Pension Benefits - Summary Of Pension Plan Assets Using Fair Value Hierarchy By Asset Class (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 335	$ 293	$ 262
United States | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	217	93
United States | Investment Assets at Fair Value | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39	8
United States | Investment Assets at Fair Value | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	17
United States | Investment Assets at Fair Value | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	85	27
United States | Investment Assets at Fair Value | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58	12
United States | Investment Assets at Fair Value | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	10
United States | Investment Assets at Fair Value | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	19
United States | Investment Assets at Fair Value | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
United States | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	46	25
United States | Investment Assets at Fair Value | Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39	8
United States | Investment Assets at Fair Value | Level 1 | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	17
United States | Investment Assets at Fair Value | Level 1 | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 1 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
United States | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	171	68
United States | Investment Assets at Fair Value | Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 2 | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 2 | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 2 | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	85	27
United States | Investment Assets at Fair Value | Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58	12
United States | Investment Assets at Fair Value | Level 2 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	10
United States | Investment Assets at Fair Value | Level 2 | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	19
United States | Investment Assets at Fair Value | Level 2 | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 2 | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 2 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
United States | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Investment Assets at Fair Value | Level 3 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
United States | Assets held at NAV practical expedient (1) | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54	131
United States | Assets held at NAV practical expedient (1) | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	53	59
United States | Assets held at NAV practical expedient (1) | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	10
United States | Assets held at NAV practical expedient (1) | Other
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	687	623	$ 607
Non-U.S. Plans | Investment Assets at Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	598	403
Non-U.S. Plans | Investment Assets at Fair Value | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	2
Non-U.S. Plans | Investment Assets at Fair Value | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	135	53
Non-U.S. Plans | Investment Assets at Fair Value | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	118	92
Non-U.S. Plans | Investment Assets at Fair Value | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	250	199
Non-U.S. Plans | Investment Assets at Fair Value | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64	49
Non-U.S. Plans | Investment Assets at Fair Value | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	8
Non-U.S. Plans | Investment Assets at Fair Value | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26
Non-U.S. Plans | Investment Assets at Fair Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	187	130
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	2
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41	13
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	24
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	114	69
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	20
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Non-U.S. Plans | Investment Assets at Fair Value | Level 1 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22
Non-U.S. Plans | Investment Assets at Fair Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	407	257
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	94	40
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	113	68
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	136	120
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64	29
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 2 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	16
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	10
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Mortgage-backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Asset-backed securities and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	6
Non-U.S. Plans | Investment Assets at Fair Value | Level 3 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4
Non-U.S. Plans | Assets held at NAV practical expedient (1) | Equity commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27	94
Non-U.S. Plans | Assets held at NAV practical expedient (1) | Fixed income commingled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	53
Non-U.S. Plans | Assets held at NAV practical expedient (1) | Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	13
Non-U.S. Plans | Assets held at NAV practical expedient (1) | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 62	$ 60