Summary of Stock Option and Restricted Stock Activity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 8	[1]	$ 11	[1]	$ 15	[1]
Fair value of vested RSUs	11	[1]	1	[1]	3	[1]
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	1
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	7,106,639
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0		552,998		859,390
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	$ 9.06		$ 9.06		$ 9.06		$ 9.06
Stock Options Shares
Beginning balance	10,929,371		13,311,652		15,869,417
Exercised/vested	(426,889)		(712,981)		(973,048)
Cancelled/expired/forfeited	(2,774,725)		(2,222,298)		(2,444,107)
Ending balance	7,727,757		10,929,371		13,311,652		15,869,417
Stock Options Weighted Average Exercise Price
Beginning balance	$ 49.86		$ 50.15		$ 48.53
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0.00		$ 27.41		$ 21.92
Cancelled/expired/forfeited	$ 71.10		$ 56.55		$ 45.73
Ending balance	$ 43.84		$ 49.86		$ 50.15		$ 48.53
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 45.47
Restricted Stock Shares
Beginning balance	3,983,538		3,686,321		4,622,167
Ending balance	2,929,859		3,983,538		3,686,321		4,622,167
Restricted Stock Deferred Compensation
Beginning balance	50		48		48
Ending balance	21		50		48		48
Restricted Stock Weighted Average Grant Price
Beginning balance	$ 27.04		$ 25.56		$ 21.46
Ending balance	$ 26.45		$ 27.04		$ 25.56		$ 21.46
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 20.86		$ 16.94		$ 9.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 150.45		$ 150.45		$ 150.45		$ 150.45
Share Based Compensation Shares Authorized Under Stock Option Plans Grants in Period Exercise Price Range Lower Range Limit	$ 0.00		$ 27.41		$ 21.67
Share Based Compensation Shares Authorized Under Stock Option Plans Grants in Period Exercise Price Range Upper Range Limit	$ 0.00		$ 27.41		$ 23.68
Share Based Compensation Shares Authorized Under Stock Option Plans Vested in Period Exercise Price Range Lower Range Limit	$ 9.06		$ 9.06		$ 9.06
Share Based Compensation Shares Authorized Under Stock Option Plans Vested in Period Exercise Price Range Upper Range Limit	$ 32.27		$ 27.79		$ 22.69
Share Based Compensation Shares Authorized Under Stock Option Plans Forfeitures and Expirations in Period Exercise Price Range Lower Range Limit	$ 23.70		$ 21.67		$ 9.06
Share Based Compensation Shares Authorized Under Stock Option Plans Forfeitures and Expirations in Period Exercise Price Range Upper Range Limit	$ 149.81		$ 118.18		$ 85.06
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	28	[1]	21	[1]	31	[1]
Restricted Stock Shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	21,427		1,314,277		1,737,202
Exercised/vested	(957,308)		(821,636)		(2,148,764)
Cancelled/expired/forfeited	(117,798)		(195,424)		(524,284)
Restricted Stock Deferred Compensation
Granted	0		39		38
Cancelled/expired/forfeited	(2)		(5)		(8)
Amortization of restricted stock compensation	(27)		(32)		(30)
Restricted Stock Weighted Average Grant Price
Granted	$ 39.20		$ 29.58		$ 21.97
Exercised/vested	$ 29.31		$ 25.95		$ 14.62
Cancelled/expired/forfeited	$ 25.60		$ 27.41		$ 19.91
Deferred Compensation Arrangement, Vested	$ 0		$ 0		$ 0
Restricted Stock Units (RSUs) [Member]
Restricted Stock Shares
Beginning balance	2,496,178		1,930,646		405,475
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1,590,075		593,093		1,717,148
Exercised/vested	(338,196)		(41,790)		109,149
Cancelled/expired/forfeited	58,793		14,229		(82,828)
Ending balance	3,689,264		2,496,178		1,930,646
Restricted Stock Weighted Average Grant Price
Beginning balance	$ 26.69		$ 25.16		$ 35.98
Granted	$ 36.67		$ 24.65		$ 22.65
Exercised/vested	$ 32.80		$ 28.73		$ 27.73
Cancelled/expired/forfeited	$ 37.73		$ 20.54		$ 22.79
Ending balance	$ 31.15		$ 26.69		$ 25.16

[1] 1 Measured as of the grant date.