PREFERRED STOCK - Additional Information (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Preferred stock dividends declared					$ 1,095	$ 1,109	$ 1,174
Subsequent event
Class of Stock [Line Items]
Preferred stock dividends declared				$ 292
Preferred Stock
Class of Stock [Line Items]
Distribution of preferred dividends					$ 1,095
Issuance of new preferred stock (in shares)					120	60
Issuance of new preferred stock					$ 3,000	$ 1,500
Preferred Stock | Subsequent event | Series X
Class of Stock [Line Items]
Issuance of new preferred stock (in shares)				2,300,000
Preferred Stock | Subsequent event | Series S
Class of Stock [Line Items]
Issuance of new preferred stock				$ 1,035
Preferred Stock | Subsequent event | Series R
Class of Stock [Line Items]
Issuance of new preferred stock (in shares)				465,000
Forecast | Preferred Stock
Class of Stock [Line Items]
Distribution of preferred dividends	$ 254	$ 293	$ 254