Byline Bancorp (BY) 10-K 15 Mar 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 14, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	BY
Entity Registrant Name	Byline Bancorp, Inc.
Entity Central Index Key	0001702750
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 552,556,258
Entity Common Stock, Shares Outstanding		36,369,982
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

CONSOLIDATED STATEMENTS OF FINA

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks	$ 30,190	$ 19,404
Interest bearing deposits with other banks	91,670	38,945
Cash and cash equivalents	121,860	58,349
Securities available-for-sale, at fair value	817,656	583,236
Securities held-to-maturity, at amortized cost ($97,739 and $117,277 fair value at December 31, 2018 and 2017, respectively)	99,266	117,163
Restricted stock, at cost	19,202	16,343
Loans held for sale	19,827	5,212
Loans and leases:
Loans and leases	3,501,626	2,277,492
Allowance for loan and lease losses	(25,201)	(16,706)
Net loans and leases	3,476,425	2,260,786
Servicing assets, at fair value	19,693	21,400
Accrued interest receivable	10,863	7,670
Premises and equipment, net	97,680	95,224
Assets held for sale	14,489	9,779
Other real estate owned, net	5,314	10,626
Goodwill	128,177	54,562
Other intangible assets, net	33,419	16,756
Bank-owned life insurance	5,961	5,718
Deferred tax assets, net	35,643	47,376
Due from counterparty	5,338	39,824
Other assets	31,761	16,106
Total assets	4,942,574	3,366,130
LIABILITIES
Non-interest-bearing demand deposits	1,192,873	760,887
Interest-bearing deposits:
NOW, savings accounts, and money market accounts	1,413,158	973,685
Time deposits	1,143,885	708,757
Total deposits	3,749,916	2,443,329
Accrued interest payable	3,484	1,306
Federal Home Loan Bank advances	425,000	361,506
Securities sold under agreements to repurchase	34,166	31,187
Junior subordinated debentures issued to capital trusts, net	36,768	27,647
Accrued expenses and other liabilities	42,568	42,577
Total liabilities	4,291,902	2,907,552
COMMITMENTS AND CONTINGENT LIABILITIES (Note 17)
STOCKHOLDERS’ EQUITY (Note 25)
Preferred stock	10,438	10,438
Common stock, voting $0.01 par value at December 31, 2018 and 2017; 150,000,000 shares authorized at December 31, 2018 and 2017; 36,343,239 shares issued and outstanding at December 31, 2018 and 29,317,298 issued and outstanding at December 31, 2017	361	292
Additional paid-in capital	546,849	391,586
Retained earnings	102,522	61,349
Accumulated other comprehensive loss, net of tax	(9,498)	(5,087)
Total stockholders’ equity	650,672	458,578
Total liabilities and stockholders’ equity	$ 4,942,574	$ 3,366,130

CONSOLIDATED STATEMENTS OF FI_2

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Securities held-to-maturity, fair value	$ 97,739	$ 117,277
Common stock, voting par value	$ 0.01	$ 0.01
Common stock, voting shares authorized	150,000,000	150,000,000
Common stock, voting shares issued	36,343,239	29,317,298
Common stock, voting shares outstanding	36,343,239	29,317,298

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INTEREST AND DIVIDEND INCOME
Interest and fees on loans and leases	$ 184,972,000	$ 120,406,000	$ 83,150,000
Interest on taxable securities	19,037,000	14,892,000	14,169,000
Interest on tax-exempt securities	1,095,000	634,000	653,000
Other interest and dividend income	1,847,000	871,000	393,000
Total interest and dividend income	206,951,000	136,803,000	98,365,000
INTEREST EXPENSE
Deposits	19,329,000	7,736,000	4,580,000
Federal Home Loan Bank advances	6,160,000	3,291,000	706,000
Subordinated debentures and other borrowings	2,857,000	2,864,000	2,461,000
Total interest expense	28,346,000	13,891,000	7,747,000
Net interest income	178,605,000	122,912,000	90,618,000
PROVISION FOR LOAN AND LEASE LOSSES	18,795,000	12,653,000	10,352,000
Net interest income after provision for loan and lease losses	159,810,000	110,259,000	80,266,000
NON-INTEREST INCOME
ATM and interchange fees	5,426,000	5,840,000	5,856,000
Net gains on sales of securities available-for-sale	164,000	8,000	3,227,000
Net gains on sales of loans	31,551,000	33,062,000	4,323,000
Wealth management and trust income	1,545,000
Other non-interest income	5,505,000	2,201,000	4,927,000
Total non-interest income	51,639,000	50,058,000	25,904,000
NON-INTEREST EXPENSE
Salaries and employee benefits	80,382,000	67,269,000	50,585,000
Occupancy expense, net	15,829,000	14,078,000	14,330,000
Equipment expense	2,419,000	2,472,000	2,032,000
Loan and lease related expenses	6,109,000	3,685,000	2,004,000
Legal, audit and other professional fees	11,373,000	7,027,000	5,862,000
Data processing	18,242,000	9,539,000	8,157,000
Net loss (gain) recognized on other real estate owned and other related expenses	235,000	(294,000)	1,719,000
Regulatory assessments	1,744,000	1,193,000	2,553,000
Other intangible assets amortization expense	5,629,000	3,074,000	3,003,000
Advertising and promotions	1,723,000	1,035,000	623,000
Telecommunications	1,710,000	1,593,000	1,698,000
Other non-interest expense	10,614,000	8,852,000	8,120,000
Total non-interest expense	156,009,000	119,523,000	100,686,000
INCOME BEFORE PROVISION FOR INCOME TAXES	55,440,000	40,794,000	5,484,000
PROVISION (BENEFIT) FOR INCOME TAXES	14,247,000	19,099,000	(61,245,000)
NET INCOME	41,193,000	21,695,000	66,729,000
Dividends on preferred shares	783,000	11,277,000
INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 40,410,000	$ 10,418,000	$ 66,729,000
EARNINGS PER COMMON SHARE
Basic	$ 1.21	$ 0.39	$ 3.31
Diluted	$ 1.18	$ 0.38	$ 3.27
Fees and Service Charges on Deposits [Member]
NON-INTEREST INCOME
Fees and charges	$ 6,445,000	$ 5,289,000	$ 5,665,000
Loan Servicing Revenue [Member]
NON-INTEREST INCOME
Fees and charges	10,272,000	9,599,000	1,649,000
Loan Servicing Asset Revaluation [Member]
NON-INTEREST INCOME
Fees and charges	$ (9,269,000)	$ (5,941,000)	$ 257,000

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Other Comprehensive Income [Abstract]
Net income	$ 41,193,000	$ 21,695,000	$ 66,729,000
Securities available-for-sale
Unrealized holding gains (losses) arising during the period	(6,503,000)	2,111,000	(3,100,000)
Reclassification adjustments for net gains included in net income	(164,000)	(8,000)	(3,227,000)
Tax effect	1,856,000	(602,000)	2,533,000
Net of tax	(4,811,000)	1,501,000	(3,794,000)
Cash flow hedges
Unrealized holding gains arising during the period	2,960,000	688,000	3,684,000
Reclassification adjustments for net (gains) losses included in net income	(1,348,000)	579,000	40,000
Tax effect	(449,000)	(587,000)	(1,491,000)
Net of tax	1,163,000	680,000	2,233,000
Total other comprehensive income (loss)	(3,648,000)	2,181,000	(1,561,000)
Comprehensive income	$ 37,545,000	$ 23,876,000	$ 65,168,000

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2015	$ 188,274	$ 15,003		$ 194,774	$ (15,796)	$ (5,707)
Beginning balance, shares at Dec. 31, 2015		15,003	17,332,775
Net income	66,729				66,729
Other comprehensive income (loss), net of tax	(1,561)					(1,561)
Issuance of common stock, net of issuance cost	49,592			49,592
Issuance of common stock, net of issuance cost, shares			3,078,075
Issuance of common stock due to business combination	68,247			68,247
Issuance of common stock due to business combination, shares			4,199,791
Issuance of preferred stock	9,388	$ 9,388
Issuance of preferred stock, shares		9,388
Subscription of preferred stock	1,050	$ 1,050
Subscription of preferred stock, shares		1,050
Share-based compensation expense	899			899
Exercise of stock options, net of tax	40			40
Exercise of stock options, net of tax, shares			6,065
Ending balance at Dec. 31, 2016	382,658	$ 25,441		313,552	50,933	(7,268)
Ending balance, shares at Dec. 31, 2016		25,441	24,616,706
Net income	21,695				21,695
Other comprehensive income (loss), net of tax	2,181					2,181
Issuance of common stock in connection with reincorporation merger			$ 246	(246)
Repurchase of preferred stock	(15,003)	$ (15,003)
Repurchase of preferred stock, shares		(15,003)
Issuance of common stock, net of issuance cost	76,829		$ 46	76,783
Issuance of common stock, net of issuance cost, shares			4,630,194
Issuance of common stock in connection with restricted stock awards, shares			70,798
Forfeiture of restricted stock awards, shares			(400)
Cash dividends declared on preferred stock	(11,277)				(11,277)
Cash paid in lieu of fractional shares	(2)				(2)
Share-based compensation expense	1,497			1,497
Ending balance at Dec. 31, 2017	458,578	$ 10,438	$ 292	391,586	61,349	(5,087)
Ending balance, shares at Dec. 31, 2017		10,438	29,317,298
Net income	41,193				41,193
Other comprehensive income (loss), net of tax	(3,648)					(3,648)
Issuance of common stock due to business combination	151,275		$ 67	151,208
Issuance of common stock due to business combination, shares			6,682,850
Issuance of common stock in connection with restricted stock awards, shares			131,157
Forfeiture of restricted stock awards, shares			(2,100)
Issuance of common stock in connection with employee stock purchase plan	203			203
Issuance of common stock in connection with employee stock purchase plan, shares			8,882
Reclassification of certain income tax effects from accumulated other comprehensive income (loss)	(763)				763	(763)
Cash dividends declared on preferred stock	(783)				(783)
Share-based compensation expense	1,514			1,514
Exercise of stock options, net of tax	2,340		$ 2	2,338
Exercise of stock options, net of tax, shares			205,152
Ending balance at Dec. 31, 2018	$ 650,672	$ 10,438	$ 361	$ 546,849	$ 102,522	$ (9,498)
Ending balance, shares at Dec. 31, 2018		10,438	36,343,239

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 41,193,000	$ 21,695,000	$ 66,729,000
Adjustments to reconcile net income to net cash from operating activities:
PROVISION FOR LOAN AND LEASE LOSSES	18,795,000	12,653,000	10,352,000
Impairment loss on premises and equipment			327,000
Impairment loss on assets held for sale	627,000	951,000	408,000
Depreciation and amortization of premises and equipment	5,579,000	5,193,000	5,060,000
Net amortization of securities	3,192,000	4,670,000	7,090,000
Net gains on sales of securities available-for-sale	(164,000)	(8,000)	(3,227,000)
Losses on disposal of premises and equipment	151,000	110,000	20,000
Net losses (gains) on sales of assets held for sale	(1,103,000)	217,000	(967,000)
Net gains on sales of loans	(31,551,000)	(33,062,000)	(4,323,000)
Originations of mortgage loans held for sale		(4,000)	(5,687,000)
Net proceeds from mortgage loans sold		155,000	6,003,000
Originations of U.S. government guaranteed loans	(336,212,000)	(293,615,000)	(35,949,000)
Proceeds from U.S. government guaranteed loans sold	384,681,000	309,164,000	30,624,000
Accretion of premiums and discounts on acquired loans, net	(20,599,000)	(8,677,000)	(2,827,000)
Net change in servicing assets	1,707,000	(309,000)	(796,000)
Net valuation adjustments on other real estate owned	636,000	883,000	1,058,000
Net gains on sales of other real estate owned	(383,000)	(2,147,000)	(1,366,000)
Other intangible assets amortization expense	5,629,000	3,074,000	3,003,000
Amortization of time deposit premium	(404,000)	(778,000)	(590,000)
Amortization of Federal Home Loan Bank advances premium	(19,000)	(209,000)	(44,000)
Accretion of junior subordinated debentures discount	624,000	721,000	876,000
Share-based compensation expense	1,514,000	1,497,000	899,000
Exercise of share-based awards			40,000
Deferred tax provision (benefit), net of valuation	15,442,000	16,604,000	(61,503,000)
Increase in cash surrender value of bank owned life insurance	(243,000)	(247,000)	(223,000)
Net gain on death benefit of bank owned life insurance		(313,000)
Changes in assets and liabilities:
Accrued interest receivable	(160,000)	(799,000)	(503,000)
Other assets	(5,344,000)	(350,000)	(3,948,000)
Accrued interest payable	1,608,000	(1,121,000)	1,355,000
Accrued expenses and other liabilities	(5,261,000)	(9,095,000)	(7,655,000)
Net cash provided by operating activities	79,935,000	26,853,000	4,236,000
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of securities available-for-sale	(206,046,000)	(53,480,000)	(557,527,000)
Proceeds from maturities and calls of securities available-for-sale	29,593,000	7,917,000	95,412,000
Proceeds from paydowns of securities available-for-sale	60,557,000	69,320,000	105,837,000
Proceeds from sales and calls of securities available-for-sale	544,000	8,000	534,418,000
Purchases of securities held-to-maturity			(59,436,000)
Proceeds from maturities and calls of securities held-to-maturity		655,000	30,469,000
Proceeds from paydowns of securities held-to-maturity	16,892,000	19,747,000
Purchases of Federal Home Loan Bank stock	(36,633,000)	(19,485,000)	(6,454,000)
Federal Home Loan Bank stock repurchases	35,134,000	18,135,000
Proceeds from other loans sold		9,984,000	2,213,000
Net change in loans and leases	(300,142,000)	(132,568,000)	(450,522,000)
Purchases of premises and equipment	(2,578,000)	(2,538,000)	(5,948,000)
Proceeds from sales of premises and equipment	1,440,000		1,156,000
Proceeds from sales of assets held for sale	4,415,000	5,373,000	2,566,000
Proceeds from sales of other real estate owned	7,051,000	13,898,000	17,306,000
Proceeds from bank owned life insurance death benefit		1,399,000
Net cash received (paid) in acquisition of business	20,374,000		(11,273,000)
Net cash used in investing activities	(369,399,000)	(61,635,000)	(301,783,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) increase in deposits	284,723,000	(46,287,000)	(51,010,000)
Proceeds from Federal Home Loan Bank advances	5,932,000,000	3,037,000,000	6,512,100,000
Repayments of Federal Home Loan Bank advances	(5,868,487,000)	(2,989,000,000)	(6,246,114,000)
Proceeds from line of credit			30,000,000
Repayments of line of credit		(20,650,000)	(9,350,000)
Net increase in securities sold under agreements to repurchase	2,979,000	13,938,000	4,590,000
Dividends paid on preferred stock	(783,000)	(11,277,000)
Cash paid in lieu of fractional shares		(2,000)
Proceeds from issuance of common stock, upon exercise of stock options	2,340,000
Proceeds from issuance of common stock	203,000	76,829,000	49,592,000
Proceeds from issuance of preferred stock		1,050,000	9,388,000
Repurchase of preferred stock		(15,003,000)
Net cash provided by financing activities	352,975,000	46,598,000	299,196,000
NET INCREASE IN CASH AND CASH EQUIVALENTS	63,511,000	11,816,000	1,649,000
CASH AND CASH EQUIVALENTS, beginning of period	58,349,000	46,533,000	44,884,000
CASH AND CASH EQUIVALENTS, end of period	121,860,000	58,349,000	46,533,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid during the period for interest	25,967,000	15,279,000	6,150,000
Cash payments (refunds) during the period for taxes	3,513,000	2,849,000	(250,000)
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Change in fair value of available-for-sale securities, net of tax	(4,811,000)	1,501,000	(3,794,000)
Change in fair value of cash flow hedges, net of tax	1,163,000	680,000	2,233,000
Delayed payments of mortgage-backed securities	398,000	311,000	121,000
Transfers of loans to loans held for sale		10,061,000	1,477,000
Transfers of loans to other real estate owned	2,436,000	6,690,000	6,659,000
Internally financed sale of other real estate owned	444,000		1,447,000
Internally financed sale of assets held for sale		1,800,000
Transfers of land and premises to assets held for sale	9,058,000	3,372,000	14,496,000
Transfers of assets held for sale to premises and equipment	425,000
Transfers of premises and equipment to other assets	35,000	713,000
Transfer of other assets to assets held for sale	16,000
Subscription receivable of preferred stock			1,050,000
Due to broker		9,838,000	9,978,000
Due from counterparties	5,338,000	$ 39,824,000
Total assets acquired from acquisition	1,142,125,000		456,153,000
Total liabilities assumed from acquisition	1,036,609,000		377,440,000
Common stock and stock options issued due to acquisition of business	$ 152,127,000		$ 68,247,000

Business and Summary of Signifi

Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Business Description And Accounting Policies [Abstract]
Business and Summary of Significant Accounting Policies	Note 1—Business and Summary of Significant Accounting Policies Nature of business —Byline Bancorp, Inc. (the “Company,” “we,” “us,” “our”) is a bank holding company whose principal activity is the ownership and management of its subsidiary bank, Byline Bank (the “Bank”). The Bank originates commercial, mortgage and consumer loans and leases, U.S. government guaranteed loans, and receives deposits from customers located primarily in the Chicago, Illinois metropolitan area. The Bank operates 57 Chicago metropolitan area and one Brookfield, Wisconsin, banking offices. The Bank operates under an Illinois state bank charter, provides a full range of banking services, and has full trust powers. As an Illinois state‑chartered financial institution that is not a member of the Federal Reserve System, the Bank is subject to regulation by the Illinois Department of Financial and Professional Regulation and the Federal Deposit Insurance Corporation. The Company is regulated by the Board of Governors of the Federal Reserve System. As a result of its acquisition of Ridgestone Financial Services, Inc. (“Ridgestone”) on October 14, 2016, the Bank is a participant in the Small Business Administration (“SBA”) and the United States Department of Agriculture (“USDA”) (collectively referred to as “U.S. government guaranteed loans”) lending programs and originates U.S. government guaranteed loans. As a result of its acquisition of First Evanston Bancorp, Inc. (“First Evanston”) on May 31, 2018, the Bank also provides wealth management services to our customers. See Note 3—Acquisition of a Business for additional information regarding the transaction. The Bank engages in short‑term direct financing lease contracts through BFG Corporation, doing business as Byline Financial Group (“BFG”), a wholly‑owned subsidiary of the Bank. BFG is located in Bannockburn, Illinois with sales offices in Illinois and New York, and sales representatives in Illinois, Michigan, New Jersey and New York. On June 14, 2017, stockholders of record as of May 22, 2017 voted to approve an Agreement and Plan of Merger between Byline Bancorp, Inc., an Illinois corporation (“Byline Illinois”), and Byline Bancorp, Inc., a wholly owned Delaware subsidiary of the Company, including the amended and restated certificate of incorporation and by‑laws of the Company. Each share of Byline Illinois common stock issued and outstanding immediately prior to the effective time of the Merger was converted automatically into the right to receive one fifth (0.20) of a share of common stock of the Company. Stockholders were paid a total of $2,000 in cash for remaining fractional shares based on the offering price of $19.00 per share. On October 17, 2018, the Company entered a definitive merger agreement with Oak Park River Forest Bankshares, Inc. (which we refer to as “Oak Park River Forest”), the parent company of Community Bank of Oak Park River Forest, to which the Company will acquire Oak Park River Forest through the merger of Oak Park River Forest with and into the Company, followed immediately by the merger of Community Bank of Oak Park River Forest with and into Byline Bank. At such time, Community Bank of Oak Park River Forest’s banking offices will become banking offices of the Bank. The above described merger agreements are anticipated to be completed during the first half of 2019, subject to the satisfaction or waiver of the conditions included in the merger agreement. No other subsequent events were identified that would have required a change to the consolidated financial statements or disclosure in the notes to the consolidated financial statements. Basis of financial statement presentation and consolidation —The consolidated financial statements include the accounts of the Company and its subsidiaries. Significant intercompany items and transactions have been eliminated in consolidation. The accounting and reporting policies of the Company conform to accounting principles generally accepted in the United States of America (“GAAP”) as contained within the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) and rules and regulations of the Securities and Exchange Commission (“SEC”), including the instructions to Regulation S‑X. In accordance with applicable accounting standards, the Company does not consolidate statutory trusts established for the sole purposes of issuing trust preferred securities and related trust common securities. See Note 15, Junior Subordinated Debentures, for additional discussion. Dollars within footnote tables disclosed within the consolidated financial statements are presented in thousands, except share and per share data. Operating results include the years ended December 31, 2018, 2017 and 2016. Use of estimates —In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the reported amounts of certain assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the Consolidated Statements of Financial Condition and certain revenues and expenses for the periods included in the Consolidated Statements of Operations and the accompanying notes. Actual results could differ from those estimates. Estimates that are particularly susceptible to significant changes in the near term relate to the determination of expected cash flows of acquired impaired loans, the allowance for loan and lease losses, valuation of servicing assets, fair value measurements for assets and liabilities, goodwill, other intangible assets, the valuation or recognition of deferred tax assets and liabilities, and the valuation of assets and liabilities acquired in business combinations. Note 1—Business and Summary of Significant Accounting Policies (continued) Business combinations —The Company accounts for business combinations under the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations (“ASC 805”). The Company recognizes the fair value of the assets acquired and liabilities assumed as of the date of acquisition, with any excess of the fair value of consideration provided over the fair value of the identifiable net tangible and intangible assets acquired recorded as goodwill. Transaction costs are immediately expensed as applicable. The results of operations of the acquired business are included in the Consolidated Statements of Operations from the effective date of the acquisition, which is the date control is obtained. In accordance with ASC 805, the acquiring company retains the right to make appropriate adjustments to the assets and liabilities of the acquired entity for information obtained during the measurement period about facts and circumstances that existed as of the acquisition date. The measurement period ends as of the earlier of (a) one year from the acquisition date or (b) the date when the acquirer receives the information necessary to complete the business combination accounting. Cash and cash equivalents —Cash and cash equivalents have original maturities of three months or less. The Company holds cash and cash equivalents on deposit with other banks and financial institutions in amounts that periodically exceed the federal deposit insurance limit. The Company evaluates the credit quality of these banks and financial institutions to mitigate its credit risk and has not experienced any losses in such accounts. Cash on hand or on deposit with the Federal Reserve Bank of Chicago was required to meet regulatory reserve and clearing requirements. The reserve requirement was $44.8 million and $15.8 million as of December 31, 2018 and 2017, respectively, and the Bank met the requirement at each balance sheet date. Securities —Securities that are held principally for resale in the near term are classified as trading and recorded at fair value with changes in fair value included in earnings. The Company did not invest in securities classified as trading during 2018, 2017 and 2016. Securities are classified as available‑for‑sale if the instrument may be sold in response to such factors including changes in market interest rates and related changes in prepayment risk, needs for liquidity, changes in the availability of and the yield on alternative instruments, and changes in funding sources and terms. Gains or losses on the sales of available‑for‑sale securities are recorded on the trade date and determined using the specific‑identification method. Unrealized holding gains or losses, net of tax, on available‑for‑sale securities are carried as accumulated other comprehensive income (loss) within stockholders’ equity until realized. Securities are classified as held‑to‑maturity and carried at amortized cost when management has the positive intent and ability to hold them to maturity. Fair values of securities are generally based on quoted market prices for the same or similar instruments. See Note 18—Fair Value Measurement for additional discussion on the determination of fair values. Interest income includes the amortization of purchase premiums and discounts, which are recognized using the effective interest method over the terms of the securities. Management evaluates securities for other‑than‑temporary impairment (“OTTI”) on a quarterly basis, and more frequently when economic or market conditions warrant such evaluation. The evaluation is based upon factors such as the creditworthiness of the issuers or guarantors, the underlying collateral, if applicable, and the continuing performance of the securities. Management also evaluates other facts and circumstances that may be indicative of an OTTI condition. This includes, but is not limited to, an evaluation of the type of security, length of time and extent to which the fair value has been less than cost, and near‑term prospects of the issuer. The Company’s assessment of OTTI considers whether it intends to sell a security or if it is likely that it would be required to sell the security before recovery of the amortized cost basis of the investment, which may be at maturity. For debt securities, if the Company intends to sell the security or it is more likely than not that it will be required to sell the security before recovering its cost basis, the entire impairment loss is recognized in earnings as an OTTI. If the Company does not intend to sell the security and it is more likely than not that it will not be required to sell the security, and the Company does not expect to recover the entire amortized cost basis of the security, only the portion of the impairment loss representing credit losses would be recognized in earnings. The credit loss on a security is measured as the difference between the amortized cost basis and the present value of the cash flows expected to be collected. Projected cash flows are discounted by the original or current effective interest rate depending on the nature of the security being measured for potential OTTI. The remaining impairment related to all other factors, the difference between the present value of the cash flows expected to be collected and fair value, is recognized as a charge to other comprehensive income (loss). Restricted stock —The Company owns stock of the Federal Home Loan Bank of Chicago (“FHLB”). No ready market exists for this stock, and it has no quoted market value. As a member of the FHLB system, the Bank is required to maintain an investment in FHLB stock. The stock is redeemable at par by the FHLB and is, therefore, carried at cost. In addition, the Company owns stock of Bankers Bank that was acquired as part of the Ridgestone transaction. The stock is redeemable at par and carried at cost. Note 1—Business and Summary of Significant Accounting Policies (continued) Restricted stock is generally viewed as a long‑term investment. Accordingly, when evaluating for impairment, its value is determined based on the ultimate recoverability of the par value rather than by recognizing temporary declines in value. The Company did not recognize impairment of its restricted stock as a result of its impairment analyses for the years ended December 31, 2018, 2017 and 2016. Loans held for sale —Loans that management has the intent and ability to sell are designated as held for sale. U.S. government guaranteed loans and mortgage loans originated are carried at either amortized cost or estimated fair value. The Company determines whether to account for loans at fair value or amortized cost at origination. The loans accounted for at fair value remain at fair value after the determination. The loans accounted for at amortized cost are carried at the lower of cost or fair value, valued on a loan by loan basis. Net unrealized losses, if any, are recorded as a valuation allowance and charged to earnings. Gains or losses on sales of U.S. government guaranteed loans are recognized based on the difference between the net sales proceeds, carrying value of the sold loan, fair value of the servicing asset recognized, and fair value of the retained loan (if any), and are reflected as operating activities in the Consolidated Statements of Cash Flows. The difference between the initial carrying balance of the retained loan and the relative fair value of the sold portion is recorded as a discount to the retained loan, establishing a new carrying balance. The recorded discount is accreted to earnings on a level yield basis. U.S. government guaranteed loans are generally sold with servicing retained. Loans transferred to loans held for sale are carried at the lower of cost or fair value, less estimated costs to sell. At the time of transfer, write‑downs are recorded as charge‑offs, establishing a new cost basis. Any subsequent adjustments are determined on an individual loan basis and are recognized as a charge to non‑interest income. Sales proceeds received that are in excess of the new cost basis within 90 days are recorded to the allowance for loan and lease losses, up to the amount previously charged off. Any remaining proceeds are recorded as a gain on sale and included in non‑interest income. Sales proceeds that are less than the new cost basis upon transfer and are received within 90 days of classifying the loans as held for sale are recorded as a charge‑off to the allowance for loan and lease losses. Any proceeds received after 90 days of classifying the loans as held for sale are recorded as a gain or loss on sale and included in other non‑interest income. Loans held for sale that have not yet settled as of year-end are classified as due-from counterparty on the Consolidated Statements of Financial Condition. Originated loans —Originated loans are stated at the amount of unpaid principal outstanding, net of purchase premiums and discounts, and any deferred fees or costs. Net deferred fees, costs, discounts and premiums are recognized as yield adjustments over the contractual life of the loan. Interest on loans is calculated daily based on the principal amount outstanding. Originated loans are classified as impaired when, based on current information and events, it is probable that the Company will be unable to collect the scheduled payments of principal and interest when due, in accordance with the terms of the original loan agreement. The carrying value of impaired loans is based on the present value of expected future cash flows (discounted at each loan’s effective interest rate) or, for collateral dependent loans, at the fair value of the collateral less estimated selling costs. If the measurement of each impaired loan’s value is less than the recorded investment in the loan, impairment is recognized and the carrying value of the loan is adjusted in the allowance for loan and lease losses as a specific component provided or through a charge‑off of the impaired portion of the loan. Accrual of interest on impaired loans is discontinued when the loan is 90 days past due or when, in management’s opinion, the borrower may be unable to make payments as they become due. When the accrual of interest is discontinued, all unpaid accrued interest is reversed through interest income. Payments received during the time a loan is on non‑accrual status are applied to principal. Interest income is not recognized until the loan is returned to accrual status or after the principal balance is paid in full. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured as evidenced by agreed upon performance for a period of not less than six months. Troubled debt restructuring —A troubled debt restructuring (“TDR”) is a formal restructuring of a loan in which the Company, for economic or legal reasons related to the borrower’s financial difficulties, grants a concession to the borrower. The concessions may be granted in various forms, including providing a below‑market interest rate, reduction in the loan balance or accrued interest, extension of the maturity date, or a combination of these. Troubled debt restructurings are considered to be impaired loans and are subject to the Company’s impaired loan accounting policy. Acquired impaired loans are not subject to TDR accounting. The Company does not accrue interest on a TDR unless it believes collection of all principal and interest under the modified terms is reasonably assured. For a TDR to begin accruing interest, the borrower must demonstrate some level of past performance and the future capacity to perform under the modified terms. Generally, six months of consecutive payment performance under the restructured terms is required before a TDR is returned to accrual status. Note 1—Business and Summary of Significant Accounting Policies (continued) Direct finance leases —The Company engages in leasing for small‑ticket equipment, software, machinery and ancillary supplies and services to customers under leases that qualify as direct financing leases for financial reporting. Certain leases qualify as operating leases for income tax purposes. Under the direct financing method of accounting, the minimum lease payments to be received under the lease contract, together with the estimated unguaranteed residual values of the related equipment, are recorded as lease receivables when the lease is signed and funded and the lease property is delivered to the customer. The excess of the minimum lease payments and residual values over the amount financed is recorded as unearned lease income. Unearned lease income is recognized over the term of the lease based on the effective yield interest method. Residual value is the estimated fair market value of the equipment on lease at lease termination. In estimating the equipment’s fair value at lease termination, the Company relies on historical experience by equipment type and manufacturer and, where available, valuations by independent appraisers, adjusted for known trends. The Company’s residual values are estimates for reasonableness; however, the amounts the Company will ultimately realize could differ from the estimated amounts. If the review of the residual value results in other‑than‑temporary impairment, the impairment is recognized in current period earnings. An upward adjustment of the estimated residual value is not recorded. The policies for delinquency and non‑accrual for direct finance leases are materially consistent with those described for all classes of loan receivables. The Company defers and amortizes certain initial direct costs over the contractual term of the lease as an adjustment to the yield. The unamortized direct costs are recorded as a reduction of unearned lease income. Acquired impaired loans —Loans initially acquired with evidence of credit quality deterioration are accounted for under ASC Topic 310‑30, Accounting for Purchased Loans with Deteriorated Credit Quality (“ASC 310‑30”). These loans are recorded either on a pool or a loan‑by‑loan basis at their estimated fair value where applicable. The Company may aggregate loans into pools based on similar credit risks and predominant risk characteristics such as delinquency status and loan type. Management estimated the fair values of acquired impaired loans at the acquisition date based on estimated future cash flows. The excess of cash flows expected to be collected over a loan’s carrying value is considered to be the accretable yield and is recognized as interest income over the estimated life of the loan or pool using the effective yield method. The acquisition date estimates of accretable yield may subsequently change due to changes in management’s estimates of timing and amounts of expected cash flows. The excess of the contractual amounts due over the cash flows expected to be collected is considered to be the non‑accretable difference. The non‑accretable difference represents the Company’s estimate of the credit losses expected to occur and is considered in determining the fair value of the loans. Reclassifications between accretable yield and non‑accretable difference represent changes in expected cash flows over the remaining estimated life of the loan or pool. Subsequent increases in expected cash flows over those expected at inception are adjusted through an increase to the accretable yield on a prospective basis. Any subsequent decreases in expected cash flows attributable to credit deterioration are recognized by recording an additional provision for loan losses. Once a pool of loans is assembled, the integrity of the pool is maintained. A loan can only be removed from a pool if either of the following conditions is met: (1) the Company sells, forecloses, or otherwise receives assets in satisfaction of the loan, or (2) the loan is written off. A refinancing or restructuring of a loan does not result in a removal of a loan from a pool. Loan sales are accounted for under ASC Topic 860, Transfers and Servicing (“ASC 860”), when control over the assets have been relinquished. See transfers of financial assets accounting policy. Acquired non‑impaired loans and leases —Acquired non‑impaired loans and leases are accounted for under ASC Subtopic 310‑20, Receivables Nonrefundable Fees and Other Costs (“ASC 310‑20”). These loans and leases were individually recorded at fair value at the time of acquisition. Any previously recognized allowance for loan and lease losses and unearned fees or discounts are not carried over and recognized at the date of acquisition. The component of fair value representing an adjustment to an asset’s outstanding principal balance is accreted or amortized over the life of the related asset as a yield adjustment. The balance of the asset is then evaluated periodically pursuant to the Company’s allowance for loan and lease loss accounting policy and any adjustment required for credit risk is recorded within the allowance for loan and lease losses. Upon reaching the maturity date, all acquired non-impaired loan premium or discount is fully amortized or accreted. If the loan is re-underwritten and renewed, it is internally reclassified as an originated loan. The loan is then evaluated periodically pursuant to the Company’s allowance for loan and lease loss accounting without any consideration of the acquisition premium or discount. Note 1—Business and Summary of Significant Accounting Policies (continued) Allowance for loan and lease losses —The allowance for loan and lease losses is maintained at a level management believes is appropriate to provide for probable loan and lease losses as of the dates of the Consolidated Statements of Financial Condition. The allowance for loan and lease losses is increased by a provision for loans and lease losses and decreased by charge‑offs, net of recoveries. Loan and lease losses are charged against the allowance for loan and lease losses when management believes the uncollectibility of a loan or lease balance is confirmed. Subsequent recoveries, if any, are credited to the allowance for loan and lease losses. The allowance for loan and lease losses is based on management’s evaluation of the loan and lease portfolio giving consideration to the nature and volume of the portfolio, the value of the underlying collateral, overall portfolio quality, review of specific problem loans or leases, and prevailing economic conditions that may affect the borrower’s ability to pay. While management uses the best information available to make its evaluation, future adjustments to the allowance for loan and lease losses may be necessary if there are significant changes in economic condition. The allowance for loan and lease losses consists of general and specific components. Allocations of the allowance for loan and lease losses not attributable to acquired impaired loans may be made for specific loans and leases, but the entire allowance is available for any loan and lease that, in management’s judgement, should be charged off. The general component covers loans and leases that are collectively evaluated for impairment. Larger groups of smaller balance homogeneous loans, such as consumer and residential real estate loans, and leases are collectively evaluated for impairment, and accordingly, they are not included in the separately identified impairment disclosures. The general component is based on a trailing 12‑quarter weighted average loss rate for each loan category based on the Company’s historical losses and its peer group and adjusted for qualitative and other economic factors. These factors include (1) changes in lending policies and procedures, including changes in underwriting standards and collections, charge‑off and recovery practices; (2) changes in international, national, regional and local conditions; (3) changes in the nature and volume of the portfolio and terms of the loans and leases; (4) changes in experience, depth and ability of lending management and other relevant staff; (5) changes in the volume and severity of past due loans and leases; (6) changes in the quality of the Company’s loan review system; (7) changes in the value of the underlying collateral for collateral dependent loans and leases; (8) existence and effect of any concentrations of credit and changes in the levels of such concentrations; and (9) the effect of other external factors (i.e., competition, legal and regulatory requirements) on the level of estimated credit losses. Based upon management’s judgement of other factors that fall outside of the predefined qualitative or historical loss rates, the allowance for loan and lease losses may include an unallocated component not included in these predefined factors. The specific component relates to loans that are risk‑rated substandard or worse, and based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Factors considered by management in determining the impairment include payment status, collateral value, strength of guarantor, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired and are reviewed on a case‑by‑case basis. TDRs are individually evaluated for impairment and are measured at the present value of estimated future cash flows using the loan’s effective rate at origination. If a TDR is considered to be a collateral dependent loan, the loan is reported at the fair value of the collateral, less estimated costs to sell. The allowance for loan losses also includes amounts representing decreases in expected cash flows attributable to credit deterioration of acquired impaired loans. The evaluation is inherently subjective, as it requires estimates that are susceptible to significant revision as more information becomes available. The factors supporting the allowance for loan and lease losses do not diminish the fact that the entire allowance for loan and lease losses not attributable to acquired impaired loans is available to absorb losses in the loan and lease portfolios and related commitment portfolio, respectively. The allowance for loan and lease losses is subject to review by regulatory agencies during examinations and may require us to recognize adjustments to the allowance for loan and lease losses. Servicing assets —Servicing assets are recognized separately when they are acquired through sales of loans. When loans are sold with servicing rights retained, servicing assets are recorded at fair value in accordance with ASC 860. Fair value is based on market prices for comparable servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. Sales of U.S. government guaranteed loans are executed on a servicing retained basis. The standard SBA loan sale agreement is structured to provide the Company with a servicing spread paid from a portion of the interest cash flow of the loan. SBA regulations require the Company to retain a portion of the cash flow from the interest payments received for a sold loan. The USDA loan sale agreements are not standardized with respect to servicing. Note 1—Business and Summary of Significant Accounting Policies (continued) Servicing fee income, which is reported on the Consolidated Statements of Operations as loan servicing revenue, is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal. Late fees and ancillary fees related to loan servicing are not material. The Company has elected the fair value measurement method and measures servicing rights at fair value at each reporting date and reports changes in fair value of servicing assets in earnings in the period in which the changes occur, and are recorded as loan servicing asset revaluation on the Consolidated Statements of Operations. The fair value of servicing rights is highly sensitive to changes in underlying assumptions. Changes in the prepayment speed and discount rate assumptions have the most significant impact on the fair value of servicing rights. Concentrations of credit risk —Most of the Company’s business activity is concentrated with customers located within its principal market areas, with the exception of government guaranteed loans and leasing activities. The Company originates commercial real estate, construction, land development and other land, commercial and industrial, residential real estate, installment and other loans, and leases. Generally, loans are secured by accounts receivable, inventory, deposit accounts, personal property or real estate. Rights to collateral vary and are legally documented to the extent practicable. The Company has a concentration in commercial real estate loans and the ability of borrowers to honor these and other contracts is dependent upon the real estate and general economic conditions within their geographic market. Transfers of financial assets —Transfers of financial assets are accounted for as sales when control over the assets has been relinquished. The Company has assessed that partial sales of financial assets meet the definition of participating interest. Control over transferred assets is deemed to be surrendered when the assets have been isolated from the Company and the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets. Gains or losses are recognized in the period of sale upon derecognition of the asset. Premises and equipment —Premises and equipment acquired through a business combination are initially stated at the acquisition date fair value less accumulated depreciation. All other premises and equipment are stated at cost less accumulated depreciation. Depreciation on premises and equipment is recognized on a straight‑line basis over their estimated useful lives ranging from three to 39 years. Land is also carried at its fair value following a business combination and is not subject to depreciation. Leasehold improvements are amortized over the shorter of the life of the related asset or expected term of the underlying lease. Gains and losses on the dispositions of premises and equipment are included in non‑interest income. Expenditures for new premises, equipment and major betterments are capitalized. Normal costs of maintenance and repairs are expensed as incurred. Long‑lived depreciable assets are evaluated periodically for impairment when events or changes in circumstances indicate the carrying amounts may be not recoverabl

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2018
Accounting Changes And Error Corrections [Abstract]
Recently Issued Accounting Pronouncements	Note 2—Recently Issued Accounting Pronouncements The following reflect recent accounting pronouncements that have been adopted or are pending adoption by the Company. As the Company qualifies as an emerging growth company and has elected the extended transition period for complying with new or revised accounting pronouncements, it is not subject to new or revised accounting standards applicable to public companies during the extended transition period. The accounting pronouncements pending adoption below reflect effective dates for the Company as an emerging growth company with the extended transition period. Revenue from Contracts with Customers —In May 2014, FASB issued Accounting Standards Update (“ASU”) No. 2014‑09, deferred by ASU No. 2015‑14 and clarifying standards, , which creates Topics 606 and 610 and supersedes Topic 605, Revenue Recognition. The core principle of Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In April 2016, FASB issued ASU No. 2016-10, . The amendments in this ASU clarify the following two aspects of Topic 606: (1) identifying performance obligations and (2) licensing implementation guidance, while retaining the related principles for those areas. In May 2016, FASB issued ASU No. 2016-12, , amending ASC Topic 606, . The amendments in this ASU affect only several narrow aspects of Topic 606. In November 2017, FASB issued ASU No. 2017-14, amending ASC Topic 606, . The ASU amends the codification to incorporate additional previously issued guidance from the SEC. The SEC issued SAB 116 to bring existing SEC staff guidance into conformity with the FASB’s adoption of and amendments to ASC Topic 606. In general, the new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. As a financial institution, the Company’s largest component of revenue is interest income, which is excluded from the scope of this ASU, and non-interest income. The new authoritative guidance was initially effective for reporting periods after January 1, 2017 but was deferred to January 1, 2018. Given our emerging growth status, the Company adopted this new guidance on January 1, 2019 and does not expect it to have a significant impact on the Company’s Consolidated Statements of Operations or Financial condition other than potential reclassification of certain non-interest expenses to non-interest income and additional footnote disclosures. Recognition and Measurement of Financial Assets and Financial Liabilities —In January 2016, FASB issued ASU No. 2016‑01, . The amendments in this ASU require equity securities to be measured at fair value with changes in the fair value recognized through net income. The amendments allow equity investments that do not have readily determinable fair values to be remeasured at fair value under certain circumstances and require enhanced disclosures about those investments. The amendments simplify the impairment assessment of equity investments without readily determinable fair values. The amendments also eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The amendments require entities to adjust fair value disclosures for financial instruments to be reflected at an exit price. The amendments in this ASU require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument‑specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This amendment excludes from net income gains or losses that the entity may not realize because those financial liabilities are not usually transferred or settled at their fair values before maturity. The amendments in this ASU require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or in the accompanying notes to the financial statements. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company adopted the provisions of ASU No. 2016-01 as of January 1, 2019. At December 31, 2018, the Company held $6.6 million of available-for-sale equity investment securities. The provisions of ASU No. 2016-01 require changes in the value of equity securities to be recognized in the Consolidated Statements of Operations which could result in additional volatility in non-interest income. Note 2—Recently Issued Accounting Pronouncements (continued) Leases (Topic 842) —In February 2016, FASB issued ASU No. 2016‑02, . The amendments in this ASU require lessees to recognize the following for all leases (with the exception of short‑term) at the commencement date; a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right‑of‑use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendments in this ASU leave lessor accounting largely unchanged, although certain targeted improvements were made to align lessor accounting with the lessee accounting model. This ASU simplifies the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off‑balance sheet financing. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales‑type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is evaluating the new guidance and its impact on the Company’s Consolidated Statements of Operations and Consolidated Statements of Financial Condition. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company expects an increase in assets and liabilities as a result of recognizing additional right-to-use assets and lease liabilities under lease contracts in which the Company is lessee. Derivatives and Hedging (Topic 815) —In August 2017, FASB issued ASU No. 2017-12, . The amendments in this ASU better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The new authoritative guidance will be effective for reporting periods after January 1, 2019. Adoption of this ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements. Compensation—Stock Compensation (Topic 718) —In May 2017, the FASB issued ASU 2017-09, . The amendments in the ASU provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. An entity should account for the effects of a modification unless all of the following are met: (1) the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) or the modified award is the same as the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification, (2) the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified, (3) the classification of the modified award is an equity instrument or liability instrument is the same as the classification of the original award immediately before the original award is modified. The amendments are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period, for reporting periods for which financial statements have not yet been issued. The amendments should be applied prospectively to an award modified on or after the adoption date. The Company adopted the provisions of ASU No. 2017-09 on January 1, 2019, which did not have a material impact on the Company’s Consolidated Financial Statements. Note 2—Recently Issued Accounting Pronouncements (continued) Financial Instruments—Credit Losses (Topic 326) —In June 2016, FASB issued ASU No. 2016‑13, . Current GAAP requires an “incurred loss” methodology for recognizing credit losses that delays recognition until it is probable a loss has been incurred. The main objective of this ASU is to provide financial statement users with more decision‑useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this ASU replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The amendments in this ASU require a financial asset (or group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) to present the net carrying value at the amount expected to be collected on the financial asset. The measurement of expected credit losses will be based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The amendments in this ASU broaden the information that an entity must consider in developing its expected credit loss estimate for assets measured either collectively or individually. The use of forecasted information incorporates more timely information in the estimate of expected credit loss, which will be more decision useful to users of the financial statements. The amendments in this ASU will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2021. The Company is still evaluating the effects this ASU will have on the Company’s Consolidated Financial Statements. While the Company has not quantified the impact of this ASU, it does expect changing from the current incurred loss model to an expected loss model will result in an earlier recognition of losses. Statement of Cash Flows (Topic 230) —In August 2016, FASB issued ASU No. 2016‑15, . There is diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows under Topic 230 and other Topics. This ASU addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. Those eight issues are (1) debt prepayment or debt extinguishment costs, (2) settlement of zero‑coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, (3) contingent consideration payments made after a business combination, (4) proceeds from the settlement of insurance claims, (5) proceeds from the settlement of corporate‑owned life insurance policies, including bank‑owned life insurance policies, (6) distributions received from equity method investees, (7) beneficial interests in securitization transactions, and (8) separately identifiable cash flows and application of the predominance principle. Current GAAP either is unclear or does not include specific guidance on these eight cash flow classification issues. These amendments provide guidance for each of the eight issues, thereby reducing current and potential future diversity in practice. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2019. The Company adopted the provisions of ASU No. 2016-15 on January 1, 2019, which did not have a material impact on the Company’s Consolidated Financial Statements. In November 2016, the FASB issued ASU No. 2016‑18, Statement of Cash Flows (Topic 230), Restricted Cash The Company adopted Business Combinations (Topic 805) —In January 2017, the FASB issued ASU No. 2017‑01, . The guidance clarifies the definition of a business to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. This guidance is effective for annual and interim periods beginning after December 15, 2017. Early adoption is permitted. The Company adopted the provisions of ASU No. 2017-01 on January 1, 2019, which did not have a material impact on the Company’s Consolidated Financial Statements. Note 2—Recently Issued Accounting Pronouncements (continued) Intangibles—Goodwill and Other (Topic 350) —In January 2017, FASB issued ASU No. 2017‑04, . The amendments in this ASU are intended to reduce the cost and complexity of the goodwill impairment test by eliminating step two from the impairment test. The amendments modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. Under the amendments in this ASU, an entity will perform its annual, or interim, goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount. An impairment charge should be recognized for the amount which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The amendments in this ASU are effective for the Company’s annual or any interim goodwill impairment test in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company early adopted these amendments in 2017 which did not have a material impact on the Company’s Consolidated Financial Statements. Other Income (Subtopic 610‑20) —In February 2017, the FASB issued ASU No. 2017‑05, . This ASU will clarify the scope of Subtopic 610‑20 and add guidance for partial sales of nonfinancial assets. The amendments should be applied either on retrospectively to each period presented or with a modified retrospective approach. The amendment is effective for annual periods beginning after December 15, 2018. The Company does not expect a material impact of this ASU on the Company’s Consolidated Financial Statements. Nonrefundable Fees and Other Costs (Subtopic 310‑20) —In March 2017, FASB issued ASU No. 2017‑08, . The amendments in the ASU shorten the amortization period for certain callable debt securities held at a premium at the earliest call date. Under current GAAP, the Company amortizes the premium as an adjustment of yield over the contractual life of the instrument. As a result, upon exercise of a call on a callable debt security held at a premium, the unamortized premium is charged to earnings. The ASU shortens the amortization period for certain callable debt securities held at a premium and requires the premium to be amortized to the earliest call date. However, the amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The amendments are effective for annual periods beginning after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Early adoption is permitted. The Company is required to apply the amendments on a modified retrospective basis through a cumulative‑effect adjustment directly to retained earnings as of the beginning of the period of adoption. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company is currently evaluating the provisions of ASU No. 2017‑08 to determine the potential impact the new standard will have on the Company’s Consolidated Financial Statements. Income Statement—Reporting Comprehensive Income (Topic 220) —In February 2018, FASB issued ASU No. 2018-02, . The ASU helps organizations address certain stranded income tax effects in accumulated other comprehensive income (AOCI) resulting from the Tax Cuts and Jobs Act. The ASU provides reporting entities with an option to reclassify stranded tax effects within AOCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The ASU requires reporting entities to disclose: a description of the accounting policy for releasing income tax effects from AOCI; whether they elect to reclassify the stranded income tax effects from the Tax Cuts and Jobs Act; and information about the other income tax effects that are reclassified. The amendments affect any organization that is required to apply the provisions of Topic 220, , and has items of other comprehensive income for which the related tax effects are presented in other comprehensive income as required by GAAP. The amendments are effective for annual periods beginning after December 15, 2018, and interim periods within those fiscal years. The Company early adopted the new guidance on January 1, 2018. The adoption did not impact the Company’s Statements of Operations, and resulted in a reclassification of $763,000 from accumulated other comprehensive income (loss) to retained earnings. Note 2—Recently Issued Accounting Pronouncements (continued) Fair Value Measurement (Topic 820) —In August 2018, FASB issued ASU No. 2018-13, — . The amendments in this ASU modify the disclosure requirements on fair value measurements in Topic 820. The amendments remove the disclosure requirements for the amount and reasons for transfers between Level 1 and Level 2 securities of the fair value hierarchy, the policy for timing of transfers between levels, and the valuation processes for Level 3 fair value measurement. The amendments modify the disclosure requirements as follows: in lieu of a rollforward for Level 3 fair value measurements, a nonpublic entity is required to disclose transfers into and out of Level 3 of the fair value hierarchy and purchases and issues of Level 3 assets and liabilities; for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s assets and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly; and clarify that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. The amendments add the following disclosure requirements: the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. This guidance is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company early adopted these amendments in 2018, which did not have a material impact on the Company’s Consolidated Financial Statements.

Acquisition of a Business

Acquisition of a Business	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisition of a Business	Note 3—Acquisition of a Business On May 31, 2018, the Company acquired all common stock of First Evanston Bancorp, Inc. (“First Evanston”) and its subsidiaries pursuant to an Agreement and Plan of Merger, dated as of November 27, 2017 (the “Merger Agreement”). First Evanston operated two wholly owned subsidiaries, First Bank & Trust and First Evanston Bancorp Trust I. First Evanston was merged with and into Byline. As a result of the merger, First Evanston’s subsidiary bank, First Bank & Trust, was merged with and into Byline Bank, with Byline Bank as the surviving bank. The acquisition improves the Company’s footprint in the Chicagoland market, diversifies its commercial banking business, and strengthens the core deposit base. At the effective time of the merger (the “Effective Time”), each share of First Evanston’s common stock was converted into the right to receive: (1) 3.994 shares of Byline’s common stock, and (2) an amount in cash equal to $27.0 million divided by the number of outstanding shares of First Evanston common stock as of the closing date, with cash paid in lieu of any fractional shares. The per share cash consideration was based on the total $27.0 million divided by the outstanding shares of First Evanston common stock, or $16.136 per outstanding share. Based on the closing price of shares of the Company’s common stock of $21.62, as reported by the New York Stock Exchange, and 6,682,850 shares of common stock issued with respect to the outstanding shares of First Evanston common stock, the stock consideration was valued at $144.5 million. Options to acquire 144,090 shares of First Evanston common stock that were outstanding at the Effective Time were converted into options to acquire 680,787 shares of Byline common stock, resulting in a consideration value of $7.6 million. The value of the total merger consideration at closing was $179.1 million before the issuance costs of $852,000. The transaction resulted in goodwill of $73.6 million, which is nondeductible for tax purposes, as this acquisition was a nontaxable transaction. Goodwill represents the premium paid over the fair value of the net tangible and intangible assets acquired and reflects related synergies expected from the combined operations. The Company incurred First Evanston merger-related expenses, including acquisition advisory expenses, of $1.7 million and $1.3 million for the years ended December 31, 2018 and 2017, respectively. Core system conversion expenses were $9.8 million related to the First Evanston acquisition for the year ended December 31, 2018. These expenses are reflected in non-interest expense on the Consolidated Statements of Operations. The acquisition of First Evanston was accounted for using the acquisition method of accounting in accordance with ASC Topic 805. Assets acquired, liabilities assumed and consideration exchanged were recorded at their respective acquisition date fair values. Determining the fair value of assets and liabilities involves significant judgment regarding methods and assumptions used to calculate estimated fair values. The fair value adjustments associated with this transaction were finalized during the fourth quarter of 2018. Note 3—Acquisition of a Business (continued) The following table presents a summary of the estimated fair values of assets acquired and liabilities assumed as of the acquisition date: Assets Cash and cash equivalents $ 47,378 Securities available-for-sale 128,063 Restricted stock 1,360 Loans 916,011 Premises and equipment 15,890 Other intangible assets 22,276 Deferred tax assets, net 2,302 Other assets 8,845 Total assets acquired $ 1,142,125 Liabilities Deposits $ 1,022,268 Junior subordinated debentures 8,497 Accrued expenses and other liabilities 5,844 Total liabilities assumed 1,036,609 Net assets acquired $ 105,516 Consideration paid Common stock (6,682,850 shares issued at $21.62 per share) $ 144,483 Outstanding stock options converted to Byline stock options 7,644 Cash paid 27,004 Total consideration paid 179,131 Goodwill $ 73,615 The following table presents the acquired non-impaired loans as of the acquisition date: Fair value $ 890,986 Gross contractual amounts receivable 1,057,374 Estimate of contractual cash flows not expected to be collected (1) 36,544 Estimate of contractual cash flows expected to be collected 1,020,830 (1) Includes interest payments not expected to be collected due to loan prepayments as well as principal and interest payments not expected to be collected due to customer default. The discount on the acquired non-impaired loans is being accreted into income over the life of the loans on an effective yield basis. Note 3—Acquisition of a Business (continued) The following table provides the pro forma information for the results of operations for the years ended December 31, 2018 and 2017, as if the acquisition had occurred on January 1, 2017. The pro forma results combine the historical results of First Evanston into the Company’s Consolidated Statements of Operations, including the impact of certain acquisition accounting adjustments, which includes loan discount accretion, intangible assets amortization, deposit premium accretion and borrowing net discount amortization. The pro forma results have been prepared for comparative purposes only and are not necessarily indicative of the results that would have been obtained had the acquisition actually occurred on January 1, 2017. No assumptions have been applied to the pro forma results of operations regarding possible revenue enhancements, provision for credit losses, expense efficiencies or asset dispositions. The acquisition-related expenses that have been recognized are included in net income in the following table. Years ended December 31, 2018 2017 Total revenues (net interest income and non-interest income) $ 251,393 $ 225,446 Net income $ 55,329 $ 34,317 Earnings per share—basic $ 1.51 $ 0.68 Earnings per share—diluted $ 1.48 $ 0.67 The operating results of the Company include the operating results produced by the acquired assets and assumed liabilities of First Evanston for period beginning June 1, 2018 through December 31, 2018. Revenues and earnings of the acquired company since the acquisition date have not been disclosed as it is not practicable as First Evanston was merged into the Company and separate financial information is not readily available.

Securities

Securities	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Securities	Note 4—Securities The following tables summarize the amortized cost and fair values of securities available-for-sale and securities held-to-maturity at December 31, 2018 and 2017 and the corresponding amounts of gross unrealized gains and losses: 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale U.S. Treasury Notes $ 52,775 $ 81 $ (189 ) $ 52,667 U.S. Government agencies 187,427 367 (1,296 ) 186,498 Obligations of states, municipalities, and political subdivisions 60,686 133 (586 ) 60,233 Residential mortgage-backed securities Agency 284,038 101 (11,176 ) 272,963 Non-agency 84,998 199 (1,576 ) 83,621 Commercial mortgage-backed securities Agency 93,543 55 (3,164 ) 90,434 Non-agency 31,458 — (1,000 ) 30,458 Corporate securities 34,716 67 (610 ) 34,173 Other securities 4,613 2,127 (131 ) 6,609 Total $ 834,254 $ 3,130 $ (19,728 ) $ 817,656 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Held-to-maturity Obligations of states, municipalities, and political subdivisions $ 23,835 $ 40 $ (210 ) $ 23,665 Residential mortgage-backed securities Agency 40,082 93 (531 ) 39,644 Non-agency 35,349 — (919 ) 34,430 Total $ 99,266 $ 133 $ (1,660 ) $ 97,739 Note 4—Securities (continued) 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale U.S. Treasury Notes $ 14,999 $ — $ (136 ) $ 14,863 U.S. Government agencies 54,248 — (1,290 ) 52,958 Obligations of states, municipalities, and political subdivisions 33,405 100 (335 ) 33,170 Residential mortgage-backed securities Agency 315,103 — (7,646 ) 307,457 Non-agency 39,485 104 (75 ) 39,514 Commercial mortgage-backed securities Agency 70,964 45 (1,966 ) 69,043 Non-agency 31,763 — (792 ) 30,971 Corporate securities 29,573 507 (104 ) 29,976 Other securities 3,627 1,730 (73 ) 5,284 Total $ 593,167 $ 2,486 $ (12,417 ) $ 583,236 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Held-to-maturity Obligations of states, municipalities, and political subdivisions $ 24,030 $ 197 $ (82 ) $ 24,145 Residential mortgage-backed securities Agency 53,731 79 (203 ) 53,607 Non-agency 39,402 174 (51 ) 39,525 Total $ 117,163 $ 450 $ (336 ) $ 117,277 The Company did not classify securities as trading during 2018 and 2017. Gross unrealized losses and fair values, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2018 and 2017 are summarized as follows: Less than 12 Months 12 Months or Longer Total 2018 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale U.S. Treasury Notes 18 $ 23,835 $ (52 ) $ 9,865 $ (137 ) $ 33,700 $ (189 ) U.S. Government agencies 25 43,487 (80 ) 50,101 (1,216 ) 93,588 (1,296 ) Obligations of states, municipalities and political subdivisions 56 13,926 (97 ) 18,563 (489 ) 32,489 (586 ) Residential mortgage-backed securities Agency 42 4,288 (45 ) 254,121 (11,131 ) 258,409 (11,176 ) Non-agency 8 59,107 (1,378 ) 4,009 (198 ) 63,116 (1,576 ) Commercial mortgage-backed securities Agency 9 21,356 (447 ) 52,640 (2,717 ) 73,996 (3,164 ) Non-agency 5 — — 30,458 (1,000 ) 30,458 (1,000 ) Corporate securities 15 25,762 (342 ) 4,642 (268 ) 30,404 (610 ) Other securities 1 — — 2,844 (131 ) 2,844 (131 ) Total 179 $ 191,761 $ (2,441 ) $ 427,243 $ (17,287 ) $ 619,004 $ (19,728 ) Note 4—Securities (continued) Less than 12 Months 12 Months or Longer Total 2018 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Held-to-maturity Obligations of states, municipalities, and political subdivisions 23 $ 8,127 $ (58 ) $ 8,792 $ (152 ) $ 16,919 $ (210 ) Residential mortgage-backed securities Agency 16 6,625 (150 ) 21,139 (381 ) 27,764 (531 ) Non-agency 7 21,499 (503 ) 12,931 (416 ) 34,430 (919 ) Total 46 $ 36,251 $ (711 ) $ 42,862 $ (949 ) $ 79,113 $ (1,660 ) Less than 12 Months 12 Months or Longer Total 2017 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale U.S. Treasury Notes 5 $ 4,998 $ (2 ) $ 9,865 $ (134 ) $ 14,863 $ (136 ) U.S. Government agencies 9 992 (7 ) 51,966 (1,283 ) 52,958 (1,290 ) Obligations of states, municipalities and political subdivisions 29 16,059 (137 ) 4,453 (198 ) 20,512 (335 ) Residential mortgage-backed securities Agency 41 15,441 (181 ) 292,016 (7,465 ) 307,457 (7,646 ) Non-agency 1 — — 4,565 (75 ) 4,565 (75 ) Commercial mortgage-backed securities Agency 7 — — 57,442 (1,966 ) 57,442 (1,966 ) Non-agency 5 — — 30,971 (792 ) 30,971 (792 ) Corporate securities 3 2,406 (80 ) 2,489 (24 ) 4,895 (104 ) Other securities 1 — — 1,921 (73 ) 1,921 (73 ) Total 101 $ 39,896 $ (407 ) $ 455,688 $ (12,010 ) $ 495,584 $ (12,417 ) Less than 12 Months 12 Months or Longer Total 2017 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Held-to-maturity Obligations of states, municipalities, and political subdivisions 12 $ 7,409 $ (38 ) $ 1,548 $ (44 ) $ 8,957 $ (82 ) Residential mortgage-backed securities Agency 13 24,344 (107 ) 7,935 (96 ) 32,279 (203 ) Non-agency 3 10,458 (10 ) 4,382 (41 ) 14,840 (51 ) Total 28 $ 42,211 $ (155 ) $ 13,865 $ (181 ) $ 56,076 $ (336 ) Certain securities have fair values less than amortized cost and, therefore, contain unrealized losses. The Company evaluated the securities which had an unrealized loss for other than temporary impairment and determined all declines in value to be temporary. There were 179 securities available-for-sale with unrealized losses at December 31, 2018, compared to 101 at December 31, 2017. There were 46 securities held-to-maturity with unrealized losses at December 31, 2018, compared to 28 at December 31, 2017. The Company anticipates full recovery of amortized cost with respect to these securities by maturity, or sooner, in the event of a more favorable market interest rate environment. The Company does not intend to sell these securities and it is not more likely than not that the Company will be required to sell them before recovery of their amortized cost basis, which may be at maturity. Note 4—Securities (continued) The proceeds from all sales and calls of securities were available-for-sale, and the associated gains and losses for the years ended December 31, 2018, 2017, and 2016 are listed below: 2018 2017 2016 Proceeds $ 5,134 $ 8 $ 534,418 Gross gains 164 8 3,358 Gross losses — — 131 Securities pledged at December 31, 2018 and 2017 had carrying amounts of $244.7 million and $262.5 million, respectively. At December 31, 2018 and 2017, of those pledged, the carrying amounts of securities pledged as collateral for public fund deposits were $197.8 million and $99.3 million, respectively, and for customer repurchase agreements of $46.9 million and $34.8 million, respectively. At December 31, 2018, there were no securities pledged for advances from the Federal Home Loan Bank, compared to $128.4 million pledged at December 31, 2017. Other securities were pledged for derivative positions, letters of credit and for purposes required or permitted by law. At December 31, 2018 and 2017, there were no holdings of securities of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10% of stockholders’ equity. At December 31, 2018, the amortized cost and fair value of debt securities are shown by contractual maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately. Amortized Cost Fair Value Available-for-sale Due in one year or less $ 70,830 $ 70,621 Due from one to five years 172,020 170,632 Due from five to ten years 75,017 74,725 Due after ten years 18,277 18,284 Mortgage-backed securities 494,037 477,476 Other securities with no defined maturity 4,073 5,918 Total $ 834,254 $ 817,656 Held-to-maturity Due from one to five years $ 5,966 $ 5,903 Due from five to ten years 10,075 10,019 Due after ten years 7,794 7,743 Mortgage-backed securities 75,431 74,074 Total $ 99,266 $ 97,739

Loans and Lease Receivables

Loans and Lease Receivables	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans and Lease Receivables	Note 5—Loans and Lease Receivables Outstanding loan and lease receivables as of December 31, 2018 and 2017 were categorized as follows: 2018 2017 Commercial real estate $ 1,261,594 $ 891,971 Residential real estate 704,899 577,123 Construction, land development, and other land 186,258 105,996 Commercial and industrial 1,145,240 522,254 Installment and other 13,675 4,182 Lease financing receivables 187,797 174,165 Total loans and leases 3,499,463 2,275,691 Net unamortized deferred fees and costs (1,293 ) (1,720 ) Initial direct costs 3,456 3,521 Allowance for loan and lease losses (25,201 ) (16,706 ) Net loans and leases $ 3,476,425 $ 2,260,786 2018 2017 Lease financing receivables Net minimum lease payments $ 204,646 $ 188,986 Unguaranteed residual values 1,535 1,644 Unearned income (18,384 ) (16,465 ) Total lease financing receivables 187,797 174,165 Initial direct costs 3,456 3,521 Lease financial receivables before allowance for lease losses $ 191,253 $ 177,686 Total loans and leases consist of originated loans and leases, acquired impaired loans and acquired non-impaired loans and leases. At December 31, 2018 and 2017, total loans and leases included the guaranteed amount of U.S. government guaranteed loans of $108.7 million and $77.0 million, respectively. At December 31, 2018 and 2017, installment and other loans included overdraft deposits of $1.7 million and $617,000, respectively, which were reclassified as loans. At December 31, 2018 and 2017, loans and loans held for sale pledged as security for borrowings were $1.4 billion and $516.9 million, respectively. The minimum annual lease payments for lease financing receivables as of December 31, 2018 are summarized as follows: Minimum Lease Payments 2019 $ 71,802 2020 58,646 2021 39,385 2022 23,990 2023 9,752 Thereafter 1,071 Total $ 204,646 Note 5—Loans and Lease Receivables (continued) Originated loans and leases represent originations excluding loans initially acquired in a business combination. However, once an acquired non-impaired loan reaches its maturity date, and is re-underwritten and renewed, it is internally classified as an originated loan. Acquired impaired loans are loans acquired from a business combination with evidence of credit quality deterioration and are accounted for under ASC Topic 310-30. Acquired non-impaired loans and leases represent loans and leases acquired from a business combination without evidence of credit quality deterioration and are accounted for under ASC Topic 310-20. Leases and revolving loans do not qualify to be accounted for as acquired impaired loans and are accounted for under ASC Topic 310-20. The following tables summarize the balances for each respective loan and lease category as of December 31, 2018 and 2017: 2018 Originated Acquired Impaired Acquired Non- Impaired Total Commercial real estate $ 652,234 $ 146,808 $ 462,565 $ 1,261,607 Residential real estate 466,309 113,934 124,659 704,902 Construction, land development, and other land 144,128 3,779 37,442 185,349 Commercial and industrial 803,508 12,617 328,672 1,144,797 Installment and other 11,718 404 1,596 13,718 Lease financing receivables 159,901 — 31,352 191,253 Total loans and leases $ 2,237,798 $ 277,542 $ 986,286 $ 3,501,626 2017 Originated Acquired Impaired Acquired Non- Impaired Total Commercial real estate $ 513,622 $ 166,712 $ 211,359 $ 891,693 Residential real estate 400,571 144,562 32,085 577,218 Construction, land development, and other land 97,638 5,946 1,845 105,429 Commercial and industrial 416,499 10,008 94,731 521,238 Installment and other 3,724 462 42 4,228 Lease financing receivables 141,329 — 36,357 177,686 Total loans and leases $ 1,573,383 $ 327,690 $ 376,419 $ 2,277,492 Acquired impaired loans —As part of the First Evanston acquisition, the Bank acquired impaired loans that are accounted for under ASC 310‑30 in the amount of $25.0 million. Refer to Note 3—Acquisition of a Business for additional information regarding the transaction. There were no other acquired impaired loans purchased during 2018 or 2017. The following table presents a reconciliation of the undiscounted contractual cash flows, non‑accretable difference, accretable yield, and fair value of acquired impaired loans as of the acquisition date of May 31, 2018: Undiscounted contractual cash flows $ 33,594 Undiscounted cash flows not expected to be collected (non-accretable difference) (5,003 ) Undiscounted cash flows expected to be collected 28,591 Accretable yield at acquisition (3,566 ) Estimated fair value of impaired loans acquired at acquisition $ 25,025 Note 5—Loans and Lease Receivables (continued) The outstanding balance and carrying amount of all acquired impaired loans are summarized below. The balances do not include an allowance for loan and lease losses of $2.7 million and $3.9 million, at December 31, 2018 and 2017, respectively. 2018 2017 Outstanding Balance Carrying Value Outstanding Balance Carrying Value Commercial real estate $ 216,137 $ 146,808 $ 235,898 $ 166,712 Residential real estate 173,962 113,934 207,660 144,562 Construction, land development, and other land 11,962 3,779 13,270 5,946 Commercial and industrial 24,972 12,617 18,333 10,008 Installment and other 1,735 404 1,819 462 Total acquired impaired loans $ 428,768 $ 277,542 $ 476,980 $ 327,690 The following table summarizes the changes in accretable yield for acquired impaired loans for the years ended December 31, 2018, 2017 and 2016: 2018 2017 2016 Beginning balance $ 36,446 $ 36,868 $ 43,915 Additions 3,566 — 6,916 Accretion to interest income (23,982 ) (24,597 ) (26,208 ) Reclassification from nonaccretable difference 21,085 24,175 12,245 Ending balance $ 37,115 $ 36,446 $ 36,868 Acquired non‑impaired loans and leases —The Company acquired non‑impaired loans as part of the First Evanston acquisition in the amount of $891.0 million. Refer to Note 3—Acquisition of a Business for additional information regarding the transaction The unpaid principal balance and carrying value for acquired non‑impaired loans and leases at December 31, 2018 and 2017 were as follows: 2018 2017 Unpaid Principal Balance Carrying Value Unpaid Principal Balance Carrying Value Commercial real estate $ 473,262 $ 462,565 $ 221,710 $ 211,359 Residential real estate 127,478 124,659 32,605 32,085 Construction, land development, and other land 38,494 37,442 1,926 1,845 Commercial and industrial 344,879 328,672 105,529 94,731 Installment and other 1,831 1,596 355 42 Lease financing receivables 32,977 31,352 37,476 36,357 Total acquired non-impaired loans and leases $ 1,018,921 $ 986,286 $ 399,601 $ 376,419

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments	Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments Loans and leases considered for inclusion in the allowance for loan and lease losses include acquired non-impaired loans and leases, those acquired impaired loans with credit deterioration after acquisition, and originated loans and leases. Although all acquired loans and leases are included in the following table, only those with credit deterioration subsequent to acquisition date are actually included in the allowance for loan and lease losses. The following tables summarize the balance and activity within the allowance for loan and lease losses, the components of the allowance for loan and lease losses in terms of loans and leases individually and collectively evaluated for impairment, and corresponding loan and lease balances by type for the years ended December 31, 2018, 2017 and 2016 are as follows: 2018 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Allowance for loan and lease losses Beginning balance $ 4,794 $ 1,638 $ 222 $ 7,418 $ 41 $ 2,593 $ 16,706 Provisions 4,543 113 662 12,089 68 1,320 18,795 Charge-offs (1,865 ) — (418 ) (6,944 ) (60 ) (2,517 ) (11,804 ) Recoveries 68 — — 369 — 1,067 1,504 Ending balance $ 7,540 $ 1,751 $ 466 $ 12,932 $ 49 $ 2,463 $ 25,201 Ending balance: Individually evaluated for impairment $ 2,191 $ 61 $ — $ 4,397 $ — $ — $ 6,649 Collectively evaluated for impairment 4,105 1,323 466 7,413 47 2,463 15,817 Loans acquired with deteriorated credit quality 1,244 367 — 1,122 2 — 2,735 Total allowance for loan and lease losses $ 7,540 $ 1,751 $ 466 $ 12,932 $ 49 $ 2,463 $ 25,201 2018 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Loans and leases ending balance: Individually evaluated for impairment $ 11,983 $ 2,137 $ — $ 21,794 $ — $ — $ 35,914 Collectively evaluated for impairment 1,102,816 588,831 181,570 1,110,386 13,314 191,253 3,188,170 Loans acquired with deteriorated credit quality 146,808 113,934 3,779 12,617 404 — 277,542 Total loans and leases $ 1,261,607 $ 704,902 $ 185,349 $ 1,144,797 $ 13,718 $ 191,253 $ 3,501,626 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) 2017 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Allowance for loan and lease losses Beginning balance $ 1,945 $ 2,483 $ 742 $ 4,196 $ 334 $ 1,223 $ 10,923 Provisions 4,343 (405 ) (520 ) 6,058 34 3,143 12,653 Charge-offs (1,494 ) (440 ) — (2,836 ) (327 ) (3,099 ) (8,196 ) Recoveries — — — — — 1,326 1,326 Ending balance $ 4,794 $ 1,638 $ 222 $ 7,418 $ 41 $ 2,593 $ 16,706 Ending balance: Individually evaluated for impairment $ 1,101 $ 158 $ — $ 2,692 $ 14 $ — $ 3,965 Collectively evaluated for impairment 1,765 1,047 145 3,308 9 2,593 8,867 Loans acquired with deteriorated credit quality 1,928 433 77 1,418 18 — 3,874 Total allowance for loan and lease losses $ 4,794 $ 1,638 $ 222 $ 7,418 $ 41 $ 2,593 $ 16,706 2017 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Loans and leases ending balance: Individually evaluated for impairment $ 13,884 $ 2,429 $ — $ 14,784 $ 14 $ — $ 31,111 Collectively evaluated for impairment 711,097 430,227 99,483 496,446 3,752 177,686 1,918,691 Loans acquired with deteriorated credit quality 166,712 144,562 5,946 10,008 462 — 327,690 Total loans and leases $ 891,693 $ 577,218 $ 105,429 $ 521,238 $ 4,228 $ 177,686 $ 2,277,492 2016 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Allowance for loan and lease losses Beginning balance $ 2,280 $ 2,981 $ 232 $ 1,403 $ 357 $ 379 $ 7,632 Provisions 4,032 135 605 2,869 (11 ) 2,722 10,352 Charge-offs (4,367 ) (633 ) (95 ) (76 ) (12 ) (2,634 ) (7,817 ) Recoveries — — — — — 756 756 Ending balance $ 1,945 $ 2,483 $ 742 $ 4,196 $ 334 $ 1,223 $ 10,923 Ending balance: Individually evaluated for impairment $ — $ 293 $ — $ 396 $ 328 $ — $ 1,017 Collectively evaluated for impairment 1,456 1,743 742 3,126 5 1,223 8,295 Loans acquired with deteriorated credit quality 489 447 — 674 1 — 1,611 Total allowance for loan and lease losses $ 1,945 $ 2,483 $ 742 $ 4,196 $ 334 $ 1,223 $ 10,923 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) 2016 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Loans and leases ending balance: Individually evaluated for impairment $ 8,916 $ 1,300 $ — $ 1,382 $ 328 $ — $ 11,926 Collectively evaluated for impairment 580,125 433,721 133,787 423,392 2,057 158,966 1,732,048 Loans acquired with deteriorated credit quality 207,303 175,717 6,979 13,464 574 — 404,037 Total loans and leases $ 796,344 $ 610,738 $ 140,766 $ 438,238 $ 2,959 $ 158,966 $ 2,148,011 The Company increased the allowance for loan and lease losses by $8.5 million, $5.8 million, and $3.3 million for the years ended December 31, 2018, 2017 and 2016, respectively. For acquired impaired loans, the Company decreased the allowance for loan and lease losses by $1.1 million for the year ended December 31, 2018, increased the allowance for loan and lease losses by $2.3 million for the year ended December 31, 2017, and decreased the allowance for loan and lease losses by $1.7 million for the year ended December 31, 2016. The following tables summarize the recorded investment, unpaid principal balance, related allowance, average recorded investment, and interest income recognized for loans and leases considered impaired as of December 31, 2018, 2017, and 2016, which excludes acquired impaired loans: 2018 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded Commercial real estate $ 6,110 $ 7,693 $ — $ 8,968 $ 590 Residential real estate 1,886 1,858 — 1,917 43 Commercial and industrial 11,193 13,961 — 8,680 483 With an allowance recorded Commercial real estate 5,873 6,313 2,191 5,328 270 Residential real estate 251 253 61 311 4 Commercial and industrial 10,601 11,153 4,397 9,472 749 Installment and other — — — 11 — Total impaired loans $ 35,914 $ 41,231 $ 6,649 $ 34,687 $ 2,139 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded Commercial real estate $ 11,425 $ 12,936 $ — $ 10,482 $ 525 Residential real estate 2,075 2,046 — 1,781 72 Construction, land development and other land — — — 295 2 Commercial and industrial 5,470 6,774 — 2,875 265 With an allowance recorded Commercial real estate 2,459 2,634 1,101 1,988 187 Residential real estate 354 351 158 422 6 Construction, land development and other land — — — 14 — Commercial and industrial 9,314 9,724 2,692 3,460 486 Installment and other 14 14 14 162 12 Total impaired loans $ 31,111 $ 34,479 $ 3,965 $ 21,479 $ 1,555 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) 2016 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded Commercial real estate $ 8,916 $ 9,502 $ — $ 8,975 $ 305 Residential real estate 804 1,999 — 827 45 Commercial and Industrial 521 524 — 516 (2 ) With an allowance recorded Residential real estate 496 528 293 519 1 Commercial and industrial 861 869 396 914 — Installment and other 328 361 328 328 16 Total impaired loans $ 11,926 $ 13,783 $ 1,017 $ 12,079 $ 365 For purposes of these tables, the unpaid principal balance represents the outstanding contractual balance. Impaired loans include loans that are individually evaluated for impairment as well as troubled debt restructurings for all loan categories. The sum of non‑accrual loans and loans past due 90 days still on accrual will differ from the total impaired loan amount. The Bank’s credit risk rating methodology assigns risk ratings from 1 to 10, where a higher rating represents higher risk. The risk rating categories are described by the following groupings: Pass —Ratings 1‑4 define the risk levels of borrowers and guarantors that offer a minimal to an acceptable level of risk. Watch —A watch asset (rating of 5) has credit exposure that presents higher than average risk and warrants greater than routine attention by Bank personnel due to conditions affecting the borrower, the borrower’s industry or the economic environment. Special Mention —A special mention asset (rating of 6) has potential weaknesses that deserve management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the asset or in the Company’s credit position at some future date. Substandard Accrual —A substandard accrual asset (rating of 7) has well‑defined weakness or weaknesses in cash flow and collateral coverage resulting in a distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. This classification may be used in limited cases, where despite credit severity, the borrower is current on payments and there is an agreed plan for credit remediation. Substandard Non‑Accrual —A substandard asset (rating of 8) has well‑defined weakness or weaknesses in cash flow and collateral coverage resulting in the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. Doubtful —A doubtful asset (rating of 9) has all the weaknesses inherent in one classified substandard with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of currently existing facts, conditions and values, highly questionable and improbable. Loss —A loss asset (rating of 10) is considered uncollectible and of such little value that its continuance as a realizable asset is not warranted. Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) The following tables summarize the risk rating categories of the loans and leases considered for inclusion in the allowance for loan and lease losses calculation, excluding acquired impaired loans, as of December 31, 2018 and 2017: 2018 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Pass $ 1,009,041 $ 553,665 $ 147,123 $ 962,291 $ 9,997 $ 188,314 $ 2,870,431 Watch 76,276 29,522 31,376 112,996 3,302 80 253,552 Special Mention 17,602 5,656 3,071 34,314 — 1,794 62,437 Substandard 11,880 2,125 — 22,579 15 818 37,417 Doubtful — — — — — 247 247 Loss — — — — — — — Total $ 1,114,799 $ 590,968 $ 181,570 $ 1,132,180 $ 13,314 $ 191,253 $ 3,224,084 2017 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Pass $ 638,066 $ 398,743 $ 73,935 $ 415,163 $ 3,732 $ 174,672 $ 1,704,311 Watch 58,217 29,165 22,380 67,024 20 190 176,996 Special Mention 14,645 2,251 3,168 13,535 — 1,293 34,892 Substandard 14,053 2,497 — 15,508 14 1,259 33,331 Doubtful — — — — — 272 272 Loss — — — — — — — Total $ 724,981 $ 432,656 $ 99,483 $ 511,230 $ 3,766 $ 177,686 $ 1,949,802 The following tables summarize contractual delinquency information for acquired non-impaired and originated loans and leases by category as of December 31, 2018 and 2017: 2018 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days and Accruing Non- accrual Total Past Due Current Total Commercial real estate $ 6,659 $ 2,145 $ — $ 9,484 $ 18,288 $ 1,096,511 $ 1,114,799 Residential real estate 4,488 711 — 1,815 7,014 583,954 590,968 Construction, land development, and other land — — — — — 181,570 181,570 Commercial and industrial 5,829 1,376 — 13,932 21,137 1,111,043 1,132,180 Installment and other 1,932 4 — 12 1,948 11,366 13,314 Lease financing receivables 789 530 — 591 1,910 189,343 191,253 Total $ 19,697 $ 4,766 $ — $ 25,834 $ 50,297 $ 3,173,787 $ 3,224,084 2017 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days and Accruing Non- accrual Total Past Due Current Total Commercial real estate $ 4,783 $ 968 $ — $ 8,459 $ 14,210 $ 710,771 $ 724,981 Residential real estate 148 — — 2,092 2,240 430,416 432,656 Construction, land development, and other land — — — — — 99,483 99,483 Commercial and industrial 6,667 967 — 4,348 11,982 499,248 511,230 Installment and other 18 — — 14 32 3,734 3,766 Lease financing receivables 997 638 — 851 2,486 175,200 177,686 Total $ 12,613 $ 2,573 $ — $ 15,764 $ 30,950 $ 1,918,852 $ 1,949,802 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) Trouble debt restructurings are granted due to borrower financial difficulty and provide for a modification of loan repayment terms. TDRs are treated in the same manner as impaired loans for purposes of calculating the allowance for loan and lease losses. The tables below present TDRs by loan category as of December 31, 2018, 2017, and 2016. Refer to Note 1—Summary of Significant Accounting Policies for the accounting policy for TDRs. December 31, 2018 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Charge-offs Specific Reserves Accruing: Commercial real estate 4 $ 1,508 $ 1,508 $ — $ 113 Commercial and industrial 2 191 191 — 100 Residential real estate 1 114 114 — — Total accruing 7 1,813 1,813 — 213 Non-accruing: Commercial real estate 9 2,512 2,471 41 743 Commercial and industrial 6 6,714 4,843 1,871 1,290 Total non-accruing 15 9,226 7,314 1,912 2,033 Total troubled debt restructurings 22 $ 11,039 $ 9,127 $ 1,912 $ 2,246 December 31, 2017 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Charge-offs Specific Reserves Accruing: Commercial real estate 3 $ 912 $ 912 $ — $ — Residential real estate 1 149 149 — — Total accruing 4 1,061 1,061 — — Non-accruing: Commercial real estate 2 743 743 — 111 Commercial and industrial 3 1,246 759 487 246 Residential real estate 1 67 67 — — Total non-accruing 6 2,056 1,569 487 357 Total troubled debt restructurings 10 $ 3,117 $ 2,630 $ 487 $ 357 December 31, 2016 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Charge-offs Specific Reserves Accruing: Commercial real estate 1 $ 421 $ 421 $ — $ — Residential real estate 2 181 181 — — Total accruing 3 602 602 — — Non-accruing: Commercial real estate 1 477 477 — — Residential real estate 1 75 75 — — Total non-accruing 2 552 552 — — Total troubled debt restructurings 5 $ 1,154 $ 1,154 $ — $ — Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) In addition, there was a $500,000 commitment outstanding on troubled debt restructurings at December 31, 2018 and no commitments outstanding on troubled debt restructurings at December 31, 2017 or 2016. Loans modified as troubled debt restructurings that occurred during the years ended December 31, 2018, 2017, and 2016: For the Year Ended December 31, 2018 2017 2016 Accruing: Beginning balance $ 1,061 $ 602 $ 1,908 Additions 37 1,017 181 Net payments (86 ) (144 ) (1,010 ) Net transfers from (to) non-accrual 801 (414 ) (477 ) Ending balance 1,813 1,061 602 Non-accruing: Beginning balance 1,569 552 833 Additions 8,408 681 — Net payments (1,718 ) (78 ) (758 ) Charge-offs (144 ) — — Net transfers from (to) accrual (801 ) 414 477 Ending balance 7,314 1,569 552 Total troubled debt restructurings $ 9,127 $ 2,630 $ 1,154 Troubled debt restructurings that subsequently defaulted within twelve months of the restructure date during the years ended December 31, 2018, 2017, and 2016 had a recorded investment of $340,000, $144,000, and $477,000, respectively. At December 31, 2018 and 2017, the reserve for unfunded commitments was $1.2 million and $923,000, respectively. During the years ended December 31, 2018, 2017, and 2016, the provisions for unfunded commitments were $317,000, $162,000, and $493,000, respectively. There were no charge‑offs or recoveries related to the reserve for unfunded commitments during the periods.

Servicing Assets

Servicing Assets	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Servicing Assets	Note 7—Servicing Assets Activity for servicing assets and the related changes in fair value for the years ended December 31, 2018 and 2017 is as follows: 2018 2017 2016 Beginning balance $ 21,400 $ 21,091 $ — Acquired servicing assets at fair value — — 20,295 Additions, net 7,562 6,250 539 Changes in fair value (9,269 ) (5,941 ) 257 Ending balance $ 19,693 $ 21,400 $ 21,091 Loans serviced for others are not included in the Consolidated Statements of Financial Condition. The unpaid principal balances of these loans serviced for others were as follows as December 31, 2018 and 2017: 2018 2017 Loan portfolios serviced for: SBA guaranteed loans $ 1,151,915 $ 1,021,143 USDA guaranteed loans 106,184 91,758 Total $ 1,258,099 $ 1,112,901 Loan servicing revenue totaled $10.3 million, $9.6 million, and $1.6 million for the years ended December 31, 2018, 2017, and 2016, respectively. Note 7—Servicing Assets (continued) Loan servicing asset revaluation, which represents the changes in fair value of servicing assets, totaled downward valuations of $9.3 million and $5.9 million for the years ended December 31, 2018 and 2017, respectively. There was an upward valuation of $257,000 for the year ended December 31, 2016. The fair value of servicing rights is highly sensitive to changes in underlying assumptions. Changes in prepayment speed assumptions have the most significant impact on the fair value of servicing rights. Generally, as interest rates rise on variable rate loans, loan prepayments increase due to an increase in refinance activity, which may result in a decrease in the fair value of servicing assets. Measurement of fair value is limited to the condition existing and the assumptions used as of a particular point in time, and those assumptions may change over time. Refer to Note 18—Fair Value Measurement for further details.

Other Real Estate Owned

Other Real Estate Owned	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Other Real Estate Owned	Note 8—Other Real Estate Owned The following table presents the change in other real estate owned (“OREO”) for the years ended December 31, 2018, 2017 and 2016: 2018 2017 2016 Beginning balance $ 10,626 $ 16,570 $ 26,715 Acquisition of OREO through business combination — — 1,525 Net additions to OREO 2,436 6,690 6,659 Proceeds from sales of OREO (7,495 ) (13,898 ) (18,637 ) Gains on sales of OREO 383 2,147 1,366 Valuation adjustments (636 ) (883 ) (1,058 ) Ending balance $ 5,314 $ 10,626 $ 16,570 At December 31, 2018 and 2017, the balance of real estate owned included $838,000 and $3.6 million, respectively, of foreclosed residential real estate properties recorded as a result of obtaining physical possession of the property. At December 31, 2018 and 2017, the recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings were in process is $2.3 million and $1.9 million, respectively. Proceeds from sales of OREO include proceeds from internally financed sales of OREO of $444,000 for the year ended December 31, 2018 and $1.4 million for the year ended December 31, 2016. There were no internally finances sales of OREO for the year ended December 31, 2017.

Premises and Equipment and Asse

Premises and Equipment and Assets Held for Sale	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Premises and Equipment and Assets Held for Sale	Note 9—Premises and Equipment and Assets Held for Sale Classifications of premises and equipment as of December 31, 2018 and 2017 and were as follows: 2018 2017 Premises $ 62,675 $ 61,714 Furniture, fixtures and equipment 15,779 13,591 Leasehold improvements 6,544 4,245 Total cost 84,998 79,550 Less accumulated depreciation and amortization (33,679 ) (29,880 ) Net book value of premises, furniture, fixtures, equipment, leasehold improvements 51,319 49,670 Construction in progress 830 899 Land 45,531 44,655 Premises and equipment, net $ 97,680 $ 95,224 Depreciation and amortization expense related to premises and equipment for the years ended December 31, 2018, 2017 and 2016 was $5.6 million, $5.2 million and $5.1 million, respectively. Refer to Note 17—Commitments and Contingent Liabilities for additional discussion related to operating lease commitments. Note 9—Premises and Equipment and Assets Held for Sale (continued) During 2016, the Company closed and consolidated 12 2018 2017 2016 Beginning balance $ 9,779 $ 14,748 $ 2,259 Transfers in 9,074 3,372 14,496 Transfers out (425 ) — — Proceeds from sales (4,415 ) (5,373 ) (2,566 ) Internally financed sales — (1,800 ) — Net gains (losses) on sales 1,103 (217 ) 967 Impairment loss (627 ) (951 ) (408 ) Ending balance $ 14,489 $ 9,779 $ 14,748

Goodwill, Core Deposit Intangib

Goodwill, Core Deposit Intangible and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, Core Deposit Intangible and Other Intangible Assets	Note 10—Goodwill, Core Deposit Intangible and Other Intangible Assets The Company’s annual goodwill test was performed as of November 30, 2018. The Company determined that no impairment existed as of that date. Refer to Note 1—Business and Summary of Significant Accounting Policies for discussion of goodwill. The following table summarizes the changes in the Company’s goodwill and core deposit intangible assets for the years ended December 31, 2018, 2017 and 2016: 2018 2017 2016 Goodwill Core Intangible Customer Relationship Intangible Goodwill Core Deposit Intangible Customer Relationship Intangible Goodwill Core Deposit Intangible Customer Relationship Intangible Beginning balance $ 54,562 $ 16,720 $ — $ 51,975 $ 19,776 $ — $ 25,688 $ 22,275 $ — Additions 73,615 19,060 3,216 2,587 — — 26,287 486 — Amortization or accretion — (5,420 ) (157 ) — (3,056 ) — — (2,985 ) — Ending balance $ 128,177 $ 30,360 $ 3,059 $ 54,562 $ 16,720 $ — $ 51,975 $ 19,776 $ — Accumulated amortization or accretion N/A $ 18,886 157 N/A $ 13,466 N/A N/A $ 10,410 N/A Weighted average remaining amortization or accretion period N/A 6.8 Years 11.4 Years N/A 5.6 Years N/A N/A 6.6 Years N/A During 2018, the Company added additional goodwill, core deposit intangible assets, and customer relationship intangible assets in conjunction with the First Evanston acquisition. Please refer to Note 3—Acquisition of a Business for further details. The increases in goodwill and core deposit intangible for the years ended December 31, 2017 and 2016 resulted from the Ridgestone acquisition. Additionally, the Company had other intangible assets of $36,000, and $50,000 as of December 31, 2017 and 2016, respectively, associated with trademark‑related transactions. The other intangible assets were fully amortized in 2018 resulting in no remaining balance as of December 31, 2018. Note 10—Goodwill, Core Deposit Intangible and Other Intangible Assets (continued) The following table presents the estimated amortization expense for core deposit intangible and other intangible assets recognized at December 31, 2018: Estimated Amortization 2019 $ 6,925 2020 6,476 2021 6,026 2022 5,578 2023 3,645 Thereafter 4,769 Total $ 33,419

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 11—Income Taxes The following were the components of provision for income taxes for the years ended December 31, 2018, 2017, and 2016 2018 2017 2016 Current tax expense: Federal $ — $ 1,010 $ — State and local 1,078 1,485 — Total current tax expense 1,078 2,495 — Deferred tax expense: Federal 11,469 13,554 478 State and local 2,460 686 136 Remeasurement of net deferred tax assets (760 ) 2,364 — Total deferred tax expense before reversal of valuation allowance 13,169 16,604 614 Deferred tax valuation allowance — — (61,859 ) Provision (benefit) for income taxes $ 14,247 $ 19,099 $ (61,245 ) The following is a reconciliation between the statutory U.S. federal income tax rate of 21% for 2018 and 35% for 2017 and 2016 and the effective tax rate: 2018 2017 2016 Calculated tax benefit at statutory rate 21.0 % 35.0 % 35.0 % Increase (decrease) in income taxes resulting from: Reversal of valuation allowance, net of change in estimated Section 382 impact — — (1,167.6 ) State taxes, net of federal income tax 7.0 6.5 6.1 Tax exempt income (0.5 ) (0.7 ) (5.3 ) Share-based compensation (0.9 ) — — Non-deductible expenses 0.5 0.2 14.8 Remeasurement of net deferred tax assets (1.4 ) 5.8 — Total income tax expense (benefit) 25.7 % 46.8 % (1,117.0 ) % As part of a budget package passed by the Legislature of the State of Illinois, the corporate income tax rate increased from 5.25% to 7.00% effective July 1, 2017. As a result of the increase in the corporate income tax rate, we recorded a state income tax benefit of $4.8 million during 2017, primarily due to increased value of our deferred tax asset related to our Illinois net loss deduction. Note 11—Income Taxes (continued) The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017, and ASC 740 required us to reflect the changes associated with the Tax Act’s provisions in the fourth quarter of 2017. The Tax Act is complex and has extensive implications for the Company’s federal and state taxes. Among other things, the Tax Act reduced the corporate federal income tax rate from 35% to 21%, effective January 1, 2018. Also on December 22, 2017, the SEC issued Staff Accounting Bulletin No. 118 (SAB 118), which provides guidance on accounting for the Tax Act’s impact. SAB 118 provides a measurement period, not to extend beyond one year from the date of enactment during which a company, acting in good faith, may complete the accounting for the impacts of the Tax Act. At December 31, 2018, the Company’s accounting for the impact of the Tax Act on its net deferred tax assets is based upon reasonable estimates of the tax effects of the Tax Act; however, these estimates may change as additional information and interpretive guidance regarding the provisions of the Tax Act become available. As a result of the rate change, the Company’s net deferred tax assets were required to be revalued during the period in which the new legislation was enacted, and the Company recorded net income tax expense of $7.2 million during the fourth quarter of 2017 as a result of this change, and recorded an additional discrete income tax benefit of $760,000 during 2018. Included in the provisional tax expense recorded for the re-measurement of the Company’s net deferred tax assets recorded in 2017 were deferred items for which the tax effects were originally established through OCI. This resulted in a disproportionate tax effect for those items still recorded in AOCI. Under GAAP as of December 31, 2017, those items would continue to be reported in AOCI until such time as the underlying transactions were settled and would then be reclassified as a component of the provision for income taxes. However, in February 2018, the FASB issued an ASU that permits entities to reclassify the tax effects stranded in AOCI as a result of the Tax Act to retained earnings. The guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption in any period permitted. The Company early adopted this new guidance effective January 1, 2018. The adoption did not impact the Company’s Consolidated Statements of Operations, and resulted in a reclassification of $763,000 from accumulated other comprehensive income (loss) to retained earnings. The income tax benefit for the year ended December 31, 2016 was primarily attributable to the reversal of the Company’s previously established valuation allowance of $61.4 million. Management concluded that no valuation allowance was necessary on the Company’s net deferred tax assets as a result of the Ridgestone acquisition. This determination was based on Ridgestone’s actual pre‑tax income over the prior three years, and pro‑forma combined earnings for the Company and Ridgestone over the prior three years, as well as management’s expectations for sustainable profitability in the future. Management monitors deferred tax assets on a quarterly basis for changes affecting realizability. The valuation allowance could be subject to change in future periods. The following were the significant components of the deferred tax assets and liabilities as of December 31, 2018 and 2017: 2018 2017 Deferred tax assets: Net operating losses and tax credits $ 25,851 $ 42,062 Interest on non-accrual loans 3,039 2,755 Allowance for loan losses and loan basis 15,641 11,252 Deposits 90 5 Alternative minimum tax ("AMT") credit carryforward — 2,140 Other real estate owned 393 — Net unrealized holding losses on securities available-for-sale 4,622 2,766 Accrued expenses 3,747 1,576 Other 2,075 837 Total deferred tax assets 55,458 63,393 Deferred tax liabilities: Other real estate owned — (24 ) Premises and equipment (3,752 ) (3,385 ) Core deposit intangibles (9,306 ) (4,656 ) Servicing assets (337 ) (3,505 ) Trust preferred securities (2,710 ) (2,465 ) Unrealized holding gain on cash flow hedges (1,839 ) (1,390 ) Other (1,871 ) (592 ) Total deferred tax liabilities (19,815 ) (16,017 ) Net deferred tax assets after valuation allowance $ 35,643 $ 47,376 Note 11—Income Taxes (continued) 2018 2017 NOL carryforwards available to offset future taxable income: Federal gross NOL carryforwards - begin to expire in 2030 $ 1,233 $ 63,964 Illinois gross NLD carryforwards - begin to expire in 2021 340,999 381,471 AMT credit carryforward - no expiration date — 2,140 Pursuant to Sections 382 and 383 of the Internal Revenue Code, annual use of net operating loss and credit carryforwards may be limited in the event a cumulative change in ownership of more than 50 percent occurs within a three‑year period. The Company has determined that such an ownership change occurred as of June 28, 2013 as a result of our recapitalization. This ownership change resulted in estimated limitations on the utilization of tax attributes, including net operating loss carryforwards and tax credits. Pursuant to Sections 382 and 383, a portion of the limited net operating loss carryforwards and credits become available to use each year. The Company estimates that approximately $756,000 of the restricted Federal net operating losses will become available each year. The Company and the Bank file consolidated income tax returns. The Company and the Bank are no longer subject to United States federal income tax examinations for years before 2015 and state income tax examinations for years before 2014.

Federal Home Loan Bank Advances

Federal Home Loan Bank Advances	12 Months Ended
	Dec. 31, 2018
Federal Home Loan Banks [Abstract]
Federal Home Loan Bank Advances	Note 12—Federal Home Loan Bank Advances The following table summarizes the FHLB advances as of December 31, 2018 and 2017: 2018 2017 Federal Home Loan Bank advances $ 425,000 $ 361,506 Weighted average cost 2.56 % 1.49 % At December 31, 2018, fixed‑rate advances totaled $360.0 million, with interest rates ranging from 2.52% to 2.61% and maturities ranging from January 2019 to March 2019. Total variable rate advances were $65.0 million at December 31, 2018, with an interest rate of 2.41% that may reset daily, and matures in January 2019. The Company’s advances from the FHLB are collateralized by residential real estate loans, commercial real estate loans, and securities. The Company’s required investment in FHLB stock is $4.50 for every $100 in advances. Refer to Note 4—Securities for additional discussion. At December 31, 2018 and 2017, the Bank has additional borrowing capacity from the FHLB of $1.3 billion and $795.0 million, respectively, subject to the availability of proper collateral. The Bank’s maximum borrowing capacity is limited to 35% of total assets.

Other Borrowings

Other Borrowings	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Other Borrowings	Note 13—Other Borrowings The following is a summary of the Company’s other borrowings as of December 31, 2018 and 2017: 2018 2017 Securities sold under agreements to repurchase $ 34,166 $ 31,187 Line of credit — — Total $ 34,166 $ 31,187 Securities sold under agreements to repurchase represent a demand deposit product offered to customers that sweep balances in excess of the FDIC insurance limit into overnight repurchase agreements. The Company pledges securities as collateral for the repurchase agreements. Refer to Note 4—Securities for additional discussion. Note 13—Other Borrowings (continued) On October 13, 2016, the Company entered into a $30.0 million credit agreement with a correspondent bank. In April 2017, the revolving line of credit was amended to a non-revolving line of credit as long as the outstanding balance exceeds $5.0 million. When the outstanding balance is reduced to $5.0 million, the line of credit will be converted to a revolving line of credit with credit availability up to $5.0 million until maturity. In July 2017, the Company repaid the outstanding balance, in full, under this line of credit of $16.2 million with proceeds from its initial public offering (“IPO”). The line of credit matured on October 11, 2018 and carried an interest rate at either the London Interbank Offered Rate (“LIBOR”) plus 250 basis points or the Prime Rate minus 25 basis points, based on the Company’s election. On October 11, 2018, the Company entered into a third amendment to the revolving credit agreement, which increased the revolving loan commitment to $10.0 million, extended the maturity of the credit facility to October 10, 2019, and makes certain other changes, including a release of the previously executed Stock Pledge Agreement dated October 13, 2016 and execution of a Negative Pledge Agreement dated October 11, 2018. The amended revolving line of credit bears interest at either the LIBOR plus 225 basis points or the Prime Rate minus 50 basis points, based on the Company’s election, which is required to be communicated at least three business days prior to the commencement of an interest period. If the Company fails to provide timely notification, the interest rate will be Prime Rate minus 50 basis points. As of December 31, 2018 and 2017, the line of credit has not been drawn upon, so an interest rate option has not been selected. The following table presents short-term credit lines available for use, for which the Company did not have an outstanding balance as of December 31, 2018 and 2017: 2018 2017 Federal Reserve Bank of Chicago discount window line $ 293,613 $ 144,248 Available federal funds lines 55,000 55,000

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Deposits	Note 14—Deposits The following is a summary of the Company’s deposits as of December 31, 2018 and 2017: 2018 2017 Non-interest-bearing demand deposits $ 1,192,873 $ 760,887 Interest-bearing checking accounts 296,339 186,611 Money market demand accounts 640,401 349,862 Other savings 476,418 437,212 Time deposits (below $250,000) 911,603 627,255 Time deposits ($250,000 and above) 232,282 81,502 Total deposits $ 3,749,916 $ 2,443,329 Time deposits of $250,000 or more included $50.0 million of brokered deposits at December 31, 2018 and none at December 31, 2017. At December 31, 2018, the scheduled maturities of time deposits were as follows: Scheduled Maturities 2019 $ 852,780 2020 240,863 2021 33,583 2022 10,584 2023 6,075 Total $ 1,143,885

Junior Subordinated Debentures

Junior Subordinated Debentures	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Junior Subordinated Debentures	Note 15— Junior Subordinated Debentures At December 31, 2018 and 2017, the Company’s junior subordinated debentures by issuance were as follows: Name of Trust Aggregate Principal Amount 2018 Aggregate Principal Amount 2017 Stated Maturity Contractual Rate at December 31, 2018 Interest Rate Spread Metropolitan $ 35,000 $ 35,000 March 5.58 % Three-month LIBOR + 2.79% RidgeStone Capital Trust I 1,500 1,500 June 30, 2033 6.38 % Five-year LIBOR + 3.50% First Evanston Bancorp Trust I 10,000 — March 15, 2035 4.57 % Three-month LIBOR + 1.78% Total liability, at par 46,500 36,500 Discount (9,732 ) (8,853 ) Total liability, at carrying value $ 36,768 $ 27,647 In 2004, the Company’s predecessor, Metropolitan Bank Group, Inc., issued $35.0 million floating rate junior subordinated debentures to Metropolitan Statutory Trust 1, which was formed for the issuance of trust preferred securities. The debentures bear interest at three-month LIBOR plus 2.79% (5.58% and 4.39% at December 31, 2018 and 2017, respectively). Interest is payable quarterly. The Company has the right to redeem the debentures, in whole or in part, on any interest payment date on or after March 2009. Accrued interest payable was $84,000 and $62,000 as of December 31, 2018 and 2017, respectively. As part of the Ridgestone acquisition, the Company assumed the obligations to RidgeStone Capital Trust I of $1.5 million in principal amount, which was formed for the issuance of trust preferred securities. Beginning on June 30, 2008, the interest rate reset to the five-year LIBOR plus 3.50% (6.38% and 5.09% at December 31, 2018 and 2017, respectively), which is in effect until June 30, 2023 and updated every five years. Interest is paid on a quarterly basis. The Company has the right to redeem the debentures, in whole or in part, on any interest payment date on or after June 30, 2008. There was no accrued interest payable as of December 31, 2018 or 2017. As part of the First Evanston acquisition, the Company assumed the obligations to First Evanston Bancorp Trust I of $10.0 million in principal amount, which was formed for the issuance of trust preferred securities. Refer to Note 3—Acquisition of a Business for additional information. Beginning on March 15, 2010, the interest rate reset to the three-month LIBOR plus 1.78% (4.57% at December 31, 2018), which is in effect until the debentures mature in 2035. Interest is paid on a quarterly basis. The Company has the right to redeem the debentures, in whole or in part, on any interest payment date on or after March 2010. The Company has the option to defer interest payments on the debentures from time to time for a period not to exceed five consecutive years. Accrued interest payable was $21,000 as of December 31, 2018. The Trusts are not consolidated with the Company. Accordingly, the Company reports the subordinated debentures held by the Trusts as liabilities. The Company owns all of the common securities of each trust. The junior subordinated debentures qualify, and are treated as, Tier 1 regulatory capital of the Company subject to regulatory limitations. The trust preferred securities issued by each trust rank equally with the common securities in right of payment, except that if an event of default under the indenture governing the notes has occurred and is continuing, the preferred securities will rank senior to the common securities in right of payment.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
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, 2018, 2017, and 2016. The net assets of the plan are not included in the Consolidated Statements of Financial Condition. As of February 1, 2016, a 401(k) employer match contribution was adopted by the Company, pursuant to which the Company will make a contribution equal to 50% of the first 4% contributed by employees. Note 16— Employee Benefit Plans (continued) 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 common stock at a discount from the market price 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 8,882 shares in connection with the ESPP leaving 191,118 available at December 31, 2018. The first plan offering was in the first quarter of 2018, and there was $66,000 of compensation expense for the year ended December 31, 2018, and no compensation expense for the years ended December 31, 2017 or 2016.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Note 17— Commitments and Contingent Liabilities Legal contingencies —In the ordinary course of business, the Company and Bank have various outstanding commitments and contingent liabilities that are not recognized in the accompanying consolidated financial statements. In addition, the Company may be a defendant in certain claims and legal actions arising in the ordinary course of business. In the opinion of management, after consultation with legal counsel, the ultimate disposition of these matters is currently not expected to have a material adverse effect on the Company’s Consolidated Financial Statements. Operating lease commitments —The Company has entered into various operating lease agreements primarily for facilities and land on which banking facilities are located. Certain lease agreements have renewal options at the end of the original lease term and certain lease agreements have escalation clauses in the rent payments. The minimum annual rental commitments for operating leases subsequent to December 31, 2018, exclusive of taxes and other charges, are summarized as follows: Minimum Commitments 2019 $ 3,285 2020 2,725 2021 2,450 2022 1,488 2023 562 Thereafter 2,605 Total $ 13,115 The Company’s rental expenses for the years ended December 31, 2018, 2017, and 2016 were $5.5 million, $4.6 million, and $3.8 million, respectively. During the years ended December 31, 2018, 2017, and 2016 the Company received $723,000, $702,000, and $737,000, respectively, in sublease income which is included in the Consolidated Statements of Operations as a reduction of occupancy expense. The total amount of minimum rentals to be received in the future on these subleases is approximately $1.7 million, and the leases have contractual lives extending through 2025. In addition to the above required lease payments, the Company has contractual obligations related primarily to information technology contracts and other maintenance contracts. In June 2018, the Company accrued $8.1 million in data processing expense primarily related to contract termination with its core service provider in anticipation of a future system conversion Commitments to extend credit —The Company is party to financial instruments with off‑balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit. Those instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the Consolidated Statements of Financial Condition. The contractual or notional amounts of those instruments reflect the extent of involvement the Company has in particular classes of financial instruments. The Company’s exposure to credit loss in the event of non‑performance by the other party to the financial instrument for commitments to extend credit and letters of credit is represented by the contractual or notional amount of those instruments. The Company uses the same credit policies in making commitments and conditional obligations as it does for funded instruments. The Company does not anticipate any material losses as a result of the commitments and letters of credit. Note 17— Commitments and Contingent Liabilities (continued) The following table summarizes the contract or notional amount of outstanding loan and lease commitments at December 31, 2018 and 2017: 2018 2017 Fixed Rate Variable Fixed Variable Commitments to extend credit $ 74,099 $ 928,991 $ 55,924 $ 467,429 Letters of credit 1,982 34,071 1,226 3,337 Total $ 76,081 $ 963,062 $ 57,150 $ 470,766 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amount does not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the counterparty. Collateral is primarily obtained in the form of commercial and residential real estate (including income producing commercial properties). Letters of credit are conditional commitments issued by the Company to guarantee to a third-party the performance of a customer. Those guarantees are primarily issued to support public and private borrowing arrangements, bond financing and similar transactions. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. Commitments to make loans are generally made for periods of 90 days or less. The fixed rate loan commitments have interest rates ranging from 2.00% to 15.00% and maturities up to 2032. Variable rate loan commitments have interest rates ranging from 3.00% to 15.00% and maturities up to 2048.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 18— Fair Value Measurement Fair value is the exchange price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. In addition, the Company has the ability to obtain fair values for markets that are not accessible. These types of inputs create the following fair value hierarchy: Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-derived valuations whose inputs are observable or whose significant value drivers are observable. Level 3 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available. The Company’s own data used to develop unobservable inputs may be adjusted for market considerations when reasonably available. The categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to assets and liabilities. The Company used the following methods and significant assumptions to estimate fair value for certain assets measured and carried at fair value on a recurring basis: Securities available-for-sale —The Company obtains fair value measurements from an independent pricing service. Management reviews the procedures used by the third party, including significant inputs used in the fair value calculations. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things. When market quotes are not readily accessible or available, alternative approaches are utilized, such as matrix or model pricing. Note 18— Fair Value Measurement (continued) The Company’s methodology for pricing non-rated bonds focuses on three distinct inputs: equivalent rating, yield and other pricing terms. To determine the rating for a given non-rated municipal bond, the Company references a publicly issued bond by the same issuer if available as well as other additional key metrics to support the credit worthiness. Typically, pricing for these types of bonds would require a higher yield than a similar rated bond from the same issuer. A reduction in price is applied to the rating obtained from the comparable bond, as the Company believes if liquidated, a non-rated bond would be valued less than a similar bond with a verifiable rating. The reduction applied by the Company is one notch lower (i.e. a “AA” rating for a comparable bond would be reduced to “AA-” for the Company’s valuation). In 2018 and 2017, all of the ratings derived by the Company were “BBB” or better with and without comparable bond proxies. The fair value measurement of municipal bonds is sensitive to the rating input, as a higher rating typically results in an increased valuation. The remaining pricing inputs used in the bond valuation are observable. Based on the rating determined, the Company obtains a corresponding current market yield curve available to market participants. Other terms including coupon, maturity date, redemption price, number of coupon payments per year, and accrual method are obtained from the individual bond term sheets. Servicing assets —Fair value is based on a loan-by-loan basis taking into consideration the original term to maturity, the current age of the loan and the remaining term to maturity. The valuation methodology utilized for the servicing assets begins with generating future cash flows for each servicing asset, based on their unique characteristics and market-based assumptions for prepayment speeds. The present value of the future cash flows are then calculated utilizing market-based discount rate assumptions. Derivative instruments —Interest rate swaps are valued by a third party, using models that primarily use market observable inputs, such as yield curves, and are validated by comparison with valuations provided by the respective counterparties. Derivative financial instruments are included in other assets and other liabilities in the Consolidated Statements of Financial Condition. The following tables summarize the Company’s financial assets and liabilities that were measured at fair value on a recurring basis at December 31, 2018 and 2017: Fair Value Measurements Using 2018 Fair Value Level 1 Level 2 Level 3 Financial assets Securities available-for-sale U.S. Treasury Notes $ 52,667 $ 52,667 $ — $ — U.S. Government agencies 186,498 — 186,498 — Obligations of states, municipalities, and political subdivisions 60,233 — 60,038 195 Mortgage-backed securities; residential Agency 272,963 — 272,963 — Non-Agency 83,621 — 83,621 — Mortgage-backed securities; commercial Agency 90,434 — 90,434 — Non-Agency 30,458 — 30,458 — Corporate securities 34,173 — 34,173 — Other securities 6,609 2,844 3,074 691 Servicing assets 19,693 — — 19,693 Derivative assets 10,740 — 10,740 — Financial liabilities Derivative liabilities 4,243 — 4,243 — Note 18— Fair Value Measurement (continued) Fair Value Measurements Using 2017 Fair Value Level 1 Level 2 Level 3 Financial assets Securities available-for-sale U.S. Treasury Notes $ 14,863 $ 14,863 $ — $ — U.S. Government agencies 52,958 — 52,958 — Obligations of states, municipalities, and political subdivisions 33,170 — 32,795 375 Mortgage-backed securities; residential Agency 307,457 — 307,457 — Non-Agency 39,514 — 39,514 — Mortgage-backed securities; commercial Agency 69,043 — 69,043 — Non-Agency 30,971 — 30,971 — Corporate securities 29,976 — 29,976 — Other securities 5,284 1,921 2,686 677 Servicing assets 21,400 — — 21,400 Derivative assets 5,981 — 5,981 — Financial liabilities Derivative liabilities 994 — 994 — The Company has originated, and acquired through a business combination, servicing assets classified as Level 3 of the fair value hierarchy. The Company acquired single‑issuer trust preferred securities included in other securities categorized as Level 3 of the fair value hierarchy. The Company has purchased, and acquired through a business combination, privately-issued municipal securities that are categorized as Level 3. These municipal securities are bonds issued for municipal government entities located in the Chicago metropolitan area and are privately placed, non-rated bonds without Committee on Uniform Security Identification Procedures numbers. The Company did not have any transfers to or from Level 1 and Level 2 of the fair value hierarchy during the years ended December 31, 2018 and 2017. The following table presents additional information about financial assets measured at fair value on recurring basis for which the Company used significant unobservable inputs (Level 3): Years Ended December 31, 2018 2017 2018 2017 Investment Securities Servicing Assets Balance, beginning of period $ 1,052 $ 1,080 $ 21,400 $ 21,091 Acquired assets at fair value 314 — — — Additions, net — — 7,562 6,250 Maturities (494 ) (175 ) — — Amortization 5 5 — — Change in unrealized gain 9 142 — — Change in fair value — — (9,269 ) (5,941 ) Balance, end of period $ 886 $ 1,052 $ 19,693 $ 21,400 Note 18— Fair Value Measurement (continued) The following table presents additional information about the unobservable inputs used in the fair value measurements on recurring basis that were categorized within Level 3 of the fair value hierarchy as of December 31, 2018: Financial Instruments Valuation Technique Unobservable Inputs Range of Inputs Weighted Average Input Impact to Valuation from an Increased or Higher Input Value Obligations of states, municipalities, and political obligations Discounted Probability of default 2.4% 2.4 % Decrease Single issuer trust preferred Discounted cash flow Probability of default 4.9%—5.4% 5.2 % Decrease Servicing assets Discounted cash flow Prepayment speeds 2.0%—17.4% 11.5 % Decrease Discount rate 8.5%—23.1% 15.2 % Decrease Expected weighted average loan life 0.1—10.4 years 5.1 years Increase The Company used the following methods and significant assumptions to estimate fair value for certain assets measured and carried at fair value on a non-recurring basis: Loans held for sale— Mortgage loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value based on contract price. Loans transferred to loans held for sale are carried at the lower of cost or fair value, less estimated costs to sell. Impaired loans (excluding acquired impaired loans) —Impaired loans, other than those existing on the date of a business acquisition, are primarily carried at the fair value of the underlying collateral, less estimated costs to sell, if the loan is collateral dependent. Valuations of impaired loans that are collateral dependent are supported by third party appraisals in accordance with the Bank’s credit policy. Other valuation methods include analysis of discounted cash flows, which measures the present value of expected future cash flows discounted at the loan’s effective interest rate. Impaired loans that are not collateral dependent are not material. Assets held for sale —Assets held for sale consist of former branch locations and real estate previously purchased for expansion. Assets are considered held for sale when management has approved to sell the assets following a branch closure or other events. The properties are being actively marketed and transferred to assets held for sale based on the lower of carrying value or its fair value, less estimated costs to sell. Other real estate owned —Certain assets held within other real estate owned represent real estate or other collateral that has been adjusted to its estimated fair value, less cost to sell, as a result of transferring from the loan portfolio at the time of foreclosure or repossession and based on management’s periodic impairment evaluation. From time to time, non-recurring fair value adjustments to other real estate owned are recorded to reflect partial write-downs based on an observable market price or current appraised value of property. Note 18— Fair Value Measurement (continued) Adjustments to fair value based on such non-recurring transactions generally result from the application of lower-of-cost-or-market accounting or write-downs of individual assets due to impairment. The following tables summarize the Company’s assets that were measured at fair value on a non-recurring basis, excluding acquired impaired loans, as of December 31, 2018 and 2017: Fair Value Measurements Using 2018 Fair Value Level 1 Level 2 Level 3 Non-recurring Impaired loans (excluding acquired impaired loans) Commercial real estate $ 9,792 $ — $ — $ 9,792 Residential real estate 2,076 — — 2,076 Construction, land development, and other land — — — — Commercial and industrial 17,397 — — 17,397 Installment and other — — — — Assets held for sale 14,489 — — 14,489 Other real estate owned 5,314 — — 5,314 Fair Value Measurements Using 2017 Fair Value Level 1 Level 2 Level 3 Non-recurring Impaired loans (excluding acquired impaired loans) Commercial real estate $ 12,783 $ — $ — $ 12,783 Residential real estate 2,271 — — 2,271 Construction, land development, and other land — — — — Commercial and industrial 12,092 — — 12,092 Installment and other — — — — Assets held for sale 9,779 — — 9,779 Other real estate owned 10,626 — — 10,626 The following methods and assumptions were used by the Company in estimating fair values of other assets and liabilities for disclosure purposes: Cash and cash equivalents —For these short-term instruments, the carrying amount is a reasonable estimate of fair value. Securities held-to-maturity —The Company obtains fair value measurements from an independent pricing service. Management reviews the procedures used by the third party, including significant inputs used in the fair value calculations. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things. When market quotes are not readily accessible or available, alternative approaches are utilized, such as matrix or model pricing. Restricted stock —The fair value has been determined to approximate cost. Loans held for sale —The fair value of loans held for sale are based on quoted market prices, where available, and determined by discounted estimated cash flows using interest rates approximating the Company’s current origination rates for similar loans adjusted to reflect the inherent credit risk. Note 18— Fair Value Measurement (continued) Loan and lease receivables, net —For certain variable rate loans that reprice frequently and with no significant changes in credit risk, fair value is estimated at carrying value. The fair value of other types of loans is estimated by discounting future cash flows, using current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities. Deposits —The fair value of demand deposits, savings accounts, and certain money market deposits is the amount payable on demand at the reporting date. The fair value of fixed-maturity certificates of deposit is estimated by discounting future cash flows, using rates currently offered for deposits of similar remaining maturities. Federal Home Loan Bank advances —The fair value of FHLB advances is estimated by discounting the agreements based on maturities using rates currently offered for FHLB advances of similar remaining maturities adjusted for prepayment penalties that would be incurred if the borrowings were paid off on the measurement date. Securities sold under agreements to repurchase —The carrying amount approximates fair value due to maturities of less than ninety days. Junior subordinated debentures —The fair value of junior subordinated debentures, in the form of trust preferred securities, is determined using rates currently available to the Company for debt with similar terms and remaining maturities. Accrued interest receivable and payable —The carrying amount approximates fair value. Commitments to extend credit and letters of credit —The fair values of these off-balance sheet commitments to extend credit and commercial and letters of credit are not considered practicable to estimate because of the lack of quoted market prices and the inability to estimate fair value without incurring excessive costs. The estimated fair values of financial instruments and levels within the fair value hierarchy are as follows: Fair Value 2018 2017 Hierarchy Level Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Financial assets Cash and due from banks 1 $ 30,190 $ 30,190 $ 19,404 $ 19,404 Interest bearing deposits with other banks 2 91,670 91,670 38,945 38,945 Securities held-to-maturity 2 99,266 97,739 117,163 117,277 Other restricted stock 2 19,202 19,202 16,343 16,343 Loans held for sale 3 19,827 21,654 5,212 5,851 Loans and lease receivables, net (less impaired loans at fair value) 3 3,447,160 3,407,652 2,260,786 2,240,235 Accrued interest receivable 3 10,863 10,863 7,670 7,670 Financial liabilities Non-interest-bearing deposits 2 1,192,873 1,192,873 760,887 760,887 Interest-bearing deposits 2 2,557,043 2,554,329 1,682,442 1,678,535 Accrued interest payable 2 3,484 3,484 1,306 1,306 Line of credit 2 — — — — Federal Home Loan Bank advances 2 425,000 425,000 361,506 361,500 Securities sold under repurchase agreement 2 34,166 34,166 31,187 31,187 Junior subordinated debentures 3 36,768 42,351 27,647 33,907

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	Note 19— Share-Based Compensation In June 2017, the Company adopted the 2017 Omnibus Incentive Compensation Plan (the “Omnibus Plan”) in connection with our IPO. The Omnibus Plan provides for the grant of stock options, stock appreciation rights, restricted stock, restricted stock units, dividend equivalent rights and other equity-based, equity-related or cash-based awards. A total of 1,550,000 shares of our common stock have been reserved for issuance under the Omnibus Plan. As of December 31, 2018, there were 1,350,545 shares available for future grants under the Omnibus Plan. On July 6, 2017, in conjunction with the completion of the IPO, the Company granted 58,900 restricted shares of the Company’s common stock to certain key employees, pursuant to the Omnibus Plan. The restricted shares will cliff vest on the third anniversary of the grant date, subject to continued employment. A total of 11,898 restricted shares were also granted during the year ended December 31, 2017 in connection with the recruitment of employees. These restricted shares vest ratably over a four year period. During 2018, the Company granted 131,157 shares of restricted common stock, par value $0.01 per share. Of this total, 102,559 restricted shares will vest ratably over four years on each anniversary of the grant date, 15,165 restricted shares will vest ratably over three years on each anniversary of the grant date, and 2,268 restricted shares will vest on the first anniversary of the grant date, all subject to continued employment. In addition, 11,165 performance-based restricted shares were included in the 2018 grant. The number of shares which may be earned under the award is dependent upon the Company’s return on average assets over a three-year period ending December 31, 2020, measured in 2018 against the Company’s internal targets and for 2019 and 2020 against a peer group consisting of publicly-traded bank holding companies ranging in asset size from 50% to 200% of the Company’s total assets. Under the award, 25% of the shares will be earned at threshold performance, 100% will be earned at target and 50 th The following table discloses the changes in restricted shares for the year ended December 31, 2018: Omnibus Plan Number of Shares Weighted Average Grant Date Fair Value Beginning balance, January 1, 2018 70,398 $ 20.31 Granted 131,157 22.36 Vested (2,975 ) 20.96 Forfeited (2,100 ) 20.84 Ending balance outstanding at December 31, 2018 196,480 $ 21.66 A total of 2,975 restricted shares vested during the year ended December 31, 2018. The fair value of restricted shares that vested during the year ended December 31, 2018 was $62,000. No restricted shares vested during the year ended December 31, 2017. The Company recognizes share-based compensation based on the estimated fair value of the restricted stock at the grant date. Share-based compensation expense is included in non-interest expense in the Consolidated Statements of Operations. The following table summarizes restricted stock compensation expense for the years ended: Years Ended December 31, 2018 2017 Total share-based compensation - restricted stock $ 958 $ 203 Income tax benefit 267 83 Unrecognized compensation expense - restricted stock 3,167 1,227 Weighted-average amortization period remaining 2.9 years 2.8 years The fair value of the unvested restricted stock awards at December 31, 2018 was $3.3 million. Note 19— Share-Based Compensation (continued) The Company maintained a nonqualified, share-based, stock option plan adopted prior to recapitalization (“MBG Plan”). There were no options granted or exercised under this plan during the year ended December 31, 2017. At the time of the Company’s reincorporation in Delaware, in June 2017, the Board of Directors cancelled the MBG Plan and all the respective outstanding options were cancelled. In October 2014, the Company adopted the Byline Bancorp, Inc. Equity Incentive Plan (“BYB Plan”). The maximum number of shares available for grants under this plan was 2,476,122 shares. During 2016 and 2015, the Company granted options to purchase 212,400 and 1,634,568 shares, respectively, under this plan. The Company did not grant any stock options during the year ended December 31, 2017. In June 2017, the Board of Directors terminated the BYB Plan and no future grants can be made under this plan. Options to purchase a total of 1,598,872 shares remain outstanding under the BYB Plan as of December 31, 2018. The types of stock options granted under the BYB Plan were Time Options and Performance Options. The exercise price of each option is equal to the fair value of the stock as of the date of grant. These option awards have vesting periods ranging from one to five years and have 10-year contractual terms. Stock volatility was computed as the average of the volatilities of peer group companies. The vesting of Time Options is conditional based on completion of service. Performance Options have conditional vesting based on either performance targets or market performance. Certain Performance Options’ performance goals will be satisfied (in whole or in part) if the Bank achieves various performance targets such as profitability, asset quality, and conditional based on market performance, as outlined in the BYB Plan. Each of the performance goals identified are measured for achievement (or failure to achieve) independent of each other. In October 2017, the Board of Directors determined that the Performance Option goals were satisfied, in whole, and these Performance Options converted to Time Options. As a result of the previous completion of service, 414,894 performance options vested on October 3, 2017. The fair values of the stock options were determined using the Black-Scholes-Merton model for Time Options and a Monte Carlo simulation model for Performance Options. The fair values of options under the BYB Plan were determined using the following assumptions as of the grant dates: Time Options Grants 2016 Risk-free interest rate 1.34% - 1.40% Expected term (years) 5.2 - 5.6 Expected stock price volatility 20.39 % Expected dividend yield 0.00 % Weighted average grant date fair value $ 3.55 Performance Options Grants 2016 Risk-free interest rate Implied forward rates Expected term (years) Variable Expected stock price volatility 20.34% - 20.39% Expected dividend yield 0.00 % Weighted average grant date fair value $ 3.75 Note 19— Share-Based Compensation (continued) The following table discloses the activity in shares subject to options and the weighted average exercise prices, in actual dollars, for the year ended December 31, 2018: BYB Plan Number of Shares Weighted Average Exercise Price Intrinsic Value Weighted Average Remaining Contractual Term (in Years) Beginning balance, January 1, 2018 1,783,020 $ 11.91 $ 19,718 7.6 Granted — Expired — Exercised (148,748 ) 11.69 $ 1,614 Forfeited (35,400 ) 16.25 Ending balance outstanding at December 31, 2018 1,598,872 $ 11.84 $ 7,713 6.6 Exercisable at December 31, 2018 1,500,572 $ 11.55 $ 7,673 6.5 A total of 148,748 stock options were exercised during the year ended December 31, 2018. During the year ended December 31, 2018, proceeds from the exercise of stock options were $1.7 million and related tax benefit was $449,000. There were no stock options exercised during the year ended December 31, 2017. A total of 345,063 stock options vested during the year ended December 31, 2018. The Company recognizes share-based compensation based on the estimated fair value of the option at the grant date. Forfeitures are estimated based upon industry standards. Share-based compensation expense is included in non-interest expense in the Consolidated Statements of Operations. The following table summarizes stock option compensation expense for the years ended December 31, 2018, 2017 and 2016: Years Ended December 31, 2018 2017 2016 Total share-based compensation - stock options $ 458 $ 1,294 $ 899 Income tax benefit 127 521 360 Unrecognized compensation expense - stock options 146 729 1,752 Weighted-average amortization period remaining 1.1 years 1.2 years 1.8 years Pursuant to the terms of the Merger Agreement, upon the Effective Time, each outstanding First Evanston Option held by a participant in the First Evanston Bancorp, Inc. Stock Incentive Plan (the “FEB Plan”) ceased to represent a right to acquire shares of First Evanston common stock and was assumed and converted automatically into a fully vested and exercisable adjusted option to purchase shares of Byline common stock (each an “Adjusted Option”). In accordance with the Merger Agreement, the number of shares of Byline common stock to which each such Adjusted Option relates is equal to the product (rounded down to the nearest whole share of Byline common stock) of: (a) the number of shares of First Evanston common stock subject to the First Evanston Option immediately prior to May 31, 2018, multiplied by (ii) 4.725. Each Adjusted Option has an exercise price per share of Byline common stock equal to the quotient (rounded up to the nearest whole cent) of (x) the per share exercise price of such First Evanston Option immediately prior to May 31, 2018, divided by (y) 4.725. The description of the conversion process is based on, and qualified by, the Merger Agreement. Note 19— Share-Based Compensation (continued) The following table discloses the activity in shares subject to options under the FEB Plan and the weighted average exercise prices, in actual dollars, for the year ended December 31, 2018: FEB Plan Number of Shares Weighted Average Exercise Price Intrinsic Value Weighted Average Remaining Contractual Term (in Years) Beginning balance, May 31, 2018 — $ — $ — — Granted 680,787 11.26 $ 7,544 Expired — Exercised (56,404 ) 10.66 $ 602 Forfeited — Ending balance outstanding at December 31, 2018 624,383 $ 11.31 $ 3,339 5.2 Exercisable at December 31, 2018 624,383 $ 11.31 $ 3,339 5.2 A total of 56,404 stock options were exercised during the year ended December 31, 2018. During the year ended December 31, 2018, proceeds from the exercise of stock options were $601,000 and related tax benefit was $168,000. All shares of restricted performance shares of First Evanston common stock (“restricted stock”) that were previously issued under and held by Participants in the FEB Plan prior to the Merger were converted into the right to receive the per share merger consideration in connection with the Merger and pursuant to the Merger Agreement. Accordingly, no shares of First Evanston restricted stock remain outstanding under the FEB Plan.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Note 20— Related Party Transactions Loans to related parties —Loans that may be made to the Bank’s executive officers, as defined in 12 CFR 215 (Regulation O), directors, principal stockholders and their affiliates would be on substantially the same terms, including interest rates and collateral, as those prevailing at the time for comparable transactions with unrelated persons and would not involve more than normal risk of collectability. As of December 31, 2018 and 2017, there were no material loans made to the related parties described above. Deposits from related parties —Deposits from related parties were not material as of December 31, 2018 and 2017. Other —As of December 31, 2018 and 2017, there were no receivables outstanding from related parties.

Regulatory Capital Requirements

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2018
Regulatory Capital Requirements [Abstract]
Regulatory Capital Requirements	Note 21—Regulatory Capital Requirements The Company and the Bank are subject to various regulatory capital requirements administered by their respective banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and the Bank must meet specific capital guidelines that involve quantitative measures of their assets, liabilities and certain off‑balance sheet items as calculated under regulatory accounting practices. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings and other factors. Quantitative measures established by regulation to ensure capital adequacy require the Company and the Bank to maintain minimum amounts and ratios of Common Equity Tier 1 capital (“CET1”), Tier 1 capital and total capital to risk‑weighted assets and of Tier 1 capital to average consolidated assets, as defined in the regulations. Note 21—Regulatory Capital Requirements (continued) As of December 31, 2018, the most recent notification from the FDIC categorized the Bank as well‑capitalized under the framework for prompt corrective action. There are no conditions or events since that notification that management believes have changed the Bank’s category. The required regulatory capital ratios are set forth in the following tables along with the minimum capital amounts required for the Company and the Bank and well capitalized with respect to the Bank. The Company’s and the Bank’s actual capital amounts and ratios as of December 31, 2018 and 2017 are also presented. Actual Minimum Capital Required Required to be Considered Well Capitalized 2018 Amount Ratio Amount Ratio Amount Ratio Total capital to risk weighted assets: Company $ 551,079 13.99 % $ 315,093 8.00 % N/A N/A Bank 528,329 13.40 % 315,455 8.00 % 394,318 10.00 % Tier 1 capital to risk weighted assets: Company $ 523,808 13.30 % $ 236,320 6.00 % N/A N/A Bank 501,058 12.71 % 236,591 6.00 % 315,455 8.00 % Common Equity Tier 1 (CET1) to risk weighted assets: Company $ 466,870 11.85 % $ 177,240 4.50 % N/A N/A Bank 501,058 12.71 % 177,443 4.50 % 256,307 6.50 % Tier 1 capital to average assets: Company $ 523,808 11.05 % $ 189,587 4.00 % N/A N/A Bank 501,058 10.56 % 189,797 4.00 % 237,246 5.00 % Actual Minimum Capital Required Required to be Considered Well Capitalized 2017 Amount Ratio Amount Ratio Amount Ratio Total capital to risk weighted assets: Company $ 408,245 15.89 % $ 205,559 8.00 % N/A N/A Bank 365,386 14.19 % 205,981 8.00 % 257,476 10.00 % Tier 1 capital to risk weighted assets: Company $ 389,934 15.18 % $ 154,169 6.00 % N/A N/A Bank 347,075 13.48 % 154,486 6.00 % 205,981 8.00 % Common Equity Tier 1 (CET1) to risk weighted assets: Company $ 351,408 13.68 % $ 115,627 4.50 % N/A N/A Bank 347,075 13.48 % 115,864 4.50 % 167,359 6.50 % Tier 1 capital to average assets: Company $ 389,934 12.18 % $ 128,075 4.00 % N/A N/A Bank 347,075 10.82 % 128,305 4.00 % 160,382 5.00 % The Company and Byline Bank must maintain a capital conservation buffer consisting of CET1 capital greater than 2.5% of risk-weighted assets above the required minimum risk-based capital levels in order to avoid limitations on paying dividends, repurchasing shares, and paying discretionary bonuses. The capital conservation buffer requirement began to be phased in on January 1, 2016 when a buffer greater than 0.625% of risk-weighted assets was required, which amount increases each year until the buffer requirement is fully implemented on January 1, 2019. As of January 1, 2018 the capital conservation buffer requirement was 1.875%. The conservation buffers for the Company and Byline Bank exceed the fully phased in minimum capital requirement as of December 31, 2018. Provisions of state and federal banking regulations may limit, by statute, the amount of dividends that may be paid to the Company by Byline Bank without prior approval of Byline Bank’s regulatory agencies. The Company is economically dependent on the cash dividends received from Byline Bank. These dividends represent the primary cash flow from operating activities used to service obligations. For the years ended December 31, 2018 and 2017, the Company received $2.9 million and $2.8 million, respectively, in cash dividends from Byline Bank to pay the trust preferred securities interest and preferred dividends.

Derivative Instruments and Hedg

Derivative Instruments and Hedge Activities	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedge Activities	Note 22—Derivative Instruments and Hedge Activities The Company recognizes derivative financial instruments at fair value regardless of the purpose or intent for holding the instrument. The Company records derivative assets and derivative liabilities on the Consolidated Statements of Financial Condition within accrued interest receivable and other assets and accrued interest payable and other liabilities, respectively. The following tables present the fair value of the Company’s derivative financial instruments and classification on the Consolidated Statements of Financial Condition as of December 31, 2018 and 2017: 2018 2017 Fair Value Fair Value Notional Amount Other Assets Other Liabilities Notional Amount Other Assets Other Liabilities Derivatives designated as hedging instruments Interest rate swaps designated as cash flow hedges $ 250,000 $ 6,699 $ — $ 250,000 $ 5,030 $ 38 Derivatives not designated as hedging instruments Other interest rate swaps 294,545 4,041 4,237 94,726 951 956 Other credit derivatives 4,424 — 6 — — — Total derivatives $ 548,969 $ 10,740 $ 4,243 $ 344,726 $ 5,981 $ 994 Interest rate swaps designated as cash flow hedges —Cash flow hedges of interest payments associated with certain FHLB advances had notional amounts totaling $250.0 million as of December 31, 2018, and 2017. The aggregate fair value of the swaps is recorded in other assets or other liabilities with changes in fair value recorded in other comprehensive income (loss), net of taxes, to the extent effective. The amount included in accumulated other comprehensive income (loss) would be reclassified to current interest incurred from the hedged FHLB advances when it affects earnings. The Company assesses the effectiveness of each hedging relationship by comparing the changes in fair value of the derivative hedging instrument with the changes in fair value of the designated hedged transactions. The Company expects the hedges to remain highly effective during the remaining terms of the swaps and did not recognize any hedge ineffectiveness in current earnings during the years ended December 31, 2018 and 2017 Interest recorded on these swap transactions reduced FHLB interest expense by $1.3 million during the year ended December 31, 2018, and increased FHLB interest expense by $579,000 and $40,000 during the years ended December 31, 2017 and 2016, respectively, and is reported as a component of interest expense on FHLB advances. At December 31, 2018, the Company estimates $2.6 million of the unrealized gain to be reclassified as a decrease to interest expense during the next twelve months. The following table reflects the cash flow hedges as of December 31, 2018: Notional amounts $ 250,000 Derivative assets fair value 6,699 Derivative liabilities fair value — Weighted average pay rates 1.67 % Weighted average receive rates 2.37 % Weighted average maturity 3.2 years The following table reflects the net gains (losses) recorded in accumulated other comprehensive income (loss) and the Consolidated Statements of Operations relating to the cash flow derivative instruments for the year ended December 31, 2018: Amount of Gain Recognized in OCI (Effective Portion) Amount of Gain Reclassified from OCI to Income as a Decrease to Interest Expense Amount of Gain (Loss) Recognized in Other Non-Interest Income (Ineffective Portion) Interest rate swaps $ 2,960 $ 1,348 $ — Note 22—Derivative Instruments and Hedge Activities (continued) Other interest rate swaps —The total combined notional amount was $294.5 million as of December 31, 2018, with maturities ranging from April 2020 to December 2028. The fair values of the interest rate swap agreements are reflected in other assets and other liabilities with corresponding gains or losses reflected in non-interest income. During the years ended December 31, 2018, 2017, and 2016, there were $1.7 million, $393,000, and $679,000 of transaction fees, respectively, included in other non-interest income, related to these derivative instruments. The following table reflects other interest rate swaps as of December 31, 2018: Notional amounts $ 294,545 Derivative assets fair value 4,041 Derivative liabilities fair value 4,237 Weighted average pay rates 4.84 % Weighted average receive rates 4.38 % Weighted average maturity 5.8 years Other credit derivatives —The total notional amount was $4.4 million as of December 31, 2018. There were no credit derivatives as of or for the year ended December 31, 2017. The fair value of the other credit derivatives are reflected in other liabilities with corresponding gains or losses reflected in non-interest income. The credit valuation adjustment (“CVA”) related to the other credit derivatives resulted in a decrease to other non-interest income during the year ended December 31, 2018 of $6,000. There was $60,000 of transaction fees included in non-interest income related to these derivative instruments during the year ended December 31, 2018. The Company has entered into risk participation agreements with counterparty banks to assume a portion of the credit risk related to borrower transactions. The credit risk related to these other credit derivatives is managed through the Company’s loan underwriting process. Credit risk —Derivative instruments are inherently subject to market risk and credit risk. Market risk is associated with changes in interest rates and credit risk relates to the Company’s risk of loss when the counterparty to a derivative contract fails to perform according to the terms of the agreement. Market and credit risks are managed and monitored as part of the Company’s overall asset-liability management process. The credit risk related to derivatives entered into with certain qualified borrowers is managed through the Company’s loan underwriting process. The Company’s loan underwriting process also approves the Bank’s swap counterparty used to mirror the borrowers’ swap. The Company has a bilateral agreement with each swap counterparty that provides that fluctuations in derivative values are to be fully collateralized with either cash or securities. The CVA is a fair value adjustment to the derivative to account for this risk. During the years ended December 31, 2018 and 2017, the CVA resulted in decreases to non-interest income of $192,000 and $44,000, respectively. For the year ended December 31, 2016, the CVA resulted in an increase to non-interest income of $39,000. The Company has agreements with its derivative counterparties that contain a cross-default provision under which if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations. The Company also has agreements with certain derivative counterparties that contain a provision where if the Company fails to maintain its status as a well or adequately capitalized institution, then the counterparty could terminate the derivative positions and the Company would be required to settle its obligations resulted in a net asset position. Note 22—Derivative Instruments and Hedge Activities (continued) The Company records interest rate derivatives subject to master netting agreements at their gross value and does not offset derivative asset and liabilities on the Consolidated Statements of Financial Condition. The table below summarizes the Company’s interest rate derivatives and offsetting positions as of December 31, 2018 and 2017 2018 2017 Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Assets Fair Value Derivative Liabilities Fair Value Gross amounts recognized $ 10,740 $ 4,243 $ 5,981 $ 994 Less: Amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition $ 10,740 $ 4,243 $ 5,981 $ 994 Gross amounts not offset in the Consolidated Statements of Financial Condition Offsetting derivative positions (2,823 ) (2,823 ) (232 ) (232 ) Collateral posted (7,917 ) (1,317 ) (5,371 ) (745 ) Net credit exposure — $ 103 $ 378 $ 17 As of December 31, 2018, the counterparties posted collateral of $8.8 million, which resulted in no excess collateral with the Company. For purposes of this disclosure, the amount of posted collateral by the counterparties is limited to the amount offsetting the derivatives asset.

Parent Company Only Condensed F

Parent Company Only Condensed Financial Statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Company Only Condensed Financial Statements	Note 23—Parent Company Only Condensed Financial Statements The following represents the condensed financial statements of Byline Bancorp, Inc., the Parent Company: Statements of Financial Condition Parent Company Only As of December 31, 2018 2017 ASSETS Cash 18,242 39,626 Investment in banking subsidiary 667,236 445,786 Other assets 3,067 1,236 Total assets $ 688,545 $ 486,648 LIABILITIES AND STOCKHOLDERS’ EQUITY Line of credit — — Junior subordinated debentures issued to capital trusts, net 36,768 27,647 Accrued expenses and other liabilities 1,105 423 Stockholders' equity 650,672 458,578 Total liabilities and stockholders' equity $ 688,545 $ 486,648 Note 23—Parent Company Only Condensed Financial Statements (continued) Statements of Operations Parent Company Only Years ended December 31, 2018 2017 2016 INCOME Dividends from subsidiary $ 2,900 $ 2,800 $ — Other noninterest income — 9 57 Total income 2,900 2,809 57 EXPENSES Interest expense 2,716 2,782 2,460 Other noninterest expense 3,214 1,804 381 Total expenses 5,930 4,586 2,841 Loss before provision for income taxes and equity in undistributed income of subsidiary (3,030 ) (1,777 ) (2,784 ) Provision (benefit) for income taxes (1,549 ) (1,166 ) 204 Loss before equity in undistributed income of subsidiary (1,481 ) (611 ) (2,988 ) Equity in undistributed income of subsidiary 42,674 22,306 69,717 Net income $ 41,193 $ 21,695 $ 66,729 Statements of Cash Flows Parent Company Only Years ended December 31, 2018 2017 2016 CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 41,193 $ 21,695 $ 66,729 Adjustments to reconcile net income to net cash from operating activities: Equity in undistributed income of subsidiary (42,674 ) (22,306 ) (69,717 ) Stock-based compensation expense 1,514 1,497 899 Exercise of share-based awards — — 40 Accretion of junior subordinated debentures discount 624 721 876 Changes in other assets and other liabilities (3,291 ) (2,893 ) 16 Net cash used in operating activities (2,634 ) (1,286 ) (1,157 ) CASH FLOWS FROM INVESTING ACTIVITIES Investments in and advances from subsidiary — — (32,019 ) Net cash paid in acquisition of business (20,510 ) — (36,586 ) Net cash used in investing activities (20,510 ) — (68,605 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from revolving line of credit — — 30,000 Repayments of revolving line of credit — (20,650 ) (9,350 ) Dividends paid on preferred stock (783 ) (11,277 ) — Cash paid in lieu of fractional shares — (2 ) — Proceeds from issuance of common stock, net 2,543 76,829 49,592 Proceeds from issuance of preferred stock — 1,050 9,388 Repurchase of preferred stock — (15,003 ) — Net cash provided by financing activities 1,760 30,947 79,630 NET CHANGE IN CASH AND CASH EQUIVALENTS (21,384 ) 29,661 9,868 CASH AND CASH EQUIVALENTS, beginning of period 39,626 9,965 97 CASH AND CASH EQUIVALENTS, end of period $ 18,242 $ 39,626 $ 9,965

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share	Note 24—Earnings per Share A reconciliation of the numerators and denominators for earnings per common share computations is presented below. Incremental shares represent outstanding stock options for which the exercise price is less than the average market price of the Company’s common stock during the periods presented. Options to purchase 2,223,255 shares of common stock were outstanding as of December 31, 2018. Options to purchase 1,783,020 shares of common stock were outstanding as of December 31, 2017 and 2016. There were 196,480 and 70,798 restricted stock awards outstanding at December 31, 2018 and 2017, respectively. There were no restricted stock awards outstanding at December 31, 2016. Years ended December 31, 2018 2017 2016 Net income $ 41,193 $ 21,695 $ 66,729 Less: Dividends on preferred shares 783 11,277 — Net income available to common stockholders $ 40,410 $ 10,418 $ 66,729 Weighted-average common stock outstanding: Weighted-average common stock outstanding (basic) 33,292,619 26,963,517 20,141,630 Incremental shares 887,135 583,797 289,153 Weighted-average common stock outstanding (dilutive) 34,179,754 27,547,314 20,430,783 Basic earnings per common share $ 1.21 $ 0.39 $ 3.31 Diluted earnings per common share $ 1.18 $ 0.38 $ 3.27

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	Note 25—Stockholders’ Equity A summary of the Company’s preferred and common stock at December 31, 2018 and 2017 is as follows: 2018 2017 Series B 7.5% fixed to floating non-cumulative perpetual preferred stock Par value $ 0.01 $ 0.01 Shares authorized 50,000 50,000 Shares issued 10,438 10,438 Shares outstanding 10,438 10,438 Common stock, voting Par value $ 0.01 $ 0.01 Shares authorized 150,000,000 150,000,000 Shares issued 36,343,239 29,317,298 Shares outstanding 36,343,239 29,317,298 During 2016, the Company authorized and issued Series B 7.50% fixed-to-floating non-voting, noncumulative perpetual preferred stock with a liquidation preference of $1,000 per share, plus the amount of unpaid dividends, if any, which is redeemable at the Company’s option on or after March 31, 2022. Holders of Series B Preferred Stock do not have any rights to convert such stock into shares of any other class of capital stock of the Company. Holders of Series B Preferred Stock are entitled to receive a fixed dividend of 7.50% per annum from the original issue date through December 30, 2021, after which the dividend is paid at a floating rate of three-month LIBOR plus 5.41% per annum. The Company Series B Preferred Stock is included in Tier 1 capital for regulatory capital purposes and is redeemable at the option of the Company at a redemption price of $1,000 per share, plus any declared and unpaid dividends (i) in whole or part on any dividend payment date on or after March 31, 2022, and (ii) in whole but not in part prior to March 31, 2022, within 90 days following a regulatory event, as defined in the Certificate of Designations of the Company Series B Preferred Stock. The Company must receive approval of the Federal Reserve Board prior to any redemption of the Company Series B Preferred Stock. For the year ended December 31, 2018, the Company declared and paid dividends on the Series B Preferred Stock of $783,000, compared to $776,000 for the year ended December 31, 2017.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unaudited)	Note 26—Selected Quarterly Financial Data (unaudited) For the year ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Interest and dividend income $ 38,142 $ 44,841 $ 61,073 $ 62,895 Interest expense 4,447 5,785 8,480 9,634 Net interest income 33,695 39,056 52,593 53,261 Provision for loan and lease losses 5,115 3,956 5,842 3,882 Net interest income after provision for loan and lease losses 28,580 35,100 46,751 49,379 Non-interest income 11,428 14,502 11,143 14,566 Non-interest expense 31,919 45,770 37,956 40,364 Income before provision for income taxes 8,089 3,832 19,938 23,581 Provision for income taxes 1,321 1,064 5,402 6,460 Net income 6,768 2,768 14,536 17,121 Dividends on preferred shares 193 198 196 196 Income available to common stockholders $ 6,575 $ 2,570 $ 14,340 $ 16,925 Basic earnings per common share $ 0.22 $ 0.08 $ 0.40 $ 0.47 Diluted earnings per common share $ 0.22 $ 0.08 $ 0.39 $ 0.46 The Company recorded net income of $2.8 million, or $0.08 per common share, for the second quarter of 2018. The Company’s net interest income before provision for loan losses was $39.1 million. On May 31, 2018, the Company acquired the assets and assumed the liabilities of First Evanston. Revenue and expenses of the acquired company since the acquisition were included in the Company’s operating results. Additionally, during the second quarter, the Company incurred $8.1 million in data processing costs related to a termination fee for our successful core system conversion. Note 26—Selected Quarterly Financial Data (unaudited) (continued) For the year ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Interest and dividend income $ 32,488 $ 33,315 $ 35,044 $ 35,956 Interest expense 2,950 3,504 3,632 3,805 Net interest income 29,538 29,811 31,412 32,151 Provision for loan and lease losses 1,891 3,515 3,900 3,347 Net interest income after provision for loan and lease losses 27,647 26,296 27,512 28,804 Non-interest income 12,308 13,193 11,918 12,639 Non-interest expense 28,851 29,249 31,065 30,358 Income before provision for income taxes 11,104 10,240 8,365 11,085 Provision (benefit) for income taxes 4,544 4,094 (1,390 ) 11,851 Net income (loss) 6,560 6,146 9,755 (766 ) Dividends on preferred shares 189 10,697 195 196 Income available (loss attributable) to common stockholders $ 6,371 $ (4,551 ) $ 9,560 $ (962 ) Basic earnings (loss) per common share $ 0.26 $ (0.18 ) $ 0.33 $ (0.03 ) Diluted earnings (loss) per common share $ 0.25 $ (0.18 ) $ 0.32 $ (0.03 ) During the second quarter of 2017, in connection with the Company’s initial public offering, proceeds were used to repurchase Series A Preferred Stock, which included $10.5 million of dividends in arrears. During the third quarter of 2017, the Legislature of the state of Illinois passed an increase in the corporate tax rate from 5.25% to 7.00%. As a result of the increase, the Company recorded a benefit of $4.6 million resulting from an increase in the value of deferred tax assets related to Illinois net loss deductions. The Company recorded a net loss of $766,000, or $0.03 per common share, for the fourth quarter of 2017. The Company’s net interest income before provision for loan losses was $32.2 million. In December 2017, the “Tax Cuts and Jobs Act” reduced the federal corporate tax rate to 21% effective January 1, 2018. As a result of the decrease, the Company’s fourth quarter 2017 operating results included incremental tax expense of $7.2 million from enactment of Tax Cuts and Jobs Act of 2017.

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Consolidated Statements of Changes in Accumulated Other Comprehensive Income (Loss)	Note 27—Consolidated Statements of Changes in Accumulated Other Comprehensive Income (Loss) The following table summarized the change in accumulated other comprehensive income (loss) for the years ended December 31, 2018, 2017 and 2016: (dollars in thousands) Gains on Cash Flow Hedges Unrealized (Losses) on Available-for -Sale Securities Total Accumulated Other Comprehensive Income (Loss) Balance, January 1, 2016 $ — $ (5,707 ) $ (5,707 ) Other comprehensive income (loss), net of tax 2,233 (3,794 ) (1,561 ) Balance, December 31, 2016 2,233 (9,501 ) (7,268 ) Other comprehensive income, net of tax 680 1,501 2,181 Balance, December 31, 2017 2,913 (8,000 ) (5,087 ) Reclassification of certain income tax effects from accumulated other comprehensive income 687 (1,450 ) (763 ) Other comprehensive income (loss), net of tax 1,163 (4,811 ) (3,648 ) Balance, December 31, 2018 $ 4,763 $ (14,261 ) $ (9,498 )

Business and Summary of Signi_2

Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Business Description And Accounting Policies [Abstract]
Nature of business	Nature of business —Byline Bancorp, Inc. (the “Company,” “we,” “us,” “our”) is a bank holding company whose principal activity is the ownership and management of its subsidiary bank, Byline Bank (the “Bank”). The Bank originates commercial, mortgage and consumer loans and leases, U.S. government guaranteed loans, and receives deposits from customers located primarily in the Chicago, Illinois metropolitan area. The Bank operates 57 Chicago metropolitan area and one Brookfield, Wisconsin, banking offices. The Bank operates under an Illinois state bank charter, provides a full range of banking services, and has full trust powers. As an Illinois state‑chartered financial institution that is not a member of the Federal Reserve System, the Bank is subject to regulation by the Illinois Department of Financial and Professional Regulation and the Federal Deposit Insurance Corporation. The Company is regulated by the Board of Governors of the Federal Reserve System. As a result of its acquisition of Ridgestone Financial Services, Inc. (“Ridgestone”) on October 14, 2016, the Bank is a participant in the Small Business Administration (“SBA”) and the United States Department of Agriculture (“USDA”) (collectively referred to as “U.S. government guaranteed loans”) lending programs and originates U.S. government guaranteed loans. As a result of its acquisition of First Evanston Bancorp, Inc. (“First Evanston”) on May 31, 2018, the Bank also provides wealth management services to our customers. See Note 3—Acquisition of a Business for additional information regarding the transaction. The Bank engages in short‑term direct financing lease contracts through BFG Corporation, doing business as Byline Financial Group (“BFG”), a wholly‑owned subsidiary of the Bank. BFG is located in Bannockburn, Illinois with sales offices in Illinois and New York, and sales representatives in Illinois, Michigan, New Jersey and New York. On June 14, 2017, stockholders of record as of May 22, 2017 voted to approve an Agreement and Plan of Merger between Byline Bancorp, Inc., an Illinois corporation (“Byline Illinois”), and Byline Bancorp, Inc., a wholly owned Delaware subsidiary of the Company, including the amended and restated certificate of incorporation and by‑laws of the Company. Each share of Byline Illinois common stock issued and outstanding immediately prior to the effective time of the Merger was converted automatically into the right to receive one fifth (0.20) of a share of common stock of the Company. Stockholders were paid a total of $2,000 in cash for remaining fractional shares based on the offering price of $19.00 per share. On October 17, 2018, the Company entered a definitive merger agreement with Oak Park River Forest Bankshares, Inc. (which we refer to as “Oak Park River Forest”), the parent company of Community Bank of Oak Park River Forest, to which the Company will acquire Oak Park River Forest through the merger of Oak Park River Forest with and into the Company, followed immediately by the merger of Community Bank of Oak Park River Forest with and into Byline Bank. At such time, Community Bank of Oak Park River Forest’s banking offices will become banking offices of the Bank. The above described merger agreements are anticipated to be completed during the first half of 2019, subject to the satisfaction or waiver of the conditions included in the merger agreement. No other subsequent events were identified that would have required a change to the consolidated financial statements or disclosure in the notes to the consolidated financial statements.
Basis of financial statement presentation and consolidation	Basis of financial statement presentation and consolidation —The consolidated financial statements include the accounts of the Company and its subsidiaries. Significant intercompany items and transactions have been eliminated in consolidation. The accounting and reporting policies of the Company conform to accounting principles generally accepted in the United States of America (“GAAP”) as contained within the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) and rules and regulations of the Securities and Exchange Commission (“SEC”), including the instructions to Regulation S‑X. In accordance with applicable accounting standards, the Company does not consolidate statutory trusts established for the sole purposes of issuing trust preferred securities and related trust common securities. See Note 15, Junior Subordinated Debentures, for additional discussion. Dollars within footnote tables disclosed within the consolidated financial statements are presented in thousands, except share and per share data. Operating results include the years ended December 31, 2018, 2017 and 2016.
Use of estimates	Use of estimates —In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the reported amounts of certain assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the Consolidated Statements of Financial Condition and certain revenues and expenses for the periods included in the Consolidated Statements of Operations and the accompanying notes. Actual results could differ from those estimates. Estimates that are particularly susceptible to significant changes in the near term relate to the determination of expected cash flows of acquired impaired loans, the allowance for loan and lease losses, valuation of servicing assets, fair value measurements for assets and liabilities, goodwill, other intangible assets, the valuation or recognition of deferred tax assets and liabilities, and the valuation of assets and liabilities acquired in business combinations.
Business combinations	Business combinations —The Company accounts for business combinations under the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations (“ASC 805”). The Company recognizes the fair value of the assets acquired and liabilities assumed as of the date of acquisition, with any excess of the fair value of consideration provided over the fair value of the identifiable net tangible and intangible assets acquired recorded as goodwill. Transaction costs are immediately expensed as applicable. The results of operations of the acquired business are included in the Consolidated Statements of Operations from the effective date of the acquisition, which is the date control is obtained. In accordance with ASC 805, the acquiring company retains the right to make appropriate adjustments to the assets and liabilities of the acquired entity for information obtained during the measurement period about facts and circumstances that existed as of the acquisition date. The measurement period ends as of the earlier of (a) one year from the acquisition date or (b) the date when the acquirer receives the information necessary to complete the business combination accounting.
Cash and cash equivalents	Cash and cash equivalents —Cash and cash equivalents have original maturities of three months or less. The Company holds cash and cash equivalents on deposit with other banks and financial institutions in amounts that periodically exceed the federal deposit insurance limit. The Company evaluates the credit quality of these banks and financial institutions to mitigate its credit risk and has not experienced any losses in such accounts. Cash on hand or on deposit with the Federal Reserve Bank of Chicago was required to meet regulatory reserve and clearing requirements. The reserve requirement was $44.8 million and $15.8 million as of December 31, 2018 and 2017, respectively, and the Bank met the requirement at each balance sheet date.
Securities	Securities —Securities that are held principally for resale in the near term are classified as trading and recorded at fair value with changes in fair value included in earnings. The Company did not invest in securities classified as trading during 2018, 2017 and 2016. Securities are classified as available‑for‑sale if the instrument may be sold in response to such factors including changes in market interest rates and related changes in prepayment risk, needs for liquidity, changes in the availability of and the yield on alternative instruments, and changes in funding sources and terms. Gains or losses on the sales of available‑for‑sale securities are recorded on the trade date and determined using the specific‑identification method. Unrealized holding gains or losses, net of tax, on available‑for‑sale securities are carried as accumulated other comprehensive income (loss) within stockholders’ equity until realized. Securities are classified as held‑to‑maturity and carried at amortized cost when management has the positive intent and ability to hold them to maturity. Fair values of securities are generally based on quoted market prices for the same or similar instruments. See Note 18—Fair Value Measurement for additional discussion on the determination of fair values. Interest income includes the amortization of purchase premiums and discounts, which are recognized using the effective interest method over the terms of the securities. Management evaluates securities for other‑than‑temporary impairment (“OTTI”) on a quarterly basis, and more frequently when economic or market conditions warrant such evaluation. The evaluation is based upon factors such as the creditworthiness of the issuers or guarantors, the underlying collateral, if applicable, and the continuing performance of the securities. Management also evaluates other facts and circumstances that may be indicative of an OTTI condition. This includes, but is not limited to, an evaluation of the type of security, length of time and extent to which the fair value has been less than cost, and near‑term prospects of the issuer. The Company’s assessment of OTTI considers whether it intends to sell a security or if it is likely that it would be required to sell the security before recovery of the amortized cost basis of the investment, which may be at maturity. For debt securities, if the Company intends to sell the security or it is more likely than not that it will be required to sell the security before recovering its cost basis, the entire impairment loss is recognized in earnings as an OTTI. If the Company does not intend to sell the security and it is more likely than not that it will not be required to sell the security, and the Company does not expect to recover the entire amortized cost basis of the security, only the portion of the impairment loss representing credit losses would be recognized in earnings. The credit loss on a security is measured as the difference between the amortized cost basis and the present value of the cash flows expected to be collected. Projected cash flows are discounted by the original or current effective interest rate depending on the nature of the security being measured for potential OTTI. The remaining impairment related to all other factors, the difference between the present value of the cash flows expected to be collected and fair value, is recognized as a charge to other comprehensive income (loss).
Restricted stock	Restricted stock —The Company owns stock of the Federal Home Loan Bank of Chicago (“FHLB”). No ready market exists for this stock, and it has no quoted market value. As a member of the FHLB system, the Bank is required to maintain an investment in FHLB stock. The stock is redeemable at par by the FHLB and is, therefore, carried at cost. In addition, the Company owns stock of Bankers Bank that was acquired as part of the Ridgestone transaction. The stock is redeemable at par and carried at cost. Note 1—Business and Summary of Significant Accounting Policies (continued) Restricted stock is generally viewed as a long‑term investment. Accordingly, when evaluating for impairment, its value is determined based on the ultimate recoverability of the par value rather than by recognizing temporary declines in value. The Company did not recognize impairment of its restricted stock as a result of its impairment analyses for the years ended December 31, 2018, 2017 and 2016.
Loans held for sale	Loans held for sale —Loans that management has the intent and ability to sell are designated as held for sale. U.S. government guaranteed loans and mortgage loans originated are carried at either amortized cost or estimated fair value. The Company determines whether to account for loans at fair value or amortized cost at origination. The loans accounted for at fair value remain at fair value after the determination. The loans accounted for at amortized cost are carried at the lower of cost or fair value, valued on a loan by loan basis. Net unrealized losses, if any, are recorded as a valuation allowance and charged to earnings. Gains or losses on sales of U.S. government guaranteed loans are recognized based on the difference between the net sales proceeds, carrying value of the sold loan, fair value of the servicing asset recognized, and fair value of the retained loan (if any), and are reflected as operating activities in the Consolidated Statements of Cash Flows. The difference between the initial carrying balance of the retained loan and the relative fair value of the sold portion is recorded as a discount to the retained loan, establishing a new carrying balance. The recorded discount is accreted to earnings on a level yield basis. U.S. government guaranteed loans are generally sold with servicing retained. Loans transferred to loans held for sale are carried at the lower of cost or fair value, less estimated costs to sell. At the time of transfer, write‑downs are recorded as charge‑offs, establishing a new cost basis. Any subsequent adjustments are determined on an individual loan basis and are recognized as a charge to non‑interest income. Sales proceeds received that are in excess of the new cost basis within 90 days are recorded to the allowance for loan and lease losses, up to the amount previously charged off. Any remaining proceeds are recorded as a gain on sale and included in non‑interest income. Sales proceeds that are less than the new cost basis upon transfer and are received within 90 days of classifying the loans as held for sale are recorded as a charge‑off to the allowance for loan and lease losses. Any proceeds received after 90 days of classifying the loans as held for sale are recorded as a gain or loss on sale and included in other non‑interest income. Loans held for sale that have not yet settled as of year-end are classified as due-from counterparty on the Consolidated Statements of Financial Condition.
Originated loans	Originated loans —Originated loans are stated at the amount of unpaid principal outstanding, net of purchase premiums and discounts, and any deferred fees or costs. Net deferred fees, costs, discounts and premiums are recognized as yield adjustments over the contractual life of the loan. Interest on loans is calculated daily based on the principal amount outstanding. Originated loans are classified as impaired when, based on current information and events, it is probable that the Company will be unable to collect the scheduled payments of principal and interest when due, in accordance with the terms of the original loan agreement. The carrying value of impaired loans is based on the present value of expected future cash flows (discounted at each loan’s effective interest rate) or, for collateral dependent loans, at the fair value of the collateral less estimated selling costs. If the measurement of each impaired loan’s value is less than the recorded investment in the loan, impairment is recognized and the carrying value of the loan is adjusted in the allowance for loan and lease losses as a specific component provided or through a charge‑off of the impaired portion of the loan. Accrual of interest on impaired loans is discontinued when the loan is 90 days past due or when, in management’s opinion, the borrower may be unable to make payments as they become due. When the accrual of interest is discontinued, all unpaid accrued interest is reversed through interest income. Payments received during the time a loan is on non‑accrual status are applied to principal. Interest income is not recognized until the loan is returned to accrual status or after the principal balance is paid in full. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured as evidenced by agreed upon performance for a period of not less than six months.
Troubled debt restructuring	Troubled debt restructuring —A troubled debt restructuring (“TDR”) is a formal restructuring of a loan in which the Company, for economic or legal reasons related to the borrower’s financial difficulties, grants a concession to the borrower. The concessions may be granted in various forms, including providing a below‑market interest rate, reduction in the loan balance or accrued interest, extension of the maturity date, or a combination of these. Troubled debt restructurings are considered to be impaired loans and are subject to the Company’s impaired loan accounting policy. Acquired impaired loans are not subject to TDR accounting. The Company does not accrue interest on a TDR unless it believes collection of all principal and interest under the modified terms is reasonably assured. For a TDR to begin accruing interest, the borrower must demonstrate some level of past performance and the future capacity to perform under the modified terms. Generally, six months of consecutive payment performance under the restructured terms is required before a TDR is returned to accrual status.
Direct finance leases	Direct finance leases —The Company engages in leasing for small‑ticket equipment, software, machinery and ancillary supplies and services to customers under leases that qualify as direct financing leases for financial reporting. Certain leases qualify as operating leases for income tax purposes. Under the direct financing method of accounting, the minimum lease payments to be received under the lease contract, together with the estimated unguaranteed residual values of the related equipment, are recorded as lease receivables when the lease is signed and funded and the lease property is delivered to the customer. The excess of the minimum lease payments and residual values over the amount financed is recorded as unearned lease income. Unearned lease income is recognized over the term of the lease based on the effective yield interest method. Residual value is the estimated fair market value of the equipment on lease at lease termination. In estimating the equipment’s fair value at lease termination, the Company relies on historical experience by equipment type and manufacturer and, where available, valuations by independent appraisers, adjusted for known trends. The Company’s residual values are estimates for reasonableness; however, the amounts the Company will ultimately realize could differ from the estimated amounts. If the review of the residual value results in other‑than‑temporary impairment, the impairment is recognized in current period earnings. An upward adjustment of the estimated residual value is not recorded. The policies for delinquency and non‑accrual for direct finance leases are materially consistent with those described for all classes of loan receivables. The Company defers and amortizes certain initial direct costs over the contractual term of the lease as an adjustment to the yield. The unamortized direct costs are recorded as a reduction of unearned lease income.
Acquired impaired loans	Acquired impaired loans —Loans initially acquired with evidence of credit quality deterioration are accounted for under ASC Topic 310‑30, Accounting for Purchased Loans with Deteriorated Credit Quality (“ASC 310‑30”). These loans are recorded either on a pool or a loan‑by‑loan basis at their estimated fair value where applicable. The Company may aggregate loans into pools based on similar credit risks and predominant risk characteristics such as delinquency status and loan type. Management estimated the fair values of acquired impaired loans at the acquisition date based on estimated future cash flows. The excess of cash flows expected to be collected over a loan’s carrying value is considered to be the accretable yield and is recognized as interest income over the estimated life of the loan or pool using the effective yield method. The acquisition date estimates of accretable yield may subsequently change due to changes in management’s estimates of timing and amounts of expected cash flows. The excess of the contractual amounts due over the cash flows expected to be collected is considered to be the non‑accretable difference. The non‑accretable difference represents the Company’s estimate of the credit losses expected to occur and is considered in determining the fair value of the loans. Reclassifications between accretable yield and non‑accretable difference represent changes in expected cash flows over the remaining estimated life of the loan or pool. Subsequent increases in expected cash flows over those expected at inception are adjusted through an increase to the accretable yield on a prospective basis. Any subsequent decreases in expected cash flows attributable to credit deterioration are recognized by recording an additional provision for loan losses. Once a pool of loans is assembled, the integrity of the pool is maintained. A loan can only be removed from a pool if either of the following conditions is met: (1) the Company sells, forecloses, or otherwise receives assets in satisfaction of the loan, or (2) the loan is written off. A refinancing or restructuring of a loan does not result in a removal of a loan from a pool. Loan sales are accounted for under ASC Topic 860, Transfers and Servicing (“ASC 860”), when control over the assets have been relinquished. See transfers of financial assets accounting policy.
Acquired non-impaired loans and leases	Acquired non‑impaired loans and leases —Acquired non‑impaired loans and leases are accounted for under ASC Subtopic 310‑20, Receivables Nonrefundable Fees and Other Costs (“ASC 310‑20”). These loans and leases were individually recorded at fair value at the time of acquisition. Any previously recognized allowance for loan and lease losses and unearned fees or discounts are not carried over and recognized at the date of acquisition. The component of fair value representing an adjustment to an asset’s outstanding principal balance is accreted or amortized over the life of the related asset as a yield adjustment. The balance of the asset is then evaluated periodically pursuant to the Company’s allowance for loan and lease loss accounting policy and any adjustment required for credit risk is recorded within the allowance for loan and lease losses. Upon reaching the maturity date, all acquired non-impaired loan premium or discount is fully amortized or accreted. If the loan is re-underwritten and renewed, it is internally reclassified as an originated loan. The loan is then evaluated periodically pursuant to the Company’s allowance for loan and lease loss accounting without any consideration of the acquisition premium or discount.
Allowance for loan and lease losses and reserve for unfunded commitments	Allowance for loan and lease losses —The allowance for loan and lease losses is maintained at a level management believes is appropriate to provide for probable loan and lease losses as of the dates of the Consolidated Statements of Financial Condition. The allowance for loan and lease losses is increased by a provision for loans and lease losses and decreased by charge‑offs, net of recoveries. Loan and lease losses are charged against the allowance for loan and lease losses when management believes the uncollectibility of a loan or lease balance is confirmed. Subsequent recoveries, if any, are credited to the allowance for loan and lease losses. The allowance for loan and lease losses is based on management’s evaluation of the loan and lease portfolio giving consideration to the nature and volume of the portfolio, the value of the underlying collateral, overall portfolio quality, review of specific problem loans or leases, and prevailing economic conditions that may affect the borrower’s ability to pay. While management uses the best information available to make its evaluation, future adjustments to the allowance for loan and lease losses may be necessary if there are significant changes in economic condition. The allowance for loan and lease losses consists of general and specific components. Allocations of the allowance for loan and lease losses not attributable to acquired impaired loans may be made for specific loans and leases, but the entire allowance is available for any loan and lease that, in management’s judgement, should be charged off. The general component covers loans and leases that are collectively evaluated for impairment. Larger groups of smaller balance homogeneous loans, such as consumer and residential real estate loans, and leases are collectively evaluated for impairment, and accordingly, they are not included in the separately identified impairment disclosures. The general component is based on a trailing 12‑quarter weighted average loss rate for each loan category based on the Company’s historical losses and its peer group and adjusted for qualitative and other economic factors. These factors include (1) changes in lending policies and procedures, including changes in underwriting standards and collections, charge‑off and recovery practices; (2) changes in international, national, regional and local conditions; (3) changes in the nature and volume of the portfolio and terms of the loans and leases; (4) changes in experience, depth and ability of lending management and other relevant staff; (5) changes in the volume and severity of past due loans and leases; (6) changes in the quality of the Company’s loan review system; (7) changes in the value of the underlying collateral for collateral dependent loans and leases; (8) existence and effect of any concentrations of credit and changes in the levels of such concentrations; and (9) the effect of other external factors (i.e., competition, legal and regulatory requirements) on the level of estimated credit losses. Based upon management’s judgement of other factors that fall outside of the predefined qualitative or historical loss rates, the allowance for loan and lease losses may include an unallocated component not included in these predefined factors. The specific component relates to loans that are risk‑rated substandard or worse, and based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Factors considered by management in determining the impairment include payment status, collateral value, strength of guarantor, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired and are reviewed on a case‑by‑case basis. TDRs are individually evaluated for impairment and are measured at the present value of estimated future cash flows using the loan’s effective rate at origination. If a TDR is considered to be a collateral dependent loan, the loan is reported at the fair value of the collateral, less estimated costs to sell. The allowance for loan losses also includes amounts representing decreases in expected cash flows attributable to credit deterioration of acquired impaired loans. The evaluation is inherently subjective, as it requires estimates that are susceptible to significant revision as more information becomes available. The factors supporting the allowance for loan and lease losses do not diminish the fact that the entire allowance for loan and lease losses not attributable to acquired impaired loans is available to absorb losses in the loan and lease portfolios and related commitment portfolio, respectively. The allowance for loan and lease losses is subject to review by regulatory agencies during examinations and may require us to recognize adjustments to the allowance for loan and lease losses.
Servicing assets	Servicing assets —Servicing assets are recognized separately when they are acquired through sales of loans. When loans are sold with servicing rights retained, servicing assets are recorded at fair value in accordance with ASC 860. Fair value is based on market prices for comparable servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. Sales of U.S. government guaranteed loans are executed on a servicing retained basis. The standard SBA loan sale agreement is structured to provide the Company with a servicing spread paid from a portion of the interest cash flow of the loan. SBA regulations require the Company to retain a portion of the cash flow from the interest payments received for a sold loan. The USDA loan sale agreements are not standardized with respect to servicing. Note 1—Business and Summary of Significant Accounting Policies (continued) Servicing fee income, which is reported on the Consolidated Statements of Operations as loan servicing revenue, is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal. Late fees and ancillary fees related to loan servicing are not material. The Company has elected the fair value measurement method and measures servicing rights at fair value at each reporting date and reports changes in fair value of servicing assets in earnings in the period in which the changes occur, and are recorded as loan servicing asset revaluation on the Consolidated Statements of Operations. The fair value of servicing rights is highly sensitive to changes in underlying assumptions. Changes in the prepayment speed and discount rate assumptions have the most significant impact on the fair value of servicing rights.
Concentrations of credit risk	Concentrations of credit risk —Most of the Company’s business activity is concentrated with customers located within its principal market areas, with the exception of government guaranteed loans and leasing activities. The Company originates commercial real estate, construction, land development and other land, commercial and industrial, residential real estate, installment and other loans, and leases. Generally, loans are secured by accounts receivable, inventory, deposit accounts, personal property or real estate. Rights to collateral vary and are legally documented to the extent practicable. The Company has a concentration in commercial real estate loans and the ability of borrowers to honor these and other contracts is dependent upon the real estate and general economic conditions within their geographic market.
Transfers of financial assets	Transfers of financial assets —Transfers of financial assets are accounted for as sales when control over the assets has been relinquished. The Company has assessed that partial sales of financial assets meet the definition of participating interest. Control over transferred assets is deemed to be surrendered when the assets have been isolated from the Company and the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets. Gains or losses are recognized in the period of sale upon derecognition of the asset.
Premises and equipment	Premises and equipment —Premises and equipment acquired through a business combination are initially stated at the acquisition date fair value less accumulated depreciation. All other premises and equipment are stated at cost less accumulated depreciation. Depreciation on premises and equipment is recognized on a straight‑line basis over their estimated useful lives ranging from three to 39 years. Land is also carried at its fair value following a business combination and is not subject to depreciation. Leasehold improvements are amortized over the shorter of the life of the related asset or expected term of the underlying lease. Gains and losses on the dispositions of premises and equipment are included in non‑interest income. Expenditures for new premises, equipment and major betterments are capitalized. Normal costs of maintenance and repairs are expensed as incurred. Long‑lived depreciable assets are evaluated periodically for impairment when events or changes in circumstances indicate the carrying amounts may be not recoverable. Impairment exists when the undiscounted expected future cash flows of a long‑lived asset are less than its carrying value. In that event, the Company recognizes a loss for the difference between the carrying amount and the estimated fair value of the asset based on a quoted market price, if applicable, or a discounted cash flow analysis. Impairment losses are recorded in non‑interest expense.
Assets held for sale	Assets held for sale —Assets held for sale consist of former branch locations and real estate previously purchased for expansion. Assets are considered held for sale when management has approved to sell the assets following a branch closure or other events. The properties are being actively marketed and transferred to assets held for sale based at the lower of its carrying value or its fair value, less estimated costs to sell. Assets held for sale are evaluated periodically for impairment, with any impairment losses recorded in non-interest expense.
Other real estate owned	Other real estate owned —Other real estate owned (“OREO”) includes real estate assets that have been acquired through, or in lieu of, loan foreclosure or repossession and are to be sold. OREO assets are initially recorded at fair value, less estimated costs to sell, of the collateral of the loan, on the date of foreclosure or repossession, establishing a new cost basis. Adjustments that reduce loan balances to fair value at the time of foreclosure or repossession are recognized as charge‑offs in the allowance for loan and lease losses. Positive adjustments, if any, at the time of foreclosure or repossession are recognized in non‑interest expense. After foreclosure or repossession, management periodically obtains new valuations, and real estate or other assets may be adjusted to a lower carrying amount, determined by the fair value of the asset, less estimated costs to sell. Any subsequent write‑downs are recorded as a decrease in the asset and charged against other real estate owned valuation adjustments. Operating expenses of such properties, net of related income, and gains and losses on their disposition are included in non‑interest expense. Gains on internally financed other real estate owned sales are accounted for in accordance with the methods stated in ASC Topic 360‑20, Real Estate Sales (“ASC 360‑20”). Any losses on the sales of other real estate owned properties are recognized immediately.
Goodwill	Goodwill —The excess of the cost of our recapitalization and acquisitions over the fair value of the net assets acquired, including core deposit intangible, consists of goodwill. Goodwill is not amortized but is periodically evaluated for impairment under the provisions of ASC Topic 350, Intangibles—Goodwill and Other (“ASC 350”). Note 1—Business and Summary of Significant Accounting Policies (continued) The Company revised the previously issued 2017 consolidated financial statements to properly record goodwill and a deferred tax liability associated with the bad debt recapture assumed from the acquisition of Ridgestone Financial Services, Inc. and its subsidiaries on October 14, 2016. The fair value adjustments associated with this transaction were finalized during the fourth quarter of 2017. Management evaluated the effect of the error to the previously issued consolidated financial statements in accordance with Securities and Exchange Commission Staff Accounting Bulletin No. 99 and No. 108, and, based upon quantitative and qualitative factors, determined that the error was not material to our previously issued consolidated financial statements. Accordingly, the Company has reflected the change in 2017 and revised our Consolidated Statements of Financial Condition disclosed herein. Consolidated financial statements for periods not presented herein will be revised, as applicable, as they are included in future filings. All financial information presented in the accompanying notes to these consolidated financial statements was revised to reflect the change. The change did not affect net income or stockholders’ equity for the periods impacted. Impairment testing is performed using either a qualitative or quantitative approach at the reporting unit level. All of the Company’s goodwill is allocated to the Bank, which is the Company’s only applicable reporting unit for the purposes of testing goodwill for impairment. The Company has selected November 30 as the date it performs the annual goodwill impairment test. Additionally, the Company performs a goodwill impairment evaluation on an interim basis when events or circumstances indicate impairment potentially exists. The Company performs impairment testing using a qualitative approach to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. A significant amount of judgment is involved in determining if an indicator of impairment has occurred. Such indicators may include, among others, a material change in the estimated value of the Company based on current market multiples common for community banks of similar size and operations; a significant change in our stock price or market capitalization; a significant adverse change in legal factors or in the business climate; adverse action or assessment by a regulator; and unanticipated competition. If the assessment of qualitative factors indicates that it is not more likely than not that impairment exists, an impairment loss is recognized if the carrying amount of the reporting unit goodwill exceeds its fair value. Based on an annual analysis completed as of November 30, 2018, 2017 and 2016, the Company did not recognize impairment losses during the year ended December 31, 2018, 2017 and 2016.
Other intangible assets	Other intangible assets —Other intangible assets primarily consist of core deposit intangible assets. Other intangible assets with definite useful lives are amortized to their estimated residual values over their respective estimated useful lives, and are also reviewed periodically for impairment. Amortization of other intangible assets is included in other non‑interest expense. Core deposit intangibles were recognized apart from goodwill based on market valuations. Core deposit intangibles are amortized over nine-ten years. In valuing core deposit intangibles, the Company considered variables such as deposit servicing costs, attrition rates and market discount rates. If the estimated fair value is less than the carrying value, the core deposit intangible would be reduced to such value and the impairment recognized as non‑interest expense. The Company did not recognize impairment on its core deposit intangibles for the years ended December 31, 2018, 2017 and 2016.
Customer relationship intangibles	Customer relationship intangibles —Customer relationship intangibles relate to the value of existing trust and wealth management relationships and are amortized over 12 years. In valuing the relationship intangibles, the Company considered variables such as attrition, investment appreciation, and discount rates. The Company did not recognize impairment on its customer relationship intangibles for the years ended December 31, 2018
Bank-owned life insurance	Bank‑owned life insurance —The Company holds life insurance policies that provide protection against the adverse financial effects that could result from the death of current and former employees, and provide tax deferred income. Although the lives of individual current or former management‑level employees are insured, the Company is the owner and is split beneficiary on certain policies. The Company is exposed to credit risk to the extent an insurance company is unable to fulfill its financial obligations under a policy. Split‑dollar life insurance is recorded as an asset at cash surrender value. Increases in the cash value of these policies, as well as insurance proceeds received, are recorded in other non‑interest income and are not subject to income tax.
Income taxes	Income taxes —The Company uses the asset and liability method to account for income taxes. The objective of the asset and liability method is to establish deferred tax assets and liabilities for the temporary differences between the financial reporting basis and the income tax basis of the Company’s assets and liabilities at enacted tax rates expected to be in effect when such amounts are realized or settled. The Company’s annual tax rate is based on its income, statutory tax rates and available tax planning opportunities. Deferred tax assets and liabilities are adjusted through the tax provision for the effects of changes in tax laws and rates on the date of enactment. Tax laws are complex and subject to different interpretations by the taxpayer and respective governmental taxing authorities. Significant judgment is required in determining tax expense and in evaluating tax positions, including evaluating uncertainties. Note 1—Business and Summary of Significant Accounting Policies (continued) Deferred income tax assets represent amounts available to reduce income taxes payable on taxable income in future years. Such assets arise because of temporary differences between the financial reporting and tax bases of assets and liabilities, as well as from net operating loss carryforwards. The Company reviews its deferred tax positions periodically and adjusts the balances as new information becomes available. The Company evaluates the recoverability of these future tax deductions by assessing the adequacy of future expected taxable income from all sources, including reversal of taxable temporary differences, forecasted operating earnings and available tax planning strategies. The Company uses short and long‑range business forecasts to provide additional information for its evaluation of the recoverability of deferred tax assets. As of December 31, 2018 and 2017, the Company had no material uncertain tax positions. The Company elects to treat interest and penalties recognized for the underpayment of income taxes as income tax expense. However, interest and penalties imposed by taxing authorities on issues specifically addressed in ASC Topic 740 will be taken out of the tax reserves up to the amount allocated to interest and penalties. The amount of interest and penalties exceeding the amount allocated in the tax reserves will be treated as income tax expense. A deferred tax valuation allowance is established to reduce the net carrying amount of deferred tax assets if it is determined to be more likely than not that all or some of the deferred tax asset will not be realized. At December 31, 2018 and 2017, the Company did not record a deferred tax valuation allowance. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment.
Derivative financial instruments and hedging activities	Derivative financial instruments and hedging activities —The Company enters into derivative transactions principally to protect against the risk of adverse price or interest rate movements on the future cash flows of certain assets. ASC Topic 815, Derivatives and Hedging (“ASC 815”), establishes accounting and reporting standards requiring that every derivative instrument be recorded in the Consolidated Statements of Financial Condition as either an asset or liability measured at its fair value. The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and on the type of hedging relationship. On the date the derivative contract is entered into, the Company designates the derivative as a fair value hedge, a cash flow hedge, or a non‑designated derivative. Fair value hedges are accounted for by recording the changes in the fair value of the derivative instrument and the changes in the fair value related to the risk being hedged of the hedged asset or liability on the Consolidated Statements of Financial Condition with corresponding offsets recorded in the Consolidated Statements of Operations. The adjustment to the hedged asset or liability is included in the basis of the hedged item, while the fair value of the derivative is recorded as an asset or liability. Cash flow hedges are accounted for by recording the changes in the fair value of the effective portion of the derivative instrument in other comprehensive income (loss) and are recognized in the Consolidated Statements of Operations when the hedged item affects earnings. Derivative instruments that are not designated as hedges according to accounting guidance are reported in the Consolidated Statements of Financial Condition at fair value and the changes in fair value are recognized as non‑interest income during the period of the change. The Company formally documents the relationship between a derivative instrument and a hedged asset or liability, as well as its risk management objective and strategy for undertaking various hedge transactions. The Company also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the derivatives that are used in the hedging transactions are highly effective in offsetting changes in fair values or cash flows of hedged items.
Comprehensive income (loss)	Comprehensive income —Recognized revenue, expenses, gains and losses are included in net income. Certain changes in assets and liabilities, such as unrealized gains and losses on available‑for‑sale securities and adjustments related to cash flow hedges, are reported on a cumulative basis, net of tax effects, as a separate component of equity on the Consolidated Statements of Financial Condition. Changes in such items, along with net income, are components of comprehensive income.
Advertising expense	Advertising expense —Advertising costs are expensed as incurred.
Off-balance sheet instruments	Off‑balance sheet instruments —In the ordinary course of business, the Company has entered into off‑balance sheet arrangements consisting of commitments to extend credit, commercial letters of credit, and standby letters of credit. The face amount for these items represents the exposure to loss, before considering customer collateral or ability to repay. Such financial instruments are recorded in the consolidated financial statements when they are funded or when the related fees are incurred or received. Reserve for unfunded commitments —A reserve for unfunded commitments is maintained at a level that, in the opinion of management, is sufficient to absorb probable losses associated with the Company’s commitment to lend funds under existing agreements, such as letters or lines of credit. Management determines the appropriate reserve for unfunded commitments based upon reviews of individual credit facilities, current economic conditions, the risk characteristics of the various categories of commitments, and other relevant factors. The reserve for unfunded commitments is based on estimates, and ultimate losses may vary from the current estimates. These estimates are evaluated on a quarterly basis and, as adjustments become necessary, they are recognized in earnings in the provision for unfunded commitments in the periods in which they become known.
Segment reporting	Segment reporting —The Company has one reportable segment. The Company’s chief operating decision maker evaluates the operations of the Company using consolidated information for purposes of allocating resources and assessing performance. Therefore, segments disclosures are not required.
Loss contingencies	Loss contingencies —Loss contingencies, including claims and legal actions arising in the ordinary course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. Management does not believe there are any such matters that will have a material effect on the Consolidated Financial Statements for the years ended December 31, 2018 and 2017.
Share-based compensation	Share‑based compensation —The Company accounts for share‑based compensation in accordance with ASC Topic 718, Compensation—Stock Compensation (“ASC 718”), which requires compensation cost relating to share‑based compensation transactions be recognized in the Consolidated Statements of Operations, based generally upon the grant‑date fair value of the share‑based compensation granted by the Company. Share‑based awards may have service, market or performance conditions. Refer to Note 19—Share-Based Compensation for additional information.
Earnings per share	Earnings per share — Earnings per common share (“EPS”) is computed under the two-class method. Pursuant to the two-class method, non-vested stock-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents are participating securities and are included in the computation of EPS. The two-class method is an earnings allocation formula that determines earnings per share for each class of common stock and participating security according to dividends declared (or accumulated) and participation rights in undistributed earnings. Application of the two-class method resulted in the equivalent earnings per share to the treasury method. Basic earnings per common share is computed by dividing net earnings allocated to common shareholders by the weighted-average number of common shares outstanding during the applicable period, excluding outstanding participating securities. Diluted earnings per common share is computed using the weighted-average number of shares determined for the basic earnings per common share computation plus the dilutive effect of stock compensation and warrants for common stock using the treasury stock method.
Fair value of assets and liabilities	Fair value of assets and liabilities —Fair value is defined as the price that would be received to sell an asset, or paid to transfer a liability, including respective accrued interest balances, in an orderly transaction between market participants at the measurement date. The Company determines fair value based upon quoted prices when available or through the use of alternative approaches, such as matrix or model pricing, when market quotes are not readily accessible or available. The valuation techniques used are based on observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions.
Reclassifications	Reclassifications —Some items in prior years consolidated financial statements were reclassified to conform to the current presentation. Reclassifications had no effect on prior years’ net income or stockholders’ equity.
Recently Issued Accounting Pronouncements	The following reflect recent accounting pronouncements that have been adopted or are pending adoption by the Company. As the Company qualifies as an emerging growth company and has elected the extended transition period for complying with new or revised accounting pronouncements, it is not subject to new or revised accounting standards applicable to public companies during the extended transition period. The accounting pronouncements pending adoption below reflect effective dates for the Company as an emerging growth company with the extended transition period. Revenue from Contracts with Customers —In May 2014, FASB issued Accounting Standards Update (“ASU”) No. 2014‑09, deferred by ASU No. 2015‑14 and clarifying standards, , which creates Topics 606 and 610 and supersedes Topic 605, Revenue Recognition. The core principle of Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In April 2016, FASB issued ASU No. 2016-10, . The amendments in this ASU clarify the following two aspects of Topic 606: (1) identifying performance obligations and (2) licensing implementation guidance, while retaining the related principles for those areas. In May 2016, FASB issued ASU No. 2016-12, , amending ASC Topic 606, . The amendments in this ASU affect only several narrow aspects of Topic 606. In November 2017, FASB issued ASU No. 2017-14, amending ASC Topic 606, . The ASU amends the codification to incorporate additional previously issued guidance from the SEC. The SEC issued SAB 116 to bring existing SEC staff guidance into conformity with the FASB’s adoption of and amendments to ASC Topic 606. In general, the new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. As a financial institution, the Company’s largest component of revenue is interest income, which is excluded from the scope of this ASU, and non-interest income. The new authoritative guidance was initially effective for reporting periods after January 1, 2017 but was deferred to January 1, 2018. Given our emerging growth status, the Company adopted this new guidance on January 1, 2019 and does not expect it to have a significant impact on the Company’s Consolidated Statements of Operations or Financial condition other than potential reclassification of certain non-interest expenses to non-interest income and additional footnote disclosures. Recognition and Measurement of Financial Assets and Financial Liabilities —In January 2016, FASB issued ASU No. 2016‑01, . The amendments in this ASU require equity securities to be measured at fair value with changes in the fair value recognized through net income. The amendments allow equity investments that do not have readily determinable fair values to be remeasured at fair value under certain circumstances and require enhanced disclosures about those investments. The amendments simplify the impairment assessment of equity investments without readily determinable fair values. The amendments also eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The amendments require entities to adjust fair value disclosures for financial instruments to be reflected at an exit price. The amendments in this ASU require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument‑specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. This amendment excludes from net income gains or losses that the entity may not realize because those financial liabilities are not usually transferred or settled at their fair values before maturity. The amendments in this ASU require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or in the accompanying notes to the financial statements. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company adopted the provisions of ASU No. 2016-01 as of January 1, 2019. At December 31, 2018, the Company held $6.6 million of available-for-sale equity investment securities. The provisions of ASU No. 2016-01 require changes in the value of equity securities to be recognized in the Consolidated Statements of Operations which could result in additional volatility in non-interest income. Note 2—Recently Issued Accounting Pronouncements (continued) Leases (Topic 842) —In February 2016, FASB issued ASU No. 2016‑02, . The amendments in this ASU require lessees to recognize the following for all leases (with the exception of short‑term) at the commencement date; a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right‑of‑use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendments in this ASU leave lessor accounting largely unchanged, although certain targeted improvements were made to align lessor accounting with the lessee accounting model. This ASU simplifies the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off‑balance sheet financing. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales‑type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is evaluating the new guidance and its impact on the Company’s Consolidated Statements of Operations and Consolidated Statements of Financial Condition. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company expects an increase in assets and liabilities as a result of recognizing additional right-to-use assets and lease liabilities under lease contracts in which the Company is lessee. Derivatives and Hedging (Topic 815) —In August 2017, FASB issued ASU No. 2017-12, . The amendments in this ASU better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The new authoritative guidance will be effective for reporting periods after January 1, 2019. Adoption of this ASU is not expected to have a material impact on the Company’s Consolidated Financial Statements. Compensation—Stock Compensation (Topic 718) —In May 2017, the FASB issued ASU 2017-09, . The amendments in the ASU provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. An entity should account for the effects of a modification unless all of the following are met: (1) the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) or the modified award is the same as the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification, (2) the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified, (3) the classification of the modified award is an equity instrument or liability instrument is the same as the classification of the original award immediately before the original award is modified. The amendments are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period, for reporting periods for which financial statements have not yet been issued. The amendments should be applied prospectively to an award modified on or after the adoption date. The Company adopted the provisions of ASU No. 2017-09 on January 1, 2019, which did not have a material impact on the Company’s Consolidated Financial Statements. Note 2—Recently Issued Accounting Pronouncements (continued) Financial Instruments—Credit Losses (Topic 326) —In June 2016, FASB issued ASU No. 2016‑13, . Current GAAP requires an “incurred loss” methodology for recognizing credit losses that delays recognition until it is probable a loss has been incurred. The main objective of this ASU is to provide financial statement users with more decision‑useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this ASU replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The amendments in this ASU require a financial asset (or group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) to present the net carrying value at the amount expected to be collected on the financial asset. The measurement of expected credit losses will be based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The amendments in this ASU broaden the information that an entity must consider in developing its expected credit loss estimate for assets measured either collectively or individually. The use of forecasted information incorporates more timely information in the estimate of expected credit loss, which will be more decision useful to users of the financial statements. The amendments in this ASU will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2021. The Company is still evaluating the effects this ASU will have on the Company’s Consolidated Financial Statements. While the Company has not quantified the impact of this ASU, it does expect changing from the current incurred loss model to an expected loss model will result in an earlier recognition of losses. Statement of Cash Flows (Topic 230) —In August 2016, FASB issued ASU No. 2016‑15, . There is diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows under Topic 230 and other Topics. This ASU addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. Those eight issues are (1) debt prepayment or debt extinguishment costs, (2) settlement of zero‑coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, (3) contingent consideration payments made after a business combination, (4) proceeds from the settlement of insurance claims, (5) proceeds from the settlement of corporate‑owned life insurance policies, including bank‑owned life insurance policies, (6) distributions received from equity method investees, (7) beneficial interests in securitization transactions, and (8) separately identifiable cash flows and application of the predominance principle. Current GAAP either is unclear or does not include specific guidance on these eight cash flow classification issues. These amendments provide guidance for each of the eight issues, thereby reducing current and potential future diversity in practice. The amendments in this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2019. The Company adopted the provisions of ASU No. 2016-15 on January 1, 2019, which did not have a material impact on the Company’s Consolidated Financial Statements. In November 2016, the FASB issued ASU No. 2016‑18, Statement of Cash Flows (Topic 230), Restricted Cash The Company adopted Business Combinations (Topic 805) —In January 2017, the FASB issued ASU No. 2017‑01, . The guidance clarifies the definition of a business to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. This guidance is effective for annual and interim periods beginning after December 15, 2017. Early adoption is permitted. The Company adopted the provisions of ASU No. 2017-01 on January 1, 2019, which did not have a material impact on the Company’s Consolidated Financial Statements. Note 2—Recently Issued Accounting Pronouncements (continued) Intangibles—Goodwill and Other (Topic 350) —In January 2017, FASB issued ASU No. 2017‑04, . The amendments in this ASU are intended to reduce the cost and complexity of the goodwill impairment test by eliminating step two from the impairment test. The amendments modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. Under the amendments in this ASU, an entity will perform its annual, or interim, goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount. An impairment charge should be recognized for the amount which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The amendments in this ASU are effective for the Company’s annual or any interim goodwill impairment test in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company early adopted these amendments in 2017 which did not have a material impact on the Company’s Consolidated Financial Statements. Other Income (Subtopic 610‑20) —In February 2017, the FASB issued ASU No. 2017‑05, . This ASU will clarify the scope of Subtopic 610‑20 and add guidance for partial sales of nonfinancial assets. The amendments should be applied either on retrospectively to each period presented or with a modified retrospective approach. The amendment is effective for annual periods beginning after December 15, 2018. The Company does not expect a material impact of this ASU on the Company’s Consolidated Financial Statements. Nonrefundable Fees and Other Costs (Subtopic 310‑20) —In March 2017, FASB issued ASU No. 2017‑08, . The amendments in the ASU shorten the amortization period for certain callable debt securities held at a premium at the earliest call date. Under current GAAP, the Company amortizes the premium as an adjustment of yield over the contractual life of the instrument. As a result, upon exercise of a call on a callable debt security held at a premium, the unamortized premium is charged to earnings. The ASU shortens the amortization period for certain callable debt securities held at a premium and requires the premium to be amortized to the earliest call date. However, the amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The amendments are effective for annual periods beginning after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Early adoption is permitted. The Company is required to apply the amendments on a modified retrospective basis through a cumulative‑effect adjustment directly to retained earnings as of the beginning of the period of adoption. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company is currently evaluating the provisions of ASU No. 2017‑08 to determine the potential impact the new standard will have on the Company’s Consolidated Financial Statements. Income Statement—Reporting Comprehensive Income (Topic 220) —In February 2018, FASB issued ASU No. 2018-02, . The ASU helps organizations address certain stranded income tax effects in accumulated other comprehensive income (AOCI) resulting from the Tax Cuts and Jobs Act. The ASU provides reporting entities with an option to reclassify stranded tax effects within AOCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The ASU requires reporting entities to disclose: a description of the accounting policy for releasing income tax effects from AOCI; whether they elect to reclassify the stranded income tax effects from the Tax Cuts and Jobs Act; and information about the other income tax effects that are reclassified. The amendments affect any organization that is required to apply the provisions of Topic 220, , and has items of other comprehensive income for which the related tax effects are presented in other comprehensive income as required by GAAP. The amendments are effective for annual periods beginning after December 15, 2018, and interim periods within those fiscal years. The Company early adopted the new guidance on January 1, 2018. The adoption did not impact the Company’s Statements of Operations, and resulted in a reclassification of $763,000 from accumulated other comprehensive income (loss) to retained earnings. Note 2—Recently Issued Accounting Pronouncements (continued) Fair Value Measurement (Topic 820) —In August 2018, FASB issued ASU No. 2018-13, — . The amendments in this ASU modify the disclosure requirements on fair value measurements in Topic 820. The amendments remove the disclosure requirements for the amount and reasons for transfers between Level 1 and Level 2 securities of the fair value hierarchy, the policy for timing of transfers between levels, and the valuation processes for Level 3 fair value measurement. The amendments modify the disclosure requirements as follows: in lieu of a rollforward for Level 3 fair value measurements, a nonpublic entity is required to disclose transfers into and out of Level 3 of the fair value hierarchy and purchases and issues of Level 3 assets and liabilities; for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s assets and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly; and clarify that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. The amendments add the following disclosure requirements: the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. This guidance is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted. Assuming the Company remains an emerging growth company, the new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company early adopted these amendments in 2018, which did not have a material impact on the Company’s Consolidated Financial Statements.

Acquisition of a Business (Tabl

Acquisition of a Business (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Summary of Estimates of fair Values of Assets and Liabilities Assumed as of Acquisition Date	The following table presents a summary of the estimated fair values of assets acquired and liabilities assumed as of the acquisition date: Assets Cash and cash equivalents $ 47,378 Securities available-for-sale 128,063 Restricted stock 1,360 Loans 916,011 Premises and equipment 15,890 Other intangible assets 22,276 Deferred tax assets, net 2,302 Other assets 8,845 Total assets acquired $ 1,142,125 Liabilities Deposits $ 1,022,268 Junior subordinated debentures 8,497 Accrued expenses and other liabilities 5,844 Total liabilities assumed 1,036,609 Net assets acquired $ 105,516 Consideration paid Common stock (6,682,850 shares issued at $21.62 per share) $ 144,483 Outstanding stock options converted to Byline stock options 7,644 Cash paid 27,004 Total consideration paid 179,131 Goodwill $ 73,615
Summary of Acquired Non-Impaired Loans as of Acquisition Date	The following table presents the acquired non-impaired loans as of the acquisition date: Fair value $ 890,986 Gross contractual amounts receivable 1,057,374 Estimate of contractual cash flows not expected to be collected (1) 36,544 Estimate of contractual cash flows expected to be collected 1,020,830 (1) Includes interest payments not expected to be collected due to loan prepayments as well as principal and interest payments not expected to be collected due to customer default.
Summary of Pro Forma Information for Results of Operations	The following table provides the pro forma information for the results of operations for the years ended December 31, 2018 and 2017, as if the acquisition had occurred on January 1, 2017. The pro forma results combine the historical results of First Evanston into the Company’s Consolidated Statements of Operations, including the impact of certain acquisition accounting adjustments, which includes loan discount accretion, intangible assets amortization, deposit premium accretion and borrowing net discount amortization. The pro forma results have been prepared for comparative purposes only and are not necessarily indicative of the results that would have been obtained had the acquisition actually occurred on January 1, 2017. No assumptions have been applied to the pro forma results of operations regarding possible revenue enhancements, provision for credit losses, expense efficiencies or asset dispositions. The acquisition-related expenses that have been recognized are included in net income in the following table. Years ended December 31, 2018 2017 Total revenues (net interest income and non-interest income) $ 251,393 $ 225,446 Net income $ 55,329 $ 34,317 Earnings per share—basic $ 1.51 $ 0.68 Earnings per share—diluted $ 1.48 $ 0.67

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Summary of Amortized Cost and Fair Values of Securities Available-for-sale and Held to Maturity	The following tables summarize the amortized cost and fair values of securities available-for-sale and securities held-to-maturity at December 31, 2018 and 2017 and the corresponding amounts of gross unrealized gains and losses: 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale U.S. Treasury Notes $ 52,775 $ 81 $ (189 ) $ 52,667 U.S. Government agencies 187,427 367 (1,296 ) 186,498 Obligations of states, municipalities, and political subdivisions 60,686 133 (586 ) 60,233 Residential mortgage-backed securities Agency 284,038 101 (11,176 ) 272,963 Non-agency 84,998 199 (1,576 ) 83,621 Commercial mortgage-backed securities Agency 93,543 55 (3,164 ) 90,434 Non-agency 31,458 — (1,000 ) 30,458 Corporate securities 34,716 67 (610 ) 34,173 Other securities 4,613 2,127 (131 ) 6,609 Total $ 834,254 $ 3,130 $ (19,728 ) $ 817,656 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Held-to-maturity Obligations of states, municipalities, and political subdivisions $ 23,835 $ 40 $ (210 ) $ 23,665 Residential mortgage-backed securities Agency 40,082 93 (531 ) 39,644 Non-agency 35,349 — (919 ) 34,430 Total $ 99,266 $ 133 $ (1,660 ) $ 97,739 Note 4—Securities (continued) 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale U.S. Treasury Notes $ 14,999 $ — $ (136 ) $ 14,863 U.S. Government agencies 54,248 — (1,290 ) 52,958 Obligations of states, municipalities, and political subdivisions 33,405 100 (335 ) 33,170 Residential mortgage-backed securities Agency 315,103 — (7,646 ) 307,457 Non-agency 39,485 104 (75 ) 39,514 Commercial mortgage-backed securities Agency 70,964 45 (1,966 ) 69,043 Non-agency 31,763 — (792 ) 30,971 Corporate securities 29,573 507 (104 ) 29,976 Other securities 3,627 1,730 (73 ) 5,284 Total $ 593,167 $ 2,486 $ (12,417 ) $ 583,236 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Held-to-maturity Obligations of states, municipalities, and political subdivisions $ 24,030 $ 197 $ (82 ) $ 24,145 Residential mortgage-backed securities Agency 53,731 79 (203 ) 53,607 Non-agency 39,402 174 (51 ) 39,525 Total $ 117,163 $ 450 $ (336 ) $ 117,277
Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Available-for-sale and Held to Maturity	Gross unrealized losses and fair values, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2018 and 2017 are summarized as follows: Less than 12 Months 12 Months or Longer Total 2018 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale U.S. Treasury Notes 18 $ 23,835 $ (52 ) $ 9,865 $ (137 ) $ 33,700 $ (189 ) U.S. Government agencies 25 43,487 (80 ) 50,101 (1,216 ) 93,588 (1,296 ) Obligations of states, municipalities and political subdivisions 56 13,926 (97 ) 18,563 (489 ) 32,489 (586 ) Residential mortgage-backed securities Agency 42 4,288 (45 ) 254,121 (11,131 ) 258,409 (11,176 ) Non-agency 8 59,107 (1,378 ) 4,009 (198 ) 63,116 (1,576 ) Commercial mortgage-backed securities Agency 9 21,356 (447 ) 52,640 (2,717 ) 73,996 (3,164 ) Non-agency 5 — — 30,458 (1,000 ) 30,458 (1,000 ) Corporate securities 15 25,762 (342 ) 4,642 (268 ) 30,404 (610 ) Other securities 1 — — 2,844 (131 ) 2,844 (131 ) Total 179 $ 191,761 $ (2,441 ) $ 427,243 $ (17,287 ) $ 619,004 $ (19,728 ) Note 4—Securities (continued) Less than 12 Months 12 Months or Longer Total 2018 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Held-to-maturity Obligations of states, municipalities, and political subdivisions 23 $ 8,127 $ (58 ) $ 8,792 $ (152 ) $ 16,919 $ (210 ) Residential mortgage-backed securities Agency 16 6,625 (150 ) 21,139 (381 ) 27,764 (531 ) Non-agency 7 21,499 (503 ) 12,931 (416 ) 34,430 (919 ) Total 46 $ 36,251 $ (711 ) $ 42,862 $ (949 ) $ 79,113 $ (1,660 ) Less than 12 Months 12 Months or Longer Total 2017 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale U.S. Treasury Notes 5 $ 4,998 $ (2 ) $ 9,865 $ (134 ) $ 14,863 $ (136 ) U.S. Government agencies 9 992 (7 ) 51,966 (1,283 ) 52,958 (1,290 ) Obligations of states, municipalities and political subdivisions 29 16,059 (137 ) 4,453 (198 ) 20,512 (335 ) Residential mortgage-backed securities Agency 41 15,441 (181 ) 292,016 (7,465 ) 307,457 (7,646 ) Non-agency 1 — — 4,565 (75 ) 4,565 (75 ) Commercial mortgage-backed securities Agency 7 — — 57,442 (1,966 ) 57,442 (1,966 ) Non-agency 5 — — 30,971 (792 ) 30,971 (792 ) Corporate securities 3 2,406 (80 ) 2,489 (24 ) 4,895 (104 ) Other securities 1 — — 1,921 (73 ) 1,921 (73 ) Total 101 $ 39,896 $ (407 ) $ 455,688 $ (12,010 ) $ 495,584 $ (12,417 ) Less than 12 Months 12 Months or Longer Total 2017 # of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Held-to-maturity Obligations of states, municipalities, and political subdivisions 12 $ 7,409 $ (38 ) $ 1,548 $ (44 ) $ 8,957 $ (82 ) Residential mortgage-backed securities Agency 13 24,344 (107 ) 7,935 (96 ) 32,279 (203 ) Non-agency 3 10,458 (10 ) 4,382 (41 ) 14,840 (51 ) Total 28 $ 42,211 $ (155 ) $ 13,865 $ (181 ) $ 56,076 $ (336 )
Summary of Proceeds From Sales of Securities Available-for-sale and Associated Gains and Losses	The proceeds from all sales and calls of securities were available-for-sale, and the associated gains and losses for the years ended December 31, 2018, 2017, and 2016 are listed below: 2018 2017 2016 Proceeds $ 5,134 $ 8 $ 534,418 Gross gains 164 8 3,358 Gross losses — — 131
Schedule of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity	At December 31, 2018, the amortized cost and fair value of debt securities are shown by contractual maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately. Amortized Cost Fair Value Available-for-sale Due in one year or less $ 70,830 $ 70,621 Due from one to five years 172,020 170,632 Due from five to ten years 75,017 74,725 Due after ten years 18,277 18,284 Mortgage-backed securities 494,037 477,476 Other securities with no defined maturity 4,073 5,918 Total $ 834,254 $ 817,656 Held-to-maturity Due from one to five years $ 5,966 $ 5,903 Due from five to ten years 10,075 10,019 Due after ten years 7,794 7,743 Mortgage-backed securities 75,431 74,074 Total $ 99,266 $ 97,739

Loans and Lease Receivables (Ta

Loans and Lease Receivables (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Outstanding Loan and Lease Receivables	Outstanding loan and lease receivables as of December 31, 2018 and 2017 were categorized as follows: 2018 2017 Commercial real estate $ 1,261,594 $ 891,971 Residential real estate 704,899 577,123 Construction, land development, and other land 186,258 105,996 Commercial and industrial 1,145,240 522,254 Installment and other 13,675 4,182 Lease financing receivables 187,797 174,165 Total loans and leases 3,499,463 2,275,691 Net unamortized deferred fees and costs (1,293 ) (1,720 ) Initial direct costs 3,456 3,521 Allowance for loan and lease losses (25,201 ) (16,706 ) Net loans and leases $ 3,476,425 $ 2,260,786 2018 2017 Lease financing receivables Net minimum lease payments $ 204,646 $ 188,986 Unguaranteed residual values 1,535 1,644 Unearned income (18,384 ) (16,465 ) Total lease financing receivables 187,797 174,165 Initial direct costs 3,456 3,521 Lease financial receivables before allowance for lease losses $ 191,253 $ 177,686
Summary of Minimum Annual Lease Payments for Lease Financing Receivables	The minimum annual lease payments for lease financing receivables as of December 31, 2018 are summarized as follows: Minimum Lease Payments 2019 $ 71,802 2020 58,646 2021 39,385 2022 23,990 2023 9,752 Thereafter 1,071 Total $ 204,646
Summary of Balances for Each Respective Loan and Lease Category	The following tables summarize the balances for each respective loan and lease category as of December 31, 2018 and 2017: 2018 Originated Acquired Impaired Acquired Non- Impaired Total Commercial real estate $ 652,234 $ 146,808 $ 462,565 $ 1,261,607 Residential real estate 466,309 113,934 124,659 704,902 Construction, land development, and other land 144,128 3,779 37,442 185,349 Commercial and industrial 803,508 12,617 328,672 1,144,797 Installment and other 11,718 404 1,596 13,718 Lease financing receivables 159,901 — 31,352 191,253 Total loans and leases $ 2,237,798 $ 277,542 $ 986,286 $ 3,501,626 2017 Originated Acquired Impaired Acquired Non- Impaired Total Commercial real estate $ 513,622 $ 166,712 $ 211,359 $ 891,693 Residential real estate 400,571 144,562 32,085 577,218 Construction, land development, and other land 97,638 5,946 1,845 105,429 Commercial and industrial 416,499 10,008 94,731 521,238 Installment and other 3,724 462 42 4,228 Lease financing receivables 141,329 — 36,357 177,686 Total loans and leases $ 1,573,383 $ 327,690 $ 376,419 $ 2,277,492
Schedule of Estimated Fair Value of Impaired Loans Acquired at Acquisition	The following table presents a reconciliation of the undiscounted contractual cash flows, non‑accretable difference, accretable yield, and fair value of acquired impaired loans as of the acquisition date of May 31, 2018: Undiscounted contractual cash flows $ 33,594 Undiscounted cash flows not expected to be collected (non-accretable difference) (5,003 ) Undiscounted cash flows expected to be collected 28,591 Accretable yield at acquisition (3,566 ) Estimated fair value of impaired loans acquired at acquisition $ 25,025
Summary of Outstanding Balance and Carrying Amount of All Acquired Impaired Loans	The outstanding balance and carrying amount of all acquired impaired loans are summarized below. The balances do not include an allowance for loan and lease losses of $2.7 million and $3.9 million, at December 31, 2018 and 2017, respectively. 2018 2017 Outstanding Balance Carrying Value Outstanding Balance Carrying Value Commercial real estate $ 216,137 $ 146,808 $ 235,898 $ 166,712 Residential real estate 173,962 113,934 207,660 144,562 Construction, land development, and other land 11,962 3,779 13,270 5,946 Commercial and industrial 24,972 12,617 18,333 10,008 Installment and other 1,735 404 1,819 462 Total acquired impaired loans $ 428,768 $ 277,542 $ 476,980 $ 327,690
Summary of Changes in Accretable Yield for Acquired Impaired Loans	The following table summarizes the changes in accretable yield for acquired impaired loans for the years ended December 31, 2018, 2017 and 2016: 2018 2017 2016 Beginning balance $ 36,446 $ 36,868 $ 43,915 Additions 3,566 — 6,916 Accretion to interest income (23,982 ) (24,597 ) (26,208 ) Reclassification from nonaccretable difference 21,085 24,175 12,245 Ending balance $ 37,115 $ 36,446 $ 36,868
Schedule of Unpaid Principal Balance and Carrying Value for Acquired Non-Impaired Loans and Leases	The unpaid principal balance and carrying value for acquired non‑impaired loans and leases at December 31, 2018 and 2017 were as follows: 2018 2017 Unpaid Principal Balance Carrying Value Unpaid Principal Balance Carrying Value Commercial real estate $ 473,262 $ 462,565 $ 221,710 $ 211,359 Residential real estate 127,478 124,659 32,605 32,085 Construction, land development, and other land 38,494 37,442 1,926 1,845 Commercial and industrial 344,879 328,672 105,529 94,731 Installment and other 1,831 1,596 355 42 Lease financing receivables 32,977 31,352 37,476 36,357 Total acquired non-impaired loans and leases $ 1,018,921 $ 986,286 $ 399,601 $ 376,419

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Summary of Allowance for Loan and Lease Losses and Corresponding Loan and Lease Balances	The following tables summarize the balance and activity within the allowance for loan and lease losses, the components of the allowance for loan and lease losses in terms of loans and leases individually and collectively evaluated for impairment, and corresponding loan and lease balances by type for the years ended December 31, 2018, 2017 and 2016 are as follows: 2018 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Allowance for loan and lease losses Beginning balance $ 4,794 $ 1,638 $ 222 $ 7,418 $ 41 $ 2,593 $ 16,706 Provisions 4,543 113 662 12,089 68 1,320 18,795 Charge-offs (1,865 ) — (418 ) (6,944 ) (60 ) (2,517 ) (11,804 ) Recoveries 68 — — 369 — 1,067 1,504 Ending balance $ 7,540 $ 1,751 $ 466 $ 12,932 $ 49 $ 2,463 $ 25,201 Ending balance: Individually evaluated for impairment $ 2,191 $ 61 $ — $ 4,397 $ — $ — $ 6,649 Collectively evaluated for impairment 4,105 1,323 466 7,413 47 2,463 15,817 Loans acquired with deteriorated credit quality 1,244 367 — 1,122 2 — 2,735 Total allowance for loan and lease losses $ 7,540 $ 1,751 $ 466 $ 12,932 $ 49 $ 2,463 $ 25,201 2018 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Loans and leases ending balance: Individually evaluated for impairment $ 11,983 $ 2,137 $ — $ 21,794 $ — $ — $ 35,914 Collectively evaluated for impairment 1,102,816 588,831 181,570 1,110,386 13,314 191,253 3,188,170 Loans acquired with deteriorated credit quality 146,808 113,934 3,779 12,617 404 — 277,542 Total loans and leases $ 1,261,607 $ 704,902 $ 185,349 $ 1,144,797 $ 13,718 $ 191,253 $ 3,501,626 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) 2017 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Allowance for loan and lease losses Beginning balance $ 1,945 $ 2,483 $ 742 $ 4,196 $ 334 $ 1,223 $ 10,923 Provisions 4,343 (405 ) (520 ) 6,058 34 3,143 12,653 Charge-offs (1,494 ) (440 ) — (2,836 ) (327 ) (3,099 ) (8,196 ) Recoveries — — — — — 1,326 1,326 Ending balance $ 4,794 $ 1,638 $ 222 $ 7,418 $ 41 $ 2,593 $ 16,706 Ending balance: Individually evaluated for impairment $ 1,101 $ 158 $ — $ 2,692 $ 14 $ — $ 3,965 Collectively evaluated for impairment 1,765 1,047 145 3,308 9 2,593 8,867 Loans acquired with deteriorated credit quality 1,928 433 77 1,418 18 — 3,874 Total allowance for loan and lease losses $ 4,794 $ 1,638 $ 222 $ 7,418 $ 41 $ 2,593 $ 16,706 2017 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Loans and leases ending balance: Individually evaluated for impairment $ 13,884 $ 2,429 $ — $ 14,784 $ 14 $ — $ 31,111 Collectively evaluated for impairment 711,097 430,227 99,483 496,446 3,752 177,686 1,918,691 Loans acquired with deteriorated credit quality 166,712 144,562 5,946 10,008 462 — 327,690 Total loans and leases $ 891,693 $ 577,218 $ 105,429 $ 521,238 $ 4,228 $ 177,686 $ 2,277,492 2016 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Allowance for loan and lease losses Beginning balance $ 2,280 $ 2,981 $ 232 $ 1,403 $ 357 $ 379 $ 7,632 Provisions 4,032 135 605 2,869 (11 ) 2,722 10,352 Charge-offs (4,367 ) (633 ) (95 ) (76 ) (12 ) (2,634 ) (7,817 ) Recoveries — — — — — 756 756 Ending balance $ 1,945 $ 2,483 $ 742 $ 4,196 $ 334 $ 1,223 $ 10,923 Ending balance: Individually evaluated for impairment $ — $ 293 $ — $ 396 $ 328 $ — $ 1,017 Collectively evaluated for impairment 1,456 1,743 742 3,126 5 1,223 8,295 Loans acquired with deteriorated credit quality 489 447 — 674 1 — 1,611 Total allowance for loan and lease losses $ 1,945 $ 2,483 $ 742 $ 4,196 $ 334 $ 1,223 $ 10,923 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) 2016 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Loans and leases ending balance: Individually evaluated for impairment $ 8,916 $ 1,300 $ — $ 1,382 $ 328 $ — $ 11,926 Collectively evaluated for impairment 580,125 433,721 133,787 423,392 2,057 158,966 1,732,048 Loans acquired with deteriorated credit quality 207,303 175,717 6,979 13,464 574 — 404,037 Total loans and leases $ 796,344 $ 610,738 $ 140,766 $ 438,238 $ 2,959 $ 158,966 $ 2,148,011
Summary of Recorded Investment, Unpaid Principal Balance, Related Allowance, Average Recorded Investment, and Interest Income Recognized for Loans and Leases	The following tables summarize the recorded investment, unpaid principal balance, related allowance, average recorded investment, and interest income recognized for loans and leases considered impaired as of December 31, 2018, 2017, and 2016, which excludes acquired impaired loans: 2018 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded Commercial real estate $ 6,110 $ 7,693 $ — $ 8,968 $ 590 Residential real estate 1,886 1,858 — 1,917 43 Commercial and industrial 11,193 13,961 — 8,680 483 With an allowance recorded Commercial real estate 5,873 6,313 2,191 5,328 270 Residential real estate 251 253 61 311 4 Commercial and industrial 10,601 11,153 4,397 9,472 749 Installment and other — — — 11 — Total impaired loans $ 35,914 $ 41,231 $ 6,649 $ 34,687 $ 2,139 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded Commercial real estate $ 11,425 $ 12,936 $ — $ 10,482 $ 525 Residential real estate 2,075 2,046 — 1,781 72 Construction, land development and other land — — — 295 2 Commercial and industrial 5,470 6,774 — 2,875 265 With an allowance recorded Commercial real estate 2,459 2,634 1,101 1,988 187 Residential real estate 354 351 158 422 6 Construction, land development and other land — — — 14 — Commercial and industrial 9,314 9,724 2,692 3,460 486 Installment and other 14 14 14 162 12 Total impaired loans $ 31,111 $ 34,479 $ 3,965 $ 21,479 $ 1,555 Note 6—Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments (continued) 2016 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded Commercial real estate $ 8,916 $ 9,502 $ — $ 8,975 $ 305 Residential real estate 804 1,999 — 827 45 Commercial and Industrial 521 524 — 516 (2 ) With an allowance recorded Residential real estate 496 528 293 519 1 Commercial and industrial 861 869 396 914 — Installment and other 328 361 328 328 16 Total impaired loans $ 11,926 $ 13,783 $ 1,017 $ 12,079 $ 365
Summary of Risk Rating Categories of Loans and Leases Considered for Inclusion in Allowance for Loan and Lease Losses Calculation	The following tables summarize the risk rating categories of the loans and leases considered for inclusion in the allowance for loan and lease losses calculation, excluding acquired impaired loans, as of December 31, 2018 and 2017: 2018 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Pass $ 1,009,041 $ 553,665 $ 147,123 $ 962,291 $ 9,997 $ 188,314 $ 2,870,431 Watch 76,276 29,522 31,376 112,996 3,302 80 253,552 Special Mention 17,602 5,656 3,071 34,314 — 1,794 62,437 Substandard 11,880 2,125 — 22,579 15 818 37,417 Doubtful — — — — — 247 247 Loss — — — — — — — Total $ 1,114,799 $ 590,968 $ 181,570 $ 1,132,180 $ 13,314 $ 191,253 $ 3,224,084 2017 Commercial Real Estate Residential Real Estate Construction, Land Development, and Other Land Commercial and Industrial Installment and Other Lease Financing Receivables Total Pass $ 638,066 $ 398,743 $ 73,935 $ 415,163 $ 3,732 $ 174,672 $ 1,704,311 Watch 58,217 29,165 22,380 67,024 20 190 176,996 Special Mention 14,645 2,251 3,168 13,535 — 1,293 34,892 Substandard 14,053 2,497 — 15,508 14 1,259 33,331 Doubtful — — — — — 272 272 Loss — — — — — — — Total $ 724,981 $ 432,656 $ 99,483 $ 511,230 $ 3,766 $ 177,686 $ 1,949,802
Summary of Contractual Delinquency Information	The following tables summarize contractual delinquency information for acquired non-impaired and originated loans and leases by category as of December 31, 2018 and 2017: 2018 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days and Accruing Non- accrual Total Past Due Current Total Commercial real estate $ 6,659 $ 2,145 $ — $ 9,484 $ 18,288 $ 1,096,511 $ 1,114,799 Residential real estate 4,488 711 — 1,815 7,014 583,954 590,968 Construction, land development, and other land — — — — — 181,570 181,570 Commercial and industrial 5,829 1,376 — 13,932 21,137 1,111,043 1,132,180 Installment and other 1,932 4 — 12 1,948 11,366 13,314 Lease financing receivables 789 530 — 591 1,910 189,343 191,253 Total $ 19,697 $ 4,766 $ — $ 25,834 $ 50,297 $ 3,173,787 $ 3,224,084 2017 30-59 Days Past Due 60-89 Days Past Due Greater than 90 Days and Accruing Non- accrual Total Past Due Current Total Commercial real estate $ 4,783 $ 968 $ — $ 8,459 $ 14,210 $ 710,771 $ 724,981 Residential real estate 148 — — 2,092 2,240 430,416 432,656 Construction, land development, and other land — — — — — 99,483 99,483 Commercial and industrial 6,667 967 — 4,348 11,982 499,248 511,230 Installment and other 18 — — 14 32 3,734 3,766 Lease financing receivables 997 638 — 851 2,486 175,200 177,686 Total $ 12,613 $ 2,573 $ — $ 15,764 $ 30,950 $ 1,918,852 $ 1,949,802
Summary of TDR's by Loan Category	. The tables below present TDRs by loan category as of December 31, 2018, 2017, and 2016. Refer to Note 1—Summary of Significant Accounting Policies for the accounting policy for TDRs. December 31, 2018 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Charge-offs Specific Reserves Accruing: Commercial real estate 4 $ 1,508 $ 1,508 $ — $ 113 Commercial and industrial 2 191 191 — 100 Residential real estate 1 114 114 — — Total accruing 7 1,813 1,813 — 213 Non-accruing: Commercial real estate 9 2,512 2,471 41 743 Commercial and industrial 6 6,714 4,843 1,871 1,290 Total non-accruing 15 9,226 7,314 1,912 2,033 Total troubled debt restructurings 22 $ 11,039 $ 9,127 $ 1,912 $ 2,246 December 31, 2017 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Charge-offs Specific Reserves Accruing: Commercial real estate 3 $ 912 $ 912 $ — $ — Residential real estate 1 149 149 — — Total accruing 4 1,061 1,061 — — Non-accruing: Commercial real estate 2 743 743 — 111 Commercial and industrial 3 1,246 759 487 246 Residential real estate 1 67 67 — — Total non-accruing 6 2,056 1,569 487 357 Total troubled debt restructurings 10 $ 3,117 $ 2,630 $ 487 $ 357 December 31, 2016 Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Charge-offs Specific Reserves Accruing: Commercial real estate 1 $ 421 $ 421 $ — $ — Residential real estate 2 181 181 — — Total accruing 3 602 602 — — Non-accruing: Commercial real estate 1 477 477 — — Residential real estate 1 75 75 — — Total non-accruing 2 552 552 — — Total troubled debt restructurings 5 $ 1,154 $ 1,154 $ — $ —
Summary of Loans Modified as Troubled Debt Restructurings	Loans modified as troubled debt restructurings that occurred during the years ended December 31, 2018, 2017, and 2016: For the Year Ended December 31, 2018 2017 2016 Accruing: Beginning balance $ 1,061 $ 602 $ 1,908 Additions 37 1,017 181 Net payments (86 ) (144 ) (1,010 ) Net transfers from (to) non-accrual 801 (414 ) (477 ) Ending balance 1,813 1,061 602 Non-accruing: Beginning balance 1,569 552 833 Additions 8,408 681 — Net payments (1,718 ) (78 ) (758 ) Charge-offs (144 ) — — Net transfers from (to) accrual (801 ) 414 477 Ending balance 7,314 1,569 552 Total troubled debt restructurings $ 9,127 $ 2,630 $ 1,154

Servicing Assets (Tables)

Servicing Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Activity for Servicing Assets and Related Changes in Fair Value	Activity for servicing assets and the related changes in fair value for the years ended December 31, 2018 and 2017 is as follows: 2018 2017 2016 Beginning balance $ 21,400 $ 21,091 $ — Acquired servicing assets at fair value — — 20,295 Additions, net 7,562 6,250 539 Changes in fair value (9,269 ) (5,941 ) 257 Ending balance $ 19,693 $ 21,400 $ 21,091
Unpaid Principal Balances of Loans Serviced for Others	The unpaid principal balances of these loans serviced for others were as follows as December 31, 2018 and 2017: 2018 2017 Loan portfolios serviced for: SBA guaranteed loans $ 1,151,915 $ 1,021,143 USDA guaranteed loans 106,184 91,758 Total $ 1,258,099 $ 1,112,901

Other Real Estate Owned (Tables

Other Real Estate Owned (Tables)	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Change in Other Real Estate Owned	The following table presents the change in other real estate owned (“OREO”) for the years ended December 31, 2018, 2017 and 2016: 2018 2017 2016 Beginning balance $ 10,626 $ 16,570 $ 26,715 Acquisition of OREO through business combination — — 1,525 Net additions to OREO 2,436 6,690 6,659 Proceeds from sales of OREO (7,495 ) (13,898 ) (18,637 ) Gains on sales of OREO 383 2,147 1,366 Valuation adjustments (636 ) (883 ) (1,058 ) Ending balance $ 5,314 $ 10,626 $ 16,570

Premises and Equipment and As_2

Premises and Equipment and Assets Held for Sale (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Schedule for Classification of Premises and Equipment	Classifications of premises and equipment as of December 31, 2018 and 2017 and were as follows: 2018 2017 Premises $ 62,675 $ 61,714 Furniture, fixtures and equipment 15,779 13,591 Leasehold improvements 6,544 4,245 Total cost 84,998 79,550 Less accumulated depreciation and amortization (33,679 ) (29,880 ) Net book value of premises, furniture, fixtures, equipment, leasehold improvements 51,319 49,670 Construction in progress 830 899 Land 45,531 44,655 Premises and equipment, net $ 97,680 $ 95,224
Change in Assets Held for Sale	The following table presents the change in assets held for sale for the years ended December 31, 2018, 2017, and 2016: 2018 2017 2016 Beginning balance $ 9,779 $ 14,748 $ 2,259 Transfers in 9,074 3,372 14,496 Transfers out (425 ) — — Proceeds from sales (4,415 ) (5,373 ) (2,566 ) Internally financed sales — (1,800 ) — Net gains (losses) on sales 1,103 (217 ) 967 Impairment loss (627 ) (951 ) (408 ) Ending balance $ 14,489 $ 9,779 $ 14,748

Goodwill, Core Deposit Intang_2

Goodwill, Core Deposit Intangible and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Changes in Goodwill and Core Deposit Intangible Assets	The following table summarizes the changes in the Company’s goodwill and core deposit intangible assets for the years ended December 31, 2018, 2017 and 2016: 2018 2017 2016 Goodwill Core Intangible Customer Relationship Intangible Goodwill Core Deposit Intangible Customer Relationship Intangible Goodwill Core Deposit Intangible Customer Relationship Intangible Beginning balance $ 54,562 $ 16,720 $ — $ 51,975 $ 19,776 $ — $ 25,688 $ 22,275 $ — Additions 73,615 19,060 3,216 2,587 — — 26,287 486 — Amortization or accretion — (5,420 ) (157 ) — (3,056 ) — — (2,985 ) — Ending balance $ 128,177 $ 30,360 $ 3,059 $ 54,562 $ 16,720 $ — $ 51,975 $ 19,776 $ — Accumulated amortization or accretion N/A $ 18,886 157 N/A $ 13,466 N/A N/A $ 10,410 N/A Weighted average remaining amortization or accretion period N/A 6.8 Years 11.4 Years N/A 5.6 Years N/A N/A 6.6 Years N/A
Estimated Amortization Expense for Core Deposit Intangible and Other Intangible Assets Recognized	The following table presents the estimated amortization expense for core deposit intangible and other intangible assets recognized at December 31, 2018: Estimated Amortization 2019 $ 6,925 2020 6,476 2021 6,026 2022 5,578 2023 3,645 Thereafter 4,769 Total $ 33,419

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of components of provision for income taxes	The following were the components of provision for income taxes for the years ended December 31, 2018, 2017, and 2016 2018 2017 2016 Current tax expense: Federal $ — $ 1,010 $ — State and local 1,078 1,485 — Total current tax expense 1,078 2,495 — Deferred tax expense: Federal 11,469 13,554 478 State and local 2,460 686 136 Remeasurement of net deferred tax assets (760 ) 2,364 — Total deferred tax expense before reversal of valuation allowance 13,169 16,604 614 Deferred tax valuation allowance — — (61,859 ) Provision (benefit) for income taxes $ 14,247 $ 19,099 $ (61,245 )
Schedule of reconciliation between statutory U.S. federal income tax rate and effective tax rate	The following is a reconciliation between the statutory U.S. federal income tax rate of 21% for 2018 and 35% for 2017 and 2016 and the effective tax rate: 2018 2017 2016 Calculated tax benefit at statutory rate 21.0 % 35.0 % 35.0 % Increase (decrease) in income taxes resulting from: Reversal of valuation allowance, net of change in estimated Section 382 impact — — (1,167.6 ) State taxes, net of federal income tax 7.0 6.5 6.1 Tax exempt income (0.5 ) (0.7 ) (5.3 ) Share-based compensation (0.9 ) — — Non-deductible expenses 0.5 0.2 14.8 Remeasurement of net deferred tax assets (1.4 ) 5.8 — Total income tax expense (benefit) 25.7 % 46.8 % (1,117.0 ) %
Schedule of components of deferred tax assets and liabilities	The following were the significant components of the deferred tax assets and liabilities as of December 31, 2018 and 2017: 2018 2017 Deferred tax assets: Net operating losses and tax credits $ 25,851 $ 42,062 Interest on non-accrual loans 3,039 2,755 Allowance for loan losses and loan basis 15,641 11,252 Deposits 90 5 Alternative minimum tax ("AMT") credit carryforward — 2,140 Other real estate owned 393 — Net unrealized holding losses on securities available-for-sale 4,622 2,766 Accrued expenses 3,747 1,576 Other 2,075 837 Total deferred tax assets 55,458 63,393 Deferred tax liabilities: Other real estate owned — (24 ) Premises and equipment (3,752 ) (3,385 ) Core deposit intangibles (9,306 ) (4,656 ) Servicing assets (337 ) (3,505 ) Trust preferred securities (2,710 ) (2,465 ) Unrealized holding gain on cash flow hedges (1,839 ) (1,390 ) Other (1,871 ) (592 ) Total deferred tax liabilities (19,815 ) (16,017 ) Net deferred tax assets after valuation allowance $ 35,643 $ 47,376
Operating Loss and Credit Carryforwards	2018 2017 NOL carryforwards available to offset future taxable income: Federal gross NOL carryforwards - begin to expire in 2030 $ 1,233 $ 63,964 Illinois gross NLD carryforwards - begin to expire in 2021 340,999 381,471 AMT credit carryforward - no expiration date — 2,140

Federal Home Loan Bank Advanc_2

Federal Home Loan Bank Advances (Tables)	12 Months Ended
	Dec. 31, 2018
Federal Home Loan Banks [Abstract]
Summary of FHLB Advances	The following table summarizes the FHLB advances as of December 31, 2018 and 2017: 2018 2017 Federal Home Loan Bank advances $ 425,000 $ 361,506 Weighted average cost 2.56 % 1.49 %

Other Borrowings (Tables)

Other Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Summary of Other Borrowings	The following is a summary of the Company’s other borrowings as of December 31, 2018 and 2017: 2018 2017 Securities sold under agreements to repurchase $ 34,166 $ 31,187 Line of credit — — Total $ 34,166 $ 31,187
Summary of Short-term Credit Lines Available for Use	The following table presents short-term credit lines available for use, for which the Company did not have an outstanding balance as of December 31, 2018 and 2017: 2018 2017 Federal Reserve Bank of Chicago discount window line $ 293,613 $ 144,248 Available federal funds lines 55,000 55,000

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Schedule of Deposits	The following is a summary of the Company’s deposits as of December 31, 2018 and 2017: 2018 2017 Non-interest-bearing demand deposits $ 1,192,873 $ 760,887 Interest-bearing checking accounts 296,339 186,611 Money market demand accounts 640,401 349,862 Other savings 476,418 437,212 Time deposits (below $250,000) 911,603 627,255 Time deposits ($250,000 and above) 232,282 81,502 Total deposits $ 3,749,916 $ 2,443,329
Schedule of Maturities of Time Deposits	At December 31, 2018, the scheduled maturities of time deposits were as follows: Scheduled Maturities 2019 $ 852,780 2020 240,863 2021 33,583 2022 10,584 2023 6,075 Total $ 1,143,885

Junior Subordinated Debentures

Junior Subordinated Debentures (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Junior Subordinated Debentures by Issuance	At December 31, 2018 and 2017, the Company’s junior subordinated debentures by issuance were as follows: Name of Trust Aggregate Principal Amount 2018 Aggregate Principal Amount 2017 Stated Maturity Contractual Rate at December 31, 2018 Interest Rate Spread Metropolitan $ 35,000 $ 35,000 March 5.58 % Three-month LIBOR + 2.79% RidgeStone Capital Trust I 1,500 1,500 June 30, 2033 6.38 % Five-year LIBOR + 3.50% First Evanston Bancorp Trust I 10,000 — March 15, 2035 4.57 % Three-month LIBOR + 1.78% Total liability, at par 46,500 36,500 Discount (9,732 ) (8,853 ) Total liability, at carrying value $ 36,768 $ 27,647

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Summary of Minimum Annual Rental Commitments for Operating Leases	The minimum annual rental commitments for operating leases subsequent to December 31, 2018, exclusive of taxes and other charges, are summarized as follows: Minimum Commitments 2019 $ 3,285 2020 2,725 2021 2,450 2022 1,488 2023 562 Thereafter 2,605 Total $ 13,115
Summary of Contract or Notional Amount of Outstanding Loan and Lease Commitments	The following table summarizes the contract or notional amount of outstanding loan and lease commitments at December 31, 2018 and 2017: 2018 2017 Fixed Rate Variable Fixed Variable Commitments to extend credit $ 74,099 $ 928,991 $ 55,924 $ 467,429 Letters of credit 1,982 34,071 1,226 3,337 Total $ 76,081 $ 963,062 $ 57,150 $ 470,766

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables summarize the Company’s financial assets and liabilities that were measured at fair value on a recurring basis at December 31, 2018 and 2017: Fair Value Measurements Using 2018 Fair Value Level 1 Level 2 Level 3 Financial assets Securities available-for-sale U.S. Treasury Notes $ 52,667 $ 52,667 $ — $ — U.S. Government agencies 186,498 — 186,498 — Obligations of states, municipalities, and political subdivisions 60,233 — 60,038 195 Mortgage-backed securities; residential Agency 272,963 — 272,963 — Non-Agency 83,621 — 83,621 — Mortgage-backed securities; commercial Agency 90,434 — 90,434 — Non-Agency 30,458 — 30,458 — Corporate securities 34,173 — 34,173 — Other securities 6,609 2,844 3,074 691 Servicing assets 19,693 — — 19,693 Derivative assets 10,740 — 10,740 — Financial liabilities Derivative liabilities 4,243 — 4,243 — Note 18— Fair Value Measurement (continued) Fair Value Measurements Using 2017 Fair Value Level 1 Level 2 Level 3 Financial assets Securities available-for-sale U.S. Treasury Notes $ 14,863 $ 14,863 $ — $ — U.S. Government agencies 52,958 — 52,958 — Obligations of states, municipalities, and political subdivisions 33,170 — 32,795 375 Mortgage-backed securities; residential Agency 307,457 — 307,457 — Non-Agency 39,514 — 39,514 — Mortgage-backed securities; commercial Agency 69,043 — 69,043 — Non-Agency 30,971 — 30,971 — Corporate securities 29,976 — 29,976 — Other securities 5,284 1,921 2,686 677 Servicing assets 21,400 — — 21,400 Derivative assets 5,981 — 5,981 — Financial liabilities Derivative liabilities 994 — 994 —
Summary of Financial Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The following table presents additional information about financial assets measured at fair value on recurring basis for which the Company used significant unobservable inputs (Level 3): Years Ended December 31, 2018 2017 2018 2017 Investment Securities Servicing Assets Balance, beginning of period $ 1,052 $ 1,080 $ 21,400 $ 21,091 Acquired assets at fair value 314 — — — Additions, net — — 7,562 6,250 Maturities (494 ) (175 ) — — Amortization 5 5 — — Change in unrealized gain 9 142 — — Change in fair value — — (9,269 ) (5,941 ) Balance, end of period $ 886 $ 1,052 $ 19,693 $ 21,400
Summary of Unobservable Inputs Used in the Fair Value Measurements on Recurring Basis	The following table presents additional information about the unobservable inputs used in the fair value measurements on recurring basis that were categorized within Level 3 of the fair value hierarchy as of December 31, 2018: Financial Instruments Valuation Technique Unobservable Inputs Range of Inputs Weighted Average Input Impact to Valuation from an Increased or Higher Input Value Obligations of states, municipalities, and political obligations Discounted Probability of default 2.4% 2.4 % Decrease Single issuer trust preferred Discounted cash flow Probability of default 4.9%—5.4% 5.2 % Decrease Servicing assets Discounted cash flow Prepayment speeds 2.0%—17.4% 11.5 % Decrease Discount rate 8.5%—23.1% 15.2 % Decrease Expected weighted average loan life 0.1—10.4 years 5.1 years Increase
Summary of Company's Assets Measured at Fair Value on a Non-Recurring Basis	The following tables summarize the Company’s assets that were measured at fair value on a non-recurring basis, excluding acquired impaired loans, as of December 31, 2018 and 2017: Fair Value Measurements Using 2018 Fair Value Level 1 Level 2 Level 3 Non-recurring Impaired loans (excluding acquired impaired loans) Commercial real estate $ 9,792 $ — $ — $ 9,792 Residential real estate 2,076 — — 2,076 Construction, land development, and other land — — — — Commercial and industrial 17,397 — — 17,397 Installment and other — — — — Assets held for sale 14,489 — — 14,489 Other real estate owned 5,314 — — 5,314 Fair Value Measurements Using 2017 Fair Value Level 1 Level 2 Level 3 Non-recurring Impaired loans (excluding acquired impaired loans) Commercial real estate $ 12,783 $ — $ — $ 12,783 Residential real estate 2,271 — — 2,271 Construction, land development, and other land — — — — Commercial and industrial 12,092 — — 12,092 Installment and other — — — — Assets held for sale 9,779 — — 9,779 Other real estate owned 10,626 — — 10,626
Estimated Fair Values of Financial Instruments	The estimated fair values of financial instruments and levels within the fair value hierarchy are as follows: Fair Value 2018 2017 Hierarchy Level Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Financial assets Cash and due from banks 1 $ 30,190 $ 30,190 $ 19,404 $ 19,404 Interest bearing deposits with other banks 2 91,670 91,670 38,945 38,945 Securities held-to-maturity 2 99,266 97,739 117,163 117,277 Other restricted stock 2 19,202 19,202 16,343 16,343 Loans held for sale 3 19,827 21,654 5,212 5,851 Loans and lease receivables, net (less impaired loans at fair value) 3 3,447,160 3,407,652 2,260,786 2,240,235 Accrued interest receivable 3 10,863 10,863 7,670 7,670 Financial liabilities Non-interest-bearing deposits 2 1,192,873 1,192,873 760,887 760,887 Interest-bearing deposits 2 2,557,043 2,554,329 1,682,442 1,678,535 Accrued interest payable 2 3,484 3,484 1,306 1,306 Line of credit 2 — — — — Federal Home Loan Bank advances 2 425,000 425,000 361,506 361,500 Securities sold under repurchase agreement 2 34,166 34,166 31,187 31,187 Junior subordinated debentures 3 36,768 42,351 27,647 33,907

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Stock Compensation Expense	The following table summarizes stock option compensation expense for the years ended December 31, 2018, 2017 and 2016: Years Ended December 31, 2018 2017 2016 Total share-based compensation - stock options $ 458 $ 1,294 $ 899 Income tax benefit 127 521 360 Unrecognized compensation expense - stock options 146 729 1,752 Weighted-average amortization period remaining 1.1 years 1.2 years 1.8 years
Restricted Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Stock Compensation Expense	The following table summarizes restricted stock compensation expense for the years ended: Years Ended December 31, 2018 2017 Total share-based compensation - restricted stock $ 958 $ 203 Income tax benefit 267 83 Unrecognized compensation expense - restricted stock 3,167 1,227 Weighted-average amortization period remaining 2.9 years 2.8 years
Omnibus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Changes in Restricted Shares	The following table discloses the changes in restricted shares for the year ended December 31, 2018: Omnibus Plan Number of Shares Weighted Average Grant Date Fair Value Beginning balance, January 1, 2018 70,398 $ 20.31 Granted 131,157 22.36 Vested (2,975 ) 20.96 Forfeited (2,100 ) 20.84 Ending balance outstanding at December 31, 2018 196,480 $ 21.66
BYB Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair Value Assumptions of Stock Options	The fair values of the stock options were determined using the Black-Scholes-Merton model for Time Options and a Monte Carlo simulation model for Performance Options. The fair values of options under the BYB Plan were determined using the following assumptions as of the grant dates: Time Options Grants 2016 Risk-free interest rate 1.34% - 1.40% Expected term (years) 5.2 - 5.6 Expected stock price volatility 20.39 % Expected dividend yield 0.00 % Weighted average grant date fair value $ 3.55 Performance Options Grants 2016 Risk-free interest rate Implied forward rates Expected term (years) Variable Expected stock price volatility 20.34% - 20.39% Expected dividend yield 0.00 % Weighted average grant date fair value $ 3.75
Summary of Activity in shares Subjected to Options and Weighted Average Exercise Prices	The following table discloses the activity in shares subject to options and the weighted average exercise prices, in actual dollars, for the year ended December 31, 2018: BYB Plan Number of Shares Weighted Average Exercise Price Intrinsic Value Weighted Average Remaining Contractual Term (in Years) Beginning balance, January 1, 2018 1,783,020 $ 11.91 $ 19,718 7.6 Granted — Expired — Exercised (148,748 ) 11.69 $ 1,614 Forfeited (35,400 ) 16.25 Ending balance outstanding at December 31, 2018 1,598,872 $ 11.84 $ 7,713 6.6 Exercisable at December 31, 2018 1,500,572 $ 11.55 $ 7,673 6.5
FEB Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Activity in shares Subjected to Options and Weighted Average Exercise Prices	The following table discloses the activity in shares subject to options under the FEB Plan and the weighted average exercise prices, in actual dollars, for the year ended December 31, 2018: FEB Plan Number of Shares Weighted Average Exercise Price Intrinsic Value Weighted Average Remaining Contractual Term (in Years) Beginning balance, May 31, 2018 — $ — $ — — Granted 680,787 11.26 $ 7,544 Expired — Exercised (56,404 ) 10.66 $ 602 Forfeited — Ending balance outstanding at December 31, 2018 624,383 $ 11.31 $ 3,339 5.2 Exercisable at December 31, 2018 624,383 $ 11.31 $ 3,339 5.2

Regulatory Capital Requiremen_2

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2018
Regulatory Capital Requirements [Abstract]
Summary of Bank's Actual Capital Amounts and Ratios	The Company’s and the Bank’s actual capital amounts and ratios as of December 31, 2018 and 2017 are also presented. Actual Minimum Capital Required Required to be Considered Well Capitalized 2018 Amount Ratio Amount Ratio Amount Ratio Total capital to risk weighted assets: Company $ 551,079 13.99 % $ 315,093 8.00 % N/A N/A Bank 528,329 13.40 % 315,455 8.00 % 394,318 10.00 % Tier 1 capital to risk weighted assets: Company $ 523,808 13.30 % $ 236,320 6.00 % N/A N/A Bank 501,058 12.71 % 236,591 6.00 % 315,455 8.00 % Common Equity Tier 1 (CET1) to risk weighted assets: Company $ 466,870 11.85 % $ 177,240 4.50 % N/A N/A Bank 501,058 12.71 % 177,443 4.50 % 256,307 6.50 % Tier 1 capital to average assets: Company $ 523,808 11.05 % $ 189,587 4.00 % N/A N/A Bank 501,058 10.56 % 189,797 4.00 % 237,246 5.00 % Actual Minimum Capital Required Required to be Considered Well Capitalized 2017 Amount Ratio Amount Ratio Amount Ratio Total capital to risk weighted assets: Company $ 408,245 15.89 % $ 205,559 8.00 % N/A N/A Bank 365,386 14.19 % 205,981 8.00 % 257,476 10.00 % Tier 1 capital to risk weighted assets: Company $ 389,934 15.18 % $ 154,169 6.00 % N/A N/A Bank 347,075 13.48 % 154,486 6.00 % 205,981 8.00 % Common Equity Tier 1 (CET1) to risk weighted assets: Company $ 351,408 13.68 % $ 115,627 4.50 % N/A N/A Bank 347,075 13.48 % 115,864 4.50 % 167,359 6.50 % Tier 1 capital to average assets: Company $ 389,934 12.18 % $ 128,075 4.00 % N/A N/A Bank 347,075 10.82 % 128,305 4.00 % 160,382 5.00 %

Derivative Instruments and He_2

Derivative Instruments and Hedge Activities (Tables)	12 Months Ended
	Dec. 31, 2018
Summary of Derivative Financial Instruments and Classification on Consolidated Statements of Financial Condition	The following tables present the fair value of the Company’s derivative financial instruments and classification on the Consolidated Statements of Financial Condition as of December 31, 2018 and 2017: 2018 2017 Fair Value Fair Value Notional Amount Other Assets Other Liabilities Notional Amount Other Assets Other Liabilities Derivatives designated as hedging instruments Interest rate swaps designated as cash flow hedges $ 250,000 $ 6,699 $ — $ 250,000 $ 5,030 $ 38 Derivatives not designated as hedging instruments Other interest rate swaps 294,545 4,041 4,237 94,726 951 956 Other credit derivatives 4,424 — 6 — — — Total derivatives $ 548,969 $ 10,740 $ 4,243 $ 344,726 $ 5,981 $ 994
Summary of Net Gains (Losses) Recorded in Accumulated Other Comprehensive Income (Loss) and Consolidated Statements of Operations Relating to Cash Flow Derivative Instruments	The following table reflects the net gains (losses) recorded in accumulated other comprehensive income (loss) and the Consolidated Statements of Operations relating to the cash flow derivative instruments for the year ended December 31, 2018: Amount of Gain Recognized in OCI (Effective Portion) Amount of Gain Reclassified from OCI to Income as a Decrease to Interest Expense Amount of Gain (Loss) Recognized in Other Non-Interest Income (Ineffective Portion) Interest rate swaps $ 2,960 $ 1,348 $ —
Summary of Other Interest Rate Swaps	The following table reflects other interest rate swaps as of December 31, 2018: Notional amounts $ 294,545 Derivative assets fair value 4,041 Derivative liabilities fair value 4,237 Weighted average pay rates 4.84 % Weighted average receive rates 4.38 % Weighted average maturity 5.8 years
Summary of Company's Interest Rate Derivative and Offsetting Positions	The Company records interest rate derivatives subject to master netting agreements at their gross value and does not offset derivative asset and liabilities on the Consolidated Statements of Financial Condition. The table below summarizes the Company’s interest rate derivatives and offsetting positions as of December 31, 2018 and 2017 2018 2017 Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Assets Fair Value Derivative Liabilities Fair Value Gross amounts recognized $ 10,740 $ 4,243 $ 5,981 $ 994 Less: Amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition $ 10,740 $ 4,243 $ 5,981 $ 994 Gross amounts not offset in the Consolidated Statements of Financial Condition Offsetting derivative positions (2,823 ) (2,823 ) (232 ) (232 ) Collateral posted (7,917 ) (1,317 ) (5,371 ) (745 ) Net credit exposure — $ 103 $ 378 $ 17 As of December 31, 2018, the counterparties posted collateral of $8.8 million, which resulted in no excess collateral with the Company. For purposes of this disclosure, the amount of posted collateral by the counterparties is limited to the amount offsetting the derivatives asset.
Cash Flow Hedges
Summary of Cash Flow Hedges	The following table reflects the cash flow hedges as of December 31, 2018: Notional amounts $ 250,000 Derivative assets fair value 6,699 Derivative liabilities fair value — Weighted average pay rates 1.67 % Weighted average receive rates 2.37 % Weighted average maturity 3.2 years

Parent Company Only Condensed_2

Parent Company Only Condensed Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Schedule of Statements of Condensed Financial Statements	The following represents the condensed financial statements of Byline Bancorp, Inc., the Parent Company: Statements of Financial Condition Parent Company Only As of December 31, 2018 2017 ASSETS Cash 18,242 39,626 Investment in banking subsidiary 667,236 445,786 Other assets 3,067 1,236 Total assets $ 688,545 $ 486,648 LIABILITIES AND STOCKHOLDERS’ EQUITY Line of credit — — Junior subordinated debentures issued to capital trusts, net 36,768 27,647 Accrued expenses and other liabilities 1,105 423 Stockholders' equity 650,672 458,578 Total liabilities and stockholders' equity $ 688,545 $ 486,648 Note 23—Parent Company Only Condensed Financial Statements (continued) Statements of Operations Parent Company Only Years ended December 31, 2018 2017 2016 INCOME Dividends from subsidiary $ 2,900 $ 2,800 $ — Other noninterest income — 9 57 Total income 2,900 2,809 57 EXPENSES Interest expense 2,716 2,782 2,460 Other noninterest expense 3,214 1,804 381 Total expenses 5,930 4,586 2,841 Loss before provision for income taxes and equity in undistributed income of subsidiary (3,030 ) (1,777 ) (2,784 ) Provision (benefit) for income taxes (1,549 ) (1,166 ) 204 Loss before equity in undistributed income of subsidiary (1,481 ) (611 ) (2,988 ) Equity in undistributed income of subsidiary 42,674 22,306 69,717 Net income $ 41,193 $ 21,695 $ 66,729 Statements of Cash Flows Parent Company Only Years ended December 31, 2018 2017 2016 CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 41,193 $ 21,695 $ 66,729 Adjustments to reconcile net income to net cash from operating activities: Equity in undistributed income of subsidiary (42,674 ) (22,306 ) (69,717 ) Stock-based compensation expense 1,514 1,497 899 Exercise of share-based awards — — 40 Accretion of junior subordinated debentures discount 624 721 876 Changes in other assets and other liabilities (3,291 ) (2,893 ) 16 Net cash used in operating activities (2,634 ) (1,286 ) (1,157 ) CASH FLOWS FROM INVESTING ACTIVITIES Investments in and advances from subsidiary — — (32,019 ) Net cash paid in acquisition of business (20,510 ) — (36,586 ) Net cash used in investing activities (20,510 ) — (68,605 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from revolving line of credit — — 30,000 Repayments of revolving line of credit — (20,650 ) (9,350 ) Dividends paid on preferred stock (783 ) (11,277 ) — Cash paid in lieu of fractional shares — (2 ) — Proceeds from issuance of common stock, net 2,543 76,829 49,592 Proceeds from issuance of preferred stock — 1,050 9,388 Repurchase of preferred stock — (15,003 ) — Net cash provided by financing activities 1,760 30,947 79,630 NET CHANGE IN CASH AND CASH EQUIVALENTS (21,384 ) 29,661 9,868 CASH AND CASH EQUIVALENTS, beginning of period 39,626 9,965 97 CASH AND CASH EQUIVALENTS, end of period $ 18,242 $ 39,626 $ 9,965

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Calculation of Basic and Diluted Earnings per Share	Years ended December 31, 2018 2017 2016 Net income $ 41,193 $ 21,695 $ 66,729 Less: Dividends on preferred shares 783 11,277 — Net income available to common stockholders $ 40,410 $ 10,418 $ 66,729 Weighted-average common stock outstanding: Weighted-average common stock outstanding (basic) 33,292,619 26,963,517 20,141,630 Incremental shares 887,135 583,797 289,153 Weighted-average common stock outstanding (dilutive) 34,179,754 27,547,314 20,430,783 Basic earnings per common share $ 1.21 $ 0.39 $ 3.31 Diluted earnings per common share $ 1.18 $ 0.38 $ 3.27

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Summary of Preferred and Common Stock	A summary of the Company’s preferred and common stock at December 31, 2018 and 2017 is as follows: 2018 2017 Series B 7.5% fixed to floating non-cumulative perpetual preferred stock Par value $ 0.01 $ 0.01 Shares authorized 50,000 50,000 Shares issued 10,438 10,438 Shares outstanding 10,438 10,438 Common stock, voting Par value $ 0.01 $ 0.01 Shares authorized 150,000,000 150,000,000 Shares issued 36,343,239 29,317,298 Shares outstanding 36,343,239 29,317,298

Selected Quarterly Financial _2

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unaudited)	For the year ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Interest and dividend income $ 38,142 $ 44,841 $ 61,073 $ 62,895 Interest expense 4,447 5,785 8,480 9,634 Net interest income 33,695 39,056 52,593 53,261 Provision for loan and lease losses 5,115 3,956 5,842 3,882 Net interest income after provision for loan and lease losses 28,580 35,100 46,751 49,379 Non-interest income 11,428 14,502 11,143 14,566 Non-interest expense 31,919 45,770 37,956 40,364 Income before provision for income taxes 8,089 3,832 19,938 23,581 Provision for income taxes 1,321 1,064 5,402 6,460 Net income 6,768 2,768 14,536 17,121 Dividends on preferred shares 193 198 196 196 Income available to common stockholders $ 6,575 $ 2,570 $ 14,340 $ 16,925 Basic earnings per common share $ 0.22 $ 0.08 $ 0.40 $ 0.47 Diluted earnings per common share $ 0.22 $ 0.08 $ 0.39 $ 0.46 For the year ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Interest and dividend income $ 32,488 $ 33,315 $ 35,044 $ 35,956 Interest expense 2,950 3,504 3,632 3,805 Net interest income 29,538 29,811 31,412 32,151 Provision for loan and lease losses 1,891 3,515 3,900 3,347 Net interest income after provision for loan and lease losses 27,647 26,296 27,512 28,804 Non-interest income 12,308 13,193 11,918 12,639 Non-interest expense 28,851 29,249 31,065 30,358 Income before provision for income taxes 11,104 10,240 8,365 11,085 Provision (benefit) for income taxes 4,544 4,094 (1,390 ) 11,851 Net income (loss) 6,560 6,146 9,755 (766 ) Dividends on preferred shares 189 10,697 195 196 Income available (loss attributable) to common stockholders $ 6,371 $ (4,551 ) $ 9,560 $ (962 ) Basic earnings (loss) per common share $ 0.26 $ (0.18 ) $ 0.33 $ (0.03 ) Diluted earnings (loss) per common share $ 0.25 $ (0.18 ) $ 0.32 $ (0.03 )

Consolidated Statements of Ch_3

Consolidated Statements of Changes in Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Schedule of Consolidated Statements of Changes in Accumulated Other Comprehensive Income (Loss)	The following table summarized the change in accumulated other comprehensive income (loss) for the years ended December 31, 2018, 2017 and 2016: (dollars in thousands) Gains on Cash Flow Hedges Unrealized (Losses) on Available-for -Sale Securities Total Accumulated Other Comprehensive Income (Loss) Balance, January 1, 2016 $ — $ (5,707 ) $ (5,707 ) Other comprehensive income (loss), net of tax 2,233 (3,794 ) (1,561 ) Balance, December 31, 2016 2,233 (9,501 ) (7,268 ) Other comprehensive income, net of tax 680 1,501 2,181 Balance, December 31, 2017 2,913 (8,000 ) (5,087 ) Reclassification of certain income tax effects from accumulated other comprehensive income 687 (1,450 ) (763 ) Other comprehensive income (loss), net of tax 1,163 (4,811 ) (3,648 ) Balance, December 31, 2018 $ 4,763 $ (14,261 ) $ (9,498 )

Business and Summary of Signi_3

Business and Summary of Significant Accounting Policies - Nature of business (Details)	Jun. 14, 2017USD ($)$ / shares	Dec. 31, 2018item
Nature of business
Merger transaction, the number of shares into which each share of common stock issued and outstanding prior to merger was converted	0.20
Merger transaction, cash paid to stockholders for remaining fractional shares | $	$ 2,000
Offering price per share | $ / shares	$ 19
Chicago metropolitan area
Nature of business
Number of bank branches		57
Wisconsin
Nature of business
Number of bank branches		1

Business and Summary of Signi_4

Business and Summary of Significant Accounting Policies - Cash and cash equivalents (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Business Description And Accounting Policies [Abstract]
Reserve requirement	$ 44.8	$ 15.8

Business and Summary of Signi_5

Business and Summary of Significant Accounting Policies - Premises and equipment (Details)	12 Months Ended
	Dec. 31, 2018
Minimum
Premises and equipment
Estimated useful lives (in years)	3 years
Maximum
Premises and equipment
Estimated useful lives (in years)	39 years

Business and Summary of Signi_6

Business and Summary of Significant Accounting Policies - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Description And Accounting Policies [Abstract]
Goodwill, impairment loss	$ 0	$ 0	$ 0

Business and Summary of Signi_7

Business and Summary of Significant Accounting Policies - Other intangible assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Minimum
Finite Lived Intangible Assets [Line Items]
Intangibles amortization period (in years)	9 years
Maximum
Finite Lived Intangible Assets [Line Items]
Intangibles amortization period (in years)	10 years
Core Deposits
Finite Lived Intangible Assets [Line Items]
Impairment on intangible assets	$ 0	$ 0	$ 0

Business and Summary of Signi_8

Business and Summary of Significant Accounting Policies - Customer Relationship Intangibles (Details) - Customer Relationships $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Finite Lived Intangible Assets [Line Items]
Intangibles amortization period (in years)	12 years
Impairment on intangible assets	$ 0

Business and Summary of Signi_9

Business and Summary of Significant Accounting Policies - Income taxes (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Business Description And Accounting Policies [Abstract]
Uncertain tax positions	$ 0	$ 0

Business and Summary of Sign_10

Business and Summary of Significant Accounting Policies - Segment reporting (Details)	12 Months Ended
	Dec. 31, 2018segment
Business Description And Accounting Policies [Abstract]
Number of reportable segment	1

Recently Issued Accounting Pr_2

Recently Issued Accounting Pronouncements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification of certain income tax effects from accumulated other comprehensive income (loss)	$ (763,000)
ASU 2016-01
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Available-for-sale equity investment securities	6,600,000
ASU 2018-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification of certain income tax effects from accumulated other comprehensive income (loss)	$ 763,000

Acquisition of a Business - Add

Acquisition of a Business - Additional Information (Details) - USD ($)	May 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 128,177,000	$ 54,562,000	$ 51,975,000	$ 25,688,000
First Evanston Bancorp, Inc.
Business Acquisition [Line Items]
Business acquisition date of agreement		May 31, 2018
Right to receive common stock upon conversion	3.994
Consideration paid in cash	$ 27,004,000
Common stock outstanding value per share	$ 16.136
Common stock issued price per share	$ 21.62
Issuance of common shares	6,682,850
Value of common stock consideration	$ 144,500,000
Options to acquire common stock shares	144,090
Options to acquire conversion of common stock shares	680,787
Option to acquire common stock value	$ 7,600,000
Total merger consideration	179,131,000
Stock issuance costs	852,000
Goodwill	$ 73,615,000
First Evanston Bancorp, Inc. | Non-interest Expense
Business Acquisition [Line Items]
Acquisition advisory expenses		$ 1,700,000	$ 1,300,000
Core system conversion expenses		$ 9,800,000

Acquisition of a Business - Sum

Acquisition of a Business - Summary of Estimated fair Values of Assets and Liabilities Assumed as of Acquisition Date (Details) - USD ($) $ in Thousands	May 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consideration paid
Goodwill		$ 128,177	$ 54,562	$ 51,975	$ 25,688
First Evanston Bancorp, Inc.
Assets
Cash and cash equivalents	$ 47,378
Securities available-for-sale	128,063
Restricted stock	1,360
Loans	916,011
Premises and equipment	15,890
Other intangible assets	22,276
Deferred tax assets, net	2,302
Other assets	8,845
Total assets acquired	1,142,125
Liabilities
Deposits	1,022,268
Junior subordinated debentures	8,497
Accrued expenses and other liabilities	5,844
Total liabilities assumed	1,036,609
Net assets acquired	105,516
Consideration paid
Common stock (6,682,850 shares issued at $21.62 per share)	144,483
Outstanding stock options converted to Byline stock options	7,644
Cash paid	27,004
Total consideration paid	179,131
Goodwill	$ 73,615

Acquisition of a Business - S_2

Acquisition of a Business - Summary of Estimated fair Values of Assets and Liabilities Assumed as of Acquisition Date (Parenthetical) (Details) - Ridgestone	May 31, 2018$ / sharesshares
Business Acquisition [Line Items]
Stock issued (in shares) | shares	6,682,850
Stock issued (in dollars per share) | $ / shares	$ 21.62

Acquisition of a Business - S_3

Acquisition of a Business - Summary of Acquired Non-Impaired Loans as of Acquisition Date (Details) $ in Thousands	May 31, 2018USD ($)
Business Combinations [Abstract]
Fair value	$ 890,986
Gross contractual amounts receivable	1,057,374
Estimate of contractual cash flows not expected to be collected	36,544	[1]
Estimate of contractual cash flows expected to be collected	$ 1,020,830
[1]	Includes interest payments not expected to be collected due to loan prepayments as well as principal and interest payments not expected to be collected due to customer default

Acquisition of a Business - S_4

Acquisition of a Business - Summary of Pro Forma Information for Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Total revenues (net interest income and non-interest income)	$ 251,393	$ 225,446
Net income	$ 55,329	$ 34,317
Earnings per share—basic	$ 1.51	$ 0.68
Earnings per share—diluted	$ 1.48	$ 0.67

Securities - Summary of Amortiz

Securities - Summary of Amortized Cost and Fair Values of Securities Available-for-sale (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	$ 834,254	$ 593,167
Available-for-sale Securities, Gross Unrealized Gains	3,130	2,486
Available-for-sale Securities, Gross Unrealized Losses	(19,728)	(12,417)
Securities available-for-sale, at fair value	817,656	583,236
U.S. Treasury Notes
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	52,775	14,999
Available-for-sale Securities, Gross Unrealized Gains	81
Available-for-sale Securities, Gross Unrealized Losses	(189)	(136)
Securities available-for-sale, at fair value	52,667	14,863
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	187,427	54,248
Available-for-sale Securities, Gross Unrealized Gains	367
Available-for-sale Securities, Gross Unrealized Losses	(1,296)	(1,290)
Securities available-for-sale, at fair value	186,498	52,958
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	60,686	33,405
Available-for-sale Securities, Gross Unrealized Gains	133	100
Available-for-sale Securities, Gross Unrealized Losses	(586)	(335)
Securities available-for-sale, at fair value	60,233	33,170
Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	284,038	315,103
Available-for-sale Securities, Gross Unrealized Gains	101
Available-for-sale Securities, Gross Unrealized Losses	(11,176)	(7,646)
Securities available-for-sale, at fair value	272,963	307,457
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	84,998	39,485
Available-for-sale Securities, Gross Unrealized Gains	199	104
Available-for-sale Securities, Gross Unrealized Losses	(1,576)	(75)
Securities available-for-sale, at fair value	83,621	39,514
Agency, Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	93,543	70,964
Available-for-sale Securities, Gross Unrealized Gains	55	45
Available-for-sale Securities, Gross Unrealized Losses	(3,164)	(1,966)
Securities available-for-sale, at fair value	90,434	69,043
Non-Agency, Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	31,458	31,763
Available-for-sale Securities, Gross Unrealized Losses	(1,000)	(792)
Securities available-for-sale, at fair value	30,458	30,971
Corporate Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	34,716	29,573
Available-for-sale Securities, Gross Unrealized Gains	67	507
Available-for-sale Securities, Gross Unrealized Losses	(610)	(104)
Securities available-for-sale, at fair value	34,173	29,976
Other Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	4,613	3,627
Available-for-sale Securities, Gross Unrealized Gains	2,127	1,730
Available-for-sale Securities, Gross Unrealized Losses	(131)	(73)
Securities available-for-sale, at fair value	$ 6,609	$ 5,284

Securities - Summary of Amort_2

Securities - Summary of Amortized Cost and Fair Values of Securities Held-to-maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost	$ 99,266	$ 117,163
Held-to-maturity Securities, Gross Unrealized Gains	133	450
Held-to-maturity Securities, Gross Unrealized Losses	(1,660)	(336)
Securities held-to-maturity, fair value	97,739	117,277
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost	23,835	24,030
Held-to-maturity Securities, Gross Unrealized Gains	40	197
Held-to-maturity Securities, Gross Unrealized Losses	(210)	(82)
Securities held-to-maturity, fair value	23,665	24,145
Agency, Residential Mortgage-Backed Securities
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost	40,082	53,731
Held-to-maturity Securities, Gross Unrealized Gains	93	79
Held-to-maturity Securities, Gross Unrealized Losses	(531)	(203)
Securities held-to-maturity, fair value	39,644	53,607
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Amortized Cost	35,349	39,402
Held-to-maturity Securities, Gross Unrealized Gains		174
Held-to-maturity Securities, Gross Unrealized Losses	(919)	(51)
Securities held-to-maturity, fair value	$ 34,430	$ 39,525

Securities - Additional Informa

Securities - Additional Information (Details)	Dec. 31, 2018USD ($)Security	Dec. 31, 2017USD ($)Security
Schedule Of Investments [Line Items]
Trading securities	$ 0	$ 0
Carrying amount of securities pledged as collateral	$ 244,700,000	$ 262,500,000
Minimum
Schedule Of Investments [Line Items]
Percentage of shareholders equity for which securities holdings exceeds for no issuer other than U.S. Government and agencies	10.00%	10.00%
Federal Home Loan Bank Advances
Schedule Of Investments [Line Items]
Carrying amount of securities pledged as collateral	$ 128,400,000	$ 0
Public Fund Deposits
Schedule Of Investments [Line Items]
Carrying amount of securities pledged as collateral	197,800,000	99,300,000
Customer Repurchase Agreements
Schedule Of Investments [Line Items]
Carrying amount of securities pledged as collateral	$ 46,900,000	$ 34,800,000
Available-for-sale Securities
Schedule Of Investments [Line Items]
Investment securities with unrealized losses | Security	179	101
Held-to-maturity Securities
Schedule Of Investments [Line Items]
Investment securities with unrealized losses | Security	46	28

Securities - Summary of Gross U

Securities - Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Available-for-sale (Details) $ in Thousands	Dec. 31, 2018USD ($)Security	Dec. 31, 2017USD ($)Security
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	179	101
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 191,761	$ 39,896
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(2,441)	(407)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	427,243	455,688
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(17,287)	(12,010)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	619,004	495,584
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (19,728)	$ (12,417)
U.S. Treasury Notes
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	18	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 23,835	$ 4,998
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(52)	(2)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	9,865	9,865
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(137)	(134)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	33,700	14,863
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (189)	$ (136)
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	25	9
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 43,487	$ 992
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(80)	(7)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	50,101	51,966
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(1,216)	(1,283)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	93,588	52,958
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,296)	$ (1,290)
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	56	29
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 13,926	$ 16,059
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(97)	(137)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	18,563	4,453
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(489)	(198)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	32,489	20,512
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (586)	$ (335)
Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	42	41
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 4,288	$ 15,441
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(45)	(181)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	254,121	292,016
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(11,131)	(7,465)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	258,409	307,457
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (11,176)	$ (7,646)
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	8	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 59,107
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(1,378)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	4,009	$ 4,565
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(198)	(75)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	63,116	4,565
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,576)	$ (75)
Agency, Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	9	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 21,356
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(447)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	52,640	$ 57,442
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(2,717)	(1,966)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	73,996	57,442
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (3,164)	$ (1,966)
Non-Agency, Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	5	5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	$ 30,458	$ 30,971
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(1,000)	(792)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	30,458	30,971
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,000)	$ (792)
Corporate Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	15	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 25,762	$ 2,406
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(342)	(80)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	4,642	2,489
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(268)	(24)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	30,404	4,895
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (610)	$ (104)
Other Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	$ 2,844	$ 1,921
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(131)	(73)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	2,844	1,921
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (131)	$ (73)

Securities - Summary of Gross_2

Securities - Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Held-to-maturity (Details) $ in Thousands	Dec. 31, 2018USD ($)Security	Dec. 31, 2017USD ($)Security
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	46	28
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 36,251	$ 42,211
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(711)	(155)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	42,862	13,865
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(949)	(181)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	79,113	56,076
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,660)	$ (336)
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	23	12
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 8,127	$ 7,409
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(58)	(38)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	8,792	1,548
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(152)	(44)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	16,919	8,957
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (210)	$ (82)
Agency, Residential Mortgage-Backed Securities
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	16	13
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 6,625	$ 24,344
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(150)	(107)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	21,139	7,935
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(381)	(96)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	27,764	32,279
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (531)	$ (203)
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	7	3
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 21,499	$ 10,458
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(503)	(10)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	12,931	4,382
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(416)	(41)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	34,430	14,840
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (919)	$ (51)

Securities - Summary of Proceed

Securities - Summary of Proceeds From Sales of Securities Available-for-sale and Associated Gains and Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Available For Sale Securities Gross Realized Gain Loss [Abstract]
Proceeds	$ 5,134	$ 8	$ 534,418
Gross gains	$ 164	$ 8	3,358
Gross losses			$ 131

Securities - Schedule of Amorti

Securities - Schedule of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities Debt Maturities, Amortized Cost [Abstract]
Available-for-sale Securities, Due in one year or less, Amortized Cost	$ 70,830
Available-for-sale Securities, Due from one to five years, Amortized Cost	172,020
Available-for-sale Securities, Due from five to ten years, Amortized Cost	75,017
Available-for-sale Securities, Due after ten years, Amortized Cost	18,277
Available-for-sale Securities, Amortized Cost	834,254	$ 593,167
Held-to-maturity Securities Debt Maturities, Amortized Cost [Abstract]
Held-to-maturity Securities, Due from one to five years, Amortized Cost	5,966
Held-to-maturity Securities, Due from five to ten years, Amortized Cost	10,075
Held-to-maturity Securities, Due after ten years, Amortized Cost	7,794
Held-to-maturity Securities, Amortized Cost	99,266	117,163
Available-for-sale Securities Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Due in one year or less, Fair Value	70,621
Available-for-sale Securities, Due from one to five years, Fair Value	170,632
Available-for-sale Securities, Due from five to ten years, Fair Value	74,725
Available-for-sale Securities, Due after ten years, Fair Value	18,284
Total	817,656	583,236
Held-to-maturity Securities Debt Maturities, Fair Value [Abstract]
Held-to-maturity Securities, Due from one to five years, Fair Value	5,903
Held-to-maturity Securities, Due from five to ten years, Fair Value	10,019
Held-to-maturity Securities, Due after ten years, Fair Value	7,743
Total	97,739	117,277
Mortgage-Backed Securities
Available-for-sale Securities Debt Maturities, Amortized Cost [Abstract]
Available-for-sale Securities, Not due at single maturity, Amortized Cost	494,037
Held-to-maturity Securities Debt Maturities, Amortized Cost [Abstract]
Held-to-maturity Securities, Mortgage-backed securities, Amortized Cost	75,431
Available-for-sale Securities Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Not due at single maturity, Fair Value	477,476
Held-to-maturity Securities Debt Maturities, Fair Value [Abstract]
Held-to-maturity Securities, Mortgage-backed securities, Fair Value	74,074
Other Securities With No Defined Maturity
Available-for-sale Securities Debt Maturities, Amortized Cost [Abstract]
Available-for-sale Securities, Not due at single maturity, Amortized Cost	4,073
Available-for-sale Securities, Amortized Cost	4,613	3,627
Available-for-sale Securities Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Not due at single maturity, Fair Value	5,918
Total	$ 6,609	$ 5,284

Loans and Lease Receivables - S

Loans and Lease Receivables - Schedule of Outstanding Loan and Lease Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	$ 3,499,463	$ 2,275,691
Net unamortized deferred fees and costs	(1,293)	(1,720)
Initial direct costs	3,456	3,521
Allowance for loan and lease losses	(25,201)	(16,706)	$ (10,923)	$ (7,632)
Net loans and leases	3,476,425	2,260,786
Lease financing receivables
Net minimum lease payments	204,646	188,986
Unguaranteed residual values	1,535	1,644
Unearned income	(18,384)	(16,465)
Total lease financing receivables	187,797	174,165
Initial direct costs	3,456	3,521
Lease financial receivables before allowance for lease losses	191,253	177,686
Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	1,261,594	891,971
Allowance for loan and lease losses	(7,540)	(4,794)	(1,945)	(2,280)
Residential Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	704,899	577,123
Allowance for loan and lease losses	(1,751)	(1,638)	(2,483)	(2,981)
Construction, Land Development, and Other Land
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	186,258	105,996
Allowance for loan and lease losses	(466)	(222)	(742)	(232)
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	1,145,240	522,254
Allowance for loan and lease losses	(12,932)	(7,418)	(4,196)	(1,403)
Installment and Other
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	13,675	4,182
Allowance for loan and lease losses	(49)	(41)	(334)	(357)
Lease Financing Receivables
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	187,797	174,165
Allowance for loan and lease losses	$ (2,463)	$ (2,593)	$ (1,223)	$ (379)

Loans and Lease Receivables - A

Loans and Lease Receivables - Additional Information (Details) - USD ($)	Dec. 31, 2018	May 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	$ 3,499,463,000		$ 2,275,691,000
Loans held for sale pledged as security for borrowings	1,400,000,000		516,900,000
Allowance for loan and lease losses	25,201,000		16,706,000	$ 10,923,000	$ 7,632,000
Acquired Impaired Loans
Accounts Notes And Loans Receivable [Line Items]
Loans acquired	0	$ 25,025,000	0
Allowance for loan and lease losses	2,700,000		3,900,000
Acquired Non-Impaired Loans and Leases | First Evanston
Accounts Notes And Loans Receivable [Line Items]
Loans acquired	891,000,000
Installment and Other
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	13,675,000		4,182,000
Overdraft deposits reclassified as loans	1,700,000		617,000
Allowance for loan and lease losses	49,000		41,000	$ 334,000	$ 357,000
U.S. Government Guaranteed Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	$ 108,700,000		$ 77,000,000

Loans and Lease Receivables -_2

Loans and Lease Receivables - Summary of Minimum Annual Lease Payments for Lease Financing Receivables (Details) $ in Thousands	Dec. 31, 2018USD ($)
Receivables [Abstract]
2019	$ 71,802
2020	58,646
2021	39,385
2022	23,990
2023	9,752
Thereafter	1,071
Total	$ 204,646

Loans and Lease Receivables -_3

Loans and Lease Receivables - Summary of Balances for Each Respective Loan and Lease Category (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	$ 3,501,626	$ 2,277,492	$ 2,148,011
Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	2,237,798	1,573,383
Acquired Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	277,542	327,690
Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	986,286	376,419
Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	1,261,607	891,693	796,344
Commercial Real Estate | Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	652,234	513,622
Commercial Real Estate | Acquired Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	146,808	166,712
Commercial Real Estate | Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	462,565	211,359
Residential Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	704,902	577,218	610,738
Residential Real Estate | Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	466,309	400,571
Residential Real Estate | Acquired Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	113,934	144,562
Residential Real Estate | Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	124,659	32,085
Construction, Land Development, and Other Land
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	185,349	105,429	140,766
Construction, Land Development, and Other Land | Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	144,128	97,638
Construction, Land Development, and Other Land | Acquired Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	3,779	5,946
Construction, Land Development, and Other Land | Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	37,442	1,845
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	1,144,797	521,238	438,238
Commercial and Industrial | Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	803,508	416,499
Commercial and Industrial | Acquired Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	12,617	10,008
Commercial and Industrial | Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	328,672	94,731
Installment and Other
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	13,718	4,228	2,959
Installment and Other | Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	11,718	3,724
Installment and Other | Acquired Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	404	462
Installment and Other | Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	1,596	42
Lease Financing Receivables
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	191,253	177,686	$ 158,966
Lease Financing Receivables | Originated
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	159,901	141,329
Lease Financing Receivables | Acquired Non-Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans and leases	$ 31,352	$ 36,357

Loans and Lease Receivables - E

Loans and Lease Receivables - Estimated Fair Value of Impaired Loans Acquired at Acquisition (Details) - Acquired Impaired Loans - USD ($)	Dec. 31, 2018	May 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Undiscounted contractual cash flows		$ 33,594,000
Undiscounted cash flows not expected to be collected (non-accretable difference)		5,003,000
Undiscounted cash flows expected to be collected		28,591,000
Accretable yield at acquisition		(3,566,000)
Estimated fair value of impaired loans acquired at acquisition	$ 0	$ 25,025,000	$ 0

Loans and Lease Receivables -_4

Loans and Lease Receivables - Summary of Outstanding Balance and Carrying Amount of All Acquired Impaired Loans (Details) - Acquired Impaired Loans - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Outstanding Balance	$ 428,768	$ 476,980
Carrying Value	277,542	327,690
Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Outstanding Balance	216,137	235,898
Carrying Value	146,808	166,712
Residential Real Estate
Accounts Notes And Loans Receivable [Line Items]
Outstanding Balance	173,962	207,660
Carrying Value	113,934	144,562
Construction, Land Development, and Other Land
Accounts Notes And Loans Receivable [Line Items]
Outstanding Balance	11,962	13,270
Carrying Value	3,779	5,946
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Outstanding Balance	24,972	18,333
Carrying Value	12,617	10,008
Installment and Other
Accounts Notes And Loans Receivable [Line Items]
Outstanding Balance	1,735	1,819
Carrying Value	$ 404	$ 462

Loans and Lease Receivables -_5

Loans and Lease Receivables - Summary of Changes in Accretable Yield for Acquired Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Beginning balance	$ 36,446	$ 36,868	$ 43,915
Additions	3,566		6,916
Accretion to interest income	(23,982)	(24,597)	(26,208)
Reclassification from nonaccretable difference	21,085	24,175	12,245
Ending balance	$ 37,115	$ 36,446	$ 36,868

Loans and Lease Receivables -_6

Loans and Lease Receivables - Schedule of Unpaid Principal Balance and Carrying Value for Acquired Non-impaired Loans and Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	$ 3,501,626	$ 2,277,492	$ 2,148,011
Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	1,018,921	399,601
Loans and leases	986,286	376,419
Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	1,261,607	891,693	796,344
Commercial Real Estate | Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	473,262	221,710
Loans and leases	462,565	211,359
Residential Real Estate
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	704,902	577,218	610,738
Residential Real Estate | Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	127,478	32,605
Loans and leases	124,659	32,085
Construction, Land Development, and Other Land
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	185,349	105,429	140,766
Construction, Land Development, and Other Land | Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	38,494	1,926
Loans and leases	37,442	1,845
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	1,144,797	521,238	438,238
Commercial and Industrial | Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	344,879	105,529
Loans and leases	328,672	94,731
Installment and Other
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	13,718	4,228	2,959
Installment and Other | Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	1,831	355
Loans and leases	1,596	42
Lease Financing Receivables
Accounts Notes And Loans Receivable [Line Items]
Loans and leases	191,253	177,686	$ 158,966
Lease Financing Receivables | Acquired Non-impaired Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Unpaid Principal Balance	32,977	37,476
Loans and leases	$ 31,352	$ 36,357

Allowance for Loan and Lease _3

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of Allowance for Loan and Lease Losses and Corresponding Loan and Lease Balances (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for loan and lease losses
Beginning balance				$ 16,706				$ 10,923	$ 16,706	$ 10,923	$ 7,632
Provisions	$ 3,882	$ 5,842	$ 3,956	5,115	$ 3,347	$ 3,900	$ 3,515	1,891	18,795	12,653	10,352
Charge-offs									(11,804)	(8,196)	(7,817)
Recoveries									1,504	1,326	756
Ending balance	25,201				16,706				25,201	16,706	10,923
Ending balance:
Individually evaluated for impairment												$ 6,649	$ 3,965	$ 1,017
Collectively evaluated for impairment												15,817	8,867	8,295
Allowance for loan and lease losses	25,201			16,706	16,706			10,923	25,201	16,706	10,923	25,201	16,706	10,923
Loans and leases ending balance:
Individually evaluated for impairment												35,914	31,111	11,926
Collectively evaluated for impairment												3,188,170	1,918,691	1,732,048
Total loans and leases												3,501,626	2,277,492	2,148,011
Loans Acquired with Deteriorated Credit Quality
Ending balance:
Loans acquired with deteriorated credit quality												2,735	3,874	1,611
Loans and leases ending balance:
Loans acquired with deteriorated credit quality												277,542	327,690	404,037
Commercial Real Estate
Allowance for loan and lease losses
Beginning balance				4,794				1,945	4,794	1,945	2,280
Provisions									4,543	4,343	4,032
Charge-offs									(1,865)	(1,494)	(4,367)
Recoveries									68
Ending balance	7,540				4,794				7,540	4,794	1,945
Ending balance:
Individually evaluated for impairment												2,191	1,101
Collectively evaluated for impairment												4,105	1,765	1,456
Allowance for loan and lease losses	7,540			4,794	4,794			1,945	4,794	4,794	1,945	7,540	4,794	1,945
Loans and leases ending balance:
Individually evaluated for impairment												11,983	13,884	8,916
Collectively evaluated for impairment												1,102,816	711,097	580,125
Total loans and leases												1,261,607	891,693	796,344
Commercial Real Estate | Loans Acquired with Deteriorated Credit Quality
Ending balance:
Loans acquired with deteriorated credit quality												1,244	1,928	489
Loans and leases ending balance:
Loans acquired with deteriorated credit quality												146,808	166,712	207,303
Residential Real Estate
Allowance for loan and lease losses
Beginning balance				1,638				2,483	1,638	2,483	2,981
Provisions									113	(405)	135
Charge-offs										(440)	(633)
Ending balance	1,751				1,638				1,751	1,638	2,483
Ending balance:
Individually evaluated for impairment												61	158	293
Collectively evaluated for impairment												1,323	1,047	1,743
Allowance for loan and lease losses	1,751			1,638	1,638			2,483	1,638	1,638	2,483	1,751	1,638	2,483
Loans and leases ending balance:
Individually evaluated for impairment												2,137	2,429	1,300
Collectively evaluated for impairment												588,831	430,227	433,721
Total loans and leases												704,902	577,218	610,738
Residential Real Estate | Loans Acquired with Deteriorated Credit Quality
Ending balance:
Loans acquired with deteriorated credit quality												367	433	447
Loans and leases ending balance:
Loans acquired with deteriorated credit quality												113,934	144,562	175,717
Construction, Land Development, and Other Land
Allowance for loan and lease losses
Beginning balance				222				742	222	742	232
Provisions									662	(520)	605
Charge-offs									(418)		(95)
Ending balance	466				222				466	222	742
Ending balance:
Collectively evaluated for impairment												466	145	742
Allowance for loan and lease losses	466			222	222			742	222	222	742	466	222	742
Loans and leases ending balance:
Collectively evaluated for impairment												181,570	99,483	133,787
Total loans and leases												185,349	105,429	140,766
Construction, Land Development, and Other Land | Loans Acquired with Deteriorated Credit Quality
Ending balance:
Loans acquired with deteriorated credit quality													77
Loans and leases ending balance:
Loans acquired with deteriorated credit quality												3,779	5,946	6,979
Commercial and Industrial
Allowance for loan and lease losses
Beginning balance				7,418				4,196	7,418	4,196	1,403
Provisions									12,089	6,058	2,869
Charge-offs									(6,944)	(2,836)	(76)
Recoveries									369
Ending balance	12,932				7,418				12,932	7,418	4,196
Ending balance:
Individually evaluated for impairment												4,397	2,692	396
Collectively evaluated for impairment												7,413	3,308	3,126
Allowance for loan and lease losses	12,932			7,418	7,418			4,196	7,418	7,418	4,196	12,932	7,418	4,196
Loans and leases ending balance:
Individually evaluated for impairment												21,794	14,784	1,382
Collectively evaluated for impairment												1,110,386	496,446	423,392
Total loans and leases												1,144,797	521,238	438,238
Commercial and Industrial | Loans Acquired with Deteriorated Credit Quality
Ending balance:
Loans acquired with deteriorated credit quality												1,122	1,418	674
Loans and leases ending balance:
Loans acquired with deteriorated credit quality												12,617	10,008	13,464
Installment and Other
Allowance for loan and lease losses
Beginning balance				41				334	41	334	357
Provisions									68	34	(11)
Charge-offs									(60)	(327)	(12)
Ending balance	49				41				49	41	334
Ending balance:
Individually evaluated for impairment													14	328
Collectively evaluated for impairment												47	9	5
Allowance for loan and lease losses	49			41	41			334	41	41	334	49	41	334
Loans and leases ending balance:
Individually evaluated for impairment													14	328
Collectively evaluated for impairment												13,314	3,752	2,057
Total loans and leases												13,718	4,228	2,959
Installment and Other | Loans Acquired with Deteriorated Credit Quality
Ending balance:
Loans acquired with deteriorated credit quality												2	18	1
Loans and leases ending balance:
Loans acquired with deteriorated credit quality												404	462	574
Lease Financing Receivables
Allowance for loan and lease losses
Beginning balance				2,593				1,223	2,593	1,223	379
Provisions									1,320	3,143	2,722
Charge-offs									(2,517)	(3,099)	(2,634)
Recoveries									1,067	1,326	756
Ending balance	2,463				2,593				2,463	2,593	1,223
Ending balance:
Collectively evaluated for impairment												2,463	2,593	1,223
Allowance for loan and lease losses	$ 2,463			$ 2,593	$ 2,593			$ 1,223	$ 2,593	$ 2,593	$ 1,223	2,463	2,593	1,223
Loans and leases ending balance:
Collectively evaluated for impairment												191,253	177,686	158,966
Total loans and leases												$ 191,253	$ 177,686	$ 158,966

Allowance for Loan and Lease _4

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans And Leases Receivable Disclosure [Line Items]
Increase (decrease) in allowance for loan and lease losses	$ 8,500,000	$ 5,800,000	$ 3,300,000
Commitments outstanding on troubled debt restructurings	500,000	0	0
Recorded investment in troubled debt restructurings that subsequently defaulted within twelve months	340,000	144,000	477,000
Reserve for unfunded commitments	1,200,000	923,000
Provisions for unfunded commitments	317,000	162,000
Charge-offs or recoveries related to reserve for unfunded commitments	0	0
Acquired Impaired Loans
Loans And Leases Receivable Disclosure [Line Items]
Increase (decrease) in allowance for loan and lease losses	$ (1,100,000)	$ 2,300,000	$ (1,700,000)

Allowance for Loan and Lease _5

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of Recorded Investment, Unpaid Principal Balance, Related Allowance, Average Recorded Investment and Interest Income Recognized (Details) - Loans Excluding Acquired Impaired Loans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Impaired [Line Items]
Recorded Investment	$ 35,914	$ 31,111	$ 11,926
Unpaid Principal Balance	41,231	34,479	13,783
Related Allowance	6,649	3,965	1,017
Average Recorded Investment	34,687	21,479	12,079
Interest Income Recognized	2,139	1,555	365
Commercial Real Estate
Financing Receivable Impaired [Line Items]
Recorded Investment, With no related allowance recorded	6,110	11,425	8,916
Recorded Investment, With an allowance recorded	5,873	2,459
Unpaid Principal Balance, With no related allowance recorded	7,693	12,936	9,502
Unpaid Principal Balance, With an allowance recorded	6,313	2,634
Related Allowance	2,191	1,101
Average Recorded Investment, With no related allowance recorded	8,968	10,482	8,975
Average Recorded Investment, With an allowance recorded	5,328	1,988
Interest Income Recognized, With no related allowance recorded	590	525	305
Interest Income Recognized, With an allowance recorded	270	187
Residential Real Estate
Financing Receivable Impaired [Line Items]
Recorded Investment, With no related allowance recorded	1,886	2,075	804
Recorded Investment, With an allowance recorded	251	354	496
Unpaid Principal Balance, With no related allowance recorded	1,858	2,046	1,999
Unpaid Principal Balance, With an allowance recorded	253	351	528
Related Allowance	61	158	293
Average Recorded Investment, With no related allowance recorded	1,917	1,781	827
Average Recorded Investment, With an allowance recorded	311	422	519
Interest Income Recognized, With no related allowance recorded	43	72	45
Interest Income Recognized, With an allowance recorded	4	6	1
Construction, Land Development, and Other Land
Financing Receivable Impaired [Line Items]
Average Recorded Investment, With no related allowance recorded		295
Average Recorded Investment, With an allowance recorded		14
Interest Income Recognized, With no related allowance recorded		2
Commercial and Industrial
Financing Receivable Impaired [Line Items]
Recorded Investment, With no related allowance recorded	11,193	5,470	521
Recorded Investment, With an allowance recorded	10,601	9,314	861
Unpaid Principal Balance, With no related allowance recorded	13,961	6,774	524
Unpaid Principal Balance, With an allowance recorded	11,153	9,724	869
Related Allowance	4,397	2,692	396
Average Recorded Investment, With no related allowance recorded	8,680	2,875	516
Average Recorded Investment, With an allowance recorded	9,472	3,460	914
Interest Income Recognized, With no related allowance recorded	483	265	(2)
Interest Income Recognized, With an allowance recorded	749	486
Installment and Other
Financing Receivable Impaired [Line Items]
Recorded Investment, With an allowance recorded		14	328
Unpaid Principal Balance, With an allowance recorded		14	361
Related Allowance		14	328
Average Recorded Investment, With an allowance recorded	$ 11	162	328
Interest Income Recognized, With an allowance recorded		$ 12	$ 16

Allowance for Loan and Lease _6

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of Risk Rating Categories of Loans and Leases Considered for Inclusion in Allowance for Loan and Lease Losses Calculation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 3,501,626	$ 2,277,492	$ 2,148,011
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,261,607	891,693	796,344
Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	704,902	577,218	610,738
Construction, Land Development, and Other Land
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	185,349	105,429	140,766
Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,144,797	521,238	438,238
Installment and Other
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	13,718	4,228	2,959
Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	191,253	177,686	$ 158,966
Loans Excluding Acquired Impaired Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	3,224,084	1,949,802
Loans Excluding Acquired Impaired Loans | Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,114,799	724,981
Loans Excluding Acquired Impaired Loans | Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	590,968	432,656
Loans Excluding Acquired Impaired Loans | Construction, Land Development, and Other Land
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	181,570	99,483
Loans Excluding Acquired Impaired Loans | Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,132,180	511,230
Loans Excluding Acquired Impaired Loans | Installment and Other
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	13,314	3,766
Loans Excluding Acquired Impaired Loans | Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	191,253	177,686
Loans Excluding Acquired Impaired Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	2,870,431	1,704,311
Loans Excluding Acquired Impaired Loans | Pass | Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,009,041	638,066
Loans Excluding Acquired Impaired Loans | Pass | Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	553,665	398,743
Loans Excluding Acquired Impaired Loans | Pass | Construction, Land Development, and Other Land
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	147,123	73,935
Loans Excluding Acquired Impaired Loans | Pass | Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	962,291	415,163
Loans Excluding Acquired Impaired Loans | Pass | Installment and Other
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	9,997	3,732
Loans Excluding Acquired Impaired Loans | Pass | Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	188,314	174,672
Loans Excluding Acquired Impaired Loans | Watch
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	253,552	176,996
Loans Excluding Acquired Impaired Loans | Watch | Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	76,276	58,217
Loans Excluding Acquired Impaired Loans | Watch | Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	29,522	29,165
Loans Excluding Acquired Impaired Loans | Watch | Construction, Land Development, and Other Land
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	31,376	22,380
Loans Excluding Acquired Impaired Loans | Watch | Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	112,996	67,024
Loans Excluding Acquired Impaired Loans | Watch | Installment and Other
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	3,302	20
Loans Excluding Acquired Impaired Loans | Watch | Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	80	190
Loans Excluding Acquired Impaired Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	62,437	34,892
Loans Excluding Acquired Impaired Loans | Special Mention | Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	17,602	14,645
Loans Excluding Acquired Impaired Loans | Special Mention | Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	5,656	2,251
Loans Excluding Acquired Impaired Loans | Special Mention | Construction, Land Development, and Other Land
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	3,071	3,168
Loans Excluding Acquired Impaired Loans | Special Mention | Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	34,314	13,535
Loans Excluding Acquired Impaired Loans | Special Mention | Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,794	1,293
Loans Excluding Acquired Impaired Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	37,417	33,331
Loans Excluding Acquired Impaired Loans | Substandard | Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	11,880	14,053
Loans Excluding Acquired Impaired Loans | Substandard | Residential Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	2,125	2,497
Loans Excluding Acquired Impaired Loans | Substandard | Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	22,579	15,508
Loans Excluding Acquired Impaired Loans | Substandard | Installment and Other
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	15	14
Loans Excluding Acquired Impaired Loans | Substandard | Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	818	1,259
Loans Excluding Acquired Impaired Loans | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	247	272
Loans Excluding Acquired Impaired Loans | Doubtful | Lease Financing Receivables
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 247	$ 272

Allowance for Loan and Lease _7

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of Contractual Delinquency Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	$ 3,501,626	$ 2,277,492	$ 2,148,011
Commercial Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	1,261,607	891,693	796,344
Residential Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	704,902	577,218	610,738
Construction, Land Development, and Other Land
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	185,349	105,429	140,766
Commercial and Industrial
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	1,144,797	521,238	438,238
Installment and Other
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	13,718	4,228	2,959
Lease Financing Receivables
Financing Receivable Recorded Investment Past Due [Line Items]
Total loans and leases	191,253	177,686	$ 158,966
Acquired Non-Impaired and Originated Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	50,297	30,950
Non-accrual	25,834	15,764
Current	3,173,787	1,918,852
Total loans and leases	3,224,084	1,949,802
Acquired Non-Impaired and Originated Loans | 30-59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	19,697	12,613
Acquired Non-Impaired and Originated Loans | 60-89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	4,766	2,573
Acquired Non-Impaired and Originated Loans | Commercial Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	18,288	14,210
Non-accrual	9,484	8,459
Current	1,096,511	710,771
Total loans and leases	1,114,799	724,981
Acquired Non-Impaired and Originated Loans | Commercial Real Estate | 30-59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	6,659	4,783
Acquired Non-Impaired and Originated Loans | Commercial Real Estate | 60-89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,145	968
Acquired Non-Impaired and Originated Loans | Residential Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	7,014	2,240
Non-accrual	1,815	2,092
Current	583,954	430,416
Total loans and leases	590,968	432,656
Acquired Non-Impaired and Originated Loans | Residential Real Estate | 30-59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	4,488	148
Acquired Non-Impaired and Originated Loans | Residential Real Estate | 60-89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	711
Acquired Non-Impaired and Originated Loans | Construction, Land Development, and Other Land
Financing Receivable Recorded Investment Past Due [Line Items]
Current	181,570	99,483
Total loans and leases	181,570	99,483
Acquired Non-Impaired and Originated Loans | Commercial and Industrial
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	21,137	11,982
Non-accrual	13,932	4,348
Current	1,111,043	499,248
Total loans and leases	1,132,180	511,230
Acquired Non-Impaired and Originated Loans | Commercial and Industrial | 30-59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	5,829	6,667
Acquired Non-Impaired and Originated Loans | Commercial and Industrial | 60-89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,376	967
Acquired Non-Impaired and Originated Loans | Installment and Other
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,948	32
Non-accrual	12	14
Current	11,366	3,734
Total loans and leases	13,314	3,766
Acquired Non-Impaired and Originated Loans | Installment and Other | 30-59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,932	18
Acquired Non-Impaired and Originated Loans | Installment and Other | 60-89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	4
Acquired Non-Impaired and Originated Loans | Lease Financing Receivables
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,910	2,486
Non-accrual	591	851
Current	189,343	175,200
Total loans and leases	191,253	177,686
Acquired Non-Impaired and Originated Loans | Lease Financing Receivables | 30-59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	789	997
Acquired Non-Impaired and Originated Loans | Lease Financing Receivables | 60-89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 530	$ 638

Allowance for Loan and Lease _8

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of TDR's by Loan Category (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)Loan	Dec. 31, 2017USD ($)Loan	Dec. 31, 2016USD ($)Loan
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	22	10	5
Pre-Modification Outstanding Recorded Investment	$ 11,039	$ 3,117	$ 1,154
Post-Modification Outstanding Recorded Investment	9,127	2,630	$ 1,154
Charge-offs	1,912	487
Specific Reserves	$ 2,246	$ 357
Accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	7	4	3
Pre-Modification Outstanding Recorded Investment	$ 1,813	$ 1,061	$ 602
Post-Modification Outstanding Recorded Investment	1,813	$ 1,061	$ 602
Specific Reserves	$ 213
Non-accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	15	6	2
Pre-Modification Outstanding Recorded Investment	$ 9,226	$ 2,056	$ 552
Post-Modification Outstanding Recorded Investment	7,314	1,569	$ 552
Charge-offs	1,912	487
Specific Reserves	$ 2,033	$ 357
Commercial Real Estate | Accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	4	3	1
Pre-Modification Outstanding Recorded Investment	$ 1,508	$ 912	$ 421
Post-Modification Outstanding Recorded Investment	1,508	$ 912	$ 421
Specific Reserves	$ 113
Commercial Real Estate | Non-accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	9	2	1
Pre-Modification Outstanding Recorded Investment	$ 2,512	$ 743	$ 477
Post-Modification Outstanding Recorded Investment	2,471	743	$ 477
Charge-offs	41
Specific Reserves	$ 743	$ 111
Commercial and Industrial | Accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	2
Pre-Modification Outstanding Recorded Investment	$ 191
Post-Modification Outstanding Recorded Investment	191
Specific Reserves	$ 100
Commercial and Industrial | Non-accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	6	3
Pre-Modification Outstanding Recorded Investment	$ 6,714	$ 1,246
Post-Modification Outstanding Recorded Investment	4,843	759
Charge-offs	1,871	487
Specific Reserves	$ 1,290	$ 246
Residential Real Estate | Accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan	1	1	2
Pre-Modification Outstanding Recorded Investment	$ 114	$ 149	$ 181
Post-Modification Outstanding Recorded Investment	$ 114	$ 149	$ 181
Residential Real Estate | Non-accruing
Financing Receivable Modifications [Line Items]
Number of Loans | Loan		1	1
Pre-Modification Outstanding Recorded Investment		$ 67	$ 75
Post-Modification Outstanding Recorded Investment		$ 67	$ 75

Allowance for Loan and Lease _9

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Summary of Loans Modified as Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Beginning balance	$ 1,061	$ 602	$ 1,908
Additions	37	1,017	181
Net payments	(86)	(144)	(1,010)
Net transfers from (to) non-accrual	801	(414)	(477)
Ending balance	1,813	1,061	602
Beginning balance	1,569	552	833
Additions	8,408	681
Net payments	(1,718)	(78)	(758)
Charge-offs	(144)
Net transfers from (to) accrual	(801)	414	477
Ending balance	7,314	1,569	552
Total troubled debt restructurings	$ 9,127	$ 2,630	$ 1,154

Servicing Assets - Activity for

Servicing Assets - Activity for Servicing Assets and Related Changes in Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Transfers And Servicing [Abstract]
Beginning balance	$ 21,400	$ 21,091
Acquired servicing assets at fair value			$ 20,295
Additions, net	7,562	6,250	539
Changes in fair value	(9,269)	(5,941)	257
Ending balance	$ 19,693	$ 21,400	$ 21,091

Servicing Assets - Unpaid Princ

Servicing Assets - Unpaid Principal Balances of Loans Serviced for Others (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loan portfolios serviced for:
Unpaid principal balances of loans serviced	$ 1,258,099	$ 1,112,901
SBA guaranteed loans
Loan portfolios serviced for:
Unpaid principal balances of loans serviced	1,151,915	1,021,143
USDA guaranteed loans
Loan portfolios serviced for:
Unpaid principal balances of loans serviced	$ 106,184	$ 91,758

Servicing Assets - Additional I

Servicing Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loan Servicing Revenue [Member]
Accounts Notes And Loans Receivable [Line Items]
Fees and charges	$ 10,272,000	$ 9,599,000	$ 1,649,000
Loan Servicing Asset Revaluation [Member]
Accounts Notes And Loans Receivable [Line Items]
Fees and charges	$ (9,300,000)	$ (5,900,000)	$ 257,000

Other Real Estate Owned - Chang

Other Real Estate Owned - Change in Other Real Estate Owned (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Banking And Thrift [Abstract]
Other real estate owned, beginning balance	$ 10,626	$ 16,570	$ 26,715
Acquisition of OREO through business combination			1,525
Net additions to OREO	2,436	6,690	6,659
Proceeds from sales of OREO	(7,495)	(13,898)	(18,637)
Gains on sales of OREO	383	2,147	1,366
Valuation adjustments	(636)	(883)	(1,058)
Other real estate owned, ending balance	$ 5,314	$ 10,626	$ 16,570

Other Real Estate Owned - Addit

Other Real Estate Owned - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate [Line Items]
Foreclosed real estate properties recorded as result of obtaining physical possession of property	$ 5,314,000	$ 10,626,000	$ 16,570,000	$ 26,715,000
Residential consumer mortgage loans in process of foreclosure	2,300,000	1,900,000
Proceeds from sale of internally financed sales of OREO	444,000	0	$ 1,400,000
Residential Real Estate
Real Estate [Line Items]
Foreclosed real estate properties recorded as result of obtaining physical possession of property	$ 838,000	$ 3,600,000

Premises and Equipment and As_3

Premises and Equipment and Assets Held For Sale - Schedule for Classification of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Premises and equipment
Premises	$ 62,675	$ 61,714
Furniture, fixtures and equipment	15,779	13,591
Leasehold improvements	6,544	4,245
Total cost	84,998	79,550
Less accumulated depreciation and amortization	(33,679)	(29,880)
Premises and equipment, net	97,680	95,224
Net book value of premises, furniture, fixtures, equipment, leasehold improvements
Premises and equipment
Premises and equipment, net	51,319	49,670
Construction in progress
Premises and equipment
Premises and equipment, net	830	899
Land
Premises and equipment
Premises and equipment, net	$ 45,531	$ 44,655

Premises and Equipment and As_4

Premises and Equipment and Assets Held For Sale - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)item	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)item
Property Plant And Equipment [Abstract]
Depreciation and amortization of premises and equipment | $	$ 5,579	$ 5,193	$ 5,060
Number of branches closure	6	2	12
Number of other Facilities	2

Premises and Equipment and As_5

Premises and Equipment and Assets Held For Sale - Change in Assets Held for Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Beginning balance	$ 9,779	$ 14,748	$ 2,259
Transfers in	9,074	3,372	14,496
Transfers out	(425)
Proceeds from sales	(4,415)	(5,373)	(2,566)
Internally financed sales		(1,800)
Net gains (losses) on sales	1,103	(217)	967
Impairment loss	(627)	(951)	(408)
Ending balance	$ 14,489	$ 9,779	$ 14,748

Goodwill, Core Deposit Intang_3

Goodwill, Core Deposit Intangible and Other Intangible Assets - Summary of Changes in Goodwill and Core Deposit Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Goodwill And Intangible Assets [Line Items]
Beginning balance, Goodwill	$ 54,562	$ 51,975	$ 25,688
Additions	73,615	2,587	26,287
Ending balance, Goodwill	128,177	54,562	51,975
Amortization or accretion	(5,629)	(3,074)	(3,003)
Core Deposits
Schedule Of Goodwill And Intangible Assets [Line Items]
Beginning balance	16,720	19,776	22,275
Additions	19,060		486
Amortization or accretion	(5,420)	(3,056)	(2,985)
Ending balance	30,360	16,720	19,776
Accumulated amortization or accretion	$ 18,886	$ 13,466	$ 10,410
Weighted average remaining amortization or accretion period	6 years 9 months 18 days	5 years 7 months 6 days	6 years 7 months 6 days
Customer Relationships
Schedule Of Goodwill And Intangible Assets [Line Items]
Additions	$ 3,216
Amortization or accretion	(157)
Ending balance	3,059
Accumulated amortization or accretion	$ 157
Weighted average remaining amortization or accretion period	11 years 4 months 24 days

Goodwill, Core Deposit Intang_4

Goodwill, Core Deposit Intangible and Other Intangible Assets - Additional Information (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Indefinite Lived Intangible Assets By Major Class [Line Items]
Other intangible assets, net	$ 0
Trademark
Indefinite Lived Intangible Assets By Major Class [Line Items]
Other intangible assets, net		$ 36,000	$ 50,000

Goodwill, Core Deposit Intang_5

Goodwill, Core Deposit Intangible and Other Intangible Assets - Estimated Amortization Expense for Core Deposit Intangible and Other Intangible Assets Recognized (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2019	$ 6,925
2020	6,476
2021	6,026
2022	5,578
2023	3,645
Thereafter	4,769
Total	$ 33,419	$ 16,756

Income Taxes - Provision for in

Income Taxes - Provision for income taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current tax expense:
Federal										$ 1,010
State and local									$ 1,078	1,485
Total current tax expense									1,078	2,495
Deferred tax expense:
Federal									11,469	13,554	$ 478
State and local									2,460	686	136
Remeasurement of net deferred tax assets									(760)	2,364
Total deferred tax expense before reversal of valuation allowance									13,169	16,604	614
Deferred tax valuation allowance											(61,859)
Provision (benefit) for income taxes	$ 6,460	$ 5,402	$ 1,064	$ 1,321	$ 11,851	$ (1,390)	$ 4,094	$ 4,544	$ 14,247	$ 19,099	$ (61,245)

Income Taxes - Reconciliation b

Income Taxes - Reconciliation between statutory and effective tax rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation between statutory U.S. federal income tax rate and effective tax rate
Calculated tax benefit at statutory rate	21.00%	35.00%	35.00%
Increase (decrease) in income taxes resulting from:
Reversal of valuation allowance, net of change in estimated Section 382 impact			(1167.60%)
State taxes, net of federal income tax	7.00%	6.50%	6.10%
Tax exempt income	(0.50%)	(0.70%)	(5.30%)
Share-based compensation	(0.90%)
Non-deductible expenses	0.50%	0.20%	14.80%
Remeasurement of net deferred tax assets	(1.40%)	5.80%
Total income tax expense (benefit)	25.70%	46.80%	(1117.00%)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	Jul. 01, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax [Line Items]
Corporate federal income tax rate				21.00%	35.00%	35.00%
Net income tax expense (benefit)			$ 7,200,000	$ (760,000)
Reclassification of certain income tax effects from accumulated other comprehensive income (loss)				$ (763,000)
Reversal of valuation allowance						$ 61,400,000
Operating loss carryforwards, limitations on use				Pursuant to Sections 382 and 383 of the Internal Revenue Code, annual use of net operating loss and credit carryforwards may be limited in the event a cumulative change in ownership of more than 50 percent occurs within a three-year period.
Cumulative change in ownership Percentage				50.00%
Period for cumulative change in ownership				3 years
Estimated net operating losses available eah year				$ 756,000
ASU 2018-02
Income Tax [Line Items]
Reclassification of certain income tax effects from accumulated other comprehensive income (loss)				$ 763,000
Illinois | State
Income Tax [Line Items]
Corporate income tax rate	7.00%	5.25%
State income tax benefit due to increased value of deferred tax asset related to net loss deduction					$ 4,800,000

Income Taxes - Deferred tax ass

Income Taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating losses and tax credits	$ 25,851	$ 42,062
Interest on non-accrual loans	3,039	2,755
Allowance for loan losses and loan basis	15,641	11,252
Deposits	90	5
Alternative minimum tax ("AMT") credit carryforward		2,140
Other real estate owned	393
Net unrealized holding losses on securities available-for-sale	4,622	2,766
Accrued expenses	3,747	1,576
Other	2,075	837
Total deferred tax assets	55,458	63,393
Deferred tax liabilities:
Other real estate owned		(24)
Premises and equipment	(3,752)	(3,385)
Core deposit intangibles	(9,306)	(4,656)
Servicing assets	(337)	(3,505)
Trust preferred securities	(2,710)	(2,465)
Unrealized holding gain on cash flow hedges	(1,839)	(1,390)
Other	(1,871)	(592)
Total deferred tax liabilities	(19,815)	(16,017)
Net deferred tax assets after valuation allowance	$ 35,643	$ 47,376

Income Taxes - Operating loss a

Income Taxes - Operating loss and credit carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Alternative minimum tax credits
Operating loss carryforwards
Tax credit carryforwards		$ 2,140
Federal
Operating loss carryforwards
Net operating loss carryforwards	$ 1,233	63,964
Illinois
Operating loss carryforwards
Net operating loss carryforwards	$ 340,999	$ 381,471

Income Taxes - Operating loss_2

Income Taxes - Operating loss and credit carryforwards (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2018
Federal
Operating loss carryforwards
Operating loss carryforwards expiration year	2030
Illinois
Operating loss carryforwards
Operating loss carryforwards expiration year	2021

Federal Home Loan Bank Advanc_3

Federal Home Loan Bank Advances - Summary of FHLB Advances (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Banks [Abstract]
Federal Home Loan Bank advances	$ 425,000	$ 361,506
Weighted average cost	2.56%	1.49%

Federal Home Loan Bank Advanc_4

Federal Home Loan Bank Advances - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank Advances [Line Items]
Federal home loan bank, total fixed-rate advances	$ 360,000,000
Federal home loan bank, total variable rate advances	$ 65,000,000
Federal home loan bank advances, Variable interest rate	2.41%
Federal home loan bank variable rate advances, maturity date	2019-01
Federal home loan bank, required investment conversion ratio	0.045
Additional borrowing capacity from FHLB	$ 1,300,000,000	$ 795,000,000
Federal home loan bank advances maximum borrowing capacity as percentage of total assets	35.00%
Minimum
Federal Home Loan Bank Advances [Line Items]
Federal home loan bank advances, Fixed interest rate	2.52%
Federal home loan bank fixed rate advances, maturity date	2019-01
Maximum
Federal Home Loan Bank Advances [Line Items]
Federal home loan bank advances, Fixed interest rate	2.61%
Federal home loan bank fixed rate advances, maturity date	2019-03

Other Borrowings - Summary of O

Other Borrowings - Summary of Other Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Securities sold under agreements to repurchase	$ 34,166	$ 31,187
Total	$ 34,166	$ 31,187

Other Borrowings - Additional I

Other Borrowings - Additional Information (Details) - USD ($)	Oct. 11, 2018	Jul. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 30, 2017	Oct. 13, 2016
Line Of Credit Facility [Line Items]
Repayment of lines of credit		$ 16,200,000		$ 20,650,000	$ 9,350,000
Short-term credit lines available for use, outstanding			$ 0	0
Ridgestone | Correspondent Bank | Credit agreement
Line Of Credit Facility [Line Items]
Line of credit facility, amount							$ 30,000,000
Ridgestone | Correspondent Bank | Amended Credit Agreement
Line Of Credit Facility [Line Items]
Line of credit facility, maturity date			Oct. 11, 2018
Line of credit facility, revolving credit conversion to non-revolving line of credit, description			In April 2017, the revolving line of credit was amended to a non-revolving line of credit as long as the outstanding balance exceeds $5.0 million.
Line of credit facility, revolving credit conversion to non-revolving line of credit, threshold amount						$ 5,000,000
Threshold amount for conversion of line of credit into revolving line of credit						5,000,000
Revolving line of credit facility, maximum borrowing capacity						$ 5,000,000
Ridgestone | Correspondent Bank | Amended Credit Agreement | LIBOR Rate
Line Of Credit Facility [Line Items]
Interest rate spread			2.50%
Ridgestone | Correspondent Bank | Amended Credit Agreement | Prime Rate
Line Of Credit Facility [Line Items]
Interest rate spread			0.25%
Ridgestone | Correspondent Bank | Third Amendment Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Line of credit facility, amount	$ 10,000,000		$ 0	$ 0
Line of credit facility, extended maturity date	Oct. 10, 2019
Line of credit facility, interest rate terms	The amended revolving line of credit bears interest at either the LIBOR plus 225 basis points or the Prime Rate minus 50 basis points, based on the Company’s election, which is required to be communicated at least three business days prior to the commencement of an interest period. If the Company fails to provide timely notification, the interest rate will be Prime Rate minus 50 basis points. As of December 31, 2018 and 2017, the line of credit has not been drawn upon, so an interest rate option has not been selected.
Ridgestone | Correspondent Bank | Third Amendment Revolving Credit Agreement | LIBOR Rate
Line Of Credit Facility [Line Items]
Interest rate spread	2.25%
Ridgestone | Correspondent Bank | Third Amendment Revolving Credit Agreement | Prime Rate
Line Of Credit Facility [Line Items]
Interest rate spread	0.50%

Other Borrowings - Summary of S

Other Borrowings - Summary of Short-term Credit Lines Available for Use (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Federal Reserve Bank of Chicago Discount Window Line
Debt Instrument [Line Items]
Short-term credit lines available for use	$ 293,613	$ 144,248
Available Federal Funds Line
Debt Instrument [Line Items]
Short-term credit lines available for use	$ 55,000	$ 55,000

Deposits - Schedule of Deposits

Deposits - Schedule of Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Non-interest-bearing demand deposits	$ 1,192,873	$ 760,887
Interest-bearing checking accounts	296,339	186,611
Money market demand accounts	640,401	349,862
Other savings	476,418	437,212
Time deposits (below $250,000)	911,603	627,255
Time deposits ($250,000 and above)	232,282	81,502
Total deposits	$ 3,749,916	$ 2,443,329

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Brokered deposits	$ 50,000,000	$ 0

Deposits - Scheduled Maturities

Deposits - Scheduled Maturities of Time Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Time Deposit [Abstract]
2019	$ 852,780
2020	240,863
2021	33,583
2022	10,584
2023	6,075
Total	$ 1,143,885	$ 708,757

Junior Subordinated Debenture_2

Junior Subordinated Debentures - Junior Subordinated Debentures by Issuance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Total liability, at par	$ 46,500	$ 36,500
Total liability, at carrying value	36,768	27,647
Metropolitan Statutory Trust 1
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Total liability, at par	35,000	35,000
RidgeStone Capital Trust I
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Total liability, at par	1,500	1,500
First Evanston Bancorp Trust I
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Total liability, at par	10,000
Junior Subordinated Debentures
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Discount	$ (9,732)	$ (8,853)
Junior Subordinated Debentures | Metropolitan Statutory Trust 1
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Stated Maturity	Mar. 17, 2034
Contractual Rate	5.58%	4.39%
Junior Subordinated Debentures | Metropolitan Statutory Trust 1 | Three-month LIBOR
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Interest Rate Spread, Description	Three-month LIBOR
Interest Rate Spread	2.79%	2.79%
Junior Subordinated Debentures | RidgeStone Capital Trust I
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Stated Maturity	Jun. 30, 2033
Contractual Rate	6.38%	5.09%
Junior Subordinated Debentures | RidgeStone Capital Trust I | Five-year LIBOR
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Interest Rate Spread, Description	Five-year LIBOR
Interest Rate Spread	3.50%	3.50%
Junior Subordinated Debentures | First Evanston Bancorp Trust I
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Stated Maturity	Mar. 15, 2035
Contractual Rate	4.57%
Junior Subordinated Debentures | First Evanston Bancorp Trust I | Three-month LIBOR
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Interest Rate Spread, Description	Three-month LIBOR
Interest Rate Spread	1.78%

Junior Subordinated Debenture_3

Junior Subordinated Debentures - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal amount	$ 46,500,000	$ 36,500,000
Accrued interest payable	3,484,000	1,306,000
Metropolitan Statutory Trust 1
Debt Instrument [Line Items]
Principal amount	$ 35,000,000	$ 35,000,000
Metropolitan Statutory Trust 1 | Junior Subordinated Debentures
Debt Instrument [Line Items]
Contractual rate	5.58%	4.39%
Accrued interest payable	$ 84,000	$ 62,000
Metropolitan Statutory Trust 1 | Junior Subordinated Debentures | Three-month LIBOR
Debt Instrument [Line Items]
Interest rate spread	2.79%	2.79%
RidgeStone Capital Trust I
Debt Instrument [Line Items]
Principal amount	$ 1,500,000	$ 1,500,000
RidgeStone Capital Trust I | Junior Subordinated Debentures
Debt Instrument [Line Items]
Contractual rate	6.38%	5.09%
Accrued interest payable	$ 0	$ 0
RidgeStone Capital Trust I | Junior Subordinated Debentures | Five-year LIBOR
Debt Instrument [Line Items]
Interest rate spread	3.50%	3.50%
First Evanston Bancorp Trust I
Debt Instrument [Line Items]
Principal amount	$ 10,000,000
First Evanston Bancorp Trust I | Junior Subordinated Debentures
Debt Instrument [Line Items]
Contractual rate	4.57%
Accrued interest payable	$ 21,000
First Evanston Bancorp Trust I | Junior Subordinated Debentures | Three-month LIBOR
Debt Instrument [Line Items]
Interest rate spread	1.78%

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($)	Jan. 01, 2017	Feb. 01, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 14, 2017
Employee Benefit Plans
Profit sharing contributions			$ 0	$ 0	$ 0
Employer matching contribution		50.00%
Contribution by employees		4.00%
Employer contribution to Plan			2,100,000	1,500,000	655,000
Compensation expense			$ 458,000	1,294,000	899,000
Common Stock
Employee Benefit Plans
Stock issued under employee stock purchase plans			8,882
Employee Stock Purchase Plan
Employee Benefit Plans
Common stock reserved for sale			191,118			200,000
Compensation expense			$ 66,000	$ 0	$ 0
3% contributed by employees
Employee Benefit Plans
Employer matching contribution	100.00%
Contribution by employees	3.00%
2% contributed by employees
Employee Benefit Plans
Employer matching contribution	50.00%
Contribution by employees	2.00%

Commitments and Contingent Li_3

Commitments and Contingent Liabilities - Summary of Minimum Annual Rental Commitments for Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 3,285
2020	2,725
2021	2,450
2022	1,488
2023	562
Thereafter	2,605
Total	$ 13,115

Commitments and Contingent Li_4

Commitments and Contingent Liabilities - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments And Contingencies Liabilities [Line Items]
Rental expenses			$ 5,500,000	$ 4,600,000	$ 3,800,000
Sublease income			723,000	702,000	737,000
Minimum rental to be received in future on subleases			$ 1,700,000
Sublease contract maturity year			2025
Data processing			$ 18,242,000	$ 9,539,000	$ 8,157,000
Fixed rate loan commitments maturity year			2032
Variable rate loan commitments maturity year			2048
Maximum
Commitments And Contingencies Liabilities [Line Items]
Commitments to make loans period			90 days
Loan commitments fixed interest rate			15.00%
Loan commitments variable interest rate			15.00%
Minimum
Commitments And Contingencies Liabilities [Line Items]
Loan commitments fixed interest rate			2.00%
Loan commitments variable interest rate			3.00%
Contract termination
Commitments And Contingencies Liabilities [Line Items]
Data processing	$ 8,100,000	$ 8,100,000
Remaining data processing cost balance			$ 3,700,000

Commitments and Contingent Li_5

Commitments and Contingent Liabilities - Summary of Contract or Notional Amount of Outstanding Loan and Lease Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commitments And Contingencies Liabilities [Line Items]
Fixed Rate	$ 76,081	$ 57,150
Variable Rate	963,062	470,766
Commitments to Extend Credit
Commitments And Contingencies Liabilities [Line Items]
Fixed Rate	74,099	55,924
Variable Rate	928,991	467,429
Letters of Credit
Commitments And Contingencies Liabilities [Line Items]
Fixed Rate	1,982	1,226
Variable Rate	$ 34,071	$ 3,337

Fair Value Measurement - Summar

Fair Value Measurement - Summary of Financial Assets And Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	$ 817,656	$ 583,236
Servicing assets, at fair value	19,693	21,400	$ 21,091
Derivative assets	10,740	5,981
Derivative liabilities	4,243	994
U.S. Treasury Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	52,667	14,863
U.S. Government Agencies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	186,498	52,958
Obligations of States, Municipalities, and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	60,233	33,170
Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	34,173	29,976
Other Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	6,609	5,284
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Servicing assets, at fair value	19,693	21,400
Derivative assets	10,740	5,981
Derivative liabilities	4,243	994
Fair Value, Measurements, Recurring | U.S. Treasury Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	52,667	14,863
Fair Value, Measurements, Recurring | U.S. Government Agencies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	186,498	52,958
Fair Value, Measurements, Recurring | Obligations of States, Municipalities, and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	60,233	33,170
Fair Value, Measurements, Recurring | Mortgage-Backed Securities; Residential | Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	272,963	307,457
Fair Value, Measurements, Recurring | Mortgage-Backed Securities; Residential | Non-Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	83,621	39,514
Fair Value, Measurements, Recurring | Mortgage-Backed Securities; Commercial | Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	90,434	69,043
Fair Value, Measurements, Recurring | Mortgage-Backed Securities; Commercial | Non-Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	30,458	30,971
Fair Value, Measurements, Recurring | Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	34,173	29,976
Fair Value, Measurements, Recurring | Other Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	6,609	5,284
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	52,667	14,863
Fair Value, Measurements, Recurring | Level 1 | Other Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	2,844	1,921
Fair Value, Measurements, Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	10,740	5,981
Derivative liabilities	4,243	994
Fair Value, Measurements, Recurring | Level 2 | U.S. Government Agencies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	186,498	52,958
Fair Value, Measurements, Recurring | Level 2 | Obligations of States, Municipalities, and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	60,038	32,795
Fair Value, Measurements, Recurring | Level 2 | Mortgage-Backed Securities; Residential | Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	272,963	307,457
Fair Value, Measurements, Recurring | Level 2 | Mortgage-Backed Securities; Residential | Non-Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	83,621	39,514
Fair Value, Measurements, Recurring | Level 2 | Mortgage-Backed Securities; Commercial | Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	90,434	69,043
Fair Value, Measurements, Recurring | Level 2 | Mortgage-Backed Securities; Commercial | Non-Agency
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	30,458	30,971
Fair Value, Measurements, Recurring | Level 2 | Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	34,173	29,976
Fair Value, Measurements, Recurring | Level 2 | Other Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	3,074	2,686
Fair Value, Measurements, Recurring | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Servicing assets, at fair value	19,693	21,400
Fair Value, Measurements, Recurring | Level 3 | Obligations of States, Municipalities, and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	195	375
Fair Value, Measurements, Recurring | Level 3 | Other Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	$ 691	$ 677

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Abstract]
Fair value, assets, level 1 to level 2 transfers, amount	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0	0
Fair value, liabilities, level 1 to level 2 transfers, amount	0	0
Fair value, liabilities, level 2 to level 1 transfers, amount	0	0
Fair value, equity, level 1 to level 2 transfers, amount	0	0
Fair value, equity, level 2 to level 1 transfers, amount	$ 0	$ 0

Fair Value Measurement - Summ_2

Fair Value Measurement - Summary of Financial Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Investment Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance, beginning of period	$ 1,052	$ 1,080
Acquired assets at fair value	314
Maturities	(494)	(175)
Amortization	5	5
Change in unrealized gain	9	142
Balance, end of period	886	1,052
Servicing Assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance, beginning of period	21,400	21,091
Additions, net	7,562	6,250
Change in fair value	(9,269)	(5,941)
Balance, end of period	$ 19,693	$ 21,400

Fair Value Measurement - Summ_3

Fair Value Measurement - Summary of Unobservable Inputs Used in Fair Value Measurements on Recurring Basis Categorized Within Level 3 of Fair Value Hierarchy (Details) - Fair Value, Measurements, Recurring - Level 3	12 Months Ended
	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impact to Valuation from an Increased or Higher Input Value	Decrease
Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected weighted average loan life	1 month 6 days
Minimum | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.085
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected weighted average loan life	10 years 4 months 24 days
Maximum | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.231
Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected weighted average loan life	5 years 1 month 6 days
Weighted Average | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.152
Obligations of States, Municipalities, and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impact to Valuation from an Increased or Higher Input Value	Decrease
Unobservable Inputs	0.024
Debt Securities, Available-for-sale, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Debt Securities, Available-for-sale, Measurement Input [Extensible List]	us-gaap:MeasurementInputDefaultRateMember
Obligations of States, Municipalities, and Political Subdivisions | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.024
Single Issuer Trust Preferred
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impact to Valuation from an Increased or Higher Input Value	Decrease
Debt Instrument, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Debt Instrument, Measurement Input [Extensible List]	us-gaap:MeasurementInputDefaultRateMember
Single Issuer Trust Preferred | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.049
Single Issuer Trust Preferred | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.054
Single Issuer Trust Preferred | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.052
Servicing Assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impact to Valuation from an Increased or Higher Input Value	Decrease
Servicing Asset, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Servicing Assets | Minimum | Prepayment Speeds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.020
Servicing Assets | Maximum | Prepayment Speeds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.174
Servicing Assets | Weighted Average | Prepayment Speeds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unobservable Inputs	0.115

Fair Value Measurement - Summ_4

Fair Value Measurement - Summary of Assets Measured at Fair Value on Non-recurring Basis, Excluding Acquired Impaired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Commercial Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	$ 9,792	$ 12,783
Residential Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	2,076	2,271
Commercial and Industrial
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	17,397	12,092
Other Real Estate Owned
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	5,314	10,626
Level 3 | Commercial Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	9,792	12,783
Level 3 | Residential Real Estate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	2,076	2,271
Level 3 | Commercial and Industrial
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	17,397	12,092
Level 3 | Other Real Estate Owned
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	5,314	10,626
Assets Held For Sale
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	14,489	9,779
Assets Held For Sale | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Assets, Fair Value	$ 14,489	$ 9,779

Fair Value Measurement - Summ_5

Fair Value Measurement - Summary of Estimated Fair Values of Financial Instruments and Levels Within Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial assets
Cash and due from banks	$ 30,190	$ 19,404
Interest bearing deposits with other banks	91,670	38,945
Securities held-to-maturity, fair value	97,739	117,277
Restricted stock, at cost	19,202	16,343
Loans held for sale	19,827	5,212
Loans and lease receivables, net (less impaired loans at fair value)	3,476,425	2,260,786
Accrued interest receivable	10,863	7,670
Financial liabilities
Federal Home Loan Bank advances	425,000	361,506
Securities sold under agreements to repurchase	34,166	31,187
Junior subordinated debentures issued to capital trusts, net	36,768	27,647
Level 1 | Carrying Amount
Financial assets
Cash and due from banks	30,190	19,404
Level 1 | Estimated Fair Value
Financial assets
Cash and due from banks	30,190	19,404
Level 2 | Carrying Amount
Financial assets
Interest bearing deposits with other banks	91,670	38,945
Securities held-to-maturity, fair value	99,266	117,163
Restricted stock, at cost	19,202	16,343
Financial liabilities
Non-interest-bearing deposits	1,192,873	760,887
Interest-bearing deposits	2,557,043	1,682,442
Accrued interest payable	3,484	1,306
Federal Home Loan Bank advances	425,000	361,506
Securities sold under agreements to repurchase	34,166	31,187
Level 2 | Estimated Fair Value
Financial assets
Interest bearing deposits with other banks	91,670	38,945
Securities held-to-maturity, fair value	97,739	117,277
Restricted stock, at cost	19,202	16,343
Financial liabilities
Non-interest-bearing deposits	1,192,873	760,887
Interest-bearing deposits	2,554,329	1,678,535
Accrued interest payable	3,484	1,306
Federal Home Loan Bank advances	425,000	361,500
Securities sold under agreements to repurchase	34,166	31,187
Level 3 | Carrying Amount
Financial assets
Loans held for sale	19,827	5,212
Loans and lease receivables, net (less impaired loans at fair value)	3,447,160	2,260,786
Accrued interest receivable	10,863	7,670
Financial liabilities
Junior subordinated debentures issued to capital trusts, net	36,768	27,647
Level 3 | Estimated Fair Value
Financial assets
Loans held for sale	21,654	5,851
Loans and lease receivables, net (less impaired loans at fair value)	3,407,652	2,240,235
Accrued interest receivable	10,863	7,670
Financial liabilities
Junior subordinated debentures issued to capital trusts, net	$ 42,351	$ 33,907

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - USD ($)	Oct. 03, 2017	Jul. 06, 2017	Oct. 31, 2014	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, voting par value				$ 0.01	$ 0.01	$ 0.01
Proceeds from the exercise of stock options					$ 2,340,000
Income tax benefit					127,000	$ 521,000	$ 360,000
Restricted Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Income tax benefit					$ 267,000	$ 83,000
Performance Options Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vested	414,894
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock in connection with restricted stock awards, shares					131,157	70,798
Number of options exercised					205,152		6,065
Omnibus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock reserved and available for issuance									1,550,000
Number of common shares available for future grants				1,350,545	1,350,545
Omnibus Plan | Restricted Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period						4 years
Shares of restricted voting common stock granted					131,157
Restricted shares vested					2,975	0
Fair value of restricted shares, vested					$ 62,000
Restricted shares vested					2,975	0
Fair value of unvested restricted stock awards				$ 3,300,000	$ 3,300,000
Omnibus Plan | Performance-based Restricted Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of restricted voting common stock granted					11,165
Period for number of shares earned under retun on average assets					3 years
Minimum target precentage in assets of peer group consisting publicly-traded bank holding companies					50.00%
Maximum target precentage in assets of peer group consisting publicly-traded bank holding companies					200.00%
Omnibus Plan | Performance-based Restricted Shares | Threshold performance
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of target number of shares to be earned					25.00%
Omnibus Plan | Performance-based Restricted Shares | 50th Percentile Performance
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of target number of shares to be earned					100.00%
Omnibus Plan | Performance-based Restricted Shares | 75th Percentile Performance
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of target number of shares to be earned					125.00%
Omnibus Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock in connection with restricted stock awards, shares		58,900				11,898
Omnibus Plan | Common Stock | Restricted Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of restricted voting common stock granted					131,157
Common stock, voting par value				$ 0.01	$ 0.01
Omnibus Plan | Common Stock | Restricted Shares | Each Anniversary of Grant Date Over Four Years
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period					4 years
Shares vest on grant date					102,559
Omnibus Plan | Common Stock | Restricted Shares | Each Anniversary of Grant Date Vest Over Three Years
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period					3 years
Shares vest on grant date					15,165
Omnibus Plan | Common Stock | Restricted Shares | First Anniversary of Grant Date
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares vest on grant date					2,268
MBG Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options granted						0
Number of options exercised						0
BYB Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common shares available for future grants									0
Number of options granted						0	212,400	1,634,568
Number of options exercised					148,748	0
Number of shares outstanding				1,598,872	1,598,872	1,783,020
Award contractual term					6 years 7 months 6 days	7 years 7 months 6 days
Options vested					345,063
Proceeds from the exercise of stock options					$ 1,700,000
Income tax benefit					$ 449,000
BYB Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common shares available for future grants			2,476,122
BYB Plan | Time Options Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award contractual term			10 years
BYB Plan | Time Options Grants | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			5 years
BYB Plan | Time Options Grants | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			1 year
BYB Plan | Performance Options Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award contractual term			10 years
BYB Plan | Performance Options Grants | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			5 years
BYB Plan | Performance Options Grants | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			1 year
FEB Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options granted				680,787
Number of options exercised				56,404	56,404
Number of shares outstanding				624,383	624,383
Award contractual term				5 years 2 months 12 days
Proceeds from the exercise of stock options					$ 601,000
Income tax benefit					$ 168,000
Conversion calculation percentage				472.50%	472.50%
FEB Plan | Restricted Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding				0	0

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Changes in Restricted Shares (Details) - Omnibus Plan - Restricted Shares - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, beginning balance	70,398
Number of shares, granted	131,157
Number of shares, vested	(2,975)	0
Number of shares, forfeited	(2,100)
Number of shares, ending balance	196,480	70,398
Weighted average grant date fair value, beginning balance	$ 20.31
Weighted average grant date fair value, granted	22.36
Weighted average grant date fair value, vested	20.96
Weighted average grant date fair value, forfeited	20.84
Weighted average grant date fair value, ending balance	$ 21.66	$ 20.31

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Stock Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation - restricted stock	$ 458	$ 1,294	$ 899
Income tax benefit	127	521	360
Unrecognized compensation expense	$ 146	$ 729	$ 1,752
Weighted-average amortization period remaining	1 year 1 month 6 days	1 year 2 months 12 days	1 year 9 months 18 days
Restricted Shares
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation - restricted stock	$ 958	$ 203
Income tax benefit	267	83
Unrecognized compensation expense	$ 3,167	$ 1,227
Weighted-average amortization period remaining	2 years 10 months 24 days	2 years 9 months 18 days

Share-Based Compensation - Fair

Share-Based Compensation - Fair Value Assumptions of Stock Options (Details) - BYB Plan	12 Months Ended
	Dec. 31, 2016$ / shares
Time Options Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.34%
Risk-free interest rate, maximum	1.40%
Expected stock price volatility	20.39%
Expected dividend yield	0.00%
Weighted average grant date fair value	$ 3.55
Time Options Grants | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 2 months 12 days
Time Options Grants | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 7 months 6 days
Performance Options Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	Implied forward rates
Expected term (years)	Variable
Expected stock price volatility, minimum	20.34%
Expected stock price volatility, maximum	20.39%
Expected dividend yield	0.00%
Weighted average grant date fair value	$ 3.75

Share-Based Compensation - Su_3

Share-Based Compensation - Summary Activity in shares Subjected to Options and Weighted Average Exercise Prices (Details) - USD ($) $ / shares in Units, $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
BYB Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Beginning balance		1,783,020
Number of Shares, Granted			0	212,400	1,634,568
Number of Shares, Exercised		(148,748)	0
Number of Shares, Forfeited		(35,400)
Number of Shares, Ending balance	1,598,872	1,598,872	1,783,020
Number of Shares, Exercisable	1,500,572	1,500,572
Weighted Average Exercise Price, Beginning balance		$ 11.91
Weighted Average Exercise Price, Exercised		11.69
Weighted Average Exercise Price, Forfeited		16.25
Weighted Average Exercise Price, Ending balance	$ 11.84	11.84	$ 11.91
Weighted Average Exercise Price, Exercisable	$ 11.55	$ 11.55
Intrinsic Value, Beginning balance		$ 19,718
Intrinsic Value, Exercised		1,614
Intrinsic Value, Ending balance	$ 7,713	7,713	$ 19,718
Intrinsic Value, Exercisable	$ 7,673	$ 7,673
Weighted Average Remaining Contractual Term (in Years)		6 years 7 months 6 days	7 years 7 months 6 days
Weighted Average Remaining Contractual Term (in Years), Exercisable		6 years 6 months
FEB Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted	680,787
Number of Shares, Exercised	(56,404)	(56,404)
Number of Shares, Ending balance	624,383	624,383
Number of Shares, Exercisable	624,383	624,383
Weighted Average Exercise Price, Granted	$ 11.26
Weighted Average Exercise Price, Exercised	10.66
Weighted Average Exercise Price, Ending balance	11.31	$ 11.31
Weighted Average Exercise Price, Exercisable	$ 11.31	$ 11.31
Intrinsic Value, Exercised	$ 602
Intrinsic Value, Ending balance	3,339	$ 3,339
Intrinsic Value, Exercisable	$ 3,339	$ 3,339
Weighted Average Remaining Contractual Term (in Years)	5 years 2 months 12 days
Weighted Average Remaining Contractual Term (in Years), Exercisable	5 years 2 months 12 days
Intrinsic Value, Granted	$ 7,544

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Related Party Transactions [Abstract]
Receivables outstanding from related parties	$ 0	$ 0

Regulatory Capital Requiremen_3

Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Total capital to risk weighted assets:
Total capital to risk weighted assets, Actual Amount	$ 551,079	$ 408,245
Total capital to risk weighted assets, Actual Ratio ( as a percentage)	13.99%	15.89%
Total capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Amount	$ 315,093	$ 205,559
Total capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	8.00%	8.00%
Tier 1 capital to risk weighted assets:
Tier 1 capital to risk weighted assets, Actual Amount	$ 523,808	$ 389,934
Tier 1 capital to risk weighted assets, Actual Ratio ( as a percentage)	13.30%	15.18%
Tier 1 capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Amount	$ 236,320	$ 154,169
Tier 1 capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	6.00%	6.00%
Common Equity Tier 1 (CET1) to risk weighted assets:
Common Equity Tier 1 (CET1) to risk weighted, Actual Amount	$ 466,870	$ 351,408
Common Equity Tier 1 (CET1) to risk weighted, Actual Ratio ( as a percentage)	11.85%	13.68%
Common Equity Tier 1 (CET1) to risk weighted, Minimum Amount Required for Adequately Capitalized Amount	$ 177,240	$ 115,627
Common Equity Tier 1 (CET1) to risk weighted, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	4.50%	4.50%
Tier 1 capital to average assets:
Tier 1 capital to average, Actual Amount	$ 523,808	$ 389,934
Tier 1 capital to average, Actual Ratio ( as a percentage)	11.05%	12.18%
Tier 1 capital to average, Minimum Amount Required for Adequately Capitalized Amount	$ 189,587	$ 128,075
Tier 1 capital to average, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	4.00%	4.00%
Bank
Total capital to risk weighted assets:
Total capital to risk weighted assets, Actual Amount	$ 528,329	$ 365,386
Total capital to risk weighted assets, Actual Ratio ( as a percentage)	13.40%	14.19%
Total capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Amount	$ 315,455	$ 205,981
Total capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	8.00%	8.00%
Total capital to risk weighted assets, Minimum Amount To Be Well Capitalized Amount	$ 394,318	$ 257,476
Total capital to risk weighted assets, Minimum Amount To Be Well Capitalized Ratio (as a percentage)	10.00%	10.00%
Tier 1 capital to risk weighted assets:
Tier 1 capital to risk weighted assets, Actual Amount	$ 501,058	$ 347,075
Tier 1 capital to risk weighted assets, Actual Ratio ( as a percentage)	12.71%	13.48%
Tier 1 capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Amount	$ 236,591	$ 154,486
Tier 1 capital to risk weighted assets, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	6.00%	6.00%
Tier 1 capital to risk weighted assets, Minimum Amount To Be Well Capitalized Amount	$ 315,455	$ 205,981
Tier 1 capital to risk weighted assets, Minimum Amount To Be Well Capitalized Ratio (asa percentage)	8.00%	8.00%
Common Equity Tier 1 (CET1) to risk weighted assets:
Common Equity Tier 1 (CET1) to risk weighted, Actual Amount	$ 501,058	$ 347,075
Common Equity Tier 1 (CET1) to risk weighted, Actual Ratio ( as a percentage)	12.71%	13.48%
Common Equity Tier 1 (CET1) to risk weighted, Minimum Amount Required for Adequately Capitalized Amount	$ 177,443	$ 115,864
Common Equity Tier 1 (CET1) to risk weighted, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	4.50%	4.50%
Common Equity Tier 1 (CET1) to risk weighted, Minimum Amount To Be Well Capitalized Amount	$ 256,307	$ 167,359
Common Equity Tier 1 (CET1) to risk weighted, Minimum Amount To Be Well Capitalized Ratio (as a percentage)	6.50%	6.50%
Tier 1 capital to average assets:
Tier 1 capital to average, Actual Amount	$ 501,058	$ 347,075
Tier 1 capital to average, Actual Ratio ( as a percentage)	10.56%	10.82%
Tier 1 capital to average, Minimum Amount Required for Adequately Capitalized Amount	$ 189,797	$ 128,305
Tier 1 capital to average, Minimum Amount Required for Adequately Capitalized Ratio ( as a percentage)	4.00%	4.00%
Tier 1 capital to average, Minimum Amount To Be Well Capitalized Amount	$ 237,246	$ 160,382
Tier 1 capital to average, Minimum Amount To Be Well Capitalized Ratio ( as a percentage)	5.00%	5.00%

Regulatory Capital Requiremen_4

Regulatory Capital Requirements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Bank
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Proceeds from Dividends Received		$ 0
Bank | Trust Preferred Securities Interest and Preferred Dividends
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Proceeds from Dividends Received	$ 2,900,000	$ 2,800,000
Federal Deposit Corporation And Federal Reserve Board | Rules Phased in beginning January 2016
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional capital conservation buffer requirement subsequent years ratio	2.50%
New capital conservation buffer requirement beginning ratio	0.625%
Capital conservation buffer requirement ratio	1.875%

Derivative Instruments and He_3

Derivative Instruments and Hedge Activities - Summary of Derivative Financial Instruments and Classification on Consolidated Statements of Financial Condition (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Derivatives Fair Value [Line Items]
Notional Amount	$ 548,969,000	$ 344,726,000
Other Assets	10,740,000	5,981,000
Other Liabilities	4,243,000	994,000
Cash Flow Hedges
Derivatives Fair Value [Line Items]
Notional Amount	250,000,000
Other Assets	6,699,000
Other Interest Rate Swaps
Derivatives Fair Value [Line Items]
Notional Amount	294,545,000
Other Assets	4,041,000
Other Liabilities	4,237,000
Derivatives Designated as Hedging Instruments | Interest Rate Swaps | Cash Flow Hedges
Derivatives Fair Value [Line Items]
Notional Amount	250,000,000	250,000,000
Other Assets	6,699,000	5,030,000
Other Liabilities		38,000
Derivatives Not Designated As Hedging Instruments | Other Credit Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	4,424,000
Other Liabilities	6,000
Derivatives Not Designated As Hedging Instruments | Other Interest Rate Swaps
Derivatives Fair Value [Line Items]
Notional Amount	294,545,000	94,726,000
Other Assets	4,041,000	951,000
Other Liabilities	$ 4,237,000	$ 956,000

Derivative Instruments and He_4

Derivative Instruments and Hedge Activities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative notional amount	$ 548,969,000	$ 344,726,000
Unrealized gain (loss) to be reclassified as an decrease to interest expense during the next twelve months	2,600,000
Credit valuation adjustment increase (decrease) to non-interest income	(192,000)	(44,000)	$ 39,000
Full collateral posted	8,800,000
Net credit exposure, excess collateral	0	378,000
Cash Flow Hedges
Derivative [Line Items]
Derivative notional amount	250,000,000
Interest Rate Swaps | Interest Expense
Derivative [Line Items]
Increase (decrease) in FHLB expense	(1,300,000)	579,000	40,000
Other Interest Rate Swaps
Derivative [Line Items]
Derivative notional amount	$ 294,545,000
Derivative maturity date, start year	Apr. 30, 2020
Derivative maturity date, end year	Dec. 31, 2028
Derivative instruments transaction fees	$ 1,700,000	393,000	$ 679,000
Other Credit Derivatives
Derivative [Line Items]
Derivative notional amount	4,400,000	0
Derivative instruments transaction fees	60,000
Credit valuation adjustment increase (decrease) to non-interest income	(6,000)
Derivatives Designated as Hedging Instruments | Interest Rate Swaps | Cash Flow Hedges
Derivative [Line Items]
Derivative notional amount	250,000,000	250,000,000
Federal Home Loan Bank Advances | Derivatives Designated as Hedging Instruments | Interest Rate Swaps | Cash Flow Hedges
Derivative [Line Items]
Derivative notional amount	$ 250,000,000	$ 250,000,000

Derivative Instruments and He_5

Derivative Instruments and Hedge Activities - Summary of Cash Flow Hedges (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 548,969,000	$ 344,726,000
Derivative assets fair value	10,740,000	5,981,000
Derivative liabilities fair value	4,243,000	$ 994,000
Cash Flow Hedges
Derivative [Line Items]
Notional Amount	250,000,000
Derivative assets fair value	$ 6,699,000
Weighted average pay rates	1.67%
Weighted average receive rates	2.37%
Weighted average maturity	3 years 2 months 12 days

Derivative Instruments and He_6

Derivative Instruments and Hedge Activities - Summary of Net Gains (Losses) Recorded in Accumulated Other Comprehensive Income (Loss) and Consolidated Statements of Operations Relating to Cash Flow Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Amount of Gain Recognized in OCI (EffectivePortion)	$ 2,960	$ 688	$ 3,684
Interest Rate Swaps
Derivative [Line Items]
Amount of Gain Recognized in OCI (EffectivePortion)	2,960
Amount of Gain Reclassified from OCI to Income as a Decrease to Interest Expense	$ 1,348

Derivative Instruments and He_7

Derivative Instruments and Hedge Activities - Summary of Other Interest Rate Swaps (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 548,969,000	$ 344,726,000
Derivative assets fair value	10,740,000	5,981,000
Derivative liabilities fair value	4,243,000	$ 994,000
Other Interest Rate Swaps
Derivative [Line Items]
Notional Amount	294,545,000
Derivative assets fair value	4,041,000
Derivative liabilities fair value	$ 4,237,000
Weighted average pay rates	4.84%
Weighted average receive rates	4.38%
Weighted average maturity	5 years 9 months 18 days

Derivative Instruments and He_8

Derivative Instruments and Hedge Activities - Summary of Company's Interest Rate Derivative and Offsetting Positions (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Gross amounts recognized	$ 10,740	$ 5,981
Net amount presented in the Consolidated Statements of Financial Condition	10,740	5,981
Gross amounts not offset in the Consolidated Statements of Financial Condition
Offsetting derivative positions	(2,823)	(232)
Collateral posted	(7,917)	(5,371)
Net credit exposure	0	378
Gross amounts recognized	4,243	994
Net amount presented in the Consolidated Statements of Financial Condition	4,243	994
Gross amounts not offset in the Consolidated Statements of Financial Condition
Offsetting derivative positions	(2,823)	(232)
Collateral posted	(1,317)	(745)
Net credit exposure	$ 103	$ 17

Parent Company Only Condensed_3

Parent Company Only Condensed Financial Statements - Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Other assets	$ 31,761	$ 16,106
Total assets	4,942,574	3,366,130
LIABILITIES AND STOCKHOLDERS’ EQUITY
Junior subordinated debentures issued to capital trusts, net	36,768	27,647
Accrued expenses and other liabilities	42,568	42,577
Stockholders' equity	650,672	458,578	$ 382,658	$ 188,274
Total liabilities and stockholders’ equity	4,942,574	3,366,130
Company
ASSETS
Cash	18,242	39,626
Investment in banking subsidiary	667,236	445,786
Other assets	3,067	1,236
Total assets	688,545	486,648
LIABILITIES AND STOCKHOLDERS’ EQUITY
Junior subordinated debentures issued to capital trusts, net	36,768	27,647
Accrued expenses and other liabilities	1,105	423
Stockholders' equity	650,672	458,578
Total liabilities and stockholders’ equity	$ 688,545	$ 486,648

Parent Company Only Condensed_4

Parent Company Only Condensed Financial Statements - Statements of Financial Operations (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INCOME
Other noninterest income									$ 5,505,000	$ 2,201,000	$ 4,927,000
EXPENSES
Interest expense	$ 9,634,000	$ 8,480,000	$ 5,785,000	$ 4,447,000	$ 3,805,000	$ 3,632,000	$ 3,504,000	$ 2,950,000	28,346,000	13,891,000	7,747,000
Other non-interest expense									10,614,000	8,852,000	8,120,000
PROVISION (BENEFIT) FOR INCOME TAXES	6,460,000	5,402,000	1,064,000	1,321,000	11,851,000	(1,390,000)	4,094,000	4,544,000	14,247,000	19,099,000	(61,245,000)
NET INCOME	$ 17,121,000	$ 14,536,000	$ 2,768,000	$ 6,768,000	$ (766,000)	$ 9,755,000	$ 6,146,000	$ 6,560,000	41,193,000	21,695,000	66,729,000
Company
INCOME
Dividends from subsidiary									2,900,000	2,800,000
Other noninterest income										9,000	57,000
Total income									2,900,000	2,809,000	57,000
EXPENSES
Interest expense									2,716,000	2,782,000	2,460,000
Other non-interest expense									3,214,000	1,804,000	381,000
Total expenses									5,930,000	4,586,000	2,841,000
Loss before provision for income taxes and equity in undistributed income of subsidiary									(3,030,000)	(1,777,000)	(2,784,000)
PROVISION (BENEFIT) FOR INCOME TAXES									(1,549,000)	(1,166,000)	204,000
Loss before equity in undistributed income of subsidiary									(1,481,000)	(611,000)	(2,988,000)
Equity in undistributed income of subsidiary									42,674,000	22,306,000	69,717,000
NET INCOME									$ 41,193,000	$ 21,695,000	$ 66,729,000

Parent Company Only Condensed_5

Parent Company Only Condensed Financial Statements - Statements of Financial Cash Flow (Details) - USD ($)	1 Months Ended	3 Months Ended								12 Months Ended
	Jul. 31, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income		$ 17,121,000	$ 14,536,000	$ 2,768,000	$ 6,768,000	$ (766,000)	$ 9,755,000	$ 6,146,000	$ 6,560,000	$ 41,193,000	$ 21,695,000	$ 66,729,000
Adjustments to reconcile net income to net cash from operating activities:
Share-based compensation expense										1,514,000	1,497,000	899,000
Exercise of share-based awards												40,000
Accretion of junior subordinated debentures discount										624,000	721,000	876,000
Net cash provided by operating activities										79,935,000	26,853,000	4,236,000
CASH FLOWS FROM INVESTING ACTIVITIES
Net cash used in investing activities										(369,399,000)	(61,635,000)	(301,783,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from revolving line of credit												30,000,000
Repayments of revolving line of credit	$ (16,200,000)										(20,650,000)	(9,350,000)
Dividends paid on preferred stock										(783,000)	(11,277,000)
Cash paid in lieu of fractional shares											(2,000)
Proceeds from issuance of common stock, net										203,000	76,829,000	49,592,000
Proceeds from issuance of preferred stock											1,050,000	9,388,000
Repurchase of preferred stock											(15,003,000)
Net cash provided by financing activities										352,975,000	46,598,000	299,196,000
NET INCREASE IN CASH AND CASH EQUIVALENTS										63,511,000	11,816,000	1,649,000
CASH AND CASH EQUIVALENTS, beginning of period					58,349,000				46,533,000	58,349,000	46,533,000	44,884,000
CASH AND CASH EQUIVALENTS, end of period		121,860,000				58,349,000				121,860,000	58,349,000	46,533,000
Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net income										41,193,000	21,695,000	66,729,000
Adjustments to reconcile net income to net cash from operating activities:
Equity in undistributed income of subsidiary										(42,674,000)	(22,306,000)	(69,717,000)
Share-based compensation expense										1,514,000	1,497,000	899,000
Exercise of share-based awards												40,000
Accretion of junior subordinated debentures discount										624,000	721,000	876,000
Changes in other assets and other liabilities										(3,291,000)	(2,893,000)	16,000
Net cash provided by operating activities										(2,634,000)	(1,286,000)	(1,157,000)
CASH FLOWS FROM INVESTING ACTIVITIES
Investments in and advances from subsidiary												(32,019,000)
Net cash paid in acquisition of business										(20,510,000)		(36,586,000)
Net cash used in investing activities										(20,510,000)		(68,605,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from revolving line of credit												30,000,000
Repayments of revolving line of credit											(20,650,000)	(9,350,000)
Dividends paid on preferred stock										(783,000)	(11,277,000)
Cash paid in lieu of fractional shares											(2,000)
Proceeds from issuance of common stock, net										2,543,000	76,829,000	49,592,000
Proceeds from issuance of preferred stock											1,050,000	9,388,000
Repurchase of preferred stock											(15,003,000)
Net cash provided by financing activities										1,760,000	30,947,000	79,630,000
NET INCREASE IN CASH AND CASH EQUIVALENTS										(21,384,000)	29,661,000	9,868,000
CASH AND CASH EQUIVALENTS, beginning of period					$ 39,626,000				$ 9,965,000	39,626,000	9,965,000	97,000
CASH AND CASH EQUIVALENTS, end of period		$ 18,242,000				$ 39,626,000				$ 18,242,000	$ 39,626,000	$ 9,965,000

Earnings per Share - Additional

Earnings per Share - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share Basic [Line Items]
Shares outstanding	33,292,619	26,963,517	20,141,630
Stock Options
Earnings Per Share Basic [Line Items]
Shares outstanding	2,223,255	1,783,020	1,783,020
Restricted Stock Award
Earnings Per Share Basic [Line Items]
Shares outstanding	196,480	70,798	0

Earnings per Share - Schedule o

Earnings per Share - Schedule of Calculation of Basic and Diluted Earnings per Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 17,121,000	$ 14,536,000	$ 2,768,000	$ 6,768,000	$ (766,000)	$ 9,755,000	$ 6,146,000	$ 6,560,000	$ 41,193,000	$ 21,695,000	$ 66,729,000
Dividends on preferred shares	196,000	196,000	198,000	193,000	196,000	195,000	10,697,000	189,000	783,000	11,277,000
Net income available to common stockholders	$ 16,925,000	$ 14,340,000	$ 2,570,000	$ 6,575,000	$ (962,000)	$ 9,560,000	$ (4,551,000)	$ 6,371,000	$ 40,410,000	$ 10,418,000	$ 66,729,000
Weighted-average common stock outstanding:
Weighted-average common stock outstanding (basic)									33,292,619	26,963,517	20,141,630
Incremental shares									887,135	583,797	289,153
Weighted-average common stock outstanding (dilutive)									34,179,754	27,547,314	20,430,783
Basic earnings per common share	$ 0.47	$ 0.40	$ 0.08	$ 0.22	$ (0.03)	$ 0.33	$ (0.18)	$ 0.26	$ 1.21	$ 0.39	$ 3.31
Diluted earnings per common share	$ 0.46	$ 0.39	$ 0.08	$ 0.22	$ (0.03)	$ 0.32	$ (0.18)	$ 0.25	$ 1.18	$ 0.38	$ 3.27

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Preferred and Common Stock (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Common stock, voting par value	$ 0.01	$ 0.01
Common stock, voting shares authorized	150,000,000	150,000,000
Common stock, voting shares issued	36,343,239	29,317,298
Common stock, voting shares outstanding	36,343,239	29,317,298
Series B 7.5% Fixed to Floating Non-Cumulative Perpetual Preferred Stock
Class Of Stock [Line Items]
Par value	$ 0.01	$ 0.01
Shares authorized	50,000	50,000
Shares issued	10,438	10,438
Shares outstanding	10,438	10,438

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Preferred and Common Stock (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Series B 7.5% Fixed to Floating Non-Cumulative Perpetual Preferred Stock
Class Of Stock [Line Items]
Preferred stock, dividend rate, percentage	7.50%	7.50%

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Dividends declared and paid	$ 783,000	$ 11,277,000
Series B Preferred Stock
Class Of Stock [Line Items]
Preferred stock, dividend rate, percentage			7.50%
Preferred stock, liquidation preference per share			$ 1,000
Preferred stock fixed dividend close date			Dec. 30, 2021
Preferred stock redemption price per share			$ 1,000
Dividends declared and paid	$ 783,000	$ 776,000
Series B Preferred Stock | Three-month LIBOR
Class Of Stock [Line Items]
Preferred stock, dividend rate, percentage			5.41%

Selected Quarterly Financial _3

Selected Quarterly Financial Data (unaudited) - Schedule of Selected Quarterly Financial Data (unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Interest and dividend income	$ 62,895,000	$ 61,073,000	$ 44,841,000	$ 38,142,000	$ 35,956,000	$ 35,044,000	$ 33,315,000	$ 32,488,000	$ 206,951,000	$ 136,803,000	$ 98,365,000
Interest expense	9,634,000	8,480,000	5,785,000	4,447,000	3,805,000	3,632,000	3,504,000	2,950,000	28,346,000	13,891,000	7,747,000
Net interest income	53,261,000	52,593,000	39,056,000	33,695,000	32,151,000	31,412,000	29,811,000	29,538,000	178,605,000	122,912,000	90,618,000
PROVISION FOR LOAN AND LEASE LOSSES	3,882,000	5,842,000	3,956,000	5,115,000	3,347,000	3,900,000	3,515,000	1,891,000	18,795,000	12,653,000	10,352,000
Net interest income after provision for loan and lease losses	49,379,000	46,751,000	35,100,000	28,580,000	28,804,000	27,512,000	26,296,000	27,647,000	159,810,000	110,259,000	80,266,000
Non-interest income	14,566,000	11,143,000	14,502,000	11,428,000	12,639,000	11,918,000	13,193,000	12,308,000	51,639,000	50,058,000	25,904,000
Non-interest expense	40,364,000	37,956,000	45,770,000	31,919,000	30,358,000	31,065,000	29,249,000	28,851,000	156,009,000	119,523,000	100,686,000
Income before provision for income taxes	23,581,000	19,938,000	3,832,000	8,089,000	11,085,000	8,365,000	10,240,000	11,104,000	55,440,000	40,794,000	5,484,000
PROVISION (BENEFIT) FOR INCOME TAXES	6,460,000	5,402,000	1,064,000	1,321,000	11,851,000	(1,390,000)	4,094,000	4,544,000	14,247,000	19,099,000	(61,245,000)
Net income (loss)	17,121,000	14,536,000	2,768,000	6,768,000	(766,000)	9,755,000	6,146,000	6,560,000	41,193,000	21,695,000	66,729,000
Dividends on preferred shares	196,000	196,000	198,000	193,000	196,000	195,000	10,697,000	189,000	783,000	11,277,000
Income (loss) available (attributable) to common stockholders	$ 16,925,000	$ 14,340,000	$ 2,570,000	$ 6,575,000	$ (962,000)	$ 9,560,000	$ (4,551,000)	$ 6,371,000	$ 40,410,000	$ 10,418,000	$ 66,729,000
Basic	$ 0.47	$ 0.40	$ 0.08	$ 0.22	$ (0.03)	$ 0.33	$ (0.18)	$ 0.26	$ 1.21	$ 0.39	$ 3.31
Diluted	$ 0.46	$ 0.39	$ 0.08	$ 0.22	$ (0.03)	$ 0.32	$ (0.18)	$ 0.25	$ 1.18	$ 0.38	$ 3.27

Selected Quarterly Financial _4

Selected Quarterly Financial Data (unaudited) - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended								6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Line Items]
Net income		$ 17,121,000	$ 14,536,000	$ 2,768,000	$ 6,768,000	$ (766,000)	$ 9,755,000	$ 6,146,000	$ 6,560,000		$ 41,193,000	$ 21,695,000	$ 66,729,000
Basic earnings per common share		$ 0.47	$ 0.40	$ 0.08	$ 0.22	$ (0.03)	$ 0.33	$ (0.18)	$ 0.26		$ 1.21	$ 0.39	$ 3.31
Net interest income before provision for loan losses		$ 53,261,000	$ 52,593,000	$ 39,056,000	$ 33,695,000	$ 32,151,000	$ 31,412,000	$ 29,811,000	$ 29,538,000		$ 178,605,000	$ 122,912,000	$ 90,618,000
Data processing costs											18,242,000	$ 9,539,000	$ 8,157,000
Incremntal tax expense from enactment of Tax Cuts and Jobs Act of 2017						$ 7,200,000					$ (760,000)
Federal corporate tax rate											21.00%	35.00%	35.00%
Scenario, Plan
Quarterly Financial Information Disclosure [Line Items]
Federal corporate tax rate											21.00%
Illinois | State
Quarterly Financial Information Disclosure [Line Items]
Corporate income tax rate							7.00%			5.25%
State income tax benefit due to increased value of deferred tax asset related to net loss deduction							$ 4,600,000
IPO | Series A Preferred Stock
Quarterly Financial Information Disclosure [Line Items]
Dividends in arrears								$ 10,500,000
Contract termination
Quarterly Financial Information Disclosure [Line Items]
Data processing costs	$ 8,100,000			$ 8,100,000

Consolidated Statements of Ch_4

Consolidated Statements of Change in Accumulated Other Comprehensive Income (Loss) - Schedule of Consolidated Statements of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 458,578	$ 382,658	$ 188,274
Reclassification of certain income tax effects from accumulated other comprehensive income	(763)
Other comprehensive income (loss), net of tax	(3,648)	2,181	(1,561)
Ending balance	650,672	458,578	382,658
Gains on Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	2,913	2,233
Reclassification of certain income tax effects from accumulated other comprehensive income	687
Other comprehensive income (loss), net of tax	1,163	680	2,233
Ending balance	4,763	2,913	2,233
Unrealized Gains (Losses) on Available-for-Sale Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(8,000)	(9,501)	(5,707)
Reclassification of certain income tax effects from accumulated other comprehensive income	(1,450)
Other comprehensive income (loss), net of tax	(4,811)	1,501	(3,794)
Ending balance	(14,261)	(8,000)	(9,501)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(5,087)	(7,268)	(5,707)
Reclassification of certain income tax effects from accumulated other comprehensive income	(763)
Other comprehensive income (loss), net of tax	(3,648)	2,181	(1,561)
Ending balance	$ (9,498)	$ (5,087)	$ (7,268)