Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 854	$ 255	$ 2,275	$ 548
Other comprehensive income (loss), net of tax:
Net gains (losses) on available-for-sale securities	0	1	3	1
Net gains (losses) on derivative instruments	16	3	25	96
Foreign currency translation adjustments	(9)	3	(8)	(12)
Total other comprehensive income (loss), net of tax	7	7	20	85
Total comprehensive income (loss)	$ 861	$ 262	$ 2,295	$ 633