Huntington Bancshares Incorporated Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details)

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	2 years 6 months
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 5,377	$ 8,375
Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	5,365	8,375
Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	12	0
Subordinated notes
Notional Disclosures [Abstract]
Derivative, Notional Amount	375	950
Subordinated notes \| Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	375	950
Subordinated notes \| Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
Securities Investment [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	12
Securities Investment [Member] \| Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	0
Securities Investment [Member] \| Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	12
Other long-term debt
Notional Disclosures [Abstract]
Derivative, Notional Amount	4,990	7,425
Other long-term debt \| Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	4,990	7,425
Other long-term debt \| Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 0	$ 0
Asset conversion swaps Receive Fixed Generic [Member]
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	1 year 8 months 12 days	0 years
Liability conversion swaps Receive Fixed Generic [Member]
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	2 years 2 months 12 days	2 years 6 months