Long-term debt (Details Textual) (USD $)	9 Months Ended
	Sep. 29, 2013	Dec. 30, 2012	Jul. 29, 2013 Unsecured Fixed Rate Notes 5.125 Percent Due 2020 [Member]	Oct. 03, 2013 UnsecuredFixedRateNotes5.125PercentDue2019[Member] Subsequent Event [Member]	Oct. 03, 2013 Unsecured Fixed Rate Notes 6.375 Percent Due 2023 [Member] Subsequent Event [Member]
Debt Instrument [Line Items]
Increase(decrease) in long term debt net of repayments and discount amortization	$ 548,100,000
Proceeds from Issuance of Long-term Debt	746,200,000
Long-term debt, interest rate, stated percentage			5.125%	5.125%	6.375%
Long-term Debt (Textual) [Abstract]
Amortization of Debt Discount (Premium)	6,900,000
Revolving credit agreements, repayments	205,000,000
Line of credit facility, remaining borrowing capacity	1,170,000,000
Line of Credit Facility, Maximum Borrowing Capacity	1,200,000,000
Letters of Credit Outstanding, Amount	34,000,000
Long-term Debt	1,980,190,000	1,432,100,000
Debt Instrument Offering Price Percentage			98.566%	98.724%	99.086%
Debt Instrument Yield To Maturity			5.375%	5.375%	6.50%
Debt Instrument, Face Amount			$ 600,000,000	$ 600,000,000	$ 650,000,000