Debt Long Term Debt Table (Details) - USD ($) $ in Millions		Jan. 31, 2016	Jan. 31, 2015
Debt Instrument [Line Items]
Long-term debt, including current maturities		$ 882.3	$ 882.5
Current portion of long-term debt		84.2	0.0
Long-term debt		798.1	882.5
2010 1.72% Notes, due September 2016 [Member]
Debt Instrument [Line Items]
Long-term debt, including current maturities	[1],[2]	84.2	84.5
2012 4.40% Series B Notes, due July 2042 [Member]
Debt Instrument [Line Items]
Long-term debt, including current maturities	[3]	250.0	250.0
2014 3.80% Senior Notes, due October 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, including current maturities	[2],[4]	249.3	249.3
2014 4.90% Senior Notes, due October 2044 [Member]
Debt Instrument [Line Items]
Long-term debt, including current maturities	[2],[4]	$ 298.8	$ 298.7

[1] These Notes were issued, at par, ¥10.0

[2] These agreements require lump sum repayments upon maturity.

[3] The agreements governing these Notes require repayments of $50.0 million in aggregate every five years beginning in 2022.

[4] These Notes were issued at a discount which will be amortized until the debt maturity.