Investment Components (Detail) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		$ 126,703
Debt investments, Recorded Basis		127,267
Derivative, net		188		$ 386
Cash and cash equivalents		11,212	$ 6,638	11,946	$ 9,221	$ 12,859	$ 7,663
Short-term Investments		120,406		121,822
Equity Investments		2,403		1,862
Cash, cash equivalents, and investments		134,021		135,630
Equity investments
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis		2,786		2,109
Cash and cash equivalents		383		246
Short-term Investments		0		1
Equity Investments		2,403		1,862
Equity investments | Other
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis		2,133		1,558
Cash and cash equivalents		0		0
Short-term Investments		0		1
Equity Investments		2,133		1,557
Equity investments | Level 1
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis		653		533
Cash and cash equivalents		383		246
Short-term Investments		0		0
Equity Investments		270		287
Equity investments | Level 3
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis				18
Cash and cash equivalents				0
Short-term Investments				0
Equity Investments				18
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cash		3,886		3,942
Cash and cash equivalents		3,886		3,942
Short-term Investments		0		0
Equity Investments		0		0
Derivatives, net
Cash, Cash Equivalents and Investments [Line Items]
Derivative, net	[1]	82		104
Cash and cash equivalents	[1]	0		0
Short-term Investments	[1]	82		104
Equity Investments	[1]	0		0
Debt investments
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		126,703		130,597
Debt investments, Unrealized Gains		944		125
Debt investments, Unrealized Losses		(380)		(1,247)
Debt investments, Recorded Basis		127,267		129,475
Cash and cash equivalents		6,943		7,758
Short-term Investments		120,324		121,717
Equity Investments		0		0
Debt investments | Commercial Paper | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		1,623		2,513
Debt investments, Unrealized Gains		0		0
Debt investments, Unrealized Losses		0		0
Debt investments, Recorded Basis		1,623		2,513
Cash and cash equivalents		1,424		2,215
Short-term Investments		199		298
Equity Investments		0		0
Debt investments | Certificates of deposit | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		1,738		2,058
Debt investments, Unrealized Gains		0		0
Debt investments, Unrealized Losses		0		0
Debt investments, Recorded Basis		1,738		2,058
Cash and cash equivalents		1,517		1,865
Short-term Investments		221		193
Equity Investments		0		0
Debt investments | U.S. government securities | Level 1
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		105,168		108,120
Debt investments, Unrealized Gains		836		62
Debt investments, Unrealized Losses		(342)		(1,167)
Debt investments, Recorded Basis		105,662		107,015
Cash and cash equivalents		0		2,280
Short-term Investments		105,662		104,735
Equity Investments		0		0
Debt investments | U.S. agency securities | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		290		1,742
Debt investments, Unrealized Gains		0		0
Debt investments, Unrealized Losses		0		0
Debt investments, Recorded Basis		290		1,742
Cash and cash equivalents		0		1,398
Short-term Investments		290		344
Equity Investments		0		0
Debt investments | Foreign government bonds | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		6,753		5,063
Debt investments, Unrealized Gains		2		1
Debt investments, Unrealized Losses		(10)		(10)
Debt investments, Recorded Basis		6,745		5,054
Cash and cash equivalents		4,002		0
Short-term Investments		2,743		5,054
Equity Investments		0		0
Debt investments | Foreign government bonds | Level 1
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis				22
Debt investments, Unrealized Gains				0
Debt investments, Unrealized Losses				0
Debt investments, Recorded Basis				22
Cash and cash equivalents				0
Short-term Investments				22
Equity Investments				0
Debt investments | Mortgage- and asset-backed securities | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		3,427		3,864
Debt investments, Unrealized Gains		5		4
Debt investments, Unrealized Losses		(8)		(13)
Debt investments, Recorded Basis		3,424		3,855
Cash and cash equivalents		0		0
Short-term Investments		3,424		3,855
Equity Investments		0		0
Debt investments | Corporate notes and bonds | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		7,426		6,929
Debt investments, Unrealized Gains		60		21
Debt investments, Unrealized Losses		(19)		(56)
Debt investments, Recorded Basis		7,467		6,894
Cash and cash equivalents		0		0
Short-term Investments		7,467		6,894
Equity Investments		0		0
Debt investments | Corporate notes and bonds | Level 3
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		15		15
Debt investments, Unrealized Gains		0		0
Debt investments, Unrealized Losses		0		0
Debt investments, Recorded Basis		15		15
Cash and cash equivalents		0		0
Short-term Investments		15		15
Equity Investments		0		0
Debt investments | Municipal securities | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		263		271
Debt investments, Unrealized Gains		41		37
Debt investments, Unrealized Losses		(1)		(1)
Debt investments, Recorded Basis		303		307
Cash and cash equivalents		0		0
Short-term Investments		303		307
Equity Investments		$ 0		$ 0

[1] Refer to Note 5 – Derivatives for further information on the fair value of our derivative instruments.