Equity (Preferred Stock - Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions			6 Months Ended	12 Months Ended
	Sep. 10, 2020	Jan. 15, 2020	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020
Class of Stock [Line Items]
Preferred Stock, Shares Issued				25,572,200	26,072,200
Preferred stock issued, net of issuance costs				$ 0	$ 1,961	$ 0
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				25,572,200	26,072,200
Preferred stock, par value				$ 0.01	$ 0.01
Preferred Stock, Shares Authorized				200,000,000	200,000,000
Preferred stock redemption premium				$ 6	$ 14	$ 0
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage				562.50%
Preferred Stock, Shares Issued				32,200	32,200
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				32,200	32,200
Preferred Stock, Dividend Payment Rate, Variable				5.625
Preferred stock, aggregate liquidation preference				$ 25,000
Preferred Stock, Shares Authorized				32,200	32,200
Series E Preferred Stock [Member] | Depositary Share [Member]
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				$ 25
Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series D, par value $0.01
Class of Stock [Line Items]
Preferred Stock, Shares Issued				500,000	500,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				500,000	500,000
Preferred Stock, Dividend Payment Rate, Variable				5.875% Fixed-to-Floating Rate
Preferred stock, aggregate liquidation preference				$ 1,000
Preferred Stock, Shares Authorized				500,000	500,000
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage			525.00%
Preferred Stock, Shares Issued				0	500,000
Preferred stock redemption price per share			$ 1,000				$ 1,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				0	500,000
Preferred stock, par value			$ 0.01
Preferred Stock, Shares Authorized				0	1,500,000		1,500,000
Redeem and Canceled Preferred Stock [Line Items]			500,000		1,000,000		1,000,000
Preferred stock redemption premium				$ 6	$ 14
Preferred Stock, Redemption Amount			$ 500		$ 1,000
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued				24,000,000	24,000,000
Preferred stock redemption price per share				$ 25
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				24,000,000	24,000,000
Preferred Stock, Dividend Payment Rate, Variable				Three-month LIBOR + 1.00%, with floor of 4.00%
Preferred Stock, Shares Authorized				27,600,000	27,600,000
Depositary Shares, each representing a 1/1,000th interest in a share of 4.75% Non-Cumulative Preferred Stock, Series F
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage		4.75%		475.00%
Preferred Stock, Shares Issued		40,000		40,000	40,000
Preferred stock issued, net of issuance costs		$ 972
Payments of Stock Issuance Costs		$ 28
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				40,000	40,000
Preferred stock, par value		$ 0.01
Preferred stock, aggregate liquidation preference		$ 25,000		$ 25,000
Preferred Stock, Shares Authorized				40,000	40,000
Depositary Shares, each representing a 1/1,000th interest in a share of 4.75% Non-Cumulative Preferred Stock, Series F | Depositary Share [Member]
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				$ 25
Fixed Rate Reset Non-Cumulative Preferred Stock, Series G, par value $0.01
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage	3.85%			385.00%
Preferred Stock, Shares Issued	1,000,000			1,000,000	1,000,000
Preferred stock issued, net of issuance costs	$ 989
Payments of Stock Issuance Costs	$ 11
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, shares outstanding				1,000,000	1,000,000
Preferred stock, par value	$ 0.01
Preferred stock, aggregate liquidation preference	$ 1,000			$ 1,000
Preferred Stock, Shares Authorized				1,000,000	1,000,000
Fixed Rate1 [Member] | Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series D, par value $0.01
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Dividend Payment Rate, Variable				5.875%
Variable Rate1 [Member] | Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series D, par value $0.01
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Dividend Payment Rate, Variable				three-month LIBOR + 2.959%
Variable Rate1 [Member] | Fixed Rate Reset Non-Cumulative Preferred Stock, Series G, par value $0.01
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Dividend Payment Rate, Variable				five year treasury rate, reset every five years, + 3.576%
RatingAgency [Member] | Series E Preferred Stock [Member]
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				$ 25,500
RatingAgency [Member] | Series E Preferred Stock [Member] | Depositary Share [Member]
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				25.50
RatingAgency [Member] | Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series D, par value $0.01
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				1,020
RatingAgency [Member] | Depositary Shares, each representing a 1/1,000th interest in a share of 4.75% Non-Cumulative Preferred Stock, Series F
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				25,500
RatingAgency [Member] | Depositary Shares, each representing a 1/1,000th interest in a share of 4.75% Non-Cumulative Preferred Stock, Series F | Depositary Share [Member]
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				25.50
RatingAgency [Member] | Fixed Rate Reset Non-Cumulative Preferred Stock, Series G, par value $0.01
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, aggregate liquidation preference				$ 1,020