Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense for stock-based compensation plans	$ 102,000,000	$ 59,000,000	$ 46,000,000
Total income tax benefit recognized for stock-based compensation plans	$ 38,000,000	$ 22,000,000	$ 17,000,000
Common Shares available for future grant under compensation plans	48,840,093
Maximum percentage of outstanding common stock that may be granted as options	6.00%
Rolling period in which a certain percentage of common stock cannot be granted as options	3 years
Exercise rate of stock options granted to employees	25.00%
Common shares, shares issued (in shares)	1,256,702,081	1,016,969,905
Weighted-average grant-date fair value of options	$ 2.14	$ 4.33	$ 5.26
Number of options, exercised	2,849,010
Total intrinsic value of exercised options	$ 12,000,000	$ 14,000,000	$ 16,000,000
Cash received from options exercised	32,000,000	22,000,000	26,000,000
Actual tax benefit realized for tax deductions from options exercised	$ 2,000,000	$ 2,000,000	$ 2,000,000
Mandatory deferred incentive awards, vesting rate (as a percent)	25.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares, shares issued (in shares)	3,000,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options, exercised	2,849,010	2,496,965	3,050,309
Unrecognized compensation cost related to nonvested options expected to vest	$ 3,000,000
Weighted-average period	2 years 9 months 6 days
Deferred Cash Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Restricted Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Equity Based Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Cash Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Deferred Compensation Plans and Other Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value granted (in dollars per share)	$ 11.46	$ 14.22	$ 13.53
Deferred Compensation Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested options expected to vest	$ 19,000,000
Weighted-average period	1 year 10 months 15 days
Fair value of units/shares vested	$ 16,000,000	$ 15,000,000	$ 12,000,000
Long-Term Incentive Compensation Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested options expected to vest	$ 70,000,000
Weighted-average period	2 years 3 months 11 days
Number of performance units vested	1,915,239	1,075,082
Fair value of units/shares vested	$ 57,000,000	$ 39,000,000	$ 36,000,000
Weighted-average grant-date fair value granted (in dollars per share)	$ 10.49	$ 13.99	$ 13.00
Long-Term Incentive Compensation Program [Member] \| Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units/shares vested	$ 21,000,000	$ 15,000,000
Discounted Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee discount on the purchase of stock through Discounted Stock Purchase Plan	10.00%
Purchases are limited to any month	$ 10,000
Purchases are limited to any calendar year	$ 50,000
Issuance of common shares	310,604	250,913	238,257
Weighted-average cost of common shares issued under the plan	11.04	12.55	12.06

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Maximum Limit Of Purchase Of Shares In Any Calendar Year

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Maximum Limit Of Purchase Of Shares In Any Month

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Opportunities For Employees To Purchase Common Shares At Discount

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Share Based Compensation Arrangement By Share Based Payment Award Vesting Percentage Of Stock Options Granted To Employees other than executive officers

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Weighted Average Cost Of Shares Issued Under Plan

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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Number of share instruments newly issued under a share-based compensation plan.

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Number of options vested.

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Number of share options (or share units) exercised during the current period.

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