Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash proceeds received	$ 93	$ 132	$ 43
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	30 days
Price at which employees are able to purchase shares of common stock of company at end of each offering period	85.00%
The number of shares newly issued during the reporting period under the plan	774,000	928,000	1,000,000
Shares available under employee stock plans	1,000,000
Number of offering periods	2
Increase in annual compensation expense due to employee stock plan	6	6	7
Increase in annual compensation expense due to employee stock plan, net of tax	4	4	4
2014 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available under employee stock plans	25,900,000
Maximum number of shares authorized for issuance under stock incentive plan				23,800,000
2009 Stock Incentive Plan Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available under employee stock plans				1,100,000
Employee Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in annual compensation expense due to employee stock plan	59	54	22
Deferred income tax benefits included in provision for income taxes	23	21	9
Currently unrecognized compensation expense that will be recognized in future periods for unvested RSU, PSU and stock option awards issued and outstanding	46
Weighted average period of under which unrecognized compensation expenses associated with all unvested awards currently outstanding is expected to be recognized	1 year 4 months 24 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock option description of vesting methods	Vest in 25% increments on the first two anniversaries of the date of grant with the remaining 50% vesting on the third anniversary
Term of options	10 years
Cash proceeds received	93	132	43
Tax benefits realized from stock option exercises	5	10	5
Aggregate intrinsic value of stock options exercised	27	41	15
Fair value of stock options granted	$ 4.55	$ 4.26	$ 4.66
Share-based compensation arrangement by share-based payment award, fair value assumptions, method used	Black-Scholes option pricing model
Stock Options [Member] | First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	12 months
Vested shares issued, percentage of the established target	25.00%
Stock Options [Member] | Second Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	12 months
Vested shares issued, percentage of the established target	25.00%
Stock Options [Member] | Third Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	12 months
Vested shares issued, percentage of the established target	50.00%
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
The number of shares newly issued during the reporting period under the plan	42,000
Total fair market value of vested awards	3	1	11
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
The number of shares newly issued during the reporting period under the plan	106,000
Total fair market value of vested awards	$ 8	$ 14	$ 32
Range of performance share units awarded at end of three year period range	0% to 200% of the targeted amount
Vested shares issued, percentage of the established target	60.00%
Performance Share Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of potential payout percentage of performance share units awarded at end of three year period range	0.00%
Performance Share Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of potential payout percentage of performance share units awarded at end of three year period range	200.00%
Deferred Units [Member] | Employee Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested deferred units outstanding	295,000