Business Combinations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Business Acquisition [Line Items]
Total assets	$ 49,459,551	$ 48,594,383	$ 47,802,487
Huntington Bancshares
Business Acquisition [Line Items]
Total assets	$ 125,800,000
Common Stock | Huntington Bancshares
Business Acquisition [Line Items]
Share conversion ratio	3.0028
Series C Preferred Stock
Business Acquisition [Line Items]
Annual rate of dividend (as a percent)	5.70%	5.70%
Series C Preferred Stock | Huntington Bancshares
Business Acquisition [Line Items]
Share conversion ratio	1
Series C Preferred Stock | TCF Financial Corporation
Business Acquisition [Line Items]
Annual rate of dividend (as a percent)	5.70%