INVESTMENT SECURITIES (Gains (Losses) and Proceeds on Sale of Investment Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Proceeds from the sales of AFS securities	$ 1,112,033	$ 416,981	$ 2,665,593	$ 1,044,645
Gross realized gains	573	2,667	33,400	6,007
Gross realized losses	(721)	(400)	(1,754)	(3,361)
Net realized gains/(losses)	(148)	2,267	31,646	2,646
Net realized gains/(losses) on trading securities	$ (100)	$ (300)	$ (1,000)	$ (600)