Annual report pursuant to Section 13 and 15(d)

HELD-TO-MATURITY SECURITIES - Narrative (Details)

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HELD-TO-MATURITY SECURITIES - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Held-to-maturity Securities [Abstract]    
Available-for-sale securities transferred to held-to-maturity securities $ 1,000,000,000 $ 2,870,000,000
Unrealized Net Losses Recognized In OCI At Time Of Transfer Of Available For Sale Securities Transferred To Held To Maturity Securities 14,000,000  
Unrealized Net Gains Recognized In OCI At Time Of Transfer Of Available For Sale Securities Transferred To Held To Maturity Securities 58,000,000  
Other than temporary impairment losses, held-to-maturity $ 0 $ 0