Aggregate dividends declared during the period for each share of common stock outstanding.

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The cash outflow to reacquire common stock during the period.

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Shareholders' Equity - Comprehensive Capital Plan (Details) - USD ($)	3 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Apr. 18, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Repurchase of common shares		$ 167,000,000	$ 156,000,000
Cash dividends declared on common shares (in usd per share)		$ 0.17	$ 0.105
2018 Capital Plan [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Authorized amount of share repurchases		$ 1,225,000,000
Common shares repurchased, value		199,000,000
Repurchase of common shares		167,000,000
Employee equity compensation program Common Share repurchases		$ 32,000,000
Cash dividends declared on common shares (in usd per share)		$ 0.17
Subsequent Event [Member] \| 2019 Capital Plan [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Authorized amount of share repurchases				$ 1,000,000,000.0
Scenario, Forecast [Member] \| 2019 Capital Plan [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash dividends declared on common shares (in usd per share)	$ 0.185