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Pension Benefits - Summary Of Pension Plan Assets Using Fair Value Hierarchy By Asset Class (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 322	$ 335	$ 293
United States | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	322	217
United States | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	46
United States | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	311	171
United States | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Cash and cash equivalents | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	39
United States | Cash and cash equivalents | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	39
United States | Cash and cash equivalents | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Cash and cash equivalents | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Common and preferred stock | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	7
United States | Common and preferred stock | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	7
United States | Common and preferred stock | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Common and preferred stock | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity commingled funds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity commingled funds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity commingled funds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity commingled funds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity commingled funds | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	54
United States | Government securities | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33	85
United States | Government securities | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Government securities | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33	85
United States | Government securities | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Corporate bonds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	273	58
United States | Corporate bonds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Corporate bonds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	273	58
United States | Corporate bonds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Mortgage-backed securities | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	7
United States | Mortgage-backed securities | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Mortgage-backed securities | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	7
United States | Mortgage-backed securities | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Asset-backed securities and other | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	21
United States | Asset-backed securities and other | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Asset-backed securities and other | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	21
United States | Asset-backed securities and other | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income commingled funds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income commingled funds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income commingled funds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income commingled funds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income commingled funds | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	53
United States | Real estate funds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Real estate funds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Real estate funds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Real estate funds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Real estate funds | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	11
United States | Other | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Other | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Other | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Other | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Other | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	642	687	$ 623
Non-U.S. Plans | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	585	598
Non-U.S. Plans | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	228	187
Non-U.S. Plans | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	348	407
Non-U.S. Plans | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	4
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	3
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	3
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Common and preferred stock | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Common and preferred stock | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Common and preferred stock | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Common and preferred stock | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	144	135
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	62	41
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	82	94
Non-U.S. Plans | Equity commingled funds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Equity commingled funds | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	27
Non-U.S. Plans | Government securities | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	139	118
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	5
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	135	113
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26	250
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	114
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	136
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Mortgage-backed securities | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Mortgage-backed securities | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Mortgage-backed securities | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Mortgage-backed securities | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Asset-backed securities and other | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Asset-backed securities and other | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Asset-backed securities and other | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Asset-backed securities and other | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	241	64
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125	0
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	110	64
Non-U.S. Plans | Fixed income commingled funds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	0
Non-U.S. Plans | Fixed income commingled funds | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Real estate funds | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	2
Non-U.S. Plans | Real estate funds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Non-U.S. Plans | Real estate funds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	0
Non-U.S. Plans | Real estate funds | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Real estate funds | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Other | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24	26
Non-U.S. Plans | Other | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	22
Non-U.S. Plans | Other | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Other | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	4
Non-U.S. Plans | Other | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 49	$ 62

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