Cash and equivalents, marketable securities and short-term investments (Tables)

12 Months Ended

Dec. 31, 2015

Cash and equivalents, marketable securities and short-term investments

Cash, cash equivalents, and short-term investments

	December 31, 2015
($ in millions)	Cost basis		Gross unrealized gains		Gross unrealized losses			Fair value		Cash and equivalents		Marketable securities and short-term investments
Cash		1,837							1,837		1,837
Time deposits		2,821							2,821		2,717		104
Other short-term investments		231							231				231
Debt securities available-for-sale:
—U.S. government obligations		120		2		(1	)		121		—		121
—Other government obligations		2		—		—			2		—		2
—Corporate		519		1		(1	)		519		11		508
Equity securities available-for-sale		658		9		—			667		—		667
Total		6,188		12		(2	)		6,198		4,565		1,633

	December 31, 2014
($ in millions)	Cost basis		Gross unrealized gains		Gross unrealized losses			Fair value		Cash and equivalents		Marketable securities and short-term investments
Cash		2,218							2,218		2,218
Time deposits		3,340							3,340		3,140		200
Other short-term investments		225							225				225
Debt securities available-for-sale:
—U.S. government obligations		135		2		(1	)		136		—		136
—Other government obligations		2		—		—			2		—		2
—Corporate		734		4		(1	)		737		85		652
Equity securities available-for-sale		98		12		—			110		—		110
Total		6,752		18		(2	)		6,768		5,443		1,325

Contractual maturities of debt securities classified as available-for-sale and held-to-maturity

	December 31, 2015
	Available-for-sale				Held-to-maturity
($ in millions)	Cost basis		Fair value		Cost basis		Fair value
Less than one year		430		430		—		—
One to five years		160		161		99		110
Six to ten years		51		51		—		—
Total		641		642		99		110