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

DERIVATIVE FINANCIAL INSTRUMENTS - Mortgage Banking Activities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Derivative assets:
Total derivative assets	$ 356		$ 322
Derivative liabilities:
Total derivative liabilities	(439)		(331)
Interest rate lock agreements
Derivative assets:
Total derivative assets	6		6
Derivative liabilities:
Total derivative liabilities	1		0
Forward trades and options
Derivative assets:
Total derivative assets	2		1
Derivative liabilities:
Total derivative liabilities	2		0
Derivative used in Mortgage Banking Activities
Derivatives, Fair Value [Line Items]
Gains losses related to derivative instruments Included in Mortgage securities	(8)	$ (1)
Derivative assets:
Total derivative assets	8		7
Derivative liabilities:
Total derivative liabilities	$ 3		$ 0