Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income:
Loans, including loan fees	$ 113,953	$ 100,541	$ 69,425
Investment securities:
Taxable	6,068	4,728	3,029
Tax-exempt	2,296	2,360	1,686
Other interest income	3,220	1,624	1,327
Total interest income	125,537	109,253	75,467
Interest Expense, Deposits	15,420	7,686	5,144
Interest Expense, Short-term Borrowings	9	84	0
Interest Expense, Long-term Debt	3,460	2,741	2,190
Interest expense:
Total interest expense	18,889	10,511	7,334
Net interest income	106,648	98,742	68,133
Provision for loan losses	1,600	2,325	1,800
Net interest income after provision for loan losses	105,048	96,417	66,333
Noninterest income:
Mortgage income, net	6,344	5,361	5,494
BOLI income	2,418	1,778	1,284
Asset gains (losses), net	1,169	2,029	54
Noninterest Income, Other	5,528	4,454	4,045
Total noninterest income	39,509	34,639	26,674
Noninterest expense:
Personnel	49,476	44,458	34,030
Occupancy, equipment and office	14,574	13,308	10,276
Business development and marketing	5,324	4,700	3,488
Data processing	9,514	8,715	6,370
Intangibles amortization	4,389	4,695	3,458
Other expense	6,481	5,480	7,320
Total noninterest expense	89,758	81,356	64,942
Income before income tax expense	54,799	49,700	28,065
Income tax expense	13,446	16,267	9,371
Net income	41,353	33,433	18,694
Less: Net income attributable to noncontrolling interest	317	283	232
Net income attributable to Nicolet Bankshares, Inc.	41,036	33,150	18,462
Less: Preferred stock dividends	0	0	633
Net income available to common shareholders	$ 41,036	$ 33,150	$ 17,829
Earnings per common share:
Basic (in dollars per share)	$ 4.26	$ 3.51	$ 2.49
Diluted (in dollars per share)	$ 4.12	$ 3.33	$ 2.37
Weighted average common shares outstanding:
Basic (in shares)	9,640,258	9,439,951	7,158,367
Diluted (in shares)	9,956,353	9,958,160	7,513,971
Trust services fee income
Noninterest income:
Fees and commisions	$ 6,498	$ 6,031	$ 5,435
Brokerage fee income
Noninterest income:
Fees and commisions	7,042	5,736	3,624
Service charges on deposit accounts
Noninterest income:
Fees and commisions	4,845	4,604	3,571
Card interchange income
Noninterest income:
Fees and commisions	$ 5,665	$ 4,646	$ 3,167