FHLBNY ADVANCES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
FHLBNY advances with an overnight contractual maturity	$ 0.0		$ 0.0
Federal Home Loan Bank of New York
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Borrowings total	1,120.0		1,120.0		$ 1,130.0
Borrowings	4,090.0		4,090.0		$ 4,130.0
Callable advances	0.0		0.0
Extinguishment of debt	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Weighted average rate			5.11%		4.55%