Retirement Benefit Liabilities (Tables)
 6 Months Ended
Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]  
Summary of retirement benefit liabilities
Retirement benefit liabilities consisted of the following (in millions):
 
March 31,
2015
 
September 30,
2014
Retiree medical liability
$
468

 
$
479

Pension liability
297

 
323

Other
15

 
16

Subtotal
780

 
818

Less: current portion (included in compensation and benefits, Note 14)
(43
)
 
(43
)
Retirement benefits
$
737

 
$
775
Components of net periodic pension and retiree medical expense
The components of net periodic pension and retiree medical expense included in continuing operations for the three months ended March 31 are as follows (in millions):
 
2015
 
2014
 
Pension
 
Retiree Medical
 
Pension
 
Retiree Medical
Interest cost
18

 
5

 
20

 
7

Assumed return on plan assets
(28
)
 
—

 
(26
)
 
—

Amortization of prior service costs
—

 
—

 
—

 
(2
)
Recognized actuarial loss
7

 
5

 
6

 
5

Total expense (income)
$
(3
)
 
$
10

 
$
—

 
$
10



The components of net periodic pension and retiree medical expense included in continuing operations for the six months ended March 31 are as follows (in millions):
 
2015
 
2014
 
Pension
 
Retiree Medical
 
Pension
 
Retiree Medical
Interest cost
36

 
10

 
40

 
13

Assumed return on plan assets
(56
)
 
—

 
(52
)
 
—

Amortization of prior service costs
—

 
—

 
—

 
(4
)
Recognized actuarial loss
14

 
10

 
12

 
11

Total expense
$
(6
)
 
$
20

 
$
—

 
$
20