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INVESTMENT SECURITIES - Roll-Forward of Credit Losses on Debt Securities Held by Corporation (Detail) - Available for sale Securities [Member] - Private label MBS [Member] - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]        
Beginning balance of credit losses on debt securities held for which a portion of an OTTI was recognized in OCI $ 6,842,000 $ 6,792,000 $ 6,842,000 $ 6,792,000
Credit impairments recognized in earnings on securities that have been previously impaired 0 0 0 0
Ending balance of credit losses on debt securities held for which a portion of an OTTI was recognized in OCI $ 6,842,000 $ 6,792,000 $ 6,842,000 $ 6,792,000