Shareholders' Equity - Narrative (Details) - USD ($)							3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 26, 2020	Feb. 26, 2020	Dec. 19, 2019	Jun. 11, 2019	Sep. 12, 2018	May 07, 2013	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Oct. 31, 2019
Class of Stock [Line Items]
Dividends declared per share of Common Stock (usd per share)							$ 0.15	$ 0.01	$ 0.30	$ 0.02
Amount authorized for repurchase												$ 800,000,000
Payment for share repurchases			$ 200,000,000				$ 0	$ 436,000,000	$ 366,000,000	$ 686,000,000
Shares delivered (in shares)		727,368	2,591,093						(8,100,000)		(21,100,000)
Number of warrants issued and outstanding (in shares)						26,050,846
Warrants issued allowing purchase of shares, percentage of common stock issued and outstanding						9.99%
Exercise price of warrants (usd per share)	$ 48.22					$ 48.75
Number of shares of common stock for which each warrant is exercisable (in shares)	1.003309771
Cash dividends, per share (usd per share)	$ 0.15					$ 0.01
Warrants net share settled, fair value						$ 94,000,000
Number of warrants exercised							0		0
Preferred Stock, par value per share							$ 0.01		$ 0.01		$ 0.01
Proceeds from issuance of preferred stock, net								$ 293,000,000	$ 0	$ 293,000,000
Issuer's redemption option, period to redeem after a redemption event									90 days
Preferred Stock, shares authorized							100,000,000		100,000,000		100,000,000
Preferred Stock, amount of preferred dividends in arrears									$ 0
Number of shares authorized to be repurchased (in shares)		3,318,461
Rating agency event
Class of Stock [Line Items]
Preferred stock, redemption price per share							$ 1,020		$ 1,020
Regulatory capital event
Class of Stock [Line Items]
Preferred stock, redemption price per share							$ 1,000		$ 1,000
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, shares issued					325,000		325,000		325,000		325,000
Preferred Stock, shares outstanding							325,000		325,000		325,000
Preferred Stock, dividend rate, percentage					6.125%
Preferred Stock, par value per share					$ 0.01
Preferred stock, liquidation preference per share					$ 1,000
Proceeds from issuance of preferred stock, net					$ 319,000,000
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock, shares issued				300,000			300,000		300,000		300,000
Preferred Stock, shares outstanding							300,000		300,000		300,000
Preferred Stock, dividend rate, percentage				5.35%
Preferred Stock, par value per share				$ 0.01
Preferred stock, liquidation preference per share				$ 1,000
Proceeds from issuance of preferred stock, net				$ 293,000,000
Number of shares of preferred stock represented by each depositary share (in shares)							0.025		0.025
Depositary Shares | Rating agency event
Class of Stock [Line Items]
Preferred stock, redemption price per share							$ 25.50		$ 25.50
Depositary Shares | Regulatory capital event
Class of Stock [Line Items]
Preferred stock, redemption price per share							$ 25.00		$ 25.00
Open market repurchase
Class of Stock [Line Items]
Payment for share repurchases									$ 366,000,000
Shares delivered (in shares)									7,390,099