Acquisition - Unaudited Pro Forma (Details) - West Suburban Bancorp, Inc - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2021 |
Dec. 31, 2020 |
|
| Business Acquisition [Line Items] | ||
| Net interest income | $ 166,495 | $ 165,283 |
| Noninterest income | 59,036 | 48,937 |
| Net income attributable to Old Second Bancorp, Inc. | $ 67,779 | $ 12,349 |