Preferred Shares (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($) shares
Series B Preferred Stock
Preferred Shares [Line Items]
Securities issued (in shares) | shares	750
Depositary shares issued (in shares) | shares	750,000
Fixed dividend rate per annum (as a percent)	5.20%
Floating dividend rate per annum (as a percent)	3.428%
Aggregate liquidation preference | $	$ 750
Carrying value | $	$ 742
Series D Preferred Stock
Preferred Shares [Line Items]
Securities issued (in shares) | shares	1,600
Depositary shares issued (in shares) | shares	1,600,000
Fixed dividend rate per annum (as a percent)	3.55%
Floating dividend rate per annum (as a percent)	2.854%
Aggregate liquidation preference | $	$ 1,600
Carrying value | $	$ 1,584