DERIVATIVE FINANCIAL INTSTRUMENTS - Summary of Outstanding Swaptions (Details) - Payer Swaption [Member] - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Long [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 11,550
Net Estimated Fair Value	$ 7,825
Derivative Instruments Average Months To Expiration	1 year 4 months 11 days
Notional Amount	$ 1,082,000
Derivative Average Fixed Interest Rate	1.25%
Derivative Avergage Receive Rate	3 Month
Term (Years)	7 years 2 months 21 days
Less Than Or Equal To One Year [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ (2,400)
Net Estimated Fair Value	$ (3,289)
Derivative Instruments Average Months To Expiration	11 months 7 days
Notional Amount	$ 436,200
Derivative Average Fixed Interest Rate	1.50%
Derivative Avergage Receive Rate	3 Month	3 Month
Term (Years)	10 years
Less Than Or Equal To One Year [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 3,450
Net Estimated Fair Value	$ 231
Derivative Instruments Average Months To Expiration	8 months 17 days
Notional Amount	$ 500,000
Derivative Average Fixed Interest Rate	0.95%
Derivative Avergage Receive Rate	3 Month
Term (Years)	4 years
One Year To Two Years [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 8,100
Net Estimated Fair Value	$ 7,594
Derivative Instruments Average Months To Expiration	1 year 11 months 6 days
Notional Amount	$ 582,000
Derivative Average Fixed Interest Rate	1.50%
Derivative Avergage Receive Rate	3 Month
Term (Years)	10 years