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Capital stock (Employee director stock options outstanding) (Details) (USD $)
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12 Months Ended | 12 Months Ended | 12 Months Ended | 12 Months Ended | 12 Months Ended | 12 Months Ended | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Dec. 28, 2013
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Dec. 29, 2012
|
Dec. 28, 2013
2013
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Dec. 28, 2013
2013
Minimum [Member]
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Dec. 28, 2013
2013
Maximum [Member]
|
Dec. 28, 2013
2014
|
Dec. 28, 2013
2014
Minimum [Member]
|
Dec. 28, 2013
2014
Maximum [Member]
|
Dec. 28, 2013
2015
|
Dec. 28, 2013
2015
Minimum [Member]
|
Dec. 28, 2013
2015
Maximum [Member]
|
Dec. 28, 2013
2016
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Dec. 28, 2013
2016
Minimum [Member]
|
Dec. 28, 2013
2016
Maximum [Member]
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Dec. 28, 2013
2017
|
Dec. 28, 2013
2017
Minimum [Member]
|
Dec. 28, 2013
2017
Maximum [Member]
|
Dec. 28, 2013
2022
|
Dec. 28, 2013
2022
Minimum [Member]
|
Dec. 28, 2013
2022
Maximum [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||||||||
| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit | $ 4.06 | $ 0.91 | $ 4.45 | $ 4.88 | $ 5.14 | $ 7.09 | ||||||||||||||
| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit | $ 13.35 | $ 1.92 | $ 5.62 | $ 7.72 | $ 5.73 | $ 8.23 | ||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number | 170,500 | 277,080 | 211,300 | 266,800 | 194,000 | 0 | ||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price | $ 4.80 | $ 5.69 | $ 1.64 | $ 4.50 | $ 7.11 | $ 5.66 | ||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 4,024,460 | 3,687,500 | 170,500 | 402,860 | 403,300 | 725,200 | 1,269,600 | 1,053,000 | ||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 5.85 | $ 5.46 | $ 5.69 | $ 1.64 | $ 4.50 | $ 7.12 | $ 5.57 | $ 7.45 | ||||||||||||