Annual report pursuant to Section 13 and 15(d)

VIEs - Trust Preferred Securities (Details)

v3.8.0.1
VIEs - Trust Preferred Securities (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2017
USD ($)
Variable Interest Entity [Line Items]  
Principal amount of subordinated note/ debenture issued to trust $ 9,335
Huntington Capital I  
Variable Interest Entity [Line Items]  
Rate 2.39%
Principal amount of subordinated note/ debenture issued to trust $ 70
Investment in unconsolidated subsidiary $ 6
Huntington Capital I | London Interbank Offered Rate (LIBOR) [Member]  
Variable Interest Entity [Line Items]  
Basis spread on variable rate 0.70%
Huntington Capital II  
Variable Interest Entity [Line Items]  
Rate 2.32%
Principal amount of subordinated note/ debenture issued to trust $ 32
Investment in unconsolidated subsidiary $ 3
Huntington Capital II | London Interbank Offered Rate (LIBOR) [Member]  
Variable Interest Entity [Line Items]  
Basis spread on variable rate 0.625%
Sky Financial Capital Trust III  
Variable Interest Entity [Line Items]  
Rate 3.09%
Principal amount of subordinated note/ debenture issued to trust $ 72
Investment in unconsolidated subsidiary $ 2
Sky Financial Capital Trust III | London Interbank Offered Rate (LIBOR) [Member]  
Variable Interest Entity [Line Items]  
Basis spread on variable rate 1.40%
Sky Financial Capital Trust IV  
Variable Interest Entity [Line Items]  
Rate 3.09%
Principal amount of subordinated note/ debenture issued to trust $ 74
Investment in unconsolidated subsidiary $ 2
Sky Financial Capital Trust IV | London Interbank Offered Rate (LIBOR) [Member]  
Variable Interest Entity [Line Items]  
Basis spread on variable rate 1.33%
Camco Financial Trust  
Variable Interest Entity [Line Items]  
Rate 3.02%
Principal amount of subordinated note/ debenture issued to trust $ 4
Investment in unconsolidated subsidiary 1
Variable Interest Entity, Not Primary Beneficiary  
Variable Interest Entity [Line Items]  
Principal amount of subordinated note/ debenture issued to trust 252
Investment in unconsolidated subsidiary $ 14