Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUES OF ASSETS AND LIABILITIES - Balance Sheet Location (Details)

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FAIR VALUES OF ASSETS AND LIABILITIES - Balance Sheet Location (Details) - USD ($)
$ in Millions
Jun. 30, 2018
Dec. 31, 2017
Financial Assets:    
Trading account securities $ 85 $ 86
Available-for-sale securities 14,070 14,869
Held-to-maturity securities 8,682 9,091
Loans held for sale [1] 709 488
Net loans and direct financing leases 71,665 69,426
Derivatives 179 132
Financial Liabilities:    
Deposits 79,587 77,041
Short-term borrowings 2,442 5,056
Long-term borrowings 9,726 9,206
Derivatives 202 86
Reported Value Measurement [Member]    
Financial Assets:    
Cash and short term assets   1,567
Trading account securities 85 86
Available-for-sale securities 14,070 14,869
Held-to-maturity securities 8,682  
Other Securities 597 600
Loans held for sale 709  
Net loans and direct financing leases   69,426
Derivatives   132
Financial Liabilities:    
Deposits 79,587 77,041
Short-term borrowings 2,442 5,056
Long-term borrowings 9,726 9,206
Derivatives 202 86
Estimate of Fair Value Measurement [Member]    
Financial Assets:    
Cash and short term assets 1,423  
Trading account securities 85 86
Available-for-sale securities 14,070 14,869
Held-to-maturity securities 8,391 8,971
Other Securities 597 600
Loans held for sale 713 491
Other securities 21 19
Net loans and direct financing leases 70,996 69,146
Derivatives   132
Financial Liabilities:    
Deposits 79,534 77,010
Short-term borrowings 2,442 5,056
Long-term borrowings 9,889 9,402
Estimate of Fair Value Measurement [Member] | Level 1    
Financial Assets:    
Trading account securities 78  
Available-for-sale securities 6 5
Held-to-maturity securities 0 0
Loans held for sale 0 0
Other securities 21 19
Net loans and direct financing leases 0 0
Financial Liabilities:    
Deposits 0 0
Short-term borrowings 2 0
Long-term borrowings 0 0
Estimate of Fair Value Measurement [Member] | Level 2    
Financial Assets:    
Trading account securities 7  
Available-for-sale securities 10,886 11,673
Held-to-maturity securities 8,391 8,971
Loans held for sale 643 413
Other securities 0 0
Net loans and direct financing leases 50 0
Financial Liabilities:    
Deposits 73,371 73,975
Short-term borrowings 0 0
Long-term borrowings 9,416 8,944
Estimate of Fair Value Measurement [Member] | Level 3    
Financial Assets:    
Trading account securities 0 0
Available-for-sale securities 3,178 3,191
Held-to-maturity securities 0 0
Loans held for sale 70 78
Other securities 0 0
Net loans and direct financing leases 70,946 69,146
Financial Liabilities:    
Deposits 6,163 3,035
Short-term borrowings 2,440 5,056
Long-term borrowings 473 458
Fair Value, Measurements, Recurring [Member]    
Financial Assets:    
Trading account securities 85 86
Available-for-sale securities 14,070 14,869
Derivatives 179 132
Financial Liabilities:    
Derivatives 202 86
Fair Value, Measurements, Recurring [Member] | Level 1    
Financial Assets:    
Trading account securities 78 83
Available-for-sale securities 6 5
Fair Value, Measurements, Recurring [Member] | Level 2    
Financial Assets:    
Trading account securities 7 3
Available-for-sale securities 10,886 11,673
Fair Value, Measurements, Recurring [Member] | Level 3    
Financial Assets:    
Trading account securities 0 0
Available-for-sale securities 3,178 3,191
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]    
Financial Assets:    
Trading account securities 80 86
Available-for-sale securities 4 2
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Level 1    
Financial Assets:    
Trading account securities 78 83
Available-for-sale securities 0 0
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Level 2    
Financial Assets:    
Trading account securities 2 3
Available-for-sale securities 4 2
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Level 3    
Financial Assets:    
Trading account securities 0 0
Available-for-sale securities 0 0
Amortized Cost [Member] | Reported Value Measurement [Member]    
Financial Assets:    
Cash and short term assets 1,423 1,567
Held-to-maturity securities 8,682 9,091
Other Securities 576 581
Net loans and direct financing leases 71,581 69,333
Financial Liabilities:    
Deposits 79,587 77,041
Short-term borrowings 2,442 5,056
Long-term borrowings 9,726 9,206
Fair Value Fair Value Option [Member] | Reported Value Measurement [Member]    
Financial Assets:    
Trading account securities 85 86
Available-for-sale securities 14,070 14,869
Other Securities 21 19
Loans held for sale 643 413
Net loans and direct financing leases 84 93
Derivatives 179 132
Financial Liabilities:    
Derivatives 202 86
LowerOfCostOrMarket [Member] | Reported Value Measurement [Member]    
Financial Assets:    
Loans held for sale $ 66 $ 75
[1] Amounts represent loans for which Huntington has elected the fair value option.