Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (35)	$ (52)	$ (50)	[1]	$ (50)
Other comprehensive income (loss) before reclassifications	19	(36)	23		(33)
Amounts reclassified from accumulated other comprehensive income (loss)	14	(1)	25		(6)
Total other comprehensive income (loss), net of tax	33	(37)	48		(39)
Ending balance	(2)	(89)	(2)		(89)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	0	7	0		(4)
Other comprehensive income (loss) before reclassifications	0	(3)	0		8
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0		0
Total other comprehensive income (loss), net of tax	0	(3)	0		8
Ending balance	0	4	0		4
Unrealized Gains (Losses) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(23)	2	(29)		39
Other comprehensive income (loss) before reclassifications	36	(42)	31		(74)
Amounts reclassified from accumulated other comprehensive income (loss)	14	(1)	25		(6)
Total other comprehensive income (loss), net of tax	50	(43)	56		(80)
Ending balance	27	(41)	27		(41)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(12)	(61)	(21)		(85)
Other comprehensive income (loss) before reclassifications	(17)	9	(8)		33
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0		0
Total other comprehensive income (loss), net of tax	(17)	9	(8)		33
Ending balance	$ (29)	$ (52)	$ (29)		$ (52)

[1] Derived from audited Consolidated Financial Statements.