PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Financial Statements, Captions [Line Items]
Interest income	$ 273,918	$ 171,559	$ 149,202
Interest expense	33,957	13,604	19,864
Net interest income	239,961	157,955	129,338
Income tax benefit	(31,477)	(20,470)	(20,476)
Net income	94,260	60,652	60,469
Nicolet Bankshares, Inc
Condensed Financial Statements, Captions [Line Items]
Interest income	81	18	39
Interest expense	8,687	2,959	2,313
Net interest income	(8,606)	(2,941)	(2,274)
Dividend income from subsidiaries	77,775	65,000	60,215
Operating expense	(457)	(2,562)	(886)
Gain (loss) on investments, net	395	3,995	(1,087)
Income tax benefit	2,373	437	1,102
Earnings before equity in undistributed income (loss) of subsidiaries	71,480	63,929	57,070
Equity in undistributed income (loss) of subsidiaries	22,780	(3,277)	3,052
Net income	$ 94,260	$ 60,652	$ 60,122