Consolidated Statements of Other Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 3,039	$ 1,019	$ 1,043
Other comprehensive income (loss), net of tax:
Net gains (losses) on available-for-sale securities	(3)	7	(5)
Net gains (losses) on derivative instruments	17	88	(121)
Foreign currency translation adjustments	(34)	(21)	18
Total other comprehensive income (loss), net of tax	(20)	74	(108)
Total comprehensive income (loss)	$ 3,019	$ 1,093	$ 935