Retirement Benefit Plans
 9 Months Ended
Oct. 29, 2016
Retirement Benefit Plans [Abstract]  
Retirement Benefit Plans
Retirement Benefit Plans
The components of net periodic benefit expense/(income) for our non-contributory qualified defined benefit pension plan (Primary Pension Plan) and non-contributory supplemental pension plans were as follows:
 
Three Months Ended
 
Nine Months Ended
($ in millions)
October 29,
2016
 
October 31,
2015
 
October 29,
2016
 
October 31,
2015
Primary Pension Plan
 
 
 
 
 
 
 
Service cost
$
14

 
$
17

 
$
41

 
$
52

Interest cost
38

 
49

 
114

 
147

Other cost
—

 
2

 
—

 
5

Expected return on plan assets
(54
)
 
(89
)
 
(161
)
 
(267
)
Amortization of prior service cost/(credit)
2

 
2

 
6

 
6

Net periodic benefit expense/(income)
$
—

 
$
(19
)
 
$
—

 
$
(57
)
 
 
 
 
 
 
 
 
Supplemental Pension Plans
 
 
 
 
 
 
 
Interest cost
1

 
2

 
5

 
5

Net periodic benefit expense/(income)
$
1

 
$
2

 
$
5

 
$
5

 
 
 
 
 
 
 
 
Primary and Supplemental Pension Plans Total
 
 
 
 
 
 
 
Service cost
$
14

 
$
17

 
$
41

 
$
52

Interest cost
39

 
51

 
119

 
152

Other cost
—

 
2

 
—

 
5

Expected return on plan assets
(54
)
 
(89
)
 
(161
)
 
(267
)
Amortization of prior service cost/(credit)
2

 
2

 
6

 
6

Net periodic benefit expense/(income)
$
1

 
$
(17
)
 
$
5

 
$
(52
)

Additionally, the Company had net periodic postretirement income of $6 million and $2 million, respectively, in the three months ended October 29, 2016 and October 31, 2015 and net periodic postretirement income of $14 million and $6 million, respectively, in the nine months ended October 29, 2016 and October 31, 2015. These amounts are related to the Company's noncontributory postretirement health and welfare plan and are included in SG&A expense in the unaudited Interim Consolidated Statements of Operations. The Company communicated to plan participants that the postretirement health and welfare plan will terminate by December 2016 and this resulted in a reduction of the accumulated plan benefit obligation from $8 million at January 30, 2016 to $1 million at October 29, 2016.