Employee Benefit Plans - Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Earnings (Details) - USD ($) $ in Millions		12 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss		$ (14.1)	$ (122.5)	$ 234.6
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	[1]	(14.7)	(30.4)	(13.1)
Prior service cost		0.0	0.0	(0.5)
Recognized Prior Service (Cost) Credit	[1]	(0.7)	(0.6)	(0.4)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		17.4	22.6	16.8
Interest cost		31.6	30.6	28.3
Expected return on plan assets		(23.5)	(24.7)	(23.6)
Curtailments		0.0	0.2	0.0
Amortization of prior service cost		0.0	0.0	0.3
Amortization of net loss		14.7	28.9	13.1
Net periodic benefit cost		40.2	57.6	34.9
Net actuarial (gain) loss		(3.6)	(102.1)	199.8
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax		(14.7)	(28.9)	(13.1)
Prior service cost		0.0	0.0	0.5
Recognized Prior Service (Cost) Credit		0.0	(0.1)	(0.3)
Total recognized in other comprehensive earnings		(18.3)	(131.1)	186.9
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Earnings		21.9	(73.5)	221.8
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		2.8	4.2	2.4
Interest cost		3.1	3.2	2.6
Expected return on plan assets		0.0	0.0	0.0
Curtailments		0.0	0.0	0.0
Amortization of prior service cost		(0.7)	(0.7)	(0.7)
Amortization of net loss		0.0	1.5	0.0
Net periodic benefit cost		5.2	8.2	4.3
Net actuarial (gain) loss		(10.5)	(20.4)	34.8
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax		0.0	(1.5)	0.0
Prior service cost		0.0	0.0	0.0
Recognized Prior Service (Cost) Credit		0.7	0.7	0.7
Total recognized in other comprehensive earnings		(9.8)	(21.2)	35.5
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Earnings		$ (4.6)	$ (13.0)	$ 39.8

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension costs (see "Note N. Employee Benefit Plans" for additional details).