Available-for-sale investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Amortized cost, gross unrealized gains, gross unrealized losses and estimated fair values of available-for-sale investments by type of security

The amortized cost, gross unrealized gains, gross unrealized losses and fair values of available-for-sale investments by type of security were as follows (in millions):

	Year ended December 31, 2017
Type of security	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. Treasury securities	$	8,313	$	1	$	(72	)	$	8,242
Other government-related debt securities:
U.S.	225		—		(2		)	223
Foreign and other	2,415		18		(11		)	2,422
Corporate debt securities:
Financial	10,089		17		(34		)	10,072
Industrial	9,688		34		(52		)	9,670
Other	1,393		3		(6		)	1,390
Residential mortgage-backed securities	2,198		—		(30		)	2,168
Other mortgage- and asset-backed securities	2,312		—		(15		)	2,297
Money market mutual funds	3,245		—		—			3,245
Other short-term interest-bearing securities	1,440		—		—			1,440
Total interest-bearing securities	41,318		73		(222		)	41,169
Equity securities	135		14		—			149
Total available-for-sale investments	$	41,453	$	87	$	(222	)	$	41,318

	Year ended December 31, 2016
Type of security	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. Treasury securities	$	6,681	$	1	$	(68	)	$	6,614
Other government-related debt securities:
U.S.	302		—		(3		)	299
Foreign and other	1,784		9		(34		)	1,759
Corporate debt securities:
Financial	8,476		21		(37		)	8,460
Industrial	8,793		59		(63		)	8,789
Other	1,079		5		(7		)	1,077
Residential mortgage-backed securities	1,968		1		(29		)	1,940
Other mortgage- and asset-backed securities	1,731		1		(13		)	1,719
Money market mutual funds	2,782		—		—			2,782
Other short-term interest-bearing securities	4,188		—		—			4,188
Total interest-bearing securities	37,784		97		(254		)	37,627
Equity securities	127		31		(4		)	154
Total available-for-sale investments	$	37,911	$	128	$	(258	)	$	37,781

Fair values of available-for-sale investments by classification in the Consolidated Balance Sheets

The fair values of available-for-sale investments by location in the Consolidated Balance Sheets were as follows (in millions):

	December 31,
Consolidated Balance Sheets location	2017		2016
Cash and cash equivalents	$	3,291	$	2,783
Marketable securities	37,878		34,844
Other assets	149		154
Total available-for-sale investments	$	41,318	$	37,781

Fair values of available-for-sale interest-bearing security investments by contractual maturity

The fair values of available-for-sale interest-bearing security investments by contractual maturity, except for mortgage- and asset-backed securities that do not have a single maturity date, were as follows (in millions):

	December 31,
Contractual maturity	2017		2016
Maturing in one year or less	$	6,733	$	8,393
Maturing after one year through three years	12,820		10,404
Maturing after three years through five years	13,836		12,157
Maturing after five years through ten years	3,263		2,974
Maturing after ten years	52		40
Mortgage- and asset-backed securities	4,465		3,659
Total interest-bearing securities	$	41,169	$	37,627

Available-for-sale securities, continuous unrealized loss position, fair value

Information on the fair values and gross unrealized losses of available-for-sale investments in an unrealized loss position aggregated by type and length of time that the securities have been in a continuous loss position was as follows (in millions):

	Less than 12 months					12 months or greater
Type of security as of December 31, 2017	Fair value		Unrealized losses			Fair value		Unrealized losses
U.S. Treasury securities	$	7,728	$	(70	)	$	195	$	(2	)
Other government-related debt securities:
U.S.	188		(1		)	34		(1		)
Foreign and other	1,163		(9		)	115		(2		)
Corporate debt securities:
Financial	5,928		(28		)	462		(6		)
Industrial	5,760		(43		)	612		(9		)
Other	868		(4		)	117		(2		)
Residential mortgage-backed securities	1,838		(24		)	276		(6		)
Other mortgage- and asset-backed securities	1,777		(12		)	250		(3		)
Total	$	25,250	$	(191	)	$	2,061	$	(31	)

	Less than 12 months					12 months or greater
Type of security as of December 31, 2016	Fair value		Unrealized losses			Fair value		Unrealized losses
U.S. Treasury securities	$	5,774	$	(68	)	$	—	$	—
Other government-related debt securities:
U.S.	201		(3		)	—		—
Foreign and other	1,192		(34		)	17		—
Corporate debt securities:
Financial	3,975		(37		)	44		—
Industrial	3,913		(61		)	149		(2		)
Other	486		(7		)	7		—
Residential mortgage-backed securities	1,631		(26		)	158		(3		)
Other mortgage- and asset-backed securities	1,087		(10		)	118		(3		)
Equity securities	22		(4		)	—		—
Total	$	18,281	$	(250	)	$	493	$	(8	)