths)	4.00%	0.00%	1.00%
Non-deductible expenses and other (in hundredths)	(9.00%)	(3.00%)	(2.00%)
Non-U.S. income subject to U.S. income tax (in hundredths)	5.00%	(8.00%)	(1.00%)
Tax effect of intangible impairment (in hundredths)	0.00%	(35.00%)	(29.00%)
Tax effect of valuation allowance (in hundredths)	(152.00%)	0.00%	0.00%
Lower foreign tax rates (in hundredths)	0.00%	0.00%	(7.00%)
Effective tax rate (in hundredths)	(117.00%)	(11.00%)	(3.00%)
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits at the beginning of the year	17,686,000	23,237,000	24,124,000
Additions to tax positions related to current year	6,558,000	1,555,000	3,172,000
Additions to tax positions related to prior years	0	0	0
Reductions to tax positions related to prior years	(1,846,000)	(5,005,000)	(1,434,000)
Lapses in statutes of limitation	(5,098,000)	(2,101,000)	(2,625,000)
Unrecognized tax benefits at the end of the year	17,300,000	17,686,000	23,237,000
Accrued interest and /or penalties related to uncertain income tax position	200,000
Open tax years range, minimum (in years)	2Y
Open tax years range, maximum (in years)	10Y
Potential audit settlement	4,400,000
Taxes on foreign earnings	200,000	700,000	3,000,000
Assets [Abstract]
Inventories	794,000	878,000
Plant and equipment	6,189,000	6,397,000
Vacation pay and other compensation	498,000	640,000
Pension expense	613,000	1,017,000
Stock awards	77,000	0
Accrued liabilities	1,788,000	2,159,000
Net operating losses - federal, state and foreign	40,130,000	19,777,000
Tax credits	20,770,000	17,958,000
Acquired intangibles	8,800,000	0
Other	124,000	2,914,000
Total deferred tax assets	79,783,000	51,740,000
Valuation allowance	(73,104,000)	(15,086,000)
Net deferred tax assets	6,679,000	36,654,000
Liabilities [Abstract]
Foreign earnings not permanently invested	11,494,000	11,460,000
Unrecognized foreign exchange gains	0	198,000
Stock awards	0	217,000
Restructuring	1,551,000	0
Acquired intangibles	461,000	(274,000)
Other	1,309,000	(1,509,000)
Total deferred tax liabilities	14,815,000	10,092,000
Net deferred tax assets	(8,136,000)	26,562,000
Short-term deferred tax assets	1,110,000	2,985,000
Short-term deferred tax liabilities	(3,816,000)	(1,202,000)
Long-term deferred tax assets	3,223,000	33,669,000
Long-term deferred tax liabilities	(8,653,000)	(8,890,000)
Net deferred tax assets	(8,136,000)	26,562,000
Earnings provided for taxes of non-U.S. subsidiaries' undistributed earnings	8,500,000
Earnings not provided for taxes of non-U.S. subsidiaries' undistributed earnings	477,000,000
Unrecognized taxes on undistributed earnings	$ 146,000,000