Consolidated Statements of Changes in Shareholders' Equity - Unaudited (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series C, par value $1.00 per share
Preferred stock, dividends, per share, cash paid (usd per share)	$ 0.4375	$ 0.4375	$ 0.8750	$ 0.8750
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series D, par value $1.00 per share
Preferred stock, dividends, per share, cash paid (usd per share)	0.40625	0.40625	0.81250	0.81250
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series E, par value $1.00 per share
Preferred stock, dividends, per share, cash paid (usd per share)	0.403125	0.403125	0.806250	0.806250
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series F, par value $1.00 per share
Preferred stock, dividends, per share, cash paid (usd per share)	$ 0.375	$ 0.375	$ 0.750	$ 0.750