Business operations and segment information Geographical Information (Details) (USD $)	12 Months Ended
	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 6,008,174,000	$ 5,161,362,000	$ 5,353,197,000
Foreign Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	539,300,000	519,800,000	546,200,000
Long-Lived Assets	$ 498,300,000	$ 566,400,000	$ 529,800,000