Goodwill and intangible assets (Goodwill Asssumptions used in estimating fair value) (Details) (Purity Life Natural Health Products [Member])	12 Months Ended
	Jan. 01, 2011
Purity Life Natural Health Products [Member]
Goodwill [Line Items]
Estimated cumulative average operating income growth	47.40%
Projected long-term annual operating income growth	2.50%
Weighted-average discount rate, actual	15.00%
Weighted-average discount rate, targeted	11.00%