| Cover | Dec. 21, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Entity Registrant Name | NICOLET BANKSHARES, INC. |
| Entity Incorporation, State or Country Code | WI |
| Entity File Number | 001-37700 |
| Entity Tax Identification Number | 47-0871001 |
| Entity Address, Address Line One | 111 North Washington Street |
| Entity Address, City or Town | Green Bay |
| Entity Address, State or Province | WI |
| Entity Address, Postal Zip Code | 54301 |
| City Area Code | 920 |
| Local Phone Number | 430-1400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, par value $0.01 per share |
| Trading Symbol | NCBS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001174850 |
| Amendment Flag | false |
| Document Period End Date | Dec. 21, 2021 |
