Credit Quality (Summary of Average Impaired Loans and Leases and Interest Income by Class) (Parenthetical) (Detail) $ in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2018 USD ($)		Mar. 31, 2017 USD ($)		Dec. 31, 2017
Financing Receivable, Impaired
Average Recorded Investment	$ 1,539		$ 1,835
Number of contracts	2,271	[1],[2]	2,059	[3],[4]
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Impaired
Average Recorded Investment	$ 22		$ 43	[5]
Number of contracts	2	[1],[2]	5	[3],[4]
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied | Variable Interest Entity, Primary Beneficiary
Financing Receivable, Impaired
Average Recorded Investment			$ 26
Number of contracts			5		5

[1] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[2] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[3] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[4] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[5] Excludes five restructured loans associated with a consolidated VIE in which the Bancorp had no continuing credit risk due to the risk being assumed by a third party, with an average recorded investment of $ 26 for the three months ended March 31, 2017. An immaterial amount of interest income was recognized during the three months ended March 31, 2017. Refer to Note 9 for further discussion on the deconsolidation of the VIE associated with these loans in the third quarter of 2017.