Commitments - Additional Information (Details) - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2014	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Loss Contingencies [Line Items]
Letters of credit	$ 2,219,000,000		$ 2,219,000,000			$ 2,041,000,000
Margin account balance held by the brokerage clearing agent	13,000,000		13,000,000			13,000,000
Amount in excess of amounts reserved	27,000,000		27,000,000
Credit loss reserve	1,143,000,000	$ 1,091,000,000	1,143,000,000	$ 1,091,000,000	$ 1,115,000,000	1,103,000,000	$ 1,077,000,000	$ 1,196,000,000
Residential Mortgage
Loss Contingencies [Line Items]
Amount in excess of amounts reserved	11,000,000		11,000,000
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	7,000,000	6,000,000	7,000,000	6,000,000	$ 7,000,000	6,000,000	7,000,000	$ 9,000,000
Outstanding Repurchase Demand Inventory	5,000,000		5,000,000			1,000,000
Outstanding balances on residential mortgage loans sold with credit recourse	$ 239,000,000		$ 239,000,000			$ 272,000,000
Delinquency Rates	2.00%		2.00%			2.20%
Credit loss reserve	$ 4,000,000		$ 4,000,000			$ 5,000,000
Repurchased Outstanding Principal	7,000,000	4,000,000	20,000,000	11,000,000
Repurchase Demand Request	10,000,000	$ 6,000,000	38,000,000	$ 17,000,000
Secured Debt
Loss Contingencies [Line Items]
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities	85,000,000		85,000,000			62,000,000
Standby Letters of Credit
Loss Contingencies [Line Items]
Reserve for unfunded commitments	$ 28,000,000		$ 28,000,000			$ 17,000,000
Standby letters of credit as a percentage of total letters of credit	99.00%		99.00%			99.00%
Standby Letters of Credit | Secured Debt
Loss Contingencies [Line Items]
Standby letters of credit as a percentage of total letters of credit	63.00%		63.00%			60.00%
Variable Rate Demand Note
Loss Contingencies [Line Items]
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs	$ 405,000,000		$ 405,000,000			$ 481,000,000
Letters of credit	3,000,000		3,000,000			6,000,000
Total Variable Rate Demand Notes	408,000,000		408,000,000			487,000,000
Letters of credit issued by the Bancorp related to variable rate demand notes	215,000,000		215,000,000			256,000,000
Variable Rate Demand Note | Trading Securities
Loss Contingencies [Line Items]
Total Variable Rate Demand Notes	0		0			9,000,000
Other Liabilities
Loss Contingencies [Line Items]
Reserve for unfunded commitments	154,000,000		154,000,000			131,000,000
Visa
Loss Contingencies [Line Items]
Recorded share of litigation formally settled by Visa and for probable future litigation settlements	146,000,000		146,000,000			$ 125,000,000
Visa IPO, shares of Visa's Class B common stock received															10.1
Visa Class B shares carryover basis															$ 0
Escrow Deposit	$ 300,000,000		$ 300,000,000				$ 600,000,000		$ 450,000,000	$ 150,000,000	$ 1,565,000,000	$ 400,000,000	$ 800,000,000	$ 500,000,000	$ 3,000,000,000