Stock-Based Compensation (Stock-Based Compensation - Additional Information) (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Stock Ownership Plan (ESOP) Disclosures
The Bancorp's total overhang (potential dilution from share-based compensation)	9.00%
SARs, RSAs, RSUs, stock options and PSAs outstanding as a percentage of issued shares	6.00%
Annual return on tangible common equity performance hurdle	2.00%
Stock-based compensation expense	$ 118	$ 111	$ 100
Income tax benefit related to stock-based compensation expense	$ 41	$ 39	$ 36
2014 Incentive Compensation Plan
Employee Stock Ownership Plan (ESOP) Disclosures
Stock authorized for issuance			6,000,000
Stock Appreciation Rights Granted
Employee Stock Ownership Plan (ESOP) Disclosures
Vesting period of share based compensation	ratably over a three or four year period of continued employment
Weighted-average grant-date fair value per share	$ 8.55	$ 5.16	$ 5.52
Shares granted	3,672,000	6,379,000	5,219,000
Restricted Stock Awards
Employee Stock Ownership Plan (ESOP) Disclosures
Vesting period of share based compensation	after three or four years or ratably over three or four years of continued employment.
Stock-based compensation expense	$ 21
Total grant-date fair value	$ 39	$ 55	$ 43
Weighted-average period over which expense is expected to be recognized	1 year 3 months 18 days
Shares granted	7,000	3,000	4,250,000
Restricted Stock Units
Employee Stock Ownership Plan (ESOP) Disclosures
Vesting period of share based compensation	after three or four years or ratably over three or four years of continued employment.
Stock-based compensation expense	$ 91
Total grant-date fair value	$ 21	$ 2	$ 2
Weighted-average period over which expense is expected to be recognized	2 years 7 months 6 days
Shares granted	3,652	5,029,000	377,000
Stock options
Employee Stock Ownership Plan (ESOP) Disclosures
Intrinsic value of stock options exercised			$ 1
Cash received from stock options exercised		$ 1	$ 2
Stock options vested	0	0	0
Performance Share Awards
Employee Stock Ownership Plan (ESOP) Disclosures
Vesting period of share based compensation	three year cliff vesting terms
Weighted-average grant-date fair value per share	$ 26.52	$ 14.87	$ 19.48
Shares granted	407,069	583,608	458,355
Employee stock purchase plan
Employee Stock Ownership Plan (ESOP) Disclosures
Stock-based compensation expense	$ 1	$ 1	$ 1
Match on qualifying employees purchase of shares of the Bancorp's common stock	15.00%
Stock purchased by plan participants	475,466	684,885	617,829

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Company Match on Qualified Employee Stock Purchases

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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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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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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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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 cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

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The number of grants made 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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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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