STOCKHOLDERS' EQUITY - Authorized Preferred Shares (Details) - USD ($)	9 Months Ended
Sep. 30, 2021	Jun. 11, 2021	Dec. 31, 2020
Preferred Stock
Preferred stock, authorized (in shares)	100,000,000		100,000,000
Preferred stock, par value (in dollars per share)	$ 25.00		$ 25.00
Preferred stock, issued (in shares)	2,050,000		2,000,000
Preferred stock, value, issued	$ 2,014,000,000		$ 1,965,000,000
Series A Preferred Stock
Preferred Stock
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	0		250,000
Preferred stock, value, issued	$ 0		$ 247,000,000
Series B Preferred Stock
Preferred Stock
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	300,000		300,000
Preferred stock, value, issued	$ 296,000,000		$ 296,000,000
Series C Preferred Stock
Preferred Stock
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	300,000		300,000
Preferred stock, value, issued	$ 297,000,000		$ 297,000,000
Series D Preferred Stock
Preferred Stock
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	300,000		300,000
Preferred stock, value, issued	$ 293,000,000		$ 293,000,000
Liquidation preference per depository share (usd per share)	$ 25
Depositary shares issued (in shares)	12,000,000
Depository share interest percentage	2.50%
Series E Preferred Stock
Preferred Stock
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	450,000		450,000
Preferred stock, value, issued	$ 437,000,000		$ 437,000,000
Liquidation preference per depository share (usd per share)	$ 25
Depositary shares issued (in shares)	18,000,000
Depository share interest percentage	2.50%
Series F Preferred Stock
Preferred Stock
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	400,000		400,000
Preferred stock, value, issued	$ 395,000,000		$ 395,000,000
Series G Preferred Stock
Preferred Stock
Preferred stock, par value (in dollars per share)		$ 25
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000
Preferred stock, issued (in shares)	300,000		0
Preferred stock, value, issued	$ 296,000,000	$ 300,000,000	$ 0

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Preferred Stock, Depositary Shares Issued

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The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share.

+ References

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.

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