Employee Benefit Plans	12 Months Ended
Dec. 31, 2019
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Employee Benefit Plans	Note 16— Employee Benefit Plans The Company’s defined contribution 401(k) savings plan (the “Plan”) covers substantially all employees that have completed certain service requirements. The Board of Directors determines the amount of any discretionary profit sharing contribution made to the Plan. There were no profit sharing contributions to the Plan for the years ended December 31, 2019, 2018, and 2017. The net assets of the Plan are not included in the Consolidated Statements of Financial Condition. Note 16— Employee Benefit Plans (continued) The 401(k) employer match contribution is equal to 100% of the first 3% and 50% for the next 2% contributed to the Plan by employees. Total expense for the employer contributions made to the Plan was $2.5 million, $2.1 million, and $1.5 million during the years ended December 31, 2019, 2018, and 2017, respectively. On June 14, 2017, the Company’s Board of Directors adopted the Byline Bancorp, Inc. Employee Stock Purchase Plan (the “ESPP”) within the meaning of Section 423 of the Internal Revenue Code, as amended. The ESPP allows employees to purchase shares of the Company’s common stock at a discount to the market price of the stock through automatic payroll deductions. A total of 200,000 shares of common stock were reserved for sale under the ESPP, subject to adjustment in accordance with the terms of the ESPP. The Company has issued 35,710 shares in connection with the ESPP, leaving 164,290 available at December 31, 2019. The initial ESPP offering was in the first quarter of 2018. The Company recognized $190,000 and $66,000 of compensation expense for the years ended December 31, 2019 and 2018, and no compensation expense for the year ended December 31, 2017.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2019

Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]

Note 16— Employee Benefit Plans

The Company’s defined contribution 401(k) savings plan (the “Plan”) covers substantially all employees that have completed certain service requirements. The Board of Directors determines the amount of any discretionary profit sharing contribution made to the Plan. There were no profit sharing contributions to the Plan for the years ended December 31, 2019, 2018, and 2017. The net assets of the Plan are not included in the Consolidated Statements of Financial Condition.

Note 16— Employee Benefit Plans (continued)

The 401(k) employer match contribution is equal to 100% of the first 3% and 50% for the next 2% contributed to the Plan by employees. Total expense for the employer contributions made to the Plan was $2.5 million, $2.1 million, and $1.5 million during the years ended December 31, 2019, 2018, and 2017, respectively.

On June 14, 2017, the Company’s Board of Directors adopted the Byline Bancorp, Inc. Employee Stock Purchase Plan (the “ESPP”) within the meaning of Section 423 of the Internal Revenue Code, as amended. The ESPP allows employees to purchase shares of the Company’s common stock at a discount to the market price of the stock through automatic payroll deductions. A total of 200,000 shares of common stock were reserved for sale under the ESPP, subject to adjustment in accordance with the terms of the ESPP. The Company has issued 35,710 shares in connection with the ESPP, leaving 164,290 available at December 31, 2019. The initial ESPP offering was in the first quarter of 2018. The Company recognized $190,000 and $66,000 of compensation expense for the years ended December 31, 2019 and 2018, and no compensation expense for the year ended December 31, 2017.