Change in Accounting for Retirement-Related Benefits (Tables)
 9 Months Ended
Oct. 29, 2016
Change in Accounting for Retirement-Related Benefits [Abstract]  
Schedule of Prior Period Adjustments Made to Consolidated Statements of Operations [Table Text Block]
Consolidated Statements of Operations
 
Three Months Ended
 
Nine Months Ended
 
October 31, 2015
 
October 31, 2015
($ in millions, except per share data)
Previously Reported
 
As Adjusted
 
Effect of Change
 
Previously Reported
 
As Adjusted
 
Effect of Change
Pension
$
12

 
$
(17
)
 
$
(29
)
 
$
35

 
$
(52
)
 
$
(87
)
Income/(loss) before income taxes
(147
)
 
(118
)
 
29

 
(461
)
 
(374
)
 
87

Income tax expense/(benefit)
(10
)
 
(3
)
 
7

 
(19
)
 
8

 
27

Net income/(loss)
$
(137
)
 
(115
)
 
$
22

 
$
(442
)
 
(382
)
 
$
60

Basic earnings/(loss) per common share
$
(0.45
)
 
$
(0.38
)
 
$
0.07

 
$
(1.45
)
 
$
(1.25
)
 
$
0.20

Diluted earnings/(loss) per common share
$
(0.45
)
 
$
(0.38
)
 
$
0.07

 
$
(1.45
)
 
$
(1.25
)
 
$
0.20
Schedule of Prior Period Adjustments Made to Consolidated Statements of Comprehensive Income/(Loss) [Table Text Block]
Consolidated Statements of Comprehensive Income/(Loss)
 
Three Months Ended
 
Nine Months Ended
 
October 31, 2015
 
October 31, 2015
($ in millions)
Previously Reported
 
As Adjusted
 
Effect of Change
 
Previously Reported
 
As Adjusted
 
Effect of Change
Net income/(loss)
$
(137
)
 
$
(115
)
 
$
22

 
$
(442
)
 
$
(382
)
 
$
60

Reclassifications for amortization of net actuarial (gain)/loss
18

 
—

 
(18
)
 
53

 
—

 
(53
)
Deferred tax valuation allowance
—

 
(4
)
 
(4
)
 
—

 
(7
)
 
(7
)
Total other comprehensive income/(loss), net of tax
12

 
(10
)
 
(22
)
 
41

 
(19
)
 
(60
)
Total comprehensive income/(loss), net of tax
$
(125
)
 
$
(125
)
 
$
—

 
$
(401
)
 
$
(401
)
 
$
—
Schedule of Prior Period Adjustments Made to Consolidated Balance Sheet [Table Text Block]
Consolidated Balance Sheets
 
October 31, 2015
($ in millions)
Previously Reported
 
As Adjusted
 
Effect of Change
Reinvested earnings/(accumulated deficit)
$
(2,221
)
 
$
(2,876
)
 
$
(655
)
Accumulated other comprehensive income/(loss)
(1,024
)
 
(369
)
 
655
Schedule of Prior Period Adjustments Made to Consolidated Statements of Cash Flows [Table Text Block]
Consolidated Statements of Cash Flows
 
Three Months Ended
 
Nine Months Ended
 
October 31, 2015
 
October 31, 2015
($ in millions)
Previously Reported
 
As Adjusted
 
Effect of Change
 
Previously Reported
 
As Adjusted
 
Effect of Change
Cash flows from operating activities:
 
 
 
 
 
 
 
 
 
 
 
Net income/(loss)
$
(137
)
 
$
(115
)
 
$
22

 
$
(442
)
 
$
(382
)
 
$
60

Benefit plans
4

 
(25
)
 
(29
)
 
14

 
(73
)
 
(87
)
Deferred taxes
$
(15
)
 
$
(8
)
 
$
7

 
$
(32
)
 
$
(5
)
 
$
27