Goodwill and Other Intangible Assets (Details Textuals) - USD ($)		3 Months Ended
	Feb. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 1,153,156,000		$ 976,239,000
Goodwill, Impairment Loss		0	$ 0
Bank Mutual
Business Acquisition [Line Items]
Goodwill acquired	$ 167,000,000
Additions to finite-lived intangible assets		58,000,000
Diversified Insurance Solutions
Business Acquisition [Line Items]
Goodwill acquired		10,000,000
Additions to finite-lived intangible assets		$ 8,000,000