DERIVATIVES - Notional Amount (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Interest rate swaps
Derivative [Line Items]
Derivative asset, notional amount	$ 11,490,000	$ 6,515,000
Interest rate swaps | Short
Derivative [Line Items]
Derivative asset, notional amount	$ 0	$ 0
Derivative, cap interest rate	0.00%	0.00%
Average remaining maturity (in months)	0 months	0 months
Interest rate swaps | Long
Derivative [Line Items]
Derivative, notional amount	$ 11,500,000	$ 6,500,000
Derivative, cap interest rate	1.10%	2.20%
Average remaining maturity (in months)	42 months	47 months
Interest rate lock commitments
Derivative [Line Items]
Derivative asset, notional amount	$ 10,653,850	$ 15,031,345
TBAs | Short
Derivative [Line Items]
Derivative liability, notional amount	22,697,706	23,529,408
Treasury futures
Derivative [Line Items]
Derivative liability, notional amount	314,500	0
Options on treasury futures
Derivative [Line Items]
Derivative asset, notional amount	$ 3,200	$ 0