SECURITIES - Realized Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Gross Realized Gains	$ 30,368	$ 117,373	$ 87,499	$ 929,010
Gross Realized Losses	(3,636)	(13,440)	(86,657)	(297,934)
Net Realized Gains (Losses)	$ 26,732	$ 103,933	$ 842	$ 631,076