Benefit Obligations - Fair Value of the Non-U.S. Pension Plan Assets and Postretirement by Asset Class (Details) - USD ($) $ in Millions		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits - Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 59	$ 60	$ 51
Pension Benefits - Non-U.S. | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		59	60
Pension Benefits - Non-U.S. | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1	4
Pension Benefits - Non-U.S. | Equity securities | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Equity securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1	4
Pension Benefits - Non-U.S. | Equity securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2	2
Pension Benefits - Non-U.S. | Debt securities | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Debt securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2	2
Pension Benefits - Non-U.S. | Debt securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Asset-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2	0
Pension Benefits - Non-U.S. | Asset-backed Securities [Member] | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Asset-backed Securities [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2	0
Pension Benefits - Non-U.S. | Asset-backed Securities [Member] | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Pension Benefits - Non-U.S. | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	54	54
Pension Benefits - Non-U.S. | Insurance contracts | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Pension Benefits - Non-U.S. | Insurance contracts | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	54	54
Pension Benefits - Non-U.S. | Insurance contracts | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Postretirement Benefits - U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		159	173	$ 164
Postretirement Benefits - U.S. | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	11
Postretirement Benefits - U.S. | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		159	162
Postretirement Benefits - U.S. | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0	0
Postretirement Benefits - U.S. | Blended asset fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	0	11
Postretirement Benefits - U.S. | Blended asset fund | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	0	11
Postretirement Benefits - U.S. | Blended asset fund | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	0	0
Postretirement Benefits - U.S. | Blended asset fund | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	0	0
Postretirement Benefits - U.S. | Group life insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	159	162
Postretirement Benefits - U.S. | Group life insurance contracts | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Postretirement Benefits - U.S. | Group life insurance contracts | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	159	162
Postretirement Benefits - U.S. | Group life insurance contracts | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	$ 0	$ 0

[1] 77% of the Company's total non-U.S. pension assets, the insurer's underlying asset allocation at September 30, 2015 was 100% fixed income securities.

[2] An investment in a broadly diversified registered investment company (mutual fund). As of September 30, 2014, the fund asset allocation was approximately 70% fixed income securities, 21% U.S. equity and 9% non-U.S. equity.

[3] The group life insurance contracts are held in a reserve of an insurance company that provides for investment of pre-funding amounts in a family of pooled separate accounts. The fair value of each group life insurance contract is primarily determined by the value of the units it owns in the pooled separate accounts that back the policy. Each of the pooled separate accounts provides a unit NAV on a daily basis, which is based on the fair value of the underlying assets owned by the account. The postretirement benefit plans can transact daily at the unit NAV without restriction. As of September 30, 2015, the asset allocation of the pooled separate accounts in which the contracts invest was approximately 60% fixed income securities, 22% U.S. equity securities and 18% non-U.S. equity securities.