Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	May. 31, 2015 shares	Dec. 31, 2015 USD ($) OfferingPeriods $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	May. 31, 2014 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash proceeds received		$ 77	$ 93	$ 132
Excess tax benefits associated with employee stock plan		$ 15	$ 5	$ 10
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 | shares		786,000	774,000	928,000
Shares available under employee stock plans | shares		3,200,000
Number of offering periods | OfferingPeriods		2
Additional shares approved for future issuance | shares	3,000,000
Increase in annual compensation expense due to employee stock plan		$ 6	$ 6	$ 6
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 | shares		24,400,000
Maximum number of shares authorized for issuance under stock incentive plan | shares					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 | shares					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		$ 64	59	54
Deferred income tax benefits included in provision for income taxes		26	23	21
Excess tax benefits associated with employee stock plan		15	5	10
Currently unrecognized compensation expense that will be recognized in future periods for unvested RSU, PSU and stock option awards issued and outstanding		$ 48
Weighted average period of under which unrecognized compensation expenses associated with all unvested awards currently outstanding is expected to be recognized		1 year 6 months
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 | shares		156,000
Total fair market value of vested awards		$ 13	3	1
Vested deferred units outstanding | shares		84,000
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 | shares		385,000
Total fair market value of vested awards		$ 35	8	14
Vested deferred units outstanding | shares		364,000
Range of performance share units awarded at end of three year period range		0% to 200% of the targeted amount
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%
Performance Share Units [Member] | First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested shares issued, percentage of the established target		96.60%
Deferred Units [Member] | Employee Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested deferred units outstanding | shares		423,000
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		$ 77	93	132
Aggregate intrinsic value of stock options exercised		$ 37	$ 27	$ 41
Fair value of stock options granted | $ / shares		$ 5.56	$ 4.55	$ 4.26
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%