Enterprise Financial Services (EFSC) 10-Q 26 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 24, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	ENTERPRISE FINANCIAL SERVICES CORP
Entity Central Index Key	1,025,835
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		23,073,472

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 78,119	$ 91,084
Federal funds sold	1,571	1,223
Interest-bearing deposits (including $1,295 and $1,365 pledged as collateral, respectively)	76,375	61,016
Total cash and cash equivalents	156,065	153,323
Interest-bearing deposits greater than 90 days	3,405	2,645
Securities available for sale	670,328	641,382
Securities held to maturity	67,131	73,749
Loans held for sale	738	3,155
Loans	4,267,430	4,097,050
Less: Allowance for loan losses	44,186	42,577
Total loans, net	4,223,244	4,054,473
Other real estate	408	498
Other investments, at cost	37,885	26,661
Fixed assets, net	32,354	32,618
Accrued interest receivable	19,879	14,069
State tax credits held for sale (including $171 and $400 carried at fair value, respectively)	45,625	43,468
Goodwill	117,345	117,345
Intangible assets, net	9,148	11,056
Other assets	133,984	114,783
Total assets	5,517,539	5,289,225
Liabilities and Shareholders' Equity
Demand deposits	1,062,126	1,123,907
Interest-bearing transaction accounts	743,351	915,653
Money market accounts	1,523,416	1,342,931
Savings	207,346	195,150
Certificates of deposit:
Brokered	202,323	115,306
Other	471,914	463,467
Total deposits	4,210,476	4,156,414
Subordinated debentures and notes (net of debt issuance cost of $1,038 and $1,136, respectively)	118,144	118,105
Federal Home Loan Bank advances	401,000	172,743
Other borrowings	161,795	253,674
Accrued interest payable	2,433	1,730
Other liabilities	36,854	37,986
Total liabilities	4,930,702	4,740,652
Shareholders' equity:
Preferred stock, $0.01 par value; 5,000,000 shares authorized; 0 shares issued and outstanding	0	0
Common stock, $0.01 par value; 30,000,000 shares authorized; 23,919,261 and 23,781,112 shares issued, respectively	239	238
Treasury stock, at cost; 827,595 and 691,673 shares, respectively	(30,108)	(23,268)
Additional paid in capital	349,317	350,061
Retained earnings	284,016	225,360
Accumulated other comprehensive loss	(16,627)	(3,818)
Total shareholders' equity	586,837	548,573
Total liabilities and shareholders' equity	$ 5,517,539	$ 5,289,225

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Assets
Collateral pledged	$ 1,295	$ 1,365
State tax credits held for sale	171	400
Payments of Debt Issuance Costs	$ 1,038	$ 1,136
Shareholders' equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	23,919,261	23,781,112
Treasury stock, shares	827,595	691,673

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest income:
Interest and fees on loans	$ 55,383	$ 48,020	$ 158,781	$ 135,253
Interest on debt securities:
Taxable	4,482	3,855	12,697	10,670
Nontaxable	263	294	816	984
Interest on interest-bearing deposits	306	173	777	537
Dividends on equity securities	323	126	729	306
Total interest income	60,757	52,468	173,800	147,750
Interest expense:
Interest-bearing transaction accounts	799	523	2,422	1,721
Money market accounts	5,423	2,410	13,221	5,841
Savings accounts	157	125	429	332
Certificates of deposit	2,878	1,493	7,115	4,081
Subordinated debentures and notes	1,483	1,316	4,305	3,768
Federal Home Loan Bank advances	1,729	832	4,435	1,684
Notes payable and other borrowings	195	144	561	423
Total interest expense	12,664	6,843	32,488	17,850
Net interest income	48,093	45,625	141,312	129,900
Provision for portfolio loan losses	2,332	2,422	6,588	7,578
Provision reversal for purchased credit impaired loan losses	(69)	0	(2,064)	(355)
Net interest income after provision for loan losses	45,830	43,203	136,788	122,677
Noninterest income:
Service charges on deposit accounts	2,997	2,820	8,855	8,146
Wealth management revenue	2,012	2,062	6,267	5,949
Fees and Commissions, Credit and Debit Cards	1,760	1,459	4,926	3,888
Gain on state tax credits, net	192	77	508	332
Gain on sale of other real estate	13	0	13	17
Gain on sale of investment securities	0	22	9	22
Miscellaneous income	1,436	1,932	7,067	4,928
Total noninterest income	8,410	8,372	27,645	23,282
Noninterest expense:
Employee compensation and benefits	16,297	15,090	49,370	46,096
Occupancy	2,394	2,434	7,142	6,628
Data processing	1,634	1,389	4,634	4,828
Professional fees	1,023	922	2,619	2,838
FDIC and other insurance	845	882	2,682	2,356
Loan legal and other real estate expense	322	586	598	1,544
Merger related expenses	0	315	0	6,462
Other	7,407	5,786	21,239	16,039
Total noninterest expense	29,922	27,404	88,284	86,791
Income before income tax expense	24,318	24,171	76,149	59,168
Income tax expense	1,802	7,856	10,461	18,507
Net income	$ 22,516	$ 16,315	$ 65,688	$ 40,661
Earnings per common share
Basic (usd per share)	$ 0.97	$ 0.70	$ 2.84	$ 1.77
Diluted (usd per share)	$ 0.97	$ 0.69	$ 2.81	$ 1.75

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 22,516	$ 16,315	$ 65,688	$ 40,661
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on investment securities arising during the period, net of income tax expense (benefit) for three months of $(1,328) and $(493), and for nine months of $(3,926) and $775, respectively	(4,048)	(805)	(11,968)	1,265
Less: Reclassification adjustment for realized gains on sale of securities available for sale included in net income, net of income tax expense for three months of $0 and $8, and for nine months of $2 and $8, respectively	0	(13)	(7)	(13)
Total other comprehensive income (loss)	(4,048)	(818)	(11,975)	1,252
Total comprehensive income	$ 18,468	$ 15,497	$ 53,713	$ 41,913

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other comprehensive income, tax:
Unrealized (loss)/gain on investment securities available for sale arising during the period, tax	$ (1,328)	$ (493)	$ (3,926)	$ 775
Reclassification adjustment for realized gains on sale of securities available for sale included in net income, tax	$ 0	$ 8	$ 2	$ 8

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Balance at Dec. 31, 2016	$ 387,098	$ 203	$ (6,632)	$ 213,078	$ 182,190	$ (1,741)
Net income	40,661	0	0	0	40,661	0
Other comprehensive income	1,252	0	0	0	0	1,252
Total comprehensive income	41,913	0	0	0	40,661	1,252
Cash dividends paid on common shares	7,709	0	0	0	7,709	0
Repurchase of common stock	16,636	0	16,636	0	0	0
Issuance under equity compensation plans, net	(2,573)	1	0	(2,574)	0	0
Share-based Compensation	2,514	0	0	2,514	0	0
Shares issued in connection with acquisition	141,729	33	0	141,696	0	0
Reclassification for the adoption of new accounting standards	0	0	0	(5,229)	5,229	0
Balance at Sep. 30, 2017	546,336	237	(23,268)	349,485	220,371	(489)
Balance at Dec. 31, 2017	548,573	238	(23,268)	350,061	225,360	(3,818)
Net income	65,688	0	0	0	65,688	0
Other comprehensive income	(11,975)	0	0	0	0	(11,975)
Total comprehensive income	53,713	0	0	0	65,688	(11,975)
Cash dividends paid on common shares	7,866	0	0	0	7,866	0
Repurchase of common stock	6,840	0	6,840	0	0	0
Issuance under equity compensation plans, net	(3,297)	1	0	(3,298)	0	0
Share-based Compensation	2,554	0	0	2,554	0	0
Reclassification for the adoption of new accounting standards	0	0	0	0	834	(834)
Balance at Sep. 30, 2018	$ 586,837	$ 239	$ (30,108)	$ 349,317	$ 284,016	$ (16,627)

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash dividends paid on common shares, per share	$ 0.34	$ 0.33
Issuance under equity compensation plans, shares	138,149	148,597

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Cash flows from operating activities:
Net income	$ 65,688	$ 40,661
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation	2,622	2,426
Provision for loan losses	4,524	7,223
Deferred income taxes	2,822	1,239
Net amortization of debt securities	1,338	2,064
Amortization of intangible assets	1,908	1,920
Gain on sale of investment securities	(9)	(22)
Mortgage loans originated for sale	(30,136)	(115,365)
Proceeds from mortgage loans sold	32,839	118,798
Gain on sale of other real estate	(13)	(17)
Gain on state tax credits, net	(508)	(332)
Share-based Compensation	2,554	2,514
Net accretion of loan discount	(1,253)	(3,796)
Changes in:
Accrued interest receivable	(5,811)	(302)
Accrued interest payable	703	249
Other assets	(16,309)	755
Other liabilities	(1,093)	(44,398)
Net cash provided by operating activities	59,866	13,617
Cash flows from investing activities:
Proceeds from Previous Acquisition	0	4,456
Net increase in loans	(172,449)	(201,715)
Proceeds from the sale of securities, available for sale	1,451	144,076
Proceeds from the paydown or maturity of securities, available for sale	61,881	126,073
Proceeds from the paydown or maturity of securities, held to maturity	4,988	4,145
Proceeds from the redemption of other investments	30,593	29,159
Proceeds from the sale of state tax credits held for sale	3,056	4,391
Proceeds from the sale of other real estate	467	2,513
Payments for the purchase/origination of:
Available for sale debt securities	(108,121)	(263,453)
Other investments	(44,597)	(45,224)
State tax credits held for sale	(4,704)	(145)
Fixed assets, net	(2,369)	(1,864)
Net cash used in investing activities	(229,804)	(197,588)
Cash flows from financing activities:
Net (decrease) increase in noninterest-bearing deposit accounts	(61,781)	20,684
Net increase in interest-bearing deposit accounts	115,843	39,998
Proceeds from Federal Home Loan Bank advances	1,142,500	1,394,181
Repayments of Federal Home Loan Bank advances	(914,000)	(1,145,681)
Proceeds from Issuance of Long-term Debt	0	10,000
Net decrease in other borrowings	(91,879)	(123,987)
Cash dividends paid on common stock	(7,866)	(7,709)
Payments for Repurchase of Common Stock	6,840	16,636
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	(3,297)	(2,573)
Net cash provided by financing activities	172,680	168,277
Net increase (decrease) in cash and cash equivalents	2,742	(15,694)
Cash and cash equivalents, beginning of period	153,323	198,802
Cash and cash equivalents, end of period	156,065	183,108
Supplemental Cash Flow Information [Abstract]
Cash paid during the period for interest	31,785	16,948
Cash paid during the period for income taxes	8,492	9,382
Noncash transactions:
Transfer to other real estate owned in settlement of loans	$ 0	$ 289
Common shares issued related to acquisition	0	141,729

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The significant accounting policies used by Enterprise Financial Services Corp (the "Company" or "Enterprise") in the preparation of the condensed consolidated financial statements are summarized below: Business and Consolidation Enterprise is a financial holding company that provides a full range of banking and wealth management services to individuals and corporate customers located in the St. Louis, Kansas City, and Phoenix metropolitan markets through its banking subsidiary, Enterprise Bank & Trust (the "Bank"). Operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results that may be expected for any other interim period or for the year ending December 31, 2018 . For further information, refer to the consolidated financial statements and footnotes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 , as filed with the Securities and Exchange Commission. Basis of Financial Statement Presentation The accompanying unaudited condensed consolidated financial statements of the Company and its subsidiaries have been prepared in accordance with the accounting principles generally accepted in the United States of America ("U.S. GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. The condensed consolidated financial statements include the accounts of the Company and its subsidiaries, all of which are wholly owned. All intercompany accounts and transactions have been eliminated. During the first quarter of 2018, the Company adopted Accounting Standards Update ("ASU") 2016-01, "Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities." ASU 2016-01 requires equity investments to be measured at fair value through earnings, and eliminates the available-for-sale classification for equity securities with readily determinable fair values. The guidance also provides an alternative to measure equity securities without readily determinable fair values at cost less impairment (if any), plus or minus observable price changes from an identical or similar investment of the same issuer (the “measurement alternative”). The Company elected the measurement alternative for its qualifying equity securities. The adoption of this update resulted in an insignificant increase to retained earnings which was reclassified from accumulated other comprehensive income. In addition, the Company early adopted ASU 2017-12, "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities" during the first quarter of 2018. The objective of ASU 2017-12 is to improve the financial reporting of hedging relationships by better aligning an entity's risk management activity with the economic objectives in undertaking those activities. The adoption of this update did not have a material effect on the Company's consolidated financial statements. The Company also early adopted ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income" during the first quarter of 2018. The ASU allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017, which among other things, reduced the maximum federal corporate tax rate from 35% to 21%. The adoption of this update resulted in an increase to retained earnings of $0.8 million which was reclassified from accumulated other comprehensive income. In the opinion of management, the consolidated financial statements contain all adjustments (consisting of normal recurring accruals) considered necessary for the fair presentation of the statements of financial position, results of operations, and cash flow for the interim periods. Revenue The Company adopted the accounting standard regarding revenue recognition in the first quarter of 2018 using the modified retrospective approach. The Company's revenues are primarily composed of interest income on financial instruments, including investment securities, which are excluded from the scope of the new guidance. Certain other noninterest income from loans, investment securities and derivative financial instruments is also excluded from this guidance. Service charges on deposit accounts, wealth management revenue, card services revenue, and gain on sale of other real estate are within the scope of the guidance; however, there were no accounting policy changes as the Company's policies were consistent with the new guidance. Other noninterest income sources of revenue are considered immaterial. Implementation of this guidance did not change current business practices or have any changes to the Company's consolidated financial statements. Descriptions of our revenue-generating activities within the scope of this guidance, which are presented in our income statement as components of noninterest income are as follows: • Service charges on deposit accounts - represents fees generated from a variety of deposit products and services provided to customers under a day-to-day contract. These fees are recognized on a daily or monthly basis. • Wealth management revenue - represents monthly fees earned from directing, holding, and managing customers’ assets. Revenue is recognized over regular intervals, either monthly or quarterly. • Card services revenue - represents revenue earned from merchant, debit and credit cards as incurred and includes a contra revenue account for rebates. • Gain on sale of other real estate - represents income recognized at delivery of control of a property at the time of a real estate closing. Income Taxes The SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Tax Cuts and Jobs Act of 2017 (“Tax Act”). SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. The Company has recorded amounts for the effects of the Tax Act using reasonable estimates based on currently available information and its interpretations thereof. This accounting may change due to, among other things, changes in interpretations the Company has made and the issuance of new tax or accounting guidance.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic earnings per common share data is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Common shares outstanding include common stock and restricted stock awards where recipients have satisfied the vesting terms. Diluted earnings per common share gives effect to all dilutive potential common shares outstanding during the period using the treasury stock method. The following table presents a summary of per common share data and amounts for the periods indicated. Three months ended Nine months ended (in thousands, except per share data) 2018 2017 2018 2017 Net income as reported $ 22,516 $ 16,315 $ 65,688 $ 40,661 Weighted average common shares outstanding 23,148 23,324 23,129 22,914 Additional dilutive common stock equivalents 181 250 211 295 Weighted average diluted common shares outstanding 23,329 23,574 23,340 23,209 Basic earnings per common share: $ 0.97 $ 0.70 $ 2.84 $ 1.77 Diluted earnings per common share: $ 0.97 $ 0.69 $ 2.81 $ 1.75 For the three and nine months ended September 30, 2018 and 2017 , there were no common stock equivalents excluded from the earnings per share calculations because their effect would have been anti-dilutive.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	INVESTMENTS The following table presents the amortized cost, gross unrealized gains and losses and fair value of securities available for sale and held to maturity: September 30, 2018 (in thousands) Amortized Cost Gross Gross Fair Value Available for sale securities: Obligations of U.S. Government-sponsored enterprises $ 99,914 $ — $ (2,233 ) $ 97,681 Obligations of states and political subdivisions 30,563 238 (268 ) 30,533 Agency mortgage-backed securities 551,552 180 (19,385 ) 532,347 U.S. Treasury bills 9,960 — (193 ) 9,767 Total securities available for sale $ 691,989 $ 418 $ (22,079 ) $ 670,328 Held to maturity securities: Obligations of states and political subdivisions $ 12,521 $ 6 $ (324 ) $ 12,203 Agency mortgage-backed securities 54,610 — (2,397 ) 52,213 Total securities held to maturity $ 67,131 $ 6 $ (2,721 ) $ 64,416 December 31, 2017 (in thousands) Amortized Cost Gross Gross Fair Value Available for sale securities: Obligations of U.S. Government-sponsored enterprises $ 99,878 $ 6 $ (660 ) $ 99,224 Obligations of states and political subdivisions 34,181 674 (213 ) 34,642 Agency mortgage-backed securities 513,082 727 (6,293 ) 507,516 Total securities available for sale $ 647,141 $ 1,407 $ (7,166 ) $ 641,382 Held to maturity securities: Obligations of states and political subdivisions $ 14,031 $ 69 $ (46 ) $ 14,054 Agency mortgage-backed securities 59,718 16 (330 ) 59,404 Total securities held to maturity $ 73,749 $ 85 $ (376 ) $ 73,458 At September 30, 2018 , and December 31, 2017 , there were no holdings of securities of any one issuer in an amount greater than 10% of shareholders’ equity, other than U.S. Government agencies and sponsored enterprises. The agency mortgage-backed securities are all issued by U.S. Government agencies and sponsored enterprises. Securities having a fair value of $365.3 million and $500.0 million at September 30, 2018 , and December 31, 2017 , respectively, were pledged as collateral to secure deposits of public institutions and for other purposes as required by law or contract provisions. The amortized cost and estimated fair value of debt securities at September 30, 2018 , by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. The weighted average life of the mortgage-backed securities is approximately 5 years. Available for sale Held to maturity (in thousands) Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Due in one year or less $ 12,193 $ 12,107 $ — $ — Due after one year through five years 110,517 108,231 868 856 Due after five years through ten years 12,688 12,678 11,294 10,995 Due after ten years 5,039 4,965 359 352 Agency mortgage-backed securities 551,552 532,347 54,610 52,213 $ 691,989 $ 670,328 $ 67,131 $ 64,416 The following table represents a summary of investment securities that had an unrealized loss: September 30, 2018 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Obligations of U.S. Government-sponsored enterprises $ 58,592 $ 1,353 $ 39,089 $ 880 $ 97,681 $ 2,233 Obligations of states and political subdivisions 24,152 468 3,296 124 27,448 592 Agency mortgage-backed securities 297,577 8,216 270,949 13,566 568,526 21,782 U.S. Treasury bills 9,767 193 — — 9,767 193 $ 390,088 $ 10,230 $ 313,334 $ 14,570 $ 703,422 $ 24,800 December 31, 2017 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Obligations of U.S. Government-sponsored enterprises $ 89,309 $ 660 $ — $ — $ 89,309 $ 660 Obligations of states and political subdivisions 13,951 259 — — 13,951 259 Agency mortgage-backed securities 469,655 6,034 12,229 589 481,884 6,623 $ 572,915 $ 6,953 $ 12,229 $ 589 $ 585,144 $ 7,542 The unrealized losses at both September 30, 2018 , and December 31, 2017 , were primarily attributable to changes in market interest rates since the securities were purchased. Management systematically evaluates investment securities for other-than-temporary declines in fair value on a quarterly basis. This analysis requires management to consider various factors, which include among other considerations (1) the present value of the cash flows expected to be collected compared to the amortized cost of the security, (2) duration and magnitude of the decline in value, (3) the financial condition of the issuer or issuers, (4) structure of the security, and (5) the intent to sell the security or whether it is more likely than not the Company would be required to sell the security before its anticipated recovery in market value. At September 30, 2018 , management performed its quarterly analysis of all securities with an unrealized loss and concluded no individual securities were other-than-temporarily impaired.

Loans

Loans	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Portfolio Loans	LOANS The loan portfolio is comprised of loans originated by the Company and loans acquired in connection with the Company’s acquisitions. These loans are accounted for using the guidance in the Accounting Standards Codification (ASC) section 310-30 and 310-20. Loans accounted for using ASC 310-30 are sometimes referred to as purchased credit impaired ("PCI") loans. The table below shows the loan portfolio composition including carrying value categorized by loans accounted for at amortized cost, which includes our originated loans, and by loans accounted for as PCI. (in thousands) September 30, 2018 December 31, 2017 Loans accounted for at amortized cost $ 4,218,341 $ 4,022,896 Loans accounted for as PCI 49,089 74,154 Total loans $ 4,267,430 $ 4,097,050 The following tables refer to loans accounted for at amortized cost. Below is a summary of loans by category at September 30, 2018 and December 31, 2017 : (in thousands) September 30, 2018 December 31, 2017 Commercial and industrial $ 2,032,929 $ 1,918,720 Real estate: Commercial - investor owned 826,447 769,275 Commercial - owner occupied 589,045 554,589 Construction and land development 326,858 303,091 Residential 308,385 341,312 Total real estate loans 2,050,735 1,968,267 Consumer and other 136,025 137,234 Loans, before unearned loan fees 4,219,689 4,024,221 Unearned loan fees, net (1,348 ) (1,325 ) Loans, including unearned loan fees $ 4,218,341 $ 4,022,896 A summary of the activity in the allowance for loan losses and the recorded investment in loans by class and category based on impairment methodology through September 30, 2018 , and at December 31, 2017 , is as follows: (in thousands) Commercial and industrial CRE - investor owned CRE - owner occupied Construction and land development Residential real estate Consumer and other Total Allowance for loan losses: Balance at December 31, 2017 $ 26,406 $ 3,890 $ 3,308 $ 1,487 $ 2,237 $ 838 $ 38,166 Provision (provision reversal) for loan losses 780 648 190 35 259 (41 ) 1,871 Losses charged off (732 ) — — — (254 ) (49 ) (1,035 ) Recoveries 956 8 4 206 73 14 1,261 Balance at March 31, 2018 $ 27,410 $ 4,546 $ 3,502 $ 1,728 $ 2,315 $ 762 $ 40,263 Provision (provision reversal) for loan losses 2,852 5 340 (206 ) (573 ) (33 ) 2,385 Losses charged off (956 ) — — — (38 ) (33 ) (1,027 ) Recoveries 118 10 3 168 59 28 386 Balance at June 30, 2018 $ 29,424 $ 4,561 $ 3,845 $ 1,690 $ 1,763 $ 724 $ 42,007 Provision (provision reversal) for loan losses 2,569 3 (197 ) 154 (187 ) (10 ) 2,332 Losses charged off (2,405 ) — (22 ) — (122 ) (46 ) (2,595 ) Recoveries 2 8 4 21 88 25 148 Balance at September 30, 2018 $ 29,590 $ 4,572 $ 3,630 $ 1,865 $ 1,542 $ 693 $ 41,892 (in thousands) Commercial and industrial CRE - investor owned CRE - owner occupied Construction and land development Residential real estate Consumer and other Total Balance September 30, 2018 Allowance for loan losses - Ending balance: Individually evaluated for impairment $ 4,128 $ — $ 177 $ — $ 9 $ — $ 4,314 Collectively evaluated for impairment 25,462 4,572 3,453 1,865 1,533 693 37,578 Total $ 29,590 $ 4,572 $ 3,630 $ 1,865 $ 1,542 $ 693 $ 41,892 Loans - Ending balance: Individually evaluated for impairment $ 12,197 $ 770 $ 2,655 $ — $ 2,477 $ 312 $ 18,411 Collectively evaluated for impairment 2,020,732 825,677 586,390 326,858 305,908 134,365 4,199,930 Total $ 2,032,929 $ 826,447 $ 589,045 $ 326,858 $ 308,385 $ 134,677 $ 4,218,341 Balance December 31, 2017 Allowance for loan losses - Ending balance: Individually evaluated for impairment $ 2,508 $ — $ 71 $ — $ — $ — $ 2,579 Collectively evaluated for impairment 23,898 3,890 3,237 1,487 2,237 838 35,587 Total $ 26,406 $ 3,890 $ 3,308 $ 1,487 $ 2,237 $ 838 $ 38,166 Loans - Ending balance: Individually evaluated for impairment $ 12,665 $ 422 $ 1,975 $ 136 $ 1,602 $ 375 $ 17,175 Collectively evaluated for impairment 1,906,055 768,853 552,614 302,955 339,710 135,534 4,005,721 Total $ 1,918,720 $ 769,275 $ 554,589 $ 303,091 $ 341,312 $ 135,909 $ 4,022,896 A summary of nonperforming loans individually evaluated for impairment by category at September 30, 2018 and December 31, 2017 , and the income recognized on impaired loans is as follows: September 30, 2018 (in thousands) Unpaid Recorded Recorded Allowance Total Related Allowance Average Commercial and industrial $ 20,938 $ 3,266 $ 8,931 $ 12,197 $ 4,128 $ 10,414 Real estate: Commercial - investor owned 1,039 770 — 770 — 657 Commercial - owner occupied 1,328 826 462 1,288 177 1,074 Construction and land development — — — — — — Residential 2,600 2,008 469 2,477 9 2,410 Consumer and other 329 312 — 312 — 334 Total $ 26,234 $ 7,182 $ 9,862 $ 17,044 $ 4,314 $ 14,889 December 31, 2017 (in thousands) Unpaid Recorded Recorded Allowance Total Related Allowance Average Commercial and industrial $ 20,750 $ 2,321 $ 10,344 $ 12,665 $ 2,508 $ 16,270 Real estate: Commercial - investor owned 560 422 — 422 — 521 Commercial - owner occupied 487 — 487 487 71 490 Construction and land development 441 136 — 136 — 331 Residential 1,730 1,602 — 1,602 — 1,735 Consumer and other 375 375 — 375 — 375 Total $ 24,343 $ 4,856 $ 10,831 $ 15,687 $ 2,579 $ 19,722 Three months ended September 30, Nine months ended September 30, (in thousands) 2018 2017 2018 2017 Total interest income that would have been recognized under original terms $ 614 $ 306 $ 1,615 $ 961 Total cash received and recognized as interest income on non-accrual loans 68 117 157 156 Total interest income recognized on accruing, impaired loans 110 8 133 55 The recorded investment in nonperforming loans by category at September 30, 2018 and December 31, 2017 , is as follows: September 30, 2018 (in thousands) Non-accrual Restructured, not on non-accrual Loans over 90 days past due and still accruing interest Total Commercial and industrial $ 10,088 $ 820 $ 1,289 $ 12,197 Real estate: Commercial - investor owned 770 — — 770 Commercial - owner occupied 1,288 — — 1,288 Construction and land development — — — — Residential 2,477 — — 2,477 Consumer and other 312 — — 312 Total $ 14,935 $ 820 $ 1,289 $ 17,044 December 31, 2017 (in thousands) Non-accrual Restructured, not on non-accrual Total Commercial and industrial $ 11,946 $ 719 $ 12,665 Real estate: Commercial - investor owned 422 — 422 Commercial - owner occupied 487 — 487 Construction and land development 136 — 136 Residential 1,602 — 1,602 Consumer and other 375 — 375 Total $ 14,968 $ 719 $ 15,687 There were no loans over 90 days past due and still accruing interest at December 31, 2017 . The recorded investment by category for the portfolio loans that have been restructured during the three and nine months ended September 30, 2018 and 2017 , is as follows: Three months ended September 30, 2018 Three months ended September 30, 2017 (in thousands, except for number of loans) Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Commercial and industrial 1 $ 187 $ 187 — $ — $ — Total 1 $ 187 $ 187 — $ — $ — Nine months ended September 30, 2018 Nine months ended September 30, 2017 (in thousands, except for number of loans) Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Commercial and industrial 1 $ 187 $ 187 1 $ 676 $ 676 Total 1 $ 187 $ 187 1 $ 676 $ 676 As of September 30, 2018 , the Company had $2.6 million in specific reserves allocated to $8.0 million of loans that have been restructured. During the three and nine months ended September 30, 2018 and 2017, there were no portfolio loans that subsequently defaulted. The aging of the recorded investment in past due loans by portfolio class and category at September 30, 2018 and December 31, 2017 , is shown below. September 30, 2018 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ 11,213 $ 6,020 $ 17,233 $ 2,015,696 $ 2,032,929 Real estate: Commercial - investor owned 1,362 129 1,491 824,956 826,447 Commercial - owner occupied 258 808 1,066 587,979 589,045 Construction and land development — — — 326,858 326,858 Residential 864 1,156 2,020 306,365 308,385 Consumer and other — — — 134,677 134,677 Total $ 13,697 $ 8,113 $ 21,810 $ 4,196,531 $ 4,218,341 December 31, 2017 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ 7,882 $ 1,770 $ 9,652 $ 1,909,068 $ 1,918,720 Real estate: Commercial - investor owned 934 — 934 768,341 769,275 Commercial - owner occupied — — — 554,589 554,589 Construction and land development 76 — 76 303,015 303,091 Residential 1,529 945 2,474 338,838 341,312 Consumer and other 407 — 407 135,502 135,909 Total $ 10,828 $ 2,715 $ 13,543 $ 4,009,353 $ 4,022,896 The Company categorizes loans into risk categories based on relevant information about the ability of borrowers to service their debt, such as current financial information, payment experience, credit documentation, and current economic factors among other factors. This analysis is performed on a quarterly basis. The Company uses the following definitions for risk ratings: • Grades 1 , 2 , and 3 – Includes loans to borrowers with a continuous record of strong earnings, sound balance sheet condition and capitalization, ample liquidity with solid cash flow, and whose management team has experience and depth within their industry. • Grade 4 – Includes loans to borrowers with positive trends in profitability, satisfactory capitalization and balance sheet condition, and sufficient liquidity and cash flow. • Grade 5 – Includes loans to borrowers that may display fluctuating trends in sales, profitability, capitalization, liquidity, and cash flow. • Grade 6 – Includes loans to borrowers where an adverse change or perceived weakness has occurred, but may be correctable in the near future. Alternatively, this rating category may also include circumstances where the borrower is starting to reverse a negative trend or condition, or has recently been upgraded from a 7 , 8 , or 9 rating. • Grade 7 – Watch credits are borrowers that have experienced financial setback of a nature that is not determined to be severe or influence ‘ongoing concern’ expectations. Although possible, no loss is anticipated, due to strong collateral and/or guarantor support. • Grade 8 – Substandard credits include those borrowers characterized by significant losses and sustained downward trends in balance sheet condition, liquidity, and cash flow. Repayment reliance may have shifted to secondary sources. Collateral exposure may exist and additional reserves may be warranted. • Grade 9 – Doubtful credits include borrowers that may show deteriorating trends that are unlikely to be corrected. Collateral values may appear insufficient for full recovery, therefore requiring a partial charge-off, or debt renegotiation with the borrower. The borrower may have declared bankruptcy or bankruptcy is likely in the near term. All doubtful rated credits will be on non-accrual. The recorded investment by risk category of the loans by portfolio class and category at September 30, 2018 , which is based upon the most recent analysis performed, and December 31, 2017 , is as follows: September 30, 2018 (in thousands) Pass (1-6) Watch (7) Classified (8 & 9) Total Commercial and industrial $ 1,835,230 $ 142,768 $ 54,931 $ 2,032,929 Real estate: Commercial - investor owned 798,116 22,275 6,056 826,447 Commercial - owner occupied 540,961 43,399 4,685 589,045 Construction and land development 315,022 11,775 61 326,858 Residential 298,076 3,058 7,251 308,385 Consumer and other 134,359 7 311 134,677 Total $ 3,921,764 $ 223,282 $ 73,295 $ 4,218,341 December 31, 2017 (in thousands) Pass (1-6) Watch (7) Classified (8 & 9) Total Commercial and industrial $ 1,769,102 $ 94,002 $ 55,616 $ 1,918,720 Real estate: Commercial - investor owned 754,010 10,840 4,425 769,275 Commercial - owner occupied 514,616 34,440 5,533 554,589 Construction and land development 292,766 9,983 342 303,091 Residential 329,742 3,648 7,922 341,312 Consumer and other 134,704 10 1,195 135,909 Total $ 3,794,940 $ 152,923 $ 75,033 $ 4,022,896

Purchased Credit Impaired ("PCI

Purchased Credit Impaired ("PCI") Loans	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Purchase Credit Impaired (PCI) Loans	Below is a summary of PCI loans by category at September 30, 2018 and December 31, 2017 : September 30, 2018 December 31, 2017 (in thousands) Weighted- Average Risk Rating 1 Recorded Investment PCI Loans Weighted- Average Risk Rating 1 Recorded Investment PCI Loans Commercial and industrial 6.39 $ 2,923 6.38 $ 3,212 Real estate: Commercial - investor owned 7.23 25,172 7.36 42,887 Commercial - owner occupied 7.45 9,520 6.48 11,332 Construction and land development 6.01 5,168 5.99 5,883 Residential 6.35 6,291 5.99 10,781 Consumer and other 7.08 15 2.84 59 Total $ 49,089 $ 74,154 1 Risk ratings are based on the borrower's contractual obligation, which is not reflective of the purchase discount. The aging of the recorded investment in past due PCI loans by portfolio class and category at September 30, 2018 and December 31, 2017 , is shown below: September 30, 2018 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ — $ — $ — $ 2,923 $ 2,923 Real estate: Commercial - investor owned 627 1,190 1,817 23,355 25,172 Commercial - owner occupied 6,230 744 6,974 2,546 9,520 Construction and land development 146 — 146 5,022 5,168 Residential 33 46 79 6,212 6,291 Consumer and other — — — 15 15 Total $ 7,036 $ 1,980 $ 9,016 $ 40,073 $ 49,089 December 31, 2017 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ — $ — $ — $ 3,212 $ 3,212 Real estate: Commercial - investor owned — 3,034 3,034 39,853 42,887 Commercial - owner occupied — 673 673 10,659 11,332 Construction and land development — — — 5,883 5,883 Residential 328 255 583 10,198 10,781 Consumer and other — — — 59 59 Total $ 328 $ 3,962 $ 4,290 $ 69,864 $ 74,154 The following table is a roll forward of PCI loans, net of the allowance for loan losses, for the nine months ended September 30, 2018 and 2017 . (in thousands) Contractual Cashflows Non-accretable Difference Accretable Yield Carrying Amount Balance December 31, 2017 $ 112,710 $ 29,005 $ 13,964 $ 69,741 Principal reductions and interest payments (38,165 ) — — (38,165 ) Accretion of loan discount — — (5,118 ) 5,118 Changes in contractual and expected cash flows due to remeasurement 4,341 (8,939 ) 3,179 10,101 Balance September 30, 2018 $ 78,886 $ 20,066 $ 12,025 $ 46,795 Balance December 31, 2016 $ 66,003 $ 18,902 $ 13,176 $ 33,925 Acquisitions 68,763 14,296 5,312 49,155 Principal reductions and interest payments (16,319 ) — — (16,319 ) Accretion of loan discount — — (5,473 ) 5,473 Changes in contractual and expected cash flows due to remeasurement 11,110 (702 ) 3,776 8,036 Reductions due to disposals (6,393 ) (1,612 ) (1,595 ) (3,186 ) Balance September 30, 2017 $ 123,164 $ 30,884 $ 15,196 $ 77,084 The accretable yield is recognized in interest income over the estimated life of the acquired loans using the effective yield method. Outstanding customer balances on PCI loans were $68.6 million and $94.9 million as of September 30, 2018 , and December 31, 2017 , respectively.

Commitments

Commitments	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments	COMMITMENTS AND CONTINGENCIES The Company issues financial instruments with off balance sheet risk in the normal course of the business of meeting the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit. These instruments may involve, to varying degrees, elements of credit and interest rate risk in excess of the amounts recognized in the consolidated balance sheets. The Company’s extent of involvement and maximum potential exposure to credit loss in the event of nonperformance by the other party to the financial instrument for commitments to extend credit and standby letters of credit is represented by the contractual amount of these instruments. The Company uses the same credit policies in making commitments and conditional obligations as it does for financial instruments included on its consolidated balance sheets. At September 30, 2018 , the amount of unadvanced commitments on impaired loans was insignificant. The contractual amounts of off-balance-sheet financial instruments as of September 30, 2018 , and December 31, 2017 , are as follows: (in thousands) September 30, 2018 December 31, 2017 Commitments to extend credit $ 1,315,284 $ 1,298,423 Letters of credit 49,633 73,790 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 usually have fixed expiration dates or other termination clauses, may have significant usage restrictions, and may require payment of a fee. Of the total commitments to extend credit at September 30, 2018 , and December 31, 2017 , approximately $91.8 million and $112.0 million , respectively, represent fixed rate loan commitments. Since certain of the commitments may expire without being drawn upon or may be revoked, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s credit worthiness 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 borrower. Collateral held varies, but may include accounts receivable, inventory, premises and equipment, and real estate. Other liabilities includes $0.4 million for estimated losses attributable to the unadvanced commitments at September 30, 2018 , and December 31, 2017 . Standby letters of credit are conditional commitments issued by the Company to guarantee the performance or payment of a customer to a third party. These standby letters of credit are issued to support contractual obligations of the Company’s customers. The credit risk involved in issuing letters of credit is essentially the same as the risk involved in extending loans to customers. As of September 30, 2018 , the approximate remaining terms of standby letters of credit range from 1 month to 3 years and 3 months . Contingencies The Company and its subsidiaries are, from time to time, parties to various legal proceedings arising out of their businesses. Management believes there are no such proceedings pending or threatened against the Company or its subsidiaries which, if determined adversely, would have a material adverse effect on the business, consolidated financial condition, results of operations or cash flows of the Company or any of its subsidiaries.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	DERIVATIVE FINANCIAL INSTRUMENTS The Company is a party to various derivative financial instruments used in the normal course of business to meet the needs of its clients and as part of its risk management activities. These instruments include interest rate swap agreements and option contracts and foreign exchange forward contracts. The Company does not enter into derivative financial instruments for trading purposes. Hedging Instruments. At September 30, 2018 , the Company had no outstanding derivative contracts used to manage risk. Client-Related Derivative Instruments. The Company enters into interest rate swaps to allow customers to hedge changes in fair value of certain loans while maintaining a variable rate loan on its own books. The Company also enters into foreign exchange forward contracts with clients, and enters into offsetting foreign exchange forward contracts with established financial institution counterparties. The table below summarizes the notional amounts and fair values of the client-related derivative instruments: Asset Derivatives (Other Assets) Liability Derivatives (Other Liabilities) Notional Amount Fair Value Fair Value (in thousands) September 30, December 31, September 30, December 31, September 30, December 31, Non-designated hedging instruments Interest rate swap contracts $ 433,664 $ 394,852 $ 4,772 $ 2,061 $ 4,772 $ 2,061 Foreign exchange forward contracts 123 1,528 123 1,528 123 1,528 Changes in the fair value of client-related derivative instruments are recognized currently in operations. For the three and nine months ended September 30, 2018 and 2017 , the gains and losses offset each other due to the Company's hedging of the client swaps and foreign exchange contracts with other bank counterparties.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Below is a description of certain assets and liabilities measured at fair value. The following table summarizes financial instruments measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 , segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value: September 30, 2018 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets Securities available for sale Obligations of U.S. Government-sponsored enterprises $ — $ 97,681 $ — $ 97,681 Obligations of states and political subdivisions — 30,533 — 30,533 Residential mortgage-backed securities — 532,347 — 532,347 U.S. Treasury bills — 9,767 — 9,767 Total securities available for sale $ — $ 670,328 $ — $ 670,328 Other investments 144 — — 144 State tax credits held for sale — — 171 171 Derivative financial instruments — 4,895 — 4,895 Total assets $ 144 $ 675,223 $ 171 $ 675,538 Liabilities Derivative financial instruments $ — $ 4,895 $ — $ 4,895 Total liabilities $ — $ 4,895 $ — $ 4,895 December 31, 2017 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets Securities available for sale Obligations of U.S. Government-sponsored enterprises $ — $ 99,224 $ — $ 99,224 Obligations of states and political subdivisions — 34,642 — 34,642 Residential mortgage-backed securities — 507,516 — 507,516 Total securities available for sale $ — $ 641,382 $ — $ 641,382 State tax credits held for sale — — 400 400 Derivative financial instruments — 3,589 — 3,589 Total assets $ — $ 644,971 $ 400 $ 645,371 Liabilities Derivative financial instruments $ — $ 3,589 $ — $ 3,589 Total liabilities $ — $ 3,589 $ — $ 3,589 • Securities available for sale . Securities classified as available for sale are reported at fair value utilizing Level 2 and Level 3 inputs. Fair values for Level 2 securities are based upon dealer quotes, market spreads, the U.S. Treasury yield curve, trade execution data, market consensus prepayment speeds, credit information and the bond's terms and conditions at the security level. • Other investments. At September 30, 2018 , of the $37.9 million of other investments on the condensed consolidated balance sheet, approximately $0.2 million were carried at fair value. The remaining $37.7 million of other investments were accounted for at cost. Other investments reported at fair value represent equity securities with quoted market prices (Level 1). • State tax credits held for sale. At September 30, 2018 , of the $45.6 million of state tax credits held for sale on the condensed consolidated balance sheet, approximately $0.1 million were carried at fair value. The remaining $45.5 million of state tax credits were accounted for at cost. The Company is not aware of an active market that exists for the 10 -year streams of state tax credit financial instruments. However, the Company’s principal market for these tax credits consists of Missouri state residents who buy these credits and local and regional accounting firms who broker them. As such, the Company employed a discounted cash flow analysis (income approach) to determine fair value. The remaining state tax credits carried at fair value are expected to be sold within the next several quarters. The state tax credit assets are reported as Level 3 assets. • Derivatives . Derivatives are reported at fair value utilizing Level 2 inputs. The Company obtains counterparty quotations to value its interest rate swaps. In addition, the Company validates the counterparty quotations with third party valuation sources. Derivatives with negative fair values are included in Other liabilities in the consolidated balance sheets. Derivatives with positive fair value are included in Other assets in the consolidated balance sheets. There were no transfers between Level 1 and Level 2 during the three and nine months ended September 30, 2018 and 2017. Level 3 financial instruments The following table presents the changes in Level 3 financial instruments measured at fair value on a recurring basis as of September 30, 2018 and 2017 . Securities available for sale, at fair value Three months ended September 30, Nine months ended September 30, (in thousands) 2018 2017 2018 2017 Beginning balance $ — $ — $ — $ 3,089 Total gains: Included in other comprehensive income — — — 4 Purchases, sales, issuances and settlements: Purchases — — — — Transfer in and/or out of Level 3 — — — (3,093 ) Ending balance $ — $ — $ — $ — Change in unrealized gains relating to assets still held at the reporting date $ — $ — $ — $ — State tax credits held for sale Three months ended September 30, Nine months ended September 30, (in thousands) 2018 2017 2018 2017 Beginning balance $ 299 $ 1,274 $ 400 $ 3,585 Total gains: Included in earnings 7 — 13 49 Purchases, sales, issuances and settlements: Sales (135 ) — (242 ) (2,360 ) Ending balance $ 171 $ 1,274 $ 171 $ 1,274 Change in unrealized gains (losses) relating to assets still held at the reporting date $ (34 ) $ — $ (60 ) $ (655 ) From time to time, the Company measures certain assets at fair value on a nonrecurring basis. These include assets measured at the lower of cost or fair value that were recognized at fair value below cost at the end of the period. The following table presents financial instruments and non-financial assets measured at fair value on a non-recurring basis as of September 30, 2018 . (1) (1) (1) (1) (in thousands) Total Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant (Level 3) Total losses for the three Total losses for the nine Impaired loans $ 485 $ — $ — $ 485 $ 248 $ 457 Other real estate — — — — — — Total $ 485 $ — $ — $ 485 $ 248 $ 457 (1) The amounts represent only balances measured at fair value during the period and still held as of the reporting date. Impaired loans are reported at the fair value of the underlying collateral for collateral dependent loans. Fair values for impaired loans are obtained from current appraisals by qualified licensed appraisers or independent valuation specialists. At September 30, 2018, impaired loans measured on a non-recurring basis had a principal balance of $0.7 million , with a valuation allowance of $0.2 million . Other real estate owned is adjusted to fair value upon foreclosure of the underlying loan. Subsequently, foreclosed assets are carried at the lower of carrying value or fair value less costs to sell. Fair value of other real estate is based upon the current appraised values of the properties as determined by qualified licensed appraisers and the Company’s judgment of other relevant market conditions. Following is a summary of the carrying amounts and fair values of the Company’s financial instruments on the consolidated balance sheets at September 30, 2018 and December 31, 2017 . Fair values that are not estimable are listed at the carrying value. September 30, 2018 December 31, 2017 (in thousands) Carrying Amount Estimated fair value Carrying Amount Estimated fair value Balance sheet assets Cash and due from banks $ 78,119 $ 78,119 $ 91,084 $ 91,084 Federal funds sold 1,571 1,571 1,223 1,223 Interest-bearing deposits 79,780 79,780 63,661 63,661 Securities available for sale 670,328 670,328 641,382 641,382 Securities held to maturity 67,131 64,416 73,749 73,458 Other investments, at cost 37,885 37,885 26,661 26,661 Loans held for sale 738 738 3,155 3,155 Derivative financial instruments 4,895 4,895 3,589 3,589 Portfolio loans, net 4,223,244 4,254,581 4,054,473 4,096,741 State tax credits, held for sale 45,625 48,622 43,468 44,271 Accrued interest receivable 19,879 19,879 14,069 14,069 Balance sheet liabilities Deposits 4,210,476 4,203,913 4,156,414 4,153,323 Subordinated debentures and notes 118,144 105,611 118,105 105,031 Federal Home Loan Bank advances 401,000 400,977 172,743 172,893 Other borrowings 161,795 161,676 253,674 253,530 Derivative financial instruments 4,895 4,895 3,589 3,589 Accrued interest payable 2,433 2,433 1,730 1,730 For information regarding the methods and assumptions used to estimate the fair value of each class of financial instruments for which it is practical to estimate such value, refer to Note 18 – Fair Value Measurements in the Company's Annual Report on Form 10 -K for the year ended December 31, 2017 , as filed with the Securities and Exchange Commission. The following table presents the level in the fair value hierarchy for the estimated fair values of only the Company’s financial instruments that are not already presented on the condensed consolidated balance sheets at fair value at September 30, 2018 , and December 31, 2017 . Estimated Fair Value Measurement at Reporting Date Using Balance at September 30, 2018 (in thousands) Level 1 Level 2 Level 3 Financial Assets: Securities held to maturity $ — $ 64,416 $ — $ 64,416 Portfolio loans, net — — 4,254,581 4,254,581 State tax credits, held for sale — — 48,451 48,451 Financial Liabilities: Deposits 3,536,239 — 667,674 4,203,913 Subordinated debentures and notes — 105,611 — 105,611 Federal Home Loan Bank advances — 400,977 — 400,977 Other borrowings — 161,676 — 161,676 Estimated Fair Value Measurement at Reporting Date Using Balance at December 31, 2017 (in thousands) Level 1 Level 2 Level 3 Financial Assets: Securities held to maturity $ — $ 73,458 $ — $ 73,458 Portfolio loans, net — — 4,096,741 4,096,741 State tax credits, held for sale — — 43,871 43,871 Financial Liabilities: Deposits 3,577,641 — 575,682 4,153,323 Subordinated debentures and notes — 105,031 — 105,031 Federal Home Loan Bank advances — 172,893 — 172,893 Other borrowings — 253,530 — 253,530

New Authoritative Accounting Gu

New Authoritative Accounting Guidance	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Authoritative Accounting Guidance	NEW AUTHORITATIVE ACCOUNTING GUIDANCE Financial Accounting Standards Board (the "FASB") ASU 2018-15 "Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement" In August 2018, the FASB issued ASU 2018-15, which amends ASC 350-402 to address a customer’s accounting for implementation costs incurred in a cloud computing arrangement (CCA) that is a service contract. ASU 2018-15 aligns the accounting for costs incurred to implement a CCA that is a service arrangement with the guidance on capitalizing costs associated with developing or obtaining internal-use software. Specifically, the ASU amends ASC 350 to include in its scope implementation costs of a CCA that is a service contract and clarifies that a customer should apply ASC 350-40 to determine which implementation costs should be capitalized in a CCA that is considered a service contract. The amendments are effective for public business entities for annual periods beginning after December 15, 2019, including interim periods within those annual periods, with early adoption being permitted. The Company is currently evaluating the new guidance and has not yet determined the impact this standard may have on its consolidated balance sheets. FASB ASU 2018-13 "Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement" In August 2018, the FASB issued ASU 2018-13, which changes the fair value measurement disclosure requirements of ASC 820. The amendments in this ASU are the result of a broader disclosure project called FASB Concepts Statement, Conceptual Framework for Financial Reporting — Chapter 8: Notes to Financial Statements, which the Board finalized on August 28, 2018. The Board used the guidance in the Concepts Statement, including consideration of costs and benefits, to improve the effectiveness of ASC 820’s disclosure requirements. The Company is currently evaluating the new guidance and has not yet determined the impact this standard may have on its consolidated balance sheets. FASB ASU 2018-11 "Leases (Topic 842): Targeted Improvements" In July 2018, the FASB issued ASU 2018-11 to provide entities with relief from the costs of implementing certain aspects of the new leasing standard, ASU 2016-02 (codified as ASC 842). Specifically, under the amendments in ASU 2018-11 (1)entities may elect not to recast the comparative periods presented when transitioning to ASC 842 (2) lessors may elect not to separate lease and nonlease components when certain conditions are met. The Company intends to utilize the optional transition method and apply the new leases standard at the adoption date of January 1, 2019. The Company is evaluating the impact of separating lease and nonlease components on its financial statements. FASB ASU 2017-08 "Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities" In March 2017, the FASB issued ASU 2017-08, "Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20)" which shortens the amortization period of certain callable debt securities held at a premium to the earliest call date. The amendments are effective for public business entities for annual periods beginning after December 15, 2018, including interim periods within those annual periods, with early adoption being permitted. The Company has evaluated the new guidance and does not expect it to have a material impact on the Company's consolidated financial statements. At September 30, 2018, the book value of callable bonds purchased at a premium totaled $22.0 million, and the amount of unamortized premium remaining on these securities was $0.7 million. FASB ASU 2016-13 "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" In June 2016, the FASB issued ASU 2016-13, "Financial Instruments (Topic 326)" which changes the methodology for evaluating impairment of most financial instruments. The ASU replaces the currently used incurred loss model with a forward-looking expected loss model, which will generally result in a more timely recognition of losses. The guidance becomes effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company has formed an implementation team that includes members of accounting, credit, and loan operations to review the requirements of ASU 2016-13, and has contracted with a software provider to aid in implementation. The Company has not yet determined the impact this standard may have on its financial statements. FASB ASU 2016-02 "Leases (Topic 842)" In February 2016, the FASB issued ASU 2016-02, "Leases (Topic 842)" which requires organizations that lease assets ("lessees") to recognize the assets and liabilities for the rights and obligations created by leases with terms of more than 12 months. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee remains dependent on its classification as a finance or operating lease. The criteria for determining whether a lease is a finance or operating lease has not been significantly changed by this ASU. The ASU also requires additional disclosure of the amount, timing, and uncertainty of cash flows arising from leases, including qualitative and quantitative requirements. The guidance becomes effective for periods beginning after December 15, 2018, including interim periods therein. Early adoption will be permitted. The Company has formed a lease implementation team that includes members of accounting, facilities and operations to review lease contracts and the requirements of ASU 2016-02. The Company is currently evaluating the impact of this amendment on its financial statements; however, it does not expect the adoption of the new standard to have a material impact on its results of operations or balance sheet as a result of the recognition of right-to-use assets and lease liabilities related to operating leases.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Business and Consolidation	Basis of Financial Statement Presentation The accompanying unaudited condensed consolidated financial statements of the Company and its subsidiaries have been prepared in accordance with the accounting principles generally accepted in the United States of America ("U.S. GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. The condensed consolidated financial statements include the accounts of the Company and its subsidiaries, all of which are wholly owned. All intercompany accounts and transactions have been eliminated. During the first quarter of 2018, the Company adopted Accounting Standards Update ("ASU") 2016-01, "Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities." ASU 2016-01 requires equity investments to be measured at fair value through earnings, and eliminates the available-for-sale classification for equity securities with readily determinable fair values. The guidance also provides an alternative to measure equity securities without readily determinable fair values at cost less impairment (if any), plus or minus observable price changes from an identical or similar investment of the same issuer (the “measurement alternative”). The Company elected the measurement alternative for its qualifying equity securities. The adoption of this update resulted in an insignificant increase to retained earnings which was reclassified from accumulated other comprehensive income. In addition, the Company early adopted ASU 2017-12, "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities" during the first quarter of 2018. The objective of ASU 2017-12 is to improve the financial reporting of hedging relationships by better aligning an entity's risk management activity with the economic objectives in undertaking those activities. The adoption of this update did not have a material effect on the Company's consolidated financial statements. The Company also early adopted ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income" during the first quarter of 2018. The ASU allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017, which among other things, reduced the maximum federal corporate tax rate from 35% to 21%. The adoption of this update resulted in an increase to retained earnings of $0.8 million which was reclassified from accumulated other comprehensive income. In the opinion of management, the consolidated financial statements contain all adjustments (consisting of normal recurring accruals) considered necessary for the fair presentation of the statements of financial position, results of operations, and cash flow for the interim periods. Revenue The Company adopted the accounting standard regarding revenue recognition in the first quarter of 2018 using the modified retrospective approach. The Company's revenues are primarily composed of interest income on financial instruments, including investment securities, which are excluded from the scope of the new guidance. Certain other noninterest income from loans, investment securities and derivative financial instruments is also excluded from this guidance. Service charges on deposit accounts, wealth management revenue, card services revenue, and gain on sale of other real estate are within the scope of the guidance; however, there were no accounting policy changes as the Company's policies were consistent with the new guidance. Other noninterest income sources of revenue are considered immaterial. Implementation of this guidance did not change current business practices or have any changes to the Company's consolidated financial statements. Descriptions of our revenue-generating activities within the scope of this guidance, which are presented in our income statement as components of noninterest income are as follows: • Service charges on deposit accounts - represents fees generated from a variety of deposit products and services provided to customers under a day-to-day contract. These fees are recognized on a daily or monthly basis. • Wealth management revenue - represents monthly fees earned from directing, holding, and managing customers’ assets. Revenue is recognized over regular intervals, either monthly or quarterly. • Card services revenue - represents revenue earned from merchant, debit and credit cards as incurred and includes a contra revenue account for rebates. • Gain on sale of other real estate - represents income recognized at delivery of control of a property at the time of a real estate closing. Income Taxes The SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Tax Cuts and Jobs Act of 2017 (“Tax Act”). SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. The Company has recorded amounts for the effects of the Tax Act using reasonable estimates based on currently available information and its interpretations thereof. This accounting may change due to, among other things, changes in interpretations the Company has made and the issuance of new tax or accounting guidance.
Available-for-sale Securities	Management systematically evaluates investment securities for other-than-temporary declines in fair value on a quarterly basis. This analysis requires management to consider various factors, which include among other considerations (1) the present value of the cash flows expected to be collected compared to the amortized cost of the security, (2) duration and magnitude of the decline in value, (3) the financial condition of the issuer or issuers, (4) structure of the security, and (5) the intent to sell the security or whether it is more likely than not the Company would be required to sell the security before its anticipated recovery in market value. At September 30, 2018 , management performed its quarterly analysis of all securities with an unrealized loss and concluded no individual securities were other-than-temporarily impaired.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Summary of Per Common Share Data and Amounts	The following table presents a summary of per common share data and amounts for the periods indicated. Three months ended Nine months ended (in thousands, except per share data) 2018 2017 2018 2017 Net income as reported $ 22,516 $ 16,315 $ 65,688 $ 40,661 Weighted average common shares outstanding 23,148 23,324 23,129 22,914 Additional dilutive common stock equivalents 181 250 211 295 Weighted average diluted common shares outstanding 23,329 23,574 23,340 23,209 Basic earnings per common share: $ 0.97 $ 0.70 $ 2.84 $ 1.77 Diluted earnings per common share: $ 0.97 $ 0.69 $ 2.81 $ 1.75

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation	The following table presents the amortized cost, gross unrealized gains and losses and fair value of securities available for sale and held to maturity: September 30, 2018 (in thousands) Amortized Cost Gross Gross Fair Value Available for sale securities: Obligations of U.S. Government-sponsored enterprises $ 99,914 $ — $ (2,233 ) $ 97,681 Obligations of states and political subdivisions 30,563 238 (268 ) 30,533 Agency mortgage-backed securities 551,552 180 (19,385 ) 532,347 U.S. Treasury bills 9,960 — (193 ) 9,767 Total securities available for sale $ 691,989 $ 418 $ (22,079 ) $ 670,328 Held to maturity securities: Obligations of states and political subdivisions $ 12,521 $ 6 $ (324 ) $ 12,203 Agency mortgage-backed securities 54,610 — (2,397 ) 52,213 Total securities held to maturity $ 67,131 $ 6 $ (2,721 ) $ 64,416 December 31, 2017 (in thousands) Amortized Cost Gross Gross Fair Value Available for sale securities: Obligations of U.S. Government-sponsored enterprises $ 99,878 $ 6 $ (660 ) $ 99,224 Obligations of states and political subdivisions 34,181 674 (213 ) 34,642 Agency mortgage-backed securities 513,082 727 (6,293 ) 507,516 Total securities available for sale $ 647,141 $ 1,407 $ (7,166 ) $ 641,382 Held to maturity securities: Obligations of states and political subdivisions $ 14,031 $ 69 $ (46 ) $ 14,054 Agency mortgage-backed securities 59,718 16 (330 ) 59,404 Total securities held to maturity $ 73,749 $ 85 $ (376 ) $ 73,458
Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation	The following table presents the amortized cost, gross unrealized gains and losses and fair value of securities available for sale and held to maturity: September 30, 2018 (in thousands) Amortized Cost Gross Gross Fair Value Available for sale securities: Obligations of U.S. Government-sponsored enterprises $ 99,914 $ — $ (2,233 ) $ 97,681 Obligations of states and political subdivisions 30,563 238 (268 ) 30,533 Agency mortgage-backed securities 551,552 180 (19,385 ) 532,347 U.S. Treasury bills 9,960 — (193 ) 9,767 Total securities available for sale $ 691,989 $ 418 $ (22,079 ) $ 670,328 Held to maturity securities: Obligations of states and political subdivisions $ 12,521 $ 6 $ (324 ) $ 12,203 Agency mortgage-backed securities 54,610 — (2,397 ) 52,213 Total securities held to maturity $ 67,131 $ 6 $ (2,721 ) $ 64,416 December 31, 2017 (in thousands) Amortized Cost Gross Gross Fair Value Available for sale securities: Obligations of U.S. Government-sponsored enterprises $ 99,878 $ 6 $ (660 ) $ 99,224 Obligations of states and political subdivisions 34,181 674 (213 ) 34,642 Agency mortgage-backed securities 513,082 727 (6,293 ) 507,516 Total securities available for sale $ 647,141 $ 1,407 $ (7,166 ) $ 641,382 Held to maturity securities: Obligations of states and political subdivisions $ 14,031 $ 69 $ (46 ) $ 14,054 Agency mortgage-backed securities 59,718 16 (330 ) 59,404 Total securities held to maturity $ 73,749 $ 85 $ (376 ) $ 73,458
Investments Classified by Contractual Maturity Date	The amortized cost and estimated fair value of debt securities at September 30, 2018 , by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. The weighted average life of the mortgage-backed securities is approximately 5 years. Available for sale Held to maturity (in thousands) Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value Due in one year or less $ 12,193 $ 12,107 $ — $ — Due after one year through five years 110,517 108,231 868 856 Due after five years through ten years 12,688 12,678 11,294 10,995 Due after ten years 5,039 4,965 359 352 Agency mortgage-backed securities 551,552 532,347 54,610 52,213 $ 691,989 $ 670,328 $ 67,131 $ 64,416
Schedule of Unrealized Loss on Investments	The following table represents a summary of investment securities that had an unrealized loss: September 30, 2018 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Obligations of U.S. Government-sponsored enterprises $ 58,592 $ 1,353 $ 39,089 $ 880 $ 97,681 $ 2,233 Obligations of states and political subdivisions 24,152 468 3,296 124 27,448 592 Agency mortgage-backed securities 297,577 8,216 270,949 13,566 568,526 21,782 U.S. Treasury bills 9,767 193 — — 9,767 193 $ 390,088 $ 10,230 $ 313,334 $ 14,570 $ 703,422 $ 24,800 December 31, 2017 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Obligations of U.S. Government-sponsored enterprises $ 89,309 $ 660 $ — $ — $ 89,309 $ 660 Obligations of states and political subdivisions 13,951 259 — — 13,951 259 Agency mortgage-backed securities 469,655 6,034 12,229 589 481,884 6,623 $ 572,915 $ 6,953 $ 12,229 $ 589 $ 585,144 $ 7,542

Loans (Tables)

Loans (Tables) - Portfolio loans, net	9 Months Ended
	Sep. 30, 2018
Non-covered Loans [Line Items]
Summary of Portfolio Loans by Category	The table below shows the loan portfolio composition including carrying value categorized by loans accounted for at amortized cost, which includes our originated loans, and by loans accounted for as PCI. (in thousands) September 30, 2018 December 31, 2017 Loans accounted for at amortized cost $ 4,218,341 $ 4,022,896 Loans accounted for as PCI 49,089 74,154 Total loans $ 4,267,430 $ 4,097,050 The following tables refer to loans accounted for at amortized cost. Below is a summary of loans by category at September 30, 2018 and December 31, 2017 : (in thousands) September 30, 2018 December 31, 2017 Commercial and industrial $ 2,032,929 $ 1,918,720 Real estate: Commercial - investor owned 826,447 769,275 Commercial - owner occupied 589,045 554,589 Construction and land development 326,858 303,091 Residential 308,385 341,312 Total real estate loans 2,050,735 1,968,267 Consumer and other 136,025 137,234 Loans, before unearned loan fees 4,219,689 4,024,221 Unearned loan fees, net (1,348 ) (1,325 ) Loans, including unearned loan fees $ 4,218,341 $ 4,022,896
Summary of Allowance for Loan Losses and the Recorded Investment in Portfolio Loans by Class and Category Based on Impairment Method	A summary of the activity in the allowance for loan losses and the recorded investment in loans by class and category based on impairment methodology through September 30, 2018 , and at December 31, 2017 , is as follows: (in thousands) Commercial and industrial CRE - investor owned CRE - owner occupied Construction and land development Residential real estate Consumer and other Total Allowance for loan losses: Balance at December 31, 2017 $ 26,406 $ 3,890 $ 3,308 $ 1,487 $ 2,237 $ 838 $ 38,166 Provision (provision reversal) for loan losses 780 648 190 35 259 (41 ) 1,871 Losses charged off (732 ) — — — (254 ) (49 ) (1,035 ) Recoveries 956 8 4 206 73 14 1,261 Balance at March 31, 2018 $ 27,410 $ 4,546 $ 3,502 $ 1,728 $ 2,315 $ 762 $ 40,263 Provision (provision reversal) for loan losses 2,852 5 340 (206 ) (573 ) (33 ) 2,385 Losses charged off (956 ) — — — (38 ) (33 ) (1,027 ) Recoveries 118 10 3 168 59 28 386 Balance at June 30, 2018 $ 29,424 $ 4,561 $ 3,845 $ 1,690 $ 1,763 $ 724 $ 42,007 Provision (provision reversal) for loan losses 2,569 3 (197 ) 154 (187 ) (10 ) 2,332 Losses charged off (2,405 ) — (22 ) — (122 ) (46 ) (2,595 ) Recoveries 2 8 4 21 88 25 148 Balance at September 30, 2018 $ 29,590 $ 4,572 $ 3,630 $ 1,865 $ 1,542 $ 693 $ 41,892 (in thousands) Commercial and industrial CRE - investor owned CRE - owner occupied Construction and land development Residential real estate Consumer and other Total Balance September 30, 2018 Allowance for loan losses - Ending balance: Individually evaluated for impairment $ 4,128 $ — $ 177 $ — $ 9 $ — $ 4,314 Collectively evaluated for impairment 25,462 4,572 3,453 1,865 1,533 693 37,578 Total $ 29,590 $ 4,572 $ 3,630 $ 1,865 $ 1,542 $ 693 $ 41,892 Loans - Ending balance: Individually evaluated for impairment $ 12,197 $ 770 $ 2,655 $ — $ 2,477 $ 312 $ 18,411 Collectively evaluated for impairment 2,020,732 825,677 586,390 326,858 305,908 134,365 4,199,930 Total $ 2,032,929 $ 826,447 $ 589,045 $ 326,858 $ 308,385 $ 134,677 $ 4,218,341 Balance December 31, 2017 Allowance for loan losses - Ending balance: Individually evaluated for impairment $ 2,508 $ — $ 71 $ — $ — $ — $ 2,579 Collectively evaluated for impairment 23,898 3,890 3,237 1,487 2,237 838 35,587 Total $ 26,406 $ 3,890 $ 3,308 $ 1,487 $ 2,237 $ 838 $ 38,166 Loans - Ending balance: Individually evaluated for impairment $ 12,665 $ 422 $ 1,975 $ 136 $ 1,602 $ 375 $ 17,175 Collectively evaluated for impairment 1,906,055 768,853 552,614 302,955 339,710 135,534 4,005,721 Total $ 1,918,720 $ 769,275 $ 554,589 $ 303,091 $ 341,312 $ 135,909 $ 4,022,896
Summary of Portfolio Loans Individually Evaluated for Impairment and Recorded Investment in Impaired Non-Covered Loans by Category	A summary of nonperforming loans individually evaluated for impairment by category at September 30, 2018 and December 31, 2017 , and the income recognized on impaired loans is as follows: September 30, 2018 (in thousands) Unpaid Recorded Recorded Allowance Total Related Allowance Average Commercial and industrial $ 20,938 $ 3,266 $ 8,931 $ 12,197 $ 4,128 $ 10,414 Real estate: Commercial - investor owned 1,039 770 — 770 — 657 Commercial - owner occupied 1,328 826 462 1,288 177 1,074 Construction and land development — — — — — — Residential 2,600 2,008 469 2,477 9 2,410 Consumer and other 329 312 — 312 — 334 Total $ 26,234 $ 7,182 $ 9,862 $ 17,044 $ 4,314 $ 14,889 December 31, 2017 (in thousands) Unpaid Recorded Recorded Allowance Total Related Allowance Average Commercial and industrial $ 20,750 $ 2,321 $ 10,344 $ 12,665 $ 2,508 $ 16,270 Real estate: Commercial - investor owned 560 422 — 422 — 521 Commercial - owner occupied 487 — 487 487 71 490 Construction and land development 441 136 — 136 — 331 Residential 1,730 1,602 — 1,602 — 1,735 Consumer and other 375 375 — 375 — 375 Total $ 24,343 $ 4,856 $ 10,831 $ 15,687 $ 2,579 $ 19,722 Three months ended September 30, Nine months ended September 30, (in thousands) 2018 2017 2018 2017 Total interest income that would have been recognized under original terms $ 614 $ 306 $ 1,615 $ 961 Total cash received and recognized as interest income on non-accrual loans 68 117 157 156 Total interest income recognized on accruing, impaired loans 110 8 133 55 The recorded investment in nonperforming loans by category at September 30, 2018 and December 31, 2017 , is as follows: September 30, 2018 (in thousands) Non-accrual Restructured, not on non-accrual Loans over 90 days past due and still accruing interest Total Commercial and industrial $ 10,088 $ 820 $ 1,289 $ 12,197 Real estate: Commercial - investor owned 770 — — 770 Commercial - owner occupied 1,288 — — 1,288 Construction and land development — — — — Residential 2,477 — — 2,477 Consumer and other 312 — — 312 Total $ 14,935 $ 820 $ 1,289 $ 17,044 December 31, 2017 (in thousands) Non-accrual Restructured, not on non-accrual Total Commercial and industrial $ 11,946 $ 719 $ 12,665 Real estate: Commercial - investor owned 422 — 422 Commercial - owner occupied 487 — 487 Construction and land development 136 — 136 Residential 1,602 — 1,602 Consumer and other 375 — 375 Total $ 14,968 $ 719 $ 15,687
Summary of Recorded Investment by Category for Portfolio Loans Restructured	The recorded investment by category for the portfolio loans that have been restructured during the three and nine months ended September 30, 2018 and 2017 , is as follows: Three months ended September 30, 2018 Three months ended September 30, 2017 (in thousands, except for number of loans) Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Commercial and industrial 1 $ 187 $ 187 — $ — $ — Total 1 $ 187 $ 187 — $ — $ — Nine months ended September 30, 2018 Nine months ended September 30, 2017 (in thousands, except for number of loans) Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Number of loans Pre-Modification Outstanding Recorded Balance Post-Modification Outstanding Recorded Balance Commercial and industrial 1 $ 187 $ 187 1 $ 676 $ 676 Total 1 $ 187 $ 187 1 $ 676 $ 676
Summary of Recorded Investment by Category for Portfolio Loans Restructured and Subsequently Defaulted	As of September 30, 2018 , the Company had $2.6 million in specific reserves allocated to $8.0 million of loans that have been restructured. During the three and nine months ended September 30, 2018 and 2017, there were no portfolio loans that subsequently defaulted.
Summary of Aging of Recorded Investment in Past Due Portfolio Loans by Portfolio Class and Category	The aging of the recorded investment in past due loans by portfolio class and category at September 30, 2018 and December 31, 2017 , is shown below. September 30, 2018 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ 11,213 $ 6,020 $ 17,233 $ 2,015,696 $ 2,032,929 Real estate: Commercial - investor owned 1,362 129 1,491 824,956 826,447 Commercial - owner occupied 258 808 1,066 587,979 589,045 Construction and land development — — — 326,858 326,858 Residential 864 1,156 2,020 306,365 308,385 Consumer and other — — — 134,677 134,677 Total $ 13,697 $ 8,113 $ 21,810 $ 4,196,531 $ 4,218,341 December 31, 2017 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ 7,882 $ 1,770 $ 9,652 $ 1,909,068 $ 1,918,720 Real estate: Commercial - investor owned 934 — 934 768,341 769,275 Commercial - owner occupied — — — 554,589 554,589 Construction and land development 76 — 76 303,015 303,091 Residential 1,529 945 2,474 338,838 341,312 Consumer and other 407 — 407 135,502 135,909 Total $ 10,828 $ 2,715 $ 13,543 $ 4,009,353 $ 4,022,896
Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category	The recorded investment by risk category of the loans by portfolio class and category at September 30, 2018 , which is based upon the most recent analysis performed, and December 31, 2017 , is as follows: September 30, 2018 (in thousands) Pass (1-6) Watch (7) Classified (8 & 9) Total Commercial and industrial $ 1,835,230 $ 142,768 $ 54,931 $ 2,032,929 Real estate: Commercial - investor owned 798,116 22,275 6,056 826,447 Commercial - owner occupied 540,961 43,399 4,685 589,045 Construction and land development 315,022 11,775 61 326,858 Residential 298,076 3,058 7,251 308,385 Consumer and other 134,359 7 311 134,677 Total $ 3,921,764 $ 223,282 $ 73,295 $ 4,218,341 December 31, 2017 (in thousands) Pass (1-6) Watch (7) Classified (8 & 9) Total Commercial and industrial $ 1,769,102 $ 94,002 $ 55,616 $ 1,918,720 Real estate: Commercial - investor owned 754,010 10,840 4,425 769,275 Commercial - owner occupied 514,616 34,440 5,533 554,589 Construction and land development 292,766 9,983 342 303,091 Residential 329,742 3,648 7,922 341,312 Consumer and other 134,704 10 1,195 135,909 Total $ 3,794,940 $ 152,923 $ 75,033 $ 4,022,896

Purchased Credit Impaired ("P_2

Purchased Credit Impaired ("PCI") Loans (Tables)	9 Months Ended
	Sep. 30, 2018
Covered Loans [Line Items]
Rollforward of PCI Loans, Net of Allowance for Loan Losses	The following table is a roll forward of PCI loans, net of the allowance for loan losses, for the nine months ended September 30, 2018 and 2017 . (in thousands) Contractual Cashflows Non-accretable Difference Accretable Yield Carrying Amount Balance December 31, 2017 $ 112,710 $ 29,005 $ 13,964 $ 69,741 Principal reductions and interest payments (38,165 ) — — (38,165 ) Accretion of loan discount — — (5,118 ) 5,118 Changes in contractual and expected cash flows due to remeasurement 4,341 (8,939 ) 3,179 10,101 Balance September 30, 2018 $ 78,886 $ 20,066 $ 12,025 $ 46,795 Balance December 31, 2016 $ 66,003 $ 18,902 $ 13,176 $ 33,925 Acquisitions 68,763 14,296 5,312 49,155 Principal reductions and interest payments (16,319 ) — — (16,319 ) Accretion of loan discount — — (5,473 ) 5,473 Changes in contractual and expected cash flows due to remeasurement 11,110 (702 ) 3,776 8,036 Reductions due to disposals (6,393 ) (1,612 ) (1,595 ) (3,186 ) Balance September 30, 2017 $ 123,164 $ 30,884 $ 15,196 $ 77,084
Covered Loans
Covered Loans [Line Items]
Summary of PCI Loans by Category	Below is a summary of PCI loans by category at September 30, 2018 and December 31, 2017 : September 30, 2018 December 31, 2017 (in thousands) Weighted- Average Risk Rating 1 Recorded Investment PCI Loans Weighted- Average Risk Rating 1 Recorded Investment PCI Loans Commercial and industrial 6.39 $ 2,923 6.38 $ 3,212 Real estate: Commercial - investor owned 7.23 25,172 7.36 42,887 Commercial - owner occupied 7.45 9,520 6.48 11,332 Construction and land development 6.01 5,168 5.99 5,883 Residential 6.35 6,291 5.99 10,781 Consumer and other 7.08 15 2.84 59 Total $ 49,089 $ 74,154 1 Risk ratings are based on the borrower's contractual obligation, which is not reflective of the purchase discount.
Summary of Aging of Recorded Investment in Past Due PCI Loans by Portfolio Class and Category	The aging of the recorded investment in past due PCI loans by portfolio class and category at September 30, 2018 and December 31, 2017 , is shown below: September 30, 2018 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ — $ — $ — $ 2,923 $ 2,923 Real estate: Commercial - investor owned 627 1,190 1,817 23,355 25,172 Commercial - owner occupied 6,230 744 6,974 2,546 9,520 Construction and land development 146 — 146 5,022 5,168 Residential 33 46 79 6,212 6,291 Consumer and other — — — 15 15 Total $ 7,036 $ 1,980 $ 9,016 $ 40,073 $ 49,089 December 31, 2017 (in thousands) 30-89 Days Past Due 90 or More Past Due Total Past Due Current Total Commercial and industrial $ — $ — $ — $ 3,212 $ 3,212 Real estate: Commercial - investor owned — 3,034 3,034 39,853 42,887 Commercial - owner occupied — 673 673 10,659 11,332 Construction and land development — — — 5,883 5,883 Residential 328 255 583 10,198 10,781 Consumer and other — — — 59 59 Total $ 328 $ 3,962 $ 4,290 $ 69,864 $ 74,154
Summary of FDIC Loss Share Receivable	Outstanding customer balances on PCI loans were $68.6 million and $94.9 million as of September 30, 2018 , and December 31, 2017 , respectively.

Commitments (Tables)

Commitments (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Commitments	The contractual amounts of off-balance-sheet financial instruments as of September 30, 2018 , and December 31, 2017 , are as follows: (in thousands) September 30, 2018 December 31, 2017 Commitments to extend credit $ 1,315,284 $ 1,298,423 Letters of credit 49,633 73,790

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables) - Client-Related	9 Months Ended
	Sep. 30, 2018
Derivative [Line Items]
Schedule of Notional Amounts and Fair Values of Derivative Instruments and Client-Related Derivative Instruments	The table below summarizes the notional amounts and fair values of the client-related derivative instruments: Asset Derivatives (Other Assets) Liability Derivatives (Other Liabilities) Notional Amount Fair Value Fair Value (in thousands) September 30, December 31, September 30, December 31, September 30, December 31, Non-designated hedging instruments Interest rate swap contracts $ 433,664 $ 394,852 $ 4,772 $ 2,061 $ 4,772 $ 2,061 Foreign exchange forward contracts 123 1,528 123 1,528 123 1,528
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	For the three and nine months ended September 30, 2018 and 2017 , the gains and losses offset each other due to the Company's hedging of the client swaps and foreign exchange contracts with other bank counterparties.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Summary of Financial Instruments Measured at Fair Value on a Recurring Basis	The following table summarizes financial instruments measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 , segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value: September 30, 2018 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets Securities available for sale Obligations of U.S. Government-sponsored enterprises $ — $ 97,681 $ — $ 97,681 Obligations of states and political subdivisions — 30,533 — 30,533 Residential mortgage-backed securities — 532,347 — 532,347 U.S. Treasury bills — 9,767 — 9,767 Total securities available for sale $ — $ 670,328 $ — $ 670,328 Other investments 144 — — 144 State tax credits held for sale — — 171 171 Derivative financial instruments — 4,895 — 4,895 Total assets $ 144 $ 675,223 $ 171 $ 675,538 Liabilities Derivative financial instruments $ — $ 4,895 $ — $ 4,895 Total liabilities $ — $ 4,895 $ — $ 4,895 December 31, 2017 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets Securities available for sale Obligations of U.S. Government-sponsored enterprises $ — $ 99,224 $ — $ 99,224 Obligations of states and political subdivisions — 34,642 — 34,642 Residential mortgage-backed securities — 507,516 — 507,516 Total securities available for sale $ — $ 641,382 $ — $ 641,382 State tax credits held for sale — — 400 400 Derivative financial instruments — 3,589 — 3,589 Total assets $ — $ 644,971 $ 400 $ 645,371 Liabilities Derivative financial instruments $ — $ 3,589 $ — $ 3,589 Total liabilities $ — $ 3,589 $ — $ 3,589
Schedule of Level 3 Financial Instruments Measured at Fair Value on a Recurring Basis	The following table presents the changes in Level 3 financial instruments measured at fair value on a recurring basis as of September 30, 2018 and 2017 . Securities available for sale, at fair value Three months ended September 30, Nine months ended September 30, (in thousands) 2018 2017 2018 2017 Beginning balance $ — $ — $ — $ 3,089 Total gains: Included in other comprehensive income — — — 4 Purchases, sales, issuances and settlements: Purchases — — — — Transfer in and/or out of Level 3 — — — (3,093 ) Ending balance $ — $ — $ — $ — Change in unrealized gains relating to assets still held at the reporting date $ — $ — $ — $ — State tax credits held for sale Three months ended September 30, Nine months ended September 30, (in thousands) 2018 2017 2018 2017 Beginning balance $ 299 $ 1,274 $ 400 $ 3,585 Total gains: Included in earnings 7 — 13 49 Purchases, sales, issuances and settlements: Sales (135 ) — (242 ) (2,360 ) Ending balance $ 171 $ 1,274 $ 171 $ 1,274 Change in unrealized gains (losses) relating to assets still held at the reporting date $ (34 ) $ — $ (60 ) $ (655 )
Summary of Financial Instruments and Non-Financial Assets Measured at Fair Value on a Non-Recurring Basis	The following table presents financial instruments and non-financial assets measured at fair value on a non-recurring basis as of September 30, 2018 . (1) (1) (1) (1) (in thousands) Total Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant (Level 3) Total losses for the three Total losses for the nine Impaired loans $ 485 $ — $ — $ 485 $ 248 $ 457 Other real estate — — — — — — Total $ 485 $ — $ — $ 485 $ 248 $ 457 (1) The amounts represent only balances measured at fair value during the period and still held as of the reporting date.
Summary of Carrying Amount and Fair Values of Financial Instruments Reported on the Balance Sheets	Following is a summary of the carrying amounts and fair values of the Company’s financial instruments on the consolidated balance sheets at September 30, 2018 and December 31, 2017 . Fair values that are not estimable are listed at the carrying value. September 30, 2018 December 31, 2017 (in thousands) Carrying Amount Estimated fair value Carrying Amount Estimated fair value Balance sheet assets Cash and due from banks $ 78,119 $ 78,119 $ 91,084 $ 91,084 Federal funds sold 1,571 1,571 1,223 1,223 Interest-bearing deposits 79,780 79,780 63,661 63,661 Securities available for sale 670,328 670,328 641,382 641,382 Securities held to maturity 67,131 64,416 73,749 73,458 Other investments, at cost 37,885 37,885 26,661 26,661 Loans held for sale 738 738 3,155 3,155 Derivative financial instruments 4,895 4,895 3,589 3,589 Portfolio loans, net 4,223,244 4,254,581 4,054,473 4,096,741 State tax credits, held for sale 45,625 48,622 43,468 44,271 Accrued interest receivable 19,879 19,879 14,069 14,069 Balance sheet liabilities Deposits 4,210,476 4,203,913 4,156,414 4,153,323 Subordinated debentures and notes 118,144 105,611 118,105 105,031 Federal Home Loan Bank advances 401,000 400,977 172,743 172,893 Other borrowings 161,795 161,676 253,674 253,530 Derivative financial instruments 4,895 4,895 3,589 3,589 Accrued interest payable 2,433 2,433 1,730 1,730
Schedule of Estimated Fair Values of Financial Instruments Not Recorded at Fair Value on Balance Sheet	The following table presents the level in the fair value hierarchy for the estimated fair values of only the Company’s financial instruments that are not already presented on the condensed consolidated balance sheets at fair value at September 30, 2018 , and December 31, 2017 . Estimated Fair Value Measurement at Reporting Date Using Balance at September 30, 2018 (in thousands) Level 1 Level 2 Level 3 Financial Assets: Securities held to maturity $ — $ 64,416 $ — $ 64,416 Portfolio loans, net — — 4,254,581 4,254,581 State tax credits, held for sale — — 48,451 48,451 Financial Liabilities: Deposits 3,536,239 — 667,674 4,203,913 Subordinated debentures and notes — 105,611 — 105,611 Federal Home Loan Bank advances — 400,977 — 400,977 Other borrowings — 161,676 — 161,676 Estimated Fair Value Measurement at Reporting Date Using Balance at December 31, 2017 (in thousands) Level 1 Level 2 Level 3 Financial Assets: Securities held to maturity $ — $ 73,458 $ — $ 73,458 Portfolio loans, net — — 4,096,741 4,096,741 State tax credits, held for sale — — 43,871 43,871 Financial Liabilities: Deposits 3,577,641 — 575,682 4,153,323 Subordinated debentures and notes — 105,031 — 105,031 Federal Home Loan Bank advances — 172,893 — 172,893 Other borrowings — 253,530 — 253,530

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income as reported	$ 22,516	$ 16,315	$ 65,688	$ 40,661
Weighted average common shares outstanding (in shares)	23,148,000	23,324,000	23,129,000	22,914,000
Additional dilutive common stock equivalents (in shares)	181,000	250,000	211,000	295,000
Weighted average diluted common shares outstanding (in shares)	23,329,000	23,574,000	23,340,000	23,209,000
Basic earnings per common share (in dollars per share)	$ 0.97	$ 0.70	$ 2.84	$ 1.77
Diluted earnings per common share (in dollars per share)	$ 0.97	$ 0.69	$ 2.81	$ 1.75
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			0	0

Investments - Schedule of Avail

Investments - Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 67,131	$ 73,749
Gross Unrealized Gains	6	85
Gross Unrealized Losses	(2,721)	(376)
Fair Value	64,416	73,458
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	691,989	647,141
Gross Unrealized Gains	418	1,407
Gross Unrealized Losses	(22,079)	(7,166)
Fair Value	670,328	641,382
US Treasury Bill Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,960
Gross Unrealized Gains	0
Gross Unrealized Losses	(193)
Fair Value	9,767
Obligations of U.S. Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	99,914	99,878
Gross Unrealized Gains	0	6
Gross Unrealized Losses	(2,233)	(660)
Fair Value	97,681	99,224
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,563	34,181
Gross Unrealized Gains	238	674
Gross Unrealized Losses	(268)	(213)
Fair Value	30,533	34,642
Agency mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	551,552	513,082
Gross Unrealized Gains	180	727
Gross Unrealized Losses	(19,385)	(6,293)
Fair Value	532,347	507,516
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	12,521	14,031
Gross Unrealized Gains	6	69
Gross Unrealized Losses	(324)	(46)
Fair Value	12,203	14,054
Agency mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	54,610	59,718
Gross Unrealized Gains	0	16
Gross Unrealized Losses	(2,397)	(330)
Fair Value	$ 52,213	$ 59,404

Investments - Investments Class

Investments - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available for sale, Amortized Cost
Due in one year or less	$ 12,193
Due after one year through five years	110,517
Due after five years through ten years	12,688
Due after ten years	5,039
Agency mortgage-backed securities	551,552
Amortized Cost	691,989	$ 647,141
Available for sale, Estimated Fair Value
Due in one year or less	12,107
Due after one year through five years	108,231
Due after five years through ten years	12,678
Due after ten years	4,965
Agency mortgage-backed securities	532,347
Available for sale, fair value	670,328	641,382
Held to maturity, Amortized Cost
Due in one year or less	0
Due after one year through five years	868
Due after five years through ten years	11,294
Due after ten years	359
Agency mortgage-backed securities	54,610
Amortized Cost	67,131	73,749
Held to maturity, Estimated Fair Value
Due in one year or less	0
Due after one year through five years	856
Due after five years through ten years	10,995
Due after ten years	352
Agency mortgage-backed securities	52,213
Held to maturity, fair value	$ 64,416	$ 73,458

Investments - Schedule of Unrea

Investments - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	$ 390,088	$ 572,915
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	10,230	6,953
12 months or more, fair value	313,334	12,229
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	14,570	589
Total, fair value	703,422	585,144
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	24,800	7,542
Obligations of U.S. Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	58,592	89,309
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,353	660
12 months or more, fair value	39,089	0
Securities Available for Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	880
Total, fair value	97,681	89,309
Securities Available for Sale Continuous Unrealized Loss Position, Total Aggregate Losses		660
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,233
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	24,152	13,951
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	468	259
12 months or more, fair value	3,296	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	124	0
Total, fair value	27,448	13,951
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	592	259
Agency mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	297,577	469,655
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8,216	6,034
12 months or more, fair value	270,949	12,229
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	13,566	589
Total, fair value	568,526	481,884
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	21,782	$ 6,623
US Treasury Bill Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	9,767
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	193
12 months or more, fair value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Total, fair value	9,767
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 193

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Other investments, at cost	$ 37,885	$ 26,661
Maximum percentage of shareholders' equity security holdings held of one issuer	10.00%	10.00%
Available-for-sale securities pledged as collateral, fair value	$ 365,300	$ 500,000
Mortgage-backed securities, weighted average life	5 years

Loans - Summary of Portfolio Lo

Loans - Summary of Portfolio Loans by Category (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, including unearned loan fees	$ 4,267,430	$ 4,097,050
Portfolio loans, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	4,219,689	4,024,221
Unearned loan fees, net	(1,348)	(1,325)
Loans, including unearned loan fees	4,218,341	4,022,896
Portfolio loans, net | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	2,032,929	1,918,720
Portfolio loans, net | Commercial - investor owned
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	826,447	769,275
Portfolio loans, net | Commercial - owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	589,045	554,589
Portfolio loans, net | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	326,858	303,091
Portfolio loans, net | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	308,385	341,312
Portfolio loans, net | Total real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	2,050,735	1,968,267
Portfolio loans, net | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, before unearned loan fees	136,025	137,234
Loans, including unearned loan fees	134,677	135,909
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	49,089	74,154
Loans, before unearned loan fees	49,089	74,154
Covered Loans [Member] | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	2,923	3,212
Loans, before unearned loan fees	2,923	3,212
Covered Loans [Member] | Commercial - investor owned
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	25,172	42,887
Loans, before unearned loan fees	25,172	42,887
Covered Loans [Member] | Commercial - owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	9,520	11,332
Loans, before unearned loan fees	9,520	11,332
Covered Loans [Member] | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	5,168	5,883
Loans, before unearned loan fees	5,168	5,883
Covered Loans [Member] | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	6,291	10,781
Loans, before unearned loan fees	6,291	10,781
Covered Loans [Member] | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	15	59
Loans, before unearned loan fees	$ 15	$ 59

Loans - Summary of Allowance fo

Loans - Summary of Allowance for Loan Losses by Portfolio Class and Category (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Allowance for Loan Losses [Roll Forward]
Balance
Portfolio loans, net
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	42,007	$ 40,263	$ 38,166
Provision (provision reversal) for loan losses	2,332	2,385	1,871
Losses charged off	(2,595)	(1,027)	(1,035)
Recoveries	148	386	1,261
Balance	41,892	42,007	40,263
Portfolio loans, net | Commercial and industrial
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	29,424	27,410	26,406
Provision (provision reversal) for loan losses	2,569	2,852	780
Losses charged off	(2,405)	(956)	(732)
Recoveries	2	118	956
Balance	29,590	29,424	27,410
Portfolio loans, net | CRE - investor owned
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	4,561	4,546	3,890
Provision (provision reversal) for loan losses	3	5	648
Losses charged off	0	0	0
Recoveries	8	10	8
Balance	4,572	4,561	4,546
Portfolio loans, net | CRE - owner occupied
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	3,845	3,502	3,308
Provision (provision reversal) for loan losses	(197)	340	190
Losses charged off	(22)	0	0
Recoveries	4	3	4
Balance	3,630	3,845	3,502
Portfolio loans, net | Construction and land development
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	1,690	1,728	1,487
Provision (provision reversal) for loan losses	154	(206)	35
Losses charged off	0	0	0
Recoveries	21	168	206
Balance	1,865	1,690	1,728
Portfolio loans, net | Residential real estate
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	1,763	2,315	2,237
Provision (provision reversal) for loan losses	(187)	(573)	259
Losses charged off	(122)	(38)	(254)
Recoveries	88	59	73
Balance	1,542	1,763	2,315
Portfolio loans, net | Consumer and other
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2017	724	762	838
Provision (provision reversal) for loan losses	(10)	(33)	(41)
Losses charged off	(46)	(33)	(49)
Recoveries	25	28	14
Balance	$ 693	$ 724	$ 762

Loans - Summary of Recorded Inv

Loans - Summary of Recorded Investment in Portfolio Loans by Class and Category Based on Impairment Method (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Total
Loans - Ending balance:
Loans and Leases Receivable, Gross	$ 4,267,430		$ 4,267,430				$ 4,097,050
Portfolio loans, net
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Financing Receivable, Modifications, Number of Contracts | loan	1	0	1	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 187	$ 0	$ 187	$ 676
Financing Receivable, Modifications, Pre-Modification Recorded Investment	187	$ 0	187	$ 676
Individually evaluated for impairment	4,314		4,314				2,579
Collectively evaluated for impairment	37,578		37,578				35,587
Total	41,892		41,892		$ 42,007	$ 40,263	38,166
Loans - Ending balance:
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	(1,348)		(1,348)				(1,325)
Individually evaluated for impairment	18,411		18,411				17,175
Collectively evaluated for impairment	4,199,930		4,199,930				4,005,721
Total	4,219,689		4,219,689				4,024,221
Loans and Leases Receivable, Gross	$ 4,218,341		$ 4,218,341				4,022,896
Portfolio loans, net | Commercial and industrial
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Financing Receivable, Modifications, Number of Contracts | loan	1	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 187	$ 0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	187	$ 0
Individually evaluated for impairment	4,128		$ 4,128				2,508
Collectively evaluated for impairment	25,462		25,462				23,898
Total	29,590		29,590		29,424	27,410	26,406
Loans - Ending balance:
Individually evaluated for impairment	12,197		12,197				12,665
Collectively evaluated for impairment	2,020,732		2,020,732				1,906,055
Total	2,032,929		2,032,929				1,918,720
Portfolio loans, net | CRE - investor owned
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Individually evaluated for impairment	0		0				0
Collectively evaluated for impairment	4,572		4,572				3,890
Total	4,572		4,572		4,561	4,546	3,890
Loans - Ending balance:
Individually evaluated for impairment	770		770				422
Collectively evaluated for impairment	825,677		825,677				768,853
Total	826,447		826,447				769,275
Portfolio loans, net | CRE - owner occupied
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Individually evaluated for impairment	177		177				71
Collectively evaluated for impairment	3,453		3,453				3,237
Total	3,630		3,630		3,845	3,502	3,308
Loans - Ending balance:
Individually evaluated for impairment	2,655		2,655				1,975
Collectively evaluated for impairment	586,390		586,390				552,614
Total	589,045		589,045				554,589
Portfolio loans, net | Construction and land development
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Individually evaluated for impairment	0		0				0
Collectively evaluated for impairment	1,865		1,865				1,487
Total	1,865		1,865		1,690	1,728	1,487
Loans - Ending balance:
Individually evaluated for impairment	0		0				136
Collectively evaluated for impairment	326,858		326,858				302,955
Total	326,858		326,858				303,091
Portfolio loans, net | Residential real estate
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Individually evaluated for impairment	9		9				0
Collectively evaluated for impairment	1,533		1,533				2,237
Total	1,542		1,542		1,763	2,315	2,237
Loans - Ending balance:
Individually evaluated for impairment	2,477		2,477				1,602
Collectively evaluated for impairment	305,908		305,908				339,710
Total	308,385		308,385				341,312
Portfolio loans, net | Consumer and other
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Individually evaluated for impairment	0		0				0
Collectively evaluated for impairment	693		693				838
Total	693		693		$ 724	$ 762	838
Loans - Ending balance:
Individually evaluated for impairment	312		312				375
Collectively evaluated for impairment	134,365		134,365				135,534
Total	136,025		136,025				137,234
Loans and Leases Receivable, Gross	$ 134,677		$ 134,677				$ 135,909

Loans - Summary of Portfolio _2

Loans - Summary of Portfolio Loans Individually Evaluated for Impairment by Category (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Related Allowance	$ 200			$ 200
Financing Receivable, Allowance for Credit Losses
Portfolio loans, net
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	2,332	$ 2,385	$ 1,871
Unpaid Contractual Principal Balance	26,234			26,234	$ 24,343
Recorded Investment With No Allowance	7,182			7,182	4,856
Recorded Investment With Allowance	9,862			9,862	10,831
Total Recorded Investment	17,044			17,044	15,687
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,314			4,314	2,579
Impaired Financing Receivable, Related Allowance	4,314			4,314	2,579
Average Recorded Investment				14,889	19,722
Financing Receivable, Allowance for Credit Losses, Write-downs	(2,595)	(1,027)	(1,035)
Financing Receivable, Allowance for Credit Losses, Recovery	148	386	1,261
Financing Receivable, Allowance for Credit Losses	41,892	42,007	40,263	41,892	38,166
Portfolio loans, net | Commercial and industrial
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	2,569	2,852	780
Unpaid Contractual Principal Balance	20,938			20,938	20,750
Recorded Investment With No Allowance	3,266			3,266	2,321
Recorded Investment With Allowance	8,931			8,931	10,344
Total Recorded Investment	12,197			12,197	12,665
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,128			4,128	2,508
Impaired Financing Receivable, Related Allowance	4,128			4,128	2,508
Average Recorded Investment				10,414	16,270
Financing Receivable, Allowance for Credit Losses, Write-downs	(2,405)	(956)	(732)
Financing Receivable, Allowance for Credit Losses, Recovery	2	118	956
Financing Receivable, Allowance for Credit Losses	29,590	29,424	27,410	29,590	26,406
Portfolio loans, net | Commercial - investor owned
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	3	5	648
Unpaid Contractual Principal Balance	1,039			1,039	560
Recorded Investment With No Allowance	770			770	422
Recorded Investment With Allowance	0			0	0
Total Recorded Investment	770			770	422
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0			0	0
Impaired Financing Receivable, Related Allowance	0			0	0
Average Recorded Investment				657	521
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0
Financing Receivable, Allowance for Credit Losses, Recovery	8	10	8
Financing Receivable, Allowance for Credit Losses	4,572	4,561	4,546	4,572	3,890
Portfolio loans, net | Commercial - owner occupied
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(197)	340	190
Unpaid Contractual Principal Balance	1,328			1,328	487
Recorded Investment With No Allowance	826			826	0
Recorded Investment With Allowance	462			462	487
Total Recorded Investment	1,288			1,288	487
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	177			177	71
Impaired Financing Receivable, Related Allowance	177			177	71
Average Recorded Investment				1,074	490
Financing Receivable, Allowance for Credit Losses, Write-downs	(22)	0	0
Financing Receivable, Allowance for Credit Losses, Recovery	4	3	4
Financing Receivable, Allowance for Credit Losses	3,630	3,845	3,502	3,630	3,308
Portfolio loans, net | Construction and land development
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	154	(206)	35
Unpaid Contractual Principal Balance	0			0	441
Recorded Investment With No Allowance	0			0	136
Recorded Investment With Allowance	0			0	0
Total Recorded Investment	0			0	136
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0			0	0
Impaired Financing Receivable, Related Allowance	0			0	0
Average Recorded Investment				0	331
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0
Financing Receivable, Allowance for Credit Losses, Recovery	21	168	206
Financing Receivable, Allowance for Credit Losses	1,865	1,690	1,728	1,865	1,487
Portfolio loans, net | Residential real estate
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(187)	(573)	259
Unpaid Contractual Principal Balance	2,600			2,600	1,730
Recorded Investment With No Allowance	2,008			2,008	1,602
Recorded Investment With Allowance	469			469	0
Total Recorded Investment	2,477			2,477	1,602
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	9			9	0
Impaired Financing Receivable, Related Allowance	9			9	0
Average Recorded Investment				2,410	1,735
Financing Receivable, Allowance for Credit Losses, Write-downs	(122)	(38)	(254)
Financing Receivable, Allowance for Credit Losses, Recovery	88	59	73
Financing Receivable, Allowance for Credit Losses	1,542	1,763	2,315	1,542	2,237
Portfolio loans, net | Consumer and other
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(10)	(33)	(41)
Unpaid Contractual Principal Balance	329			329	375
Recorded Investment With No Allowance	312			312	375
Recorded Investment With Allowance	0			0	0
Total Recorded Investment	312			312	375
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0			0	0
Impaired Financing Receivable, Related Allowance	0			0	0
Average Recorded Investment				334	375
Financing Receivable, Allowance for Credit Losses, Write-downs	(46)	(33)	(49)
Financing Receivable, Allowance for Credit Losses, Recovery	25	28	14
Financing Receivable, Allowance for Credit Losses	$ 693	$ 724	$ 762	$ 693	$ 838

Loans - Summary of Past Due and

Loans - Summary of Past Due and Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Receivables [Abstract]
Total interest income that would have been recognized under original terms	$ 614	$ 306	$ 1,615	$ 961
Total cash received and recognized as interest income on non-accrual loans	68	117	157	156
Total interest income recognized on accruing, impaired loans	$ 110	$ 8	$ 133	$ 55

Loans - Narrative (Details)

Loans - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan	Dec. 31, 2017USD ($)loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans over 90 days past due and still accruing interest | loan					0
Unadvanced commitments on impaired loans					$ 0
Specific reserves on restructured loans	$ 2,600,000		$ 2,600,000
Restructuring Reserve	8,000,000		8,000,000
Unadvanced Commitment on Impaired Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Estimated losses attributable to unadvanced commitments on impaired loans	350,000		350,000		350,000
Non-Covered Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-Modification Outstanding Recorded Balance	$ 187,000	$ 0	$ 187,000	$ 676,000
Financing Receivable, Modifications, Number of Contracts | loan	1	0	1	1
Restructuring Reserve	$ 820,000		$ 820,000		719,000
Financing Receivable, Gross	4,219,689,000		4,219,689,000		4,024,221,000
Non-Covered Loans | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructuring Reserve	0		0		0
Financing Receivable, Gross	$ 136,025,000		$ 136,025,000		$ 137,234,000

Loans - Summary of Recorded I_2

Loans - Summary of Recorded Investment in Impaired Portfolio Loans by Category (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017loan	Sep. 30, 2018USD ($)loan	Sep. 30, 2017loan	Dec. 31, 2017USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Restructured, not on non-accrual	$ 8,000		$ 8,000
Impaired Financing Receivable, Related Allowance	200		200
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 17,044		$ 17,044		$ 15,687
Financing Receivable, Modifications, Number of Contracts | loan	1	0	1	1
Non-accrual	$ 14,935		$ 14,935		14,968
Restructured, not on non-accrual	820		820		719
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	1,289		1,289
Impaired Financing Receivable, Related Allowance	4,314		4,314		2,579
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,314		4,314		2,579
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 12,197		$ 12,197		12,665
Financing Receivable, Modifications, Number of Contracts | loan	1	0	1
Non-accrual	$ 10,088		$ 10,088		11,946
Restructured, not on non-accrual	820		820		719
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	1,289		1,289
Impaired Financing Receivable, Related Allowance	4,128		4,128		2,508
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,128		4,128		2,508
Non-Covered Loans | Commercial - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	770		770		422
Non-accrual	770		770		422
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Non-Covered Loans | Commercial - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	1,288		1,288		487
Non-accrual	1,288		1,288		487
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	177		177		71
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	177		177		71
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	0		0		136
Non-accrual	0		0		136
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	2,477		2,477		1,602
Non-accrual	2,477		2,477		1,602
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	9		9		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	9		9		0
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	312		312		375
Non-accrual	312		312		375
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 0		$ 0		$ 0

Loans - Summary of Recorded I_3

Loans - Summary of Recorded Investment by Category for Portfolio Loans Restructured (Details) - Non-Covered Loans $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	0	1	1
Pre-Modification Outstanding Recorded Balance	$ 187	$ 0	$ 187	$ 676
Post-Modification Outstanding Recorded Balance	$ 187	$ 0	$ 187	$ 676
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	0	1
Pre-Modification Outstanding Recorded Balance	$ 187	$ 0
Post-Modification Outstanding Recorded Balance	$ 187	$ 0
Commercial and Industrial Sector [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan				1
Pre-Modification Outstanding Recorded Balance			$ 187	$ 676
Post-Modification Outstanding Recorded Balance			$ 187	$ 676

Loans - Summary of Aging of Rec

Loans - Summary of Aging of Recorded Investment in Past Due Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and Leases Receivable, Gross	$ 4,267,430	$ 4,097,050
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	13,697	10,828
90 or More Days Past Due	8,113	2,715
Total Past Due	21,810	13,543
Current	4,196,531	4,009,353
Loans and Leases Receivable, Gross	4,218,341	4,022,896
Total	4,219,689	4,024,221
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	11,213	7,882
90 or More Days Past Due	6,020	1,770
Total Past Due	17,233	9,652
Current	2,015,696	1,909,068
Total	2,032,929	1,918,720
Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,362	934
90 or More Days Past Due	129	0
Total Past Due	1,491	934
Current	824,956	768,341
Total	826,447	769,275
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	258	0
90 or More Days Past Due	808	0
Total Past Due	1,066	0
Current	587,979	554,589
Total	589,045	554,589
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	76
90 or More Days Past Due	0	0
Total Past Due	0	76
Current	326,858	303,015
Total	326,858	303,091
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	864	1,529
90 or More Days Past Due	1,156	945
Total Past Due	2,020	2,474
Current	306,365	338,838
Total	308,385	341,312
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	407
90 or More Days Past Due	0	0
Total Past Due	0	407
Current	134,677	135,502
Loans and Leases Receivable, Gross	134,677	135,909
Total	$ 136,025	$ 137,234

Loans - Summary of Recorded I_4

Loans - Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 4,267,430	$ 4,097,050
Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	4,219,689	4,024,221
Loans and Leases Receivable, Gross	4,218,341	4,022,896
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	2,032,929	1,918,720
Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	826,447	769,275
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	589,045	554,589
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	326,858	303,091
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	308,385	341,312
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	136,025	137,234
Loans and Leases Receivable, Gross	134,677	135,909
Pass (1-6) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	3,921,764	3,794,940
Pass (1-6) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	1,835,230	1,769,102
Pass (1-6) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	798,116	754,010
Pass (1-6) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	540,961	514,616
Pass (1-6) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	315,022	292,766
Pass (1-6) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	298,076	329,742
Pass (1-6) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	134,359	134,704
Watch (7) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	223,282	152,923
Watch (7) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	142,768	94,002
Watch (7) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	22,275	10,840
Watch (7) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	43,399	34,440
Watch (7) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	11,775	9,983
Watch (7) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	3,058	3,648
Watch (7) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	7	10
Classified (8 & 9) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	73,295	75,033
Classified (8 & 9) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	54,931	55,616
Classified (8 & 9) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	6,056	4,425
Classified (8 & 9) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	4,685	5,533
Classified (8 & 9) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	61	342
Classified (8 & 9) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	7,251	7,922
Classified (8 & 9) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	$ 311	$ 1,195

Purchased Credit Impaired ("P_3

Purchased Credit Impaired ("PCI") Loans - Summary of PCI Loans by Category (Details) - Covered Loans $ in Thousands	Sep. 30, 2018USD ($)rating	Dec. 31, 2017USD ($)rating
Covered Loans [Line Items]
Recorded Investment PCI Loans	$ 49,089	$ 74,154
Construction and land development
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	6.01	5.99
Recorded Investment PCI Loans	$ 5,168	$ 5,883
CRE - investor owned
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	7.23	7.36
Recorded Investment PCI Loans	$ 25,172	$ 42,887
CRE - owner occupied
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	7.45	6.48
Recorded Investment PCI Loans	$ 9,520	$ 11,332
Residential real estate
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	6.35	5.99
Recorded Investment PCI Loans	$ 6,291	$ 10,781
Commercial and industrial
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	6.39	6.38
Recorded Investment PCI Loans	$ 2,923	$ 3,212
Consumer and other
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	7.08	2.84
Recorded Investment PCI Loans	$ 15	$ 59

Purchased Credit Impaired ("P_4

Purchased Credit Impaired ("PCI") Loans - Summary of Aging of Recorded Investment in Past Due PCI Loans by Portfolio Class and Category (Details) - Covered Loans - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	$ 7,036	$ 328
90 or More Days Past Due	1,980	3,962
Total Past Due	9,016	4,290
Current	40,073	69,864
Total	49,089	74,154
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	2,923	3,212
Total	2,923	3,212
CRE - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	627	0
90 or More Days Past Due	1,190	3,034
Total Past Due	1,817	3,034
Current	23,355	39,853
Total	25,172	42,887
CRE - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	6,230	0
90 or More Days Past Due	744	673
Total Past Due	6,974	673
Current	2,546	10,659
Total	9,520	11,332
Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	146	0
90 or More Days Past Due	0	0
Total Past Due	146	0
Current	5,022	5,883
Total	5,168	5,883
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	33	328
90 or More Days Past Due	46	255
Total Past Due	79	583
Current	6,212	10,198
Total	6,291	10,781
Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	15	59
Total	$ 15	$ 59

Purchased Credit Impaired ("P_5

Purchased Credit Impaired ("PCI") Loans - Rollforward of PCI Loans, Net of Allowance for Loan Losses (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 69,741	$ 33,925
Acquisitions		49,155
Principal reductions and interest payments	(38,165)	(16,319)
Accretion of loan discount	5,118	5,473
Changes in contractual and expected cash flows due to remeasurement	10,101	8,036
Reductions due to disposals		(3,186)
Balance at end of period	46,795	77,084
Contractual Cashflows
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	112,710	66,003
Acquisitions		68,763
Principal reductions and interest payments	(38,165)	(16,319)
Accretion of loan discount	0	0
Changes in contractual and expected cash flows due to remeasurement	4,341	11,110
Reductions due to disposals		(6,393)
Balance at end of period	78,886	123,164
Non-accretable Difference
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	29,005	18,902
Acquisitions		14,296
Principal reductions and interest payments	0	0
Accretion of loan discount	0	0
Changes in contractual and expected cash flows due to remeasurement	(8,939)	(702)
Reductions due to disposals		(1,612)
Balance at end of period	20,066	30,884
Accretable Yield
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	13,964	13,176
Acquisitions		5,312
Principal reductions and interest payments	0	0
Accretion of loan discount	5,118	5,473
Changes in contractual and expected cash flows due to remeasurement	3,179	3,776
Reductions due to disposals		(1,595)
Balance at end of period	$ 12,025	$ 15,196

Purchased Credit Impaired ("P_6

Purchased Credit Impaired ("PCI") Loans - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Receivables [Abstract]
PCI loans outstanding	$ 68.6	$ 94.9

Commitments (Details)

Commitments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Schedule of Commitments [Line Items]
Unadvanced commitments on impaired loans		$ 0
Commitments to extend credit
Schedule of Commitments [Line Items]
Off-balance sheet financial instruments, contractual amounts	$ 1,315,284	1,298,423
Letters of credit
Schedule of Commitments [Line Items]
Off-balance sheet financial instruments, contractual amounts	$ 49,633	73,790
Letters of credit | Maximum
Schedule of Commitments [Line Items]
Remaining term	3 years 3 months
Letters of credit | Minimum
Schedule of Commitments [Line Items]
Remaining term	1 month
Unadvanced Commitment on Impaired Loan
Schedule of Commitments [Line Items]
Estimated losses attributable to unadvanced commitments on impaired loans	$ 350	350
Fixed Rate Loan Commitment | Commitments to extend credit
Schedule of Commitments [Line Items]
Off-balance sheet financial instruments, contractual amounts	$ 91,800	$ 112,000

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Risk Management [Member]
Summary of Derivative Instruments [Abstract]
Notional Amount	$ 0	$ 0
Derivative, Fair Value, Net	0	0
Non-designated hedging instruments | Client-Related | Interest rate swap contracts
Summary of Derivative Instruments [Abstract]
Notional Amount	433,664	394,852
Non-designated hedging instruments | Client-Related | Foreign Exchange Forward [Member]
Summary of Derivative Instruments [Abstract]
Notional Amount	123	1,528
Non-designated hedging instruments | Client-Related | Other Assets | Interest rate swap contracts
Summary of Derivative Instruments [Abstract]
Asset derivatives (other assets), fair value	4,772	2,061
Non-designated hedging instruments | Client-Related | Other Assets | Foreign Exchange Forward [Member]
Summary of Derivative Instruments [Abstract]
Asset derivatives (other assets), fair value	123	1,528
Non-designated hedging instruments | Client-Related | Other Liabilities | Interest rate swap contracts
Summary of Derivative Instruments [Abstract]
Liability derivatives (other liabilities), fair value	4,772	2,061
Non-designated hedging instruments | Client-Related | Other Liabilities | Foreign Exchange Forward [Member]
Summary of Derivative Instruments [Abstract]
Liability derivatives (other liabilities), fair value	$ 123	$ 1,528

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Securities available for sale	$ 670,328	$ 641,382
State tax credits held for sale	171	400
Portion at Other than Fair Value, Fair Value Disclosure
Assets
State tax credits held for sale	45,500
Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	670,328	641,382
State tax credits held for sale	48,622	44,271
Derivative financial instruments	4,895	3,589
Liabilities
Derivative financial instruments	4,895	3,589
Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	97,681	99,224
Obligations of states and political subdivisions
Assets
Securities available for sale	30,533	34,642
Residential mortgage-backed securities
Assets
Securities available for sale	532,347	507,516
US Treasury Bill Securities [Member]
Assets
Securities available for sale	9,767
Recurring basis | Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	670,328	641,382
State tax credits held for sale	171	400
Other Investments	144
Derivative financial instruments	4,895	3,589
Total assets	675,538	645,371
Liabilities
Derivative financial instruments		3,589
Total liabilities	4,895	3,589
Recurring basis | Obligations of U.S. Government-sponsored enterprises | Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	97,681	99,224
Recurring basis | Obligations of states and political subdivisions | Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	30,533	34,642
Recurring basis | Residential mortgage-backed securities | Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	532,347	507,516
Recurring basis | US Treasury Bill Securities [Member] | Estimate of Fair Value Measurement [Member]
Assets
Securities available for sale	9,767
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Securities available for sale	0	0
State tax credits held for sale	0	0
Other Investments	144
Derivative financial instruments	0	0
Total assets	144	0
Liabilities
Derivative financial instruments	0	0
Total liabilities	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Obligations of states and political subdivisions
Assets
Securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage-backed securities
Assets
Securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | US Treasury Bill Securities [Member]
Assets
Securities available for sale	0
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Securities available for sale	670,328	641,382
State tax credits held for sale	0	0
Other Investments	0
Derivative financial instruments	4,895	3,589
Total assets	675,223	644,971
Liabilities
Derivative financial instruments	4,895	3,589
Total liabilities	4,895	3,589
Recurring basis | Significant Other Observable Inputs (Level 2) | Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	97,681	99,224
Recurring basis | Significant Other Observable Inputs (Level 2) | Obligations of states and political subdivisions
Assets
Securities available for sale	30,533	34,642
Recurring basis | Significant Other Observable Inputs (Level 2) | Residential mortgage-backed securities
Assets
Securities available for sale	532,347	507,516
Recurring basis | Significant Other Observable Inputs (Level 2) | US Treasury Bill Securities [Member]
Assets
Securities available for sale	9,767
Recurring basis | Significant Unobservable Inputs (Level 3)
Assets
Securities available for sale	0	0
State tax credits held for sale	171	400
Other Investments	0
Derivative financial instruments	0	0
Total assets	171	400
Liabilities
Derivative financial instruments	0	0
Total liabilities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Obligations of U.S. Government-sponsored enterprises
Assets
Securities available for sale	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Obligations of states and political subdivisions
Assets
Securities available for sale	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Residential mortgage-backed securities
Assets
Securities available for sale	0	$ 0
Recurring basis | Significant Unobservable Inputs (Level 3) | US Treasury Bill Securities [Member]
Assets
Securities available for sale	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at cost	$ 37,885	$ 26,661
State tax credits, held for sale	45,625	43,468
State Tax Credits Held For Sale, Fair Value Disclosure	$ 171	400
State Tax Credit Term	10 years
Receivables, Fair Value Disclosure	$ 700
Impaired Financing Receivable, Related Allowance	200
Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
State tax credits, held for sale	45,600
Recurring basis | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0
State Tax Credits Held For Sale, Fair Value Disclosure	171	400
Portion at Other than Fair Value, Fair Value Disclosure
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments, Fair Value Disclosure	37,700
State Tax Credits Held For Sale, Fair Value Disclosure	45,500
Estimated fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
State Tax Credits Held For Sale, Fair Value Disclosure	48,622	44,271
Estimated fair value | Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	144
State Tax Credits Held For Sale, Fair Value Disclosure	$ 171	$ 400

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Level 3 Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - Level 3 - Recurring basis - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Securities available for sale, at fair value
Level 3 Financial Instruments Measured at Fair Value
Beginning balance	$ 0	$ 0	$ 0	$ 3,089
Total gains:
Included in other comprehensive income	0	0	0	4
Purchases, sales, issuances and settlements:
Purchases	0	0	0	0
Transfer in and/or out of Level 3	0	0	0	(3,093)
Ending balance	0	0	0	0
Change in unrealized gains relating to assets still held at the reporting date	0	0	0	0
State tax credits held for sale, at fair value
Level 3 Financial Instruments Measured at Fair Value
Beginning balance	299	1,274	400	3,585
Total gains:
Total gains:	7	0	13	49
Purchases, sales, issuances and settlements:
Sales	(135)	0	(242)	(2,360)
Ending balance	171	1,274	171	1,274
Change in unrealized gains relating to assets still held at the reporting date	$ (34)	$ 0	$ (60)	$ (655)

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Financial Instruments and Non-Financial Assets Measured at Fair Value on a Non-Recurring Basis (Details) - Fair Value, Measurements, Nonrecurring $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total (losses) gains for the year	$ 248	$ 457
Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total (losses) gains for the year	248	457
Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total (losses) gains for the year	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Significant Other Observable Inputs (Level 2) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Significant Other Observable Inputs (Level 2) | Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	485	485
Significant Unobservable Inputs (Level 3) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	485	485
Significant Unobservable Inputs (Level 3) | Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate	0	0
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	485	485
Estimate of Fair Value Measurement [Member] | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	485	485
Estimate of Fair Value Measurement [Member] | Other real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate	$ 0	$ 0

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Carrying Amount and Fair Values of Financial Instruments Reported on the Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Balance sheet assets
Securities available for sale	$ 670,328	$ 641,382
Securities held to maturity	67,131	73,749
State tax credits held for sale	171	400
Carrying Amount
Balance sheet assets
Cash and due from banks	78,119	91,084
Federal funds sold	1,571	1,223
Interest-bearing deposits	79,780	63,661
Securities available for sale	670,328	641,382
Securities held to maturity	67,131	73,749
Other investments, at cost	37,885	26,661
Loans held for sale	738	3,155
Derivative financial instruments	4,895	3,589
Portfolio loans, net	4,223,244	4,054,473
State tax credits held for sale	45,625	43,468
Accrued interest receivable	19,879	14,069
Balance sheet liabilities
Deposits	4,210,476	4,156,414
Subordinated debentures and notes	118,144	118,105
Federal Home Loan Bank advances	401,000	172,743
Other borrowings	161,795	253,674
Derivative financial instruments	4,895	3,589
Accrued interest payable	2,433	1,730
Estimated fair value
Balance sheet assets
Cash and due from banks	78,119	91,084
Federal funds sold	1,571	1,223
Interest-bearing deposits	79,780	63,661
Securities available for sale	670,328	641,382
Securities held to maturity	64,416	73,458
Other investments, at cost	37,885	26,661
Loans held for sale	738	3,155
Derivative financial instruments	4,895	3,589
Portfolio loans, net	4,254,581	4,096,741
State tax credits held for sale	48,622	44,271
Accrued interest receivable	19,879	14,069
Balance sheet liabilities
Deposits	4,203,913	4,153,323
Subordinated debentures and notes	105,611	105,031
Federal Home Loan Bank advances	400,977	172,893
Other borrowings	161,676	253,530
Derivative financial instruments	4,895	3,589
Accrued interest payable	$ 2,433	$ 1,730

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments Not Recorded at Fair Value on Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Estimated fair value | Securities held to maturity
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	$ 64,416	$ 73,458
Estimated fair value | Portfolio loans, net
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	4,254,581	4,096,741
Estimated fair value | State tax credits, held for sale
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	48,451	43,871
Estimated fair value | Deposits
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	4,203,913	4,153,323
Estimated fair value | Subordinated debentures and notes
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	105,611	105,031
Estimated fair value | Federal Home Loan Bank advances
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	400,977	172,893
Estimated fair value | Other Borrowings
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	161,676	253,530
Level 1 | Securities held to maturity
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	0	0
Level 1 | Portfolio loans, net
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	0	0
Level 1 | State tax credits, held for sale
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	0	0
Level 1 | Deposits
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	3,536,239	3,577,641
Level 1 | Subordinated debentures and notes
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	0	0
Level 1 | Federal Home Loan Bank advances
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	0	0
Level 1 | Other Borrowings
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	0	0
Level 2 | Securities held to maturity
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	64,416	73,458
Level 2 | Portfolio loans, net
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	0	0
Level 2 | State tax credits, held for sale
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	0	0
Level 2 | Deposits
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	0	0
Level 2 | Subordinated debentures and notes
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	105,611	105,031
Level 2 | Federal Home Loan Bank advances
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	400,977	172,893
Level 2 | Other Borrowings
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	161,676	253,530
Level 3 | Securities held to maturity
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	0	0
Level 3 | Portfolio loans, net
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	4,254,581	4,096,741
Level 3 | State tax credits, held for sale
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial assets not on condensed consolidated balance sheets at fair value	48,451	43,871
Level 3 | Deposits
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	667,674	575,682
Level 3 | Subordinated debentures and notes
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	0	0
Level 3 | Federal Home Loan Bank advances
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	0	0
Level 3 | Other Borrowings
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial liabilities not on condensed consolidated balance sheets at fair value	$ 0	$ 0