Bank Mutual Acquisition (Details) - USD ($) $ in Thousands	Feb. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Fair value of liabilities assumed		$ 725,764	$ 2,340,323	$ 54
BKMU Assets Acquired Liabilities Assumed Adjustments [Member]
Financing Receivable, Impaired [Line Items]
Cash and cash equivalents	$ 0
Investment securities	(6,238)
Federal Home Loan Bank stock, at cost	0
Loans	(48,043)
Premises and equipment, net	2,930
Bank owned life insurance	(24)
Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet)	58,100
Other real estate owned (included in other assets on the face of the Consolidated Balance Sheets)	199
Other Assets	7,054
Deposits	2,498
Other borrowings	1,875
Other Liabilities	4,487
BKMU Assets Acquired Liabilities Assumed [Member]
Financing Receivable, Impaired [Line Items]
Cash and cash equivalents	78,052
Investment securities	452,867
Federal Home Loan Bank stock, at cost	20,026
Loans	1,875,877
Premises and equipment, net	42,689
Bank owned life insurance	65,390
Goodwill	175,499
Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet)	58,100
Other real estate owned (included in other assets on the face of the Consolidated Balance Sheets)	4,848
Other Assets	47,158
Total assets	2,820,506
Deposits	1,840,950
Other borrowings	431,886
Other Liabilities	65,982
Fair value of liabilities assumed	2,338,818
Total consideration paid	$ 481,688