Pension Benefits - Summary Of Pension Plan Assets Using Fair Value Hierarchy By Asset Class (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 322	$ 335
United States | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	322
United States | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	11
United States | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	311
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	0	11
United States | Cash and cash equivalents | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	11
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	0
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	0
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	0
United States | Government securities | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	33
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	0	33
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	0	273
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	0	273
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	0
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	0
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	0	5
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	0	5
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	0
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	0
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	594	642	$ 687
Non-U.S. Plans | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	552	585
Non-U.S. Plans | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	215	228
Non-U.S. Plans | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	334	348
Non-U.S. Plans | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	9
Non-U.S. Plans | Cash and cash equivalents | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	6
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	13	6
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	128	144
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	53	62
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	75	82
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	8
Non-U.S. Plans | Government securities | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	145	139
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	4
Non-U.S. Plans | Government securities | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	139	135
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	31	26
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	8
Non-U.S. Plans | Corporate bonds | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17	18
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	208	241
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	107	125
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	101	110
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	0	6
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	8	5
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	3	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	2	3
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	3	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	19	24
Non-U.S. Plans | Other | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19	21
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	0	3
Non-U.S. Plans | Other | Assets held at NAV practical expedient
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 34	$ 49