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

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Certain Loans Acquired Ending and Unpaid Balances (Details)

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Certain Loans Acquired Ending and Unpaid Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance	$ 75,722		$ 102,380
Loans and Leases Receivable, Allowance	667,996	$ 672,580	638,413	$ 623,064	$ 613,719	$ 597,843
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Allowance	474,576	$ 480,308	451,091	$ 424,507	$ 422,441	$ 398,753
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance	54,942		68,338
Commercial \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance	20,780		34,042
FirstMerit Corporation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance	75,722		102,380
Purchased Credit Impaired, Unpaid Balance	116,838		156,351
Loans and Leases Receivable, Allowance	970		0
FirstMerit Corporation \| Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance	54,942		68,338
Purchased Credit Impaired, Unpaid Balance	81,934		100,031
Loans and Leases Receivable, Allowance	970		0
FirstMerit Corporation \| Commercial \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance	20,780		34,042
Purchased Credit Impaired, Unpaid Balance	34,904		56,320
Loans and Leases Receivable, Allowance	$ 0		$ 0