Financial Instruments (Cash, Cash Equivalents and Marketable Securities Measured at Adjusted Cost, Gross Unrealized Gains, Gross Unrealized Losses, and Fair Value By Significant Investment Category) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	$ 69,543	$ 63,935
Gross Unrealized Gains	531	752
Gross Unrealized Losses	(294)	(292)
Fair Value	69,780	64,395
Cash and Cash Equivalents	18,453	18,347	$ 19,620
Marketable Securities	51,327	46,048
Cash
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	12,391	9,863
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	12,391	9,863
Cash and Cash Equivalents	12,391	9,863
Marketable Securities	0	0
Level 1
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	18,350	18,840
Gross Unrealized Gains	329	465
Gross Unrealized Losses	(32)	(68)
Fair Value	18,647	19,237
Cash and Cash Equivalents	2,114	3,660
Marketable Securities	16,533	15,577
Level 1 | Money market and other funds
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	2,114	2,532
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	2,114	2,532
Cash and Cash Equivalents	2,114	2,532
Marketable Securities	0	0
Level 1 | U.S. government notes
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	15,258	15,320
Gross Unrealized Gains	63	37
Gross Unrealized Losses	0	(4)
Fair Value	15,321	15,353
Cash and Cash Equivalents	0	1,128
Marketable Securities	15,321	14,225
Level 1 | Marketable equity securities
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	978	988
Gross Unrealized Gains	266	428
Gross Unrealized Losses	(32)	(64)
Fair Value	1,212	1,352
Cash and Cash Equivalents	0	0
Marketable Securities	1,212	1,352
Level 2
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	38,802	35,232
Gross Unrealized Gains	202	287
Gross Unrealized Losses	(262)	(224)
Fair Value	38,742	35,295
Cash and Cash Equivalents	3,948	4,824
Marketable Securities	34,794	30,471
Level 2 | Money market and other funds
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	2,055	1,762
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	2,055	1,762
Cash and Cash Equivalents	2,055	1,762
Marketable Securities	0	0
Level 2 | Time deposits(1)
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	3,161	2,409
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	3,161	2,409
Cash and Cash Equivalents	1,871	2,309
Marketable Securities	1,290	100
Level 2 | Fixed-income bond funds(3)
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	370	385
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(54)	(38)
Fair Value	316	347
Cash and Cash Equivalents	0	0
Marketable Securities	316	347
Level 2 | U.S. government agencies
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	1,752	2,327
Gross Unrealized Gains	5	8
Gross Unrealized Losses	0	(1)
Fair Value	1,757	2,334
Cash and Cash Equivalents	0	750
Marketable Securities	1,757	1,584
Level 2 | Foreign government bonds
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	2,042	1,828
Gross Unrealized Gains	17	22
Gross Unrealized Losses	(13)	(10)
Fair Value	2,046	1,840
Cash and Cash Equivalents	0	0
Marketable Securities	2,046	1,840
Level 2 | Municipal securities
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	4,008	3,370
Gross Unrealized Gains	20	33
Gross Unrealized Losses	(16)	(6)
Fair Value	4,012	3,397
Cash and Cash Equivalents	22	3
Marketable Securities	3,990	3,394
Level 2 | Corporate debt securities
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	13,600	11,499
Gross Unrealized Gains	88	114
Gross Unrealized Losses	(114)	(122)
Fair Value	13,574	11,491
Cash and Cash Equivalents	0	0
Marketable Securities	13,574	11,491
Level 2 | Agency residential mortgage-backed securities
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	8,296	8,196
Gross Unrealized Gains	70	109
Gross Unrealized Losses	(63)	(42)
Fair Value	8,303	8,263
Cash and Cash Equivalents	0	0
Marketable Securities	8,303	8,263
Level 2 | Asset-backed securities
Cash, cash equivalents and marketable securities [Line Items]
Adjusted Cost	3,518	3,456
Gross Unrealized Gains	2	1
Gross Unrealized Losses	(2)	(5)
Fair Value	3,518	3,452
Cash and Cash Equivalents	0	0
Marketable Securities	$ 3,518	$ 3,452