Unrealized Losses on Debt Investments (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Jun. 30, 2021
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	$ 44,925	$ 11,389
Less than 12 Months - Unrealized Losses	(1,185)	(132)
12 Months or Greater - Fair Value	2,889	127
12 Months or Greater - Unrealized Losses	(310)	(3)
Total Fair Value	47,814	11,516
Total Unrealized Losses	(1,495)	(135)
U.S. government and agency securities
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	35,798	5,294
Less than 12 Months - Unrealized Losses	(918)	(111)
12 Months or Greater - Fair Value	2,308	0
12 Months or Greater - Unrealized Losses	(262)	0
Total Fair Value	38,106	5,294
Total Unrealized Losses	(1,180)	(111)
Foreign government bonds
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	419	3,148
Less than 12 Months - Unrealized Losses	(6)	(1)
12 Months or Greater - Fair Value	30	5
12 Months or Greater - Unrealized Losses	(4)	(1)
Total Fair Value	449	3,153
Total Unrealized Losses	(10)	(2)
Mortgage- and asset-backed securities
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	450	1,211
Less than 12 Months - Unrealized Losses	(13)	(5)
12 Months or Greater - Fair Value	33	87
12 Months or Greater - Unrealized Losses	(1)	(1)
Total Fair Value	483	1,298
Total Unrealized Losses	(14)	(6)
Corporate notes and bonds
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	8,133	1,678
Less than 12 Months - Unrealized Losses	(241)	(8)
12 Months or Greater - Fair Value	461	34
12 Months or Greater - Unrealized Losses	(36)	(1)
Total Fair Value	8,594	1,712
Total Unrealized Losses	(277)	(9)
Municipal securities
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	125	58
Less than 12 Months - Unrealized Losses	(7)	(7)
12 Months or Greater - Fair Value	57	1
12 Months or Greater - Unrealized Losses	(7)	0
Total Fair Value	182	59
Total Unrealized Losses	$ (14)	$ (7)