Acquisition - Narrative (Details) - Charter Bankshares, Inc. $ / shares in Units, $ in Millions	Aug. 26, 2022 USD ($) $ / shares shares
Business Acquisition [Line Items]
Entity shares issued per acquiree share (in shares) | shares	15.458
Cash paid per acquiree share (in dollars per share) | $ / shares	$ 475
Number of common stock issued for consideration (in shares) | shares	1,262,360
Value of Nicolet common stock consideration	$ 98
Cash consideration paid	39
Purchase price	$ 137