Financial Instruments, Risk Management Activities, and Fair Values (Schedule of interest rate hedge in AOCI) (Details) (USD $) In Millions, unless otherwise specified	Nov. 23, 2014	Jan. 31, 2014
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	$ (59.6)
5.2% Notes Due March 2015 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	(0.1)
Debt Instrument, Interest Rate, Stated Percentage	5.20%
5.7% Notes Due February 2017 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	(4.9)
Debt Instrument, Interest Rate, Stated Percentage	5.70%
5.65% Notes Due February 2019 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	2.1
Debt Instrument, Interest Rate, Stated Percentage	5.65%
3.15% Notes Due December 2021 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	(69.9)
Debt Instrument, Interest Rate, Stated Percentage	3.15%
3.65% Notes Due February 2024 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	16.4
Debt Instrument, Interest Rate, Stated Percentage	3.65%	3.65%
5.4% Notes Due June 2040 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	(14.3)
Debt Instrument, Interest Rate, Stated Percentage	5.40%
4.15% Notes Due February 2043 Member
Debt Instrument [Line Items]
Pe-tax hedge gain (loss) in AOCI	$ 11.1
Debt Instrument, Interest Rate, Stated Percentage	4.15%