Short and Long-Term Borrowings - Junior Subordinated Debentures (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Junior Subordinated Debentures
Carrying Value	$ 144,233,000	$ 53,869,000
Junior subordinated debentures
Junior Subordinated Debentures
Par	32,063,000
Unamortized Discount	(6,835,000)
Carrying Value	25,228,000	24,869,000
Junior subordinated debentures | 2005 Mid-Wisconsin Financial Services, Inc.
Junior Subordinated Debentures
Par	10,310,000
Unamortized Discount	(2,823,000)
Carrying Value	$ 7,487,000	$ 7,338,000
Effective percentage	1.55%	1.65%
Junior subordinated debentures | 2006 Baylake Corp.
Junior Subordinated Debentures
Par	$ 16,598,000
Unamortized Discount	(3,470,000)
Carrying Value	$ 13,128,000	$ 12,951,000
Effective percentage	1.48%	1.59%
Junior subordinated debentures | 2004 First Menasha Bancshares, Inc.
Junior Subordinated Debentures
Par	$ 5,155,000
Unamortized Discount	(542,000)
Carrying Value	$ 4,613,000	$ 4,580,000
Effective percentage	2.91%	3.02%
Junior subordinated debentures | London Interbank Offered Rate (LIBOR) | 2005 Mid-Wisconsin Financial Services, Inc.
Junior Subordinated Debentures
Floating interest rate basis spread	1.43%
Junior subordinated debentures | London Interbank Offered Rate (LIBOR) | 2006 Baylake Corp.
Junior Subordinated Debentures
Floating interest rate basis spread	1.35%
Junior subordinated debentures | London Interbank Offered Rate (LIBOR) | 2004 First Menasha Bancshares, Inc.
Junior Subordinated Debentures
Floating interest rate basis spread	2.79%