Stockholders' Deficit - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (1,588,000,000)	$ (1,381,000,000)	$ (1,694,000,000)	$ (1,599,000,000)
Other comprehensive (loss) income, net of tax	(10,000,000)	23,000,000	24,000,000	(9,000,000)
Ending balance	(1,355,000,000)	(2,642,000,000)	(1,355,000,000)	(2,642,000,000)
Gains (losses) related to cash flow hedges	0	0	0	0
Derivatives designated for hedge accounting | Net Investment Hedging | Currency swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Gains (losses) related to net investment hedges	98,000,000	(20,000,000)	(135,000,000)	(13,000,000)
Derivatives designated for hedge accounting | Cash Flow Hedges | Currency swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Gains (losses) related to cash flow hedges	(7,000,000)
Derivatives designated for hedge accounting | Cash Flow Hedges | Interest rate swap locks, Foreign currency forwards and Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Gains (losses) related to cash flow hedges			12,000,000
Total Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(898,000,000)	(913,000,000)	(932,000,000)	(881,000,000)
Other comprehensive income (loss) before reclassifications		24,000,000		(8,000,000)
Amounts reclassified to earnings and other		(1,000,000)		(1,000,000)
Other comprehensive (loss) income, net of tax	(10,000,000)	23,000,000	24,000,000	(9,000,000)
Ending balance	(908,000,000)	(890,000,000)	(908,000,000)	(890,000,000)
Foreign Currency Translation Adjustments, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(796,000,000)	(892,000,000)	(989,000,000)	(856,000,000)
Other comprehensive income (loss) before reclassifications		49,000,000		13,000,000
Amounts reclassified to earnings and other		0		0
Other comprehensive (loss) income, net of tax	(77,000,000)	49,000,000	116,000,000	13,000,000
Ending balance	(873,000,000)	(843,000,000)	(873,000,000)	(843,000,000)
Unrealized Gains (Losses) on Net Investment Hedges, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(125,000,000)	(7,000,000)	47,000,000	(12,000,000)
Other comprehensive income (loss) before reclassifications		(15,000,000)		(10,000,000)
Amounts reclassified to earnings and other		0		0
Other comprehensive (loss) income, net of tax	72,000,000	(15,000,000)	(100,000,000)	(10,000,000)
Ending balance	(53,000,000)	(22,000,000)	(53,000,000)	(22,000,000)
Unrealized Gains (Losses) on Net Investment Hedges, Net of Tax | Net Investment Hedging
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassification, tax benefit (expense)	26,000,000	(5,000,000)	(35,000,000)	3,000,000
Unrealized Gains (Losses) on Cash Flow and Other Hedges, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	10,000,000	3,000,000	(4,000,000)	3,000,000
Other comprehensive income (loss) before reclassifications		(9,000,000)		(9,000,000)
Amounts reclassified to earnings and other		0		0
Other comprehensive (loss) income, net of tax	(5,000,000)	(9,000,000)	9,000,000	(9,000,000)
Ending balance	5,000,000	(6,000,000)	5,000,000	(6,000,000)
Unrealized Gains (Losses) on Cash Flow and Other Hedges, Net of Tax | Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassification, tax benefit (expense)	2,000,000	3,000,000	(3,000,000)	3,000,000
Unrealized Gains (Losses) and Other Components of Benefit Plans, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	13,000,000	(17,000,000)	14,000,000	(16,000,000)
Other comprehensive income (loss) before reclassifications		(1,000,000)		(2,000,000)
Amounts reclassified to earnings and other		(1,000,000)		(1,000,000)
Other comprehensive (loss) income, net of tax	0	(2,000,000)	(1,000,000)	(3,000,000)
Ending balance	$ 13,000,000	$ (19,000,000)	$ 13,000,000	$ (19,000,000)