Shareholders' Equity, Capital Ratios and Other Regulatory Matters - Summary of Non-cumulative Perpetual Preferred Stock (Details) - USD ($) $ in Thousands	Apr. 04, 2019	May 09, 2016	Aug. 05, 2015	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Liquidation Amount		$ 237,500
Carrying Amount				$ 228,485	$ 132,097
Series B Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate			6.625%
Liquidation Amount			$ 80,000
Carrying Amount				76,812	76,812
Series C Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate		6.60%
Liquidation Amount		$ 57,500
Carrying Amount				55,285	55,285
Series D Preferred Stock
Class of Stock [Line Items]
Annual Dividend Rate	6.10%
Liquidation Amount	$ 100,000
Carrying Amount				$ 96,388	$ 0