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
Sep. 30, 2018
Dec. 31, 2017
Financial Assets:    
Trading account securities $ 83 $ 86
Available-for-sale securities 13,727 14,869
Held-to-maturity securities 8,465 9,091
Loans held for sale [1] 792 488
Net loans and direct financing leases 72,609 69,426
Derivatives 180 132
Financial Liabilities:    
Deposits 81,689 77,041
Short-term borrowings 1,348 5,056
Long-term borrowings 9,385 9,206
Derivatives 220 86
Reported Value Measurement [Member]    
Financial Assets:    
Cash and short term assets   1,567
Trading account securities 83 86
Available-for-sale securities 13,727 14,869
Held-to-maturity securities 8,465  
Other Securities 565 600
Loans held for sale 792  
Net loans and direct financing leases   69,426
Derivatives   132
Financial Liabilities:    
Deposits 81,689 77,041
Short-term borrowings 1,348 5,056
Long-term borrowings 9,385 9,206
Derivatives 220 86
Estimate of Fair Value Measurement [Member]    
Financial Assets:    
Cash and short term assets 1,342  
Trading account securities 83 86
Available-for-sale securities 13,727 14,869
Held-to-maturity securities 8,112 8,971
Other Securities 565 600
Loans held for sale 795 491
Other securities 22 19
Net loans and direct financing leases 71,918 69,146
Derivatives   132
Financial Liabilities:    
Deposits 81,631 77,010
Short-term borrowings 1,348 5,056
Long-term borrowings 9,523 9,402
Estimate of Fair Value Measurement [Member] | Level 1    
Financial Assets:    
Trading account securities 77  
Available-for-sale securities 5 5
Held-to-maturity securities 0 0
Loans held for sale 0 0
Other securities 22 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 6  
Available-for-sale securities 10,445 11,673
Held-to-maturity securities 8,112 8,971
Loans held for sale 727 413
Other securities 0 0
Net loans and direct financing leases 49 0
Financial Liabilities:    
Deposits 74,423 73,975
Short-term borrowings 0 0
Long-term borrowings 8,986 8,944
Estimate of Fair Value Measurement [Member] | Level 3    
Financial Assets:    
Trading account securities 0 0
Available-for-sale securities 3,277 3,191
Held-to-maturity securities 0 0
Loans held for sale 68 78
Other securities 0 0
Net loans and direct financing leases 71,869 69,146
Financial Liabilities:    
Deposits 7,208 3,035
Short-term borrowings 1,346 5,056
Long-term borrowings 537 458
Fair Value, Measurements, Recurring [Member]    
Financial Assets:    
Trading account securities 83 86
Available-for-sale securities 13,727 14,869
Derivatives 180 132
Financial Liabilities:    
Derivatives 220 86
Fair Value, Measurements, Recurring [Member] | Level 1    
Financial Assets:    
Trading account securities 77 83
Available-for-sale securities 5 5
Fair Value, Measurements, Recurring [Member] | Level 2    
Financial Assets:    
Trading account securities 6 3
Available-for-sale securities 10,445 11,673
Fair Value, Measurements, Recurring [Member] | Level 3    
Financial Assets:    
Trading account securities 0 0
Available-for-sale securities 3,277 3,191
Other securities | Fair Value, Measurements, Recurring [Member]    
Financial Assets:    
Trading account securities 78 86
Available-for-sale securities 4 2
Other securities | Fair Value, Measurements, Recurring [Member] | Level 1    
Financial Assets:    
Trading account securities 77 83
Available-for-sale securities 0 0
Other securities | Fair Value, Measurements, Recurring [Member] | Level 2    
Financial Assets:    
Trading account securities 1 3
Available-for-sale securities 4 2
Other securities | 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 1,342 1,567
Held-to-maturity securities 8,465 9,091
Other Securities 543 581
Net loans and direct financing leases   69,333
Financial Liabilities:    
Deposits 81,689 77,041
Short-term borrowings 1,348 5,056
Long-term borrowings 9,385 9,206
Fair Value Fair Value Option [Member] | Reported Value Measurement [Member]    
Financial Assets:    
Trading account securities 83 86
Available-for-sale securities 13,727 14,869
Other Securities 22 19
Loans held for sale 727 413
Net loans and direct financing leases   93
Derivatives 180 132
Financial Liabilities:    
Derivatives 220 86
LowerOfCostOrMarket [Member] | Reported Value Measurement [Member]    
Financial Assets:    
Loans held for sale $ 65 $ 75
[1] Amounts represent loans for which Huntington has elected the fair value option.