Fair value measurement (Details Textual) (USD $)	6 Months Ended
	Jun. 29, 2014	Dec. 29, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss	$ 15,310,000
Fair Value Measurement (Textual) [Abstract]
Contingent Consideration change in value	16,400,000
Fair value of total long-term debt	3,680,000,000	3,930,000,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair Value Disclosure	6,200,000
Publishing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss	$ 15,310,000