INVESTMENTS - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Gain (Loss) on Securities [Line Items]
Proceeds from Sale of Debt Securities, Available-for-sale			$ 361,736	$ 42,628
Available-for-sale Securities, Gross Realized Losses	$ 3,100	$ 24	$ 7,000	200
NumberOfSecuritiesInSecurityPortfolio	1,411		1,411		1,351
NumberOfSecuritiesInUnrealizedLossPosition	240		240		94
Debt Securities, Held-to-maturity, Nonaccrual	$ 0		$ 0		$ 0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0		0		$ 0
Sale of Debt Securities, Available-for-sale, Total	100,600	1,300	372,300	42,600
Debt Securities, Available-for-sale, Realized Gain	$ 2,800	$ 26	$ 6,300	$ 100