Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Millions		Jun. 30, 2019	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 69	$ 80
Derivative liabilities		2,648	3,175
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		411	465
Total liabilities		8	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		342	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		69	80
Total liabilities		8	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]	19	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]	19	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	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	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		10	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		10	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
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		69	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		69	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]	138	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]	138	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]	115	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]	115	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		59	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		59	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			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			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
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
Other Current Liabilities | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability			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]
Derivative Asset, Fair Value, Gross Liability			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]
Derivative Asset, Fair Value, Gross Liability			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]
Derivative Asset, Fair Value, Gross Liability			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		7	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		7	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
Other Current Liabilities | Fair Value, Measurements, Recurring [Member] | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		1
Other Current Liabilities | 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 liabilities		0
Other Current Liabilities | 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 liabilities		1
Other Current Liabilities | 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 liabilities		$ 0
Liabilities Held for Sale, Current [Member] | Commodity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability			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]
Derivative Asset, Fair Value, Gross Liability			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]
Derivative Asset, Fair Value, Gross Liability			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]
Derivative Asset, Fair Value, Gross Liability			$ 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.