Condensed Financial Statements of Unity Bancorp, Inc. (Parent Company Only) - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Financial Statements, Captions [Line Items]
Dividend from Bank	$ 30,325	$ 26,224	$ 23,071	$ 21,119	$ 22,270	$ 21,254	$ 20,680	$ 20,576	$ 20,288	$ 19,764	$ 19,278	$ 19,585	$ 100,739	$ 84,780	$ 78,915
Gain on sales of securities													(1,313)	609	93
Other income													2,819	1,561	1,466
Total noninterest income	1,946	1,110	2,750	2,239	2,624	2,809	2,895	3,726	4,254	3,336	2,811	2,545	8,045	12,054	12,946
Interest expenses	5,616	2,486	1,314	1,215	1,421	1,531	2,231	2,558	2,949	3,437	3,753	4,341	10,631	7,741	14,480
Market value depreciation (appreciation) on equity securities													1,313	(561)	229
Other expenses													2,251	2,325	3,499
(Benefit) provision for income taxes	3,678	3,325	3,158	2,803	3,386	3,213	2,466	2,946	2,523	1,866	1,488	1,598
Net income	$ 9,956	$ 9,942	$ 9,451	$ 9,108	$ 9,746	$ 9,459	$ 8,418	$ 8,496	$ 7,345	$ 5,760	$ 5,171	$ 5,368	38,457	36,119	23,644
Parent Company Only | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Dividend from Bank													4,510	11,285	8,200
Dividend from Nonbank subsidiary													1,100	823	575
Gain on sales of securities													0	4	5
Other income													734	532	465
Total noninterest income													6,344	13,232	9,245
Interest expenses													349	257	349
Market value depreciation (appreciation) on equity securities													885	588	246
Other expenses													252	258	259
Total expenses													1,486	515	854
Income before provision for income taxes and equity in undistributed net income of subsidiary													4,858	12,717	8,391
(Benefit) provision for income taxes													(231)	219	(22)
Income before equity in undistributed net income of subsidiary													5,089	12,498	8,413
Equity in undistributed net income of subsidiaries													33,368	23,621	15,231
Net income													$ 38,457	$ 36,119	$ 23,644