STOCKHOLDERS' EQUITY - Summary of Preferred Stock (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Carrying Value	$ 184,878	$ 189,825
Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)	191,972	197,106
Liquidation Preference	$ 191,972	$ 197,106
Carrying Value	$ 184,878	$ 189,825
Preferred Stock | Series D 7.375% non-cumulative perpetual
Class of Stock [Line Items]
Non cumulative preferred stock, dividend rate (percent)	7.375%
Preferred stock, outstanding (in shares)	93,270	96,629
Liquidation Preference	$ 93,270	$ 96,629
Carrying Value	$ 89,922	$ 93,162
Preferred Stock | Series E 7.00% non-cumulative perpetual
Class of Stock [Line Items]
Non cumulative preferred stock, dividend rate (percent)	7.00%
Preferred stock, outstanding (in shares)	98,702	100,477
Liquidation Preference	$ 98,702	$ 100,477
Carrying Value	$ 94,956	$ 96,663