Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 185	$ 854	$ 550	$ 2,275
Other comprehensive income (loss), net of tax:
Net gains (losses) on available-for-sale securities	(3)	0	8	3
Net gains (losses) on derivative instruments	(43)	16	(80)	25
Foreign currency translation adjustments	9	(9)	33	(8)
Total other comprehensive income (loss), net of tax	(37)	7	(39)	20
Total comprehensive income (loss)	$ 148	$ 861	$ 511	$ 2,295