USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2016
Derivative Instruments And Hedging Activities Disclosures [Line Items]
SWAP agreement notional amount during period	$ 1,700,000	$ 6,400,000	$ 100,000
SWAP agreement average interest rate during period	1.60%	2.17%	4.09%
Swap agreement notional amount expiring during period	$ 550,000	$ 3,150,000
SWAP agreement average interest rate expiring during period	1.40%	1.42%
SWAP agreement terminated notional amount during period	$ 1,500,000	$ 2,600,000
SWAP agreement terminated average interest rate during period	2.64%	2.72%
Futures contract notional amount during period	$ 7,200,000	$ 7,200,000
Interest Rate Swap Agreements [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Payment term of LIBOR interest rate agreement		20 years
Interest Rate Swap Agreements [Member] | Minimum [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Payment term of LIBOR interest rate agreement		2 years
Interest Rate Swap Agreements [Member] | Maximum [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Payment term of LIBOR interest rate agreement		3 years
Eurodollar Futures Contract [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Futures contract notional amount during period	$ 500,000	$ 500,000
Futures contract weighted average interest rate during period	1.62%	1.62%
Derivative, maturity date		Jun. 30, 2020
Futures contract, average maturity (in years)		3 months