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

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details)

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	$ 0	$ 1
Mortgage banking income	0	(1)
Securities gains (losses)	0	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	0	1
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee income	0
Derivative Financial Instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	(12)	(6)
Securities gains (losses)	0	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	(12)	(6)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee income	0
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	(1)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Other Expense		(1)
Mortgage banking income	0	0
Securities gains (losses)	0	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	1	(1)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee income	(1)
Asset-backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(2)
Mortgage banking income		0
Securities gains (losses)		(2)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings		(2)
Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	0	0
Mortgage banking income	0	0
Securities gains (losses)	0	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	0	$ 0
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee income	$ 0