Shareholders' Equity - Comprehensive Capital Plan (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Jan. 31, 2021
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash dividends declared on Common Shares (in usd per share)	$ 0.185	$ 0.185
2021 Capital Plan
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock repurchase program, amount authorized			$ 900
Common stock repurchased during period	$ 166
Cash dividends declared on Common Shares (in usd per share)	$ 0.185
Open Market Share Repurchases
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock repurchased during period	$ 135
Employee Equity Compensation Programs
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock repurchased during period	$ 31