PARENT COMPANY ONLY FINANCIAL INFORMATION - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Apr. 29, 2016
Assets
Cash and due from subsidiary	$ 85,896	$ 86,191
Goodwill	107,366	107,366	$ 66,000
Total assets	3,096,535	2,932,433
Liabilities and Stockholders’ Equity
Junior subordinated debentures	30,096	29,616
Other liabilities	17,740	18,444
Stockholders’ equity	386,609	364,178
Total liabilities, noncontrolling interest and stockholders’ equity	3,096,535	2,932,433
Nicolet Bankshares, Inc
Assets
Cash and due from subsidiary	45,279	28,026
Investments	4,500	4,021
Investments in subsidiaries	384,839	379,640
Goodwill	(3,266)	(3,266)
Other assets	53	147
Total assets	431,405	408,568
Liabilities and Stockholders’ Equity
Junior subordinated debentures	30,096	29,616
Subordinated notes	11,957	11,921
Other liabilities	2,743	2,853
Stockholders’ equity	386,609	364,178
Total liabilities, noncontrolling interest and stockholders’ equity	$ 431,405	$ 408,568