Preferred Stock - Non-Cumulative Perpetual Preferred Stock (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Liquidation Amount	$ 487,500
Carrying Amount, Issued	$ 470,370	$ 95,624
Series A Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate	6.20%
Liquidation Amount	$ 100,000
Carrying Amount, Issued	$ 95,624	95,624
Series B Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate	6.625%
Liquidation Amount	$ 80,000
Carrying Amount, Issued	$ 77,348	0
Series C Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate	6.60%
Liquidation Amount	$ 57,500
Carrying Amount, Issued	$ 59,084	0
Series D Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate	6.10%
Liquidation Amount	$ 100,000
Carrying Amount, Issued	$ 93,649	0
Series E Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate	6.50%
Liquidation Amount	$ 150,000
Carrying Amount, Issued	$ 144,665	$ 0