Retirement Benefit Plans (Tables)
 6 Months Ended
Aug. 04, 2018
Retirement Benefit Plans [Abstract]  
Schedule of Pension Plan Expense/(Income)
The components of net periodic pension expense/(income) for our non-contributory qualified defined benefit pension plan and supplemental pension plans were as follows:
 
Three Months Ended
 
Six Months Ended
($ in millions)
August 4,
2018
 
July 29,
2017
 
August 4,
2018
 
July 29,
2017
Service cost
$
10

 
$
10

 
$
19

 
$
21

 
 
 
 
 
 
 
 
Other components of net periodic pension cost/(income):
 
 
 
 
 
 
 
Interest cost
35

 
37

 
70

 
76

Expected return on plan assets
(56
)
 
(53
)
 
(112
)
 
(107
)
Amortization of prior service cost/(credit)
2

 
2

 
4

 
4

Settlement expense
—

 
—

 
—

 
—

Curtailment (gain)/loss recognized
—

 
—

 
—

 
7

Special termination benefit recognized
—

 
—

 
—

 
112

 
(19
)
 
(14
)
 
(38
)
 
92

Net periodic pension expense/(income)
$
(9
)
 
$
(4
)
 
$
(19
)
 
$
113