Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Millions		Dec. 31, 2018	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 64	$ 80
Derivative liabilities		3,152	3,175
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		402	465
Total liabilities		37	26
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		338	385
Total liabilities		0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		64	80
Total liabilities		37	26
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		0	0
Total liabilities		0	0
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]		14
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]		14
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]		0
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]		0
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		16	16
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		16	16
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			1
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			0
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			1
Other Current Assets | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			0
Assets Held for Sale, Current [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		1
Assets Held for Sale, Current [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Assets Held for Sale, Current [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		1
Assets Held for Sale, Current [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		1	1
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		1	1
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Deferred compensation plan assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		92	100
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Deferred compensation plan assets [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		92	100
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Deferred compensation plan assets [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Deferred compensation plan assets [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	145	148
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	145	148
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange Traded Funds in Fixed Income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange traded funds in equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	98	119
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange traded funds in equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	98	119
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange traded funds in equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Exchange traded funds in equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[1]	0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Equity swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		47	63
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Equity swap | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Equity swap | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		47	63
Other Noncurrent Assets | Fair Value, Measurements, Recurring [Member] | Equity swap | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Assets Held for Sale, Noncurrent [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		2	3
Assets Held for Sale, Noncurrent [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		2	3
Assets Held for Sale, Noncurrent [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Assets Held for Sale, Noncurrent [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure		0	0
Other Current Liabilities | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		2	2
Other Current Liabilities | Commodity Derivatives | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		0	0
Other Current Liabilities | Commodity Derivatives | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		2	2
Other Current Liabilities | Commodity Derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		0	0
Other Current Liabilities | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		24	12
Other Current Liabilities | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0	0
Other Current Liabilities | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		24	12
Other Current Liabilities | Fair Value, Measurements, Recurring [Member] | Foreign Currency Exchange Derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0	0
Liabilities Held for Sale, Current [Member] | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		11	12
Liabilities Held for Sale, Current [Member] | Commodity Derivatives | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		0	0
Liabilities Held for Sale, Current [Member] | Commodity Derivatives | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		11	12
Liabilities Held for Sale, Current [Member] | Commodity Derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring		$ 0	$ 0

[1] 1 Classified as restricted investments for payment of asbestos liabilities. See Note 20, "Commitments and Contingencies," of the notes to consolidated financial statements for further details.