Available-for-sale investments (Tables)

12 Months Ended

Dec. 31, 2015

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 estimated fair values of available-for-sale investments by type of security were as follows (in millions):

Type of security as of December 31, 2015	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
U.S. Treasury securities	$	4,298	$	—	$	(24	)	$	4,274
Other government-related debt securities:
U.S.	536		—		(2		)	534
Foreign and other	1,768		7		(36		)	1,739
Corporate debt securities:
Financial	7,904		7		(40		)	7,871
Industrial	7,961		11		(136		)	7,836
Other	905		1		(21		)	885
Residential mortgage-backed securities	1,484		1		(15		)	1,470
Other mortgage- and asset-backed securities	2,524		—		(55		)	2,469
Money market mutual funds	3,370		—		—			3,370
Other short-term interest-bearing securities	528		—		—			528
Total interest-bearing securities	31,278		27		(329		)	30,976
Equity securities	88		48		—			136
Total available-for-sale investments	$	31,366	$	75	$	(329	)	$	31,112

Type of security as of December 31, 2014	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
U.S. Treasury securities	$	3,632	$	22	$	(8	)	$	3,646
Other government-related debt securities:
U.S.	530		1		(3		)	528
Foreign and other	1,572		21		(24		)	1,569
Corporate debt securities:
Financial	6,036		21		(16		)	6,041
Industrial	6,394		23		(66		)	6,351
Other	650		3		(4		)	649
Residential mortgage-backed securities	1,708		4		(10		)	1,702
Other mortgage- and asset-backed securities	1,837		—		(41		)	1,796
Money market mutual funds	3,004		—		—			3,004
Other short-term interest-bearing securities	1,302		—		—			1,302
Total interest-bearing securities	26,665		95		(172		)	26,588
Equity securities	98		48		(2		)	144
Total available-for-sale investments	$	26,763	$	143	$	(174	)	$	26,732

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

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

	December 31,
Classification in the Consolidated Balance Sheets	2015		2014
Cash and cash equivalents	$	3,738	$	3,293
Marketable securities	27,238		23,295
Other assets — noncurrent	136		144
Total available-for-sale investments	$	31,112	$	26,732

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	2015		2014
Maturing in one year or less	$	4,578	$	4,936
Maturing after one year through three years	9,370		6,829
Maturing after three years through five years	9,932		7,840
Maturing after five years through ten years	3,087		3,267
Maturing after ten years	70		218
Mortgage- and asset-backed securities	3,939		3,498
Total interest-bearing securities	$	30,976	$	26,588

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

The unrealized losses on available-for-sale investments and their related fair values were as follows (in millions):

	Less than 12 months					12 months or greater
Type of security as of December 31, 2015	Fair value		Unrealized losses			Fair value		Unrealized losses
U.S. Treasury securities	$	4,196	$	(24	)	$	—	$	—
Other government-related debt securities:
U.S.	494		(2		)	20		—
Foreign and other	1,306		(32		)	56		(4		)
Corporate debt securities:
Financial	5,988		(38		)	228		(2		)
Industrial	5,427		(108		)	679		(28		)
Other	807		(19		)	39		(2		)
Residential mortgage-backed securities	804		(8		)	304		(7		)
Other mortgage- and asset-backed securities	1,834		(19		)	561		(36		)
Total	$	20,856	$	(250	)	$	1,887	$	(79	)

	Less than 12 months					12 months or greater
Type of security as of December 31, 2014	Fair value		Unrealized losses			Fair value		Unrealized losses
U.S. Treasury securities	$	1,770	$	(7	)	$	171	$	(1	)
Other government-related debt securities:
U.S.	160		—			178		(3		)
Foreign and other	514		(14		)	159		(10		)
Corporate debt securities:
Financial	3,150		(14		)	158		(2		)
Industrial	3,931		(62		)	222		(4		)
Other	354		(4		)	5		—
Residential mortgage-backed securities	614		(4		)	413		(6		)
Other mortgage- and asset-backed securities	1,071		(8		)	561		(33		)
Equity securities	78		(2		)	—		—
Total	$	11,642	$	(115	)	$	1,867	$	(59	)