First NBC Bank Holding (FNBCQ) 10-K 31 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 23, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	FNBC
Entity Registrant Name	First NBC Bank Holding Co
Entity Central Index Key	1496631
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		18,609,753
Entity Public Float			$518,518,877

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Cash and due from banks	$32,484	$28,140
Short-term investments	18,404	3,502
Investment in short-term receivables	237,135	246,817
Investment securities available for sale, at fair value	247,647	277,719
Investment securities held to maturity	89,076	94,904
Mortgage loans held for sale	1,622	6,577
Loans, net of allowance for loan losses of $42,336 and $32,143, respectively	2,731,928	2,325,634
Bank premises and equipment, net	52,881	51,174
Accrued interest receivable	11,451	10,994
Goodwill and other intangible assets	7,831	8,433
Investment in real estate properties	12,771	10,147
Investment in tax credit entities	140,913	117,684
Cash surrender value of bank-owned life insurance	47,289	26,187
Other real estate	5,549	3,733
Deferred Tax Assets, Net	83,461	51,191
Other assets	30,175	23,781
Total assets	3,750,617	3,286,617
Deposits:
Noninterest-bearing	364,534	291,080
Interest-bearing	2,756,316	2,439,727
Total deposits	3,120,850	2,730,807
Short-term borrowings	0	8,425
Repurchase agreements	117,991	75,957
Long-term borrowings	40,000	55,110
Accrued interest payable	6,650	6,682
Other liabilities	28,752	27,777
Total liabilities	3,314,243	2,904,758
Shareholders’ equity:
Common stock- par value $1 per share; 100,000,000 shares authorized; 18,576,488 shares issued and outstanding at December 31, 2014 and 18,514,271 shares issued and outstanding at December 31, 2013	18,576	18,514
Additional paid-in capital	239,528	237,063
Accumulated earnings	155,599	100,389
Accumulated other comprehensive loss, net	-19,737	-16,515
Total shareholders’ equity	436,372	381,857
Noncontrolling interest	2	2
Total equity	436,374	381,859
Total liabilities and equity	3,750,617	3,286,617
Convertible Preferred Stock Series C
Shareholders’ equity:
Preferred stock	4,471	4,471
Series D Preferred Stock
Shareholders’ equity:
Preferred stock	$37,935	$37,935

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Allowance for loan losses	$42,336	$32,143
Common stock, par value (in usd per share)	$1	$1
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	18,576,488	18,514,271
Common stock, shares outstanding	18,576,488	18,514,271
Convertible Preferred Stock Series C
Preferred stock, par value (in usd per share)	$0	$0
Preferred stock, shares authorized	1,680,219	1,680,219
Preferred stock, shares issued	364,983	364,983
Preferred stock, shares outstanding	364,983	364,983
Series D Preferred Stock
Preferred stock, par value (in usd per share)	$0	$0
Preferred stock, shares authorized	37,935	37,935
Preferred stock, shares issued	37,935	37,935
Preferred stock, shares outstanding	37,935	37,935

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income:
Loans, including fees	$134,256	$111,260	$97,754
Investment securities	9,147	8,170	6,499
Investment in short-term receivables	6,512	4,449	2,060
Short-term investments	63	145	144
Total operating income	149,978	124,024	106,457
Interest expense:
Deposits	40,183	36,239	29,597
Borrowings and securities sold under repurchase agreements	2,546	2,909	2,069
Total operating expense	42,729	39,148	31,666
Net interest income	107,249	84,876	74,791
Provision for loan losses	12,000	9,800	11,035
Net interest income after provision for loan losses	95,249	75,076	63,756
Noninterest income:
Service charges on deposit accounts	2,147	2,027	2,486
Investment securities gain, net	135	316	4,324
Gain on assets sold, net	64	1,081	500
Gain on sale of loans, net	649	835	603
Cash surrender value income on bank-owned life insurance	1,102	681	750
Income from sales of state tax credits	2,313	2,785	578
Community Development Entity fees	1,565	2,875	1,136
ATM fee income	1,958	1,859	1,686
Other	1,680	967	1,073
Total non-interest income	11,613	13,426	13,136
Noninterest expense:
Salaries and employee benefits	24,867	23,812	20,307
Occupancy and equipment expenses	10,848	10,204	9,755
Professional fees	7,471	6,929	3,269
Taxes, licenses and FDIC assessments	5,146	4,245	3,258
Tax credit investment amortization	14,059	8,639	4,808
Write-down of other real estate	385	235	295
Data processing	4,721	4,219	4,485
Advertising and marketing	2,886	2,427	1,904
Other	7,866	6,632	6,926
Total non-interest expense	78,249	67,342	55,007
Income before income taxes	28,613	21,160	21,885
Income tax benefit	-26,976	-19,751	-7,565
Net income	55,589	40,911	29,450
Less net income attributable to noncontrolling interests	0	0	-510
Net income attributable to Company	55,589	40,911	28,940
Less preferred stock dividends	-379	-347	-510
Less earnings allocated to participating securities	-1,066	-1,980	-1,999
Income available to common shareholders	$54,144	$38,584	$26,431
Earnings per common share – basic (in usd per share)	$2.92	$2.38	$2.04
Earnings per common share – diluted (in usd per share)	$2.84	$2.32	$2.02

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$55,589	$40,911	$29,450
Fair value of derivative instruments designated as cash flow hedges:
Change in fair value of derivative instruments designated as cash flow hedges during the period, before tax	-17,747	3,694	-6,854
Unrealized gains (losses) on investment securities:
Unrealized gains (losses) on investment securities arising during the period	12,379	-18,576	3,956
Less: reclassification adjustment for gains included in net income	-135	-316	-4,324
Transfer of unrealized loss on securities from available for sale to held to maturity during the period	0	-5,919	0
Amortization of unrealized net loss on securities transferred from available for sale to held to maturity	547	211	0
Unrealized gains (losses) on investment securities, before tax	12,791	-24,600	-368
Other comprehensive losses, before taxes	-4,956	-20,906	-7,222
Income tax benefit related to items of other comprehensive losses	-1,734	-7,317	-2,501
Other comprehensive loss, net of tax	-3,222	-13,589	-4,721
Comprehensive income	52,367	27,322	24,729
Comprehensive income attributable to noncontrolling interests	0	0	-510
Comprehensive income attributable to preferred shareholders	-379	-347	-510
Comprehensive income attributable to participating securities	-1,066	-1,980	-1,999
Comprehensive income available to common shareholders	$50,922	$24,995	$21,710

CONSOLIDATED_STATEMENTS_OF_SHA

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $)	Total	Preferred Stock Series C	Preferred Stock Series D	Common Stock	Additional Paid-In Capital	Accumulated Earnings	Accumulated Other Comprehensive Income (Loss)	Total Shareholders’ Equity	Noncontrolling Interest
In Thousands, unless otherwise specified
Beginning Balance at Dec. 31, 2011	$223,516			$12,153	$118,010	$31,395	$1,795	$221,870	$1,646
Beginning Balance at Dec. 31, 2011		20,582	37,935
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	28,940					28,940		28,940
Other comprehensive income	-4,721						-4,721	-4,721
Stock option and director plans	1,102			20	1,082			1,102
Stock offering	1,420			116	1,304			1,420
Conversion of preferred stock to common stock	0	-9,351		763	8,588
Redemption of preferred stock	-1,644								-1,644
Stock offering, net of direct cost of $10,837	1,420			116	1,304			1,420
Preferred stock dividends	-510					-510		-510
Distribution to noncontrolling interest	-1								-1
Ending Balance at Dec. 31, 2012	248,102			13,052	128,984	59,825	-2,926	248,101	1
Ending Balance at Dec. 31, 2012		11,231	37,935
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40,911					40,911		40,911
Other comprehensive income	-13,589						-13,589	-13,589
Share-based compensation	1,202				1,202			1,202
Stock option and director plans	965			87	878			965
Stock offering	104,163			4,792	99,371			104,163
Conversion of preferred stock to common stock	0	-6,760		552	6,208
Stock offering, net of direct cost of $10,837	104,163			4,792	99,371			104,163
Warrants	125			31	94			125
Net tax benefit related to stock option plans	326				326			326
Preferred stock dividends	-347					-347		-347
Equity contribution for noncontrolling interest	1								1
Ending Balance at Dec. 31, 2013	381,859			18,514	237,063	100,389	-16,515	381,857	2
Ending Balance at Dec. 31, 2013		4,471	37,935
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	55,589					55,589		55,589
Other comprehensive income	-3,222						-3,222	-3,222
Share-based compensation	1,339				1,339			1,339
Stock option and director plans	862			62	800			862
Net tax benefit related to stock option plans	326				326			326
Preferred stock dividends	-379					-379		-379
Ending Balance at Dec. 31, 2014	436,374			18,576	239,528	155,599	-19,737	436,372	2
Ending Balance at Dec. 31, 2014		$4,471	$37,935

CONSOLIDATED_STATEMENTS_OF_SHA1

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Statement of Stockholders' Equity [Abstract]
Issuance direct cost	$10,837

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Cash Flows [Abstract]
Net income	$55,589	$40,911	$29,450
Adjustments to reconcile net income to net cash provided by operating activities:
Noncontrolling interest	0	0	-510
Deferred tax benefit	-30,412	-19,937	-7,565
Amortization of tax credit investments	14,059	8,639	4,808
Net discount accretion or premium amortization	474	2,633	4,245
Gain on sale of investment securities	-135	-316	-4,324
Gain on assets sold	-64	-1,081	-535
Write-down of foreclosed assets	385	235	295
Proceeds from sale of mortgage loans held for sale	49,334	96,677	62,014
Mortgage loans originated and held for sale	-44,379	-77,394	-82,067
Gain on sale of loans	-649	-835	-603
Amounts paid on termination of interest rate hedge	-7,990	0	0
Provision for loan losses	12,000	9,800	11,035
Depreciation and amortization	3,554	2,963	3,351
Share-based and other compensation expense	800	2,124	1,102
Increase in cash surrender value of bank-owned life insurance	-1,102	-681	-750
Decrease (increase) in receivables from sales of investments	0	16,909	-16,909
Changes in operating assets and liabilities:
Change in other assets	-10,015	-5,168	1,540
Change in accrued interest receivable	-457	-2,266	-1,346
Change in accrued interest payable	-32	1,125	725
Change in other liabilities	-7,661	15,125	-2,758
Net cash provided by operating activities	33,299	89,463	1,198
Investing activities
Purchases of available for sale investment securities	-22,153	-132,123	-344,093
Proceeds from sales of available for sale investment securities	41,670	45,791	125,401
Proceeds from maturities, prepayments, and calls of available for sale investment securities	22,229	91,328	129,910
Proceeds from sales of held to maturity securities	2,650	0	0
Proceeds from maturities, prepayments, and calls of held to maturity securities	3,851	1,013	0
Net change in investments in short-term receivables	9,682	-165,773	-70,864
Reimbursement of investment in tax credit entities	24,000	0	15,607
Purchases of investments in tax credit entities	-61,288	-58,930	-20,606
Loans originated, net of repayments	-421,948	-444,592	-275,177
Proceeds from sale of bank premises and equipment	46	324	16
Purchases of bank premises and equipment	-4,706	-7,129	-18,189
Proceeds from disposition of real estate owned	2,657	5,015	3,840
Purchases of bank-owned life insurance	-20,000	0	0
Net cash used in investing activities	-423,310	-665,076	-454,155
Financing activities
Net change in repurchase agreements	42,034	39,670	18,311
Proceeds from borrowings	0	8,425	41,800
Repayment of borrowings	-23,535	-41,910	-1,625
Net increase in deposits	389,736	461,073	363,846
Proceeds from issuance of common stock, net of offering costs	1,401	104,332	1,420
Repayment of preferred stock	0	0	-1,644
Dividends paid	-379	-347	-510
Net cash provided by financing activities	409,257	571,243	421,598
Net change in cash, due from banks, and short-term investments	19,246	-4,370	-31,359
Cash, due from banks, and short-term investments at beginning of period	31,642	36,012	67,371
Cash, due from banks, and short-term investments at end of period	50,888	31,642	36,012
Supplemental cash flows information
Cash paid for interest	42,761	38,023	32,392
Cash paid for taxes	$3,170	$0	$0

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Nature of Operations
	First NBC Bank Holding Company (“Company”) is a bank holding company that offers a broad range of financial services through First NBC Bank, a Louisiana state non-member bank, to businesses, institutions, and individuals in southeastern Louisiana and the Mississippi Gulf Coast. The accounting and reporting policies of the Company conform to accounting principles generally accepted in the United States and to prevailing practices within the banking industry.
	Principles of Consolidation
	The accompanying consolidated financial statements include the accounts of the Company and First NBC Bank, and First NBC Bank’s wholly owned subsidiaries, which include First NBC Community Development, LLC (FNBC CDC), First NBC Community Development Fund, LLC (FNBC CDE) (collectively referred to as the Bank) and any variable interest entities (VIE) of which the Company is the primary beneficiary. Substantially all of the VIEs for which the Company is the primary beneficiary relate to tax credit investments. FNBC CDC is a Community Development Corporation formed to construct, purchase, and renovate affordable residential real estate properties in the New Orleans area. FNBC CDE is a Community Development Entity (CDE) formed to apply for and receive allocations of Federal New Markets Tax Credits (NMTC).
	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are susceptible to a significant change in the near term are the allowance for loan losses, income tax provision, fair value adjustments, and share-based compensation.
	Concentration of Credit Risk
	The Company’s loan portfolio consists of the various types of loans described in Note 6. Real estate or other assets secure most loans. The majority of these loans have been made to individuals and businesses in the Company’s market area of southeastern Louisiana and southern Mississippi, which are dependent on the area economy for their livelihoods and servicing of their loan obligations. The Company does not have any significant concentrations to any one industry or customer.
	The Company maintains deposits in other financial institutions that may, from time to time, exceed the federally insured deposit limits.
	Cash and Cash Equivalents
	For purposes of reporting cash flows, cash and cash equivalents include the amount in the accompanying consolidated balance sheet caption, cash and due from banks, which represents cash on hand and balances due from other financial institutions, as well as the amount in the accompanying consolidated balance sheet caption, short-term investments, which primarily represents federal funds sold with original maturities less than three months.
	Investment Securities
	Investment securities are classified either as held to maturity or available for sale. Management determines the classification of securities when they are purchased.
	Investment securities that the Company has the ability and positive intent to hold to maturity are classified as securities held to maturity and are stated at amortized cost. The amortized cost of debt securities classified as held to maturity or available for sale is adjusted for amortization of premiums and accretion of discounts over the contractual life of the security using the effective interest method or, in the case of mortgage-backed securities, over the estimated life of the security using the effective yield method. Such amortization or accretion is included in interest income on securities.
	Securities that may be sold in response to changes in interest rates, liquidity needs, or asset liability management strategies are classified as securities available for sale. These securities are carried at fair value, with net unrealized gains or losses excluded from earnings and shown as a separate component of shareholders’ equity in accumulated other comprehensive (loss) income, net of income taxes. Any expected credit loss due to the inability to collect all amounts due accordingly to the security’s contractual terms is recognized as a charge against earnings. Any remaining unrealized loss related to other factors is recognized in other comprehensive income, net of taxes.
	Realized gains and losses on both held to maturity securities and available for sale securities are computed based on the specific-identification method. Realized gains and losses and declines in value judged to be other than temporary are included in net securities gains and losses.
	Unrealized losses on securities are evaluated to determine if the losses are temporary, based on various factors, including the cause of the loss, prospects for recovery, projected cash flows, collateral values, credit enhancements and other relevant factors, and management’s intent and ability not to sell the security until the fair value exceeds amortized cost. A charge is recognized against earnings for all or a portion of the impairment if the loss is determined to be other than temporary.
	Investment in Short-Term Receivables
	The Company invests in short-term receivables which are purchased on an exchange. These short-term receivables have repayment terms of less than a year. The investments are recorded on the consolidated balance sheets at cost plus accreted discount.
	Mortgage Loans Held for Sale
	Mortgage loans originated and intended for sale in the secondary market are carried at the lower of cost or estimated fair value, in the aggregate. Net unrealized losses, if any, are recognized through a valuation allowance that is recorded as a charge to income. Loans held for sale have primarily been fixed-rate, single-family residential mortgage loans under contract to be sold in the secondary market. In most cases, loans in this category are sold within 120 days. These loans are sold with the mortgage servicing rights released. Buyers generally have recourse to return a purchased loan to the Company under limited circumstances which may include early payment default, breach of representations or warranties, and documentation deficiencies. During 2014 and 2013, an insignificant number of loans were returned to the Company.
	Transfers of Financial Assets
	Transfers of financial assets are accounted for as sales when control over the assets has been surrendered or in the case of a loan participation, a portion of the asset has been surrendered and meets the definition of a "participating interest". Control over transferred assets is deemed to be surrendered when 1) the assets have been isolated from the Company, 2) the transferee obtains the right, free of conditions that constrain it from taking advantage of that right, to pledge or exchange the transferred assets, and 3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity. Should the transfer not meet these three criteria, the transaction is treated as a secured financing.
	Loans
	Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are stated at the principal amount outstanding, net of unamortized fees and costs on originated loans and allowances for loan losses. Loan origination fees and certain direct loan origination costs are deferred and amortized over the lives of the respective loans as a yield adjustment using the effective interest method.
	Interest income on loans is accrued as earned using the interest method over the life of the loan. Interest on loans deemed uncollectible is excluded from income. The accrual of interest is discontinued and reversed against current income once loans become more than 90 days past due or earlier if conditions warrant. The past due status of loans is determined based on the contractual terms. If the decision is made to continue accruing interest on the loan, periodic reviews are made to confirm the accruing status of the loan. When a loan is placed on nonaccrual status, interest accrued and unpaid during prior periods is reversed. Generally, any payments on nonaccrual loans are applied first to outstanding loan principal amounts and then to the recovery of the charged-off loan amounts. Any excess is treated as recovery of lost interest and fees. Loans are returned to accrual status after a minimum of six consecutive monthly payments have been made in a timely manner.
	The Company considers a loan to be impaired when, based upon current information and events, it believes it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. The Company’s impaired loans include troubled debt restructurings (TDRs) and performing and nonperforming loans for which full payment of principal or interest is not expected. The Company calculates a reserve required for impaired loans based on the present value of expected future cash flows discounted using the loan’s effective interest rate or the fair value of the collateral securing the loan.
	Third-party property valuations are obtained at the time of origination for real estate-secured loans. The Company obtains updated appraisals on all impaired loans at least annually. In addition, if an intervening event occurs that, in management’s opinion, would suggest further deterioration in value, the Company obtains an updated appraisal. These policies do not vary based on loan type. Any exposure arising from the deterioration in value of collateral evidenced by the appraisal is recorded as an adjustment to the loan loss reserve in the case of an impaired loan or as an adjustment to income in the case of foreclosed property.
	Troubled Debt Restructurings
	The Company periodically grants concessions to its customers in an attempt to protect as much of its investment as possible and minimize the risk of loss. These concessions may include restructuring the terms of a customer loan, thereby adjusting the customer’s payment requirements. In order to be considered a TDR, the Company must conclude that the restructuring constitutes a concession and the customer is experiencing financial difficulties. The Company defines a concession to a customer as a modification of existing loan terms for economic or legal reasons that it would otherwise not consider. Concessions are typically granted through an agreement with the customer or are imposed by a court of law. Concessions include modifying original loan terms to reduce or defer cash payments required as part of the loan agreement, including but not limited to:
	•	A reduction of the stated interest rate for the remaining original life of the debt
	•	Extension of the maturity date or dates at a stated interest rate lower than the current market rate for new debt with similar risk characteristics
	•	Reduction of the face amount or maturity amount of the debt as stated in the agreement
	•	Reduction of accrued interest receivable on the debt
	In its determination of whether the customer is experiencing financial difficulties, the Company considers numerous indicators, including but not limited to:
	•	Whether the customer is currently in default on its existing loan or is in an economic position where it is probable the customer will be in default on its loan in the foreseeable future without a modification
	•	Whether the customer has declared or is in the process of declaring bankruptcy
	•	Whether there is substantial doubt about the customer’s ability to continue as a going concern
	•	Whether, based on its projections of the customer’s current capabilities, the Company believes the customer’s future cash flows will be insufficient to service the debt, including interest, in accordance with the contractual terms of the existing agreement for the foreseeable future
	•	Whether, without modification, the customer cannot obtain sufficient funds from other sources at an effective interest rate equal to the current market rate for similar debt for a nontroubled debtor
	If the Company concludes that both a concession has been granted and the concession was granted to a customer experiencing financial difficulties, the Company identifies the loan as a TDR. For purposes of the determination of an allowance for loan losses on these TDRs, the loan is reviewed for specific impairment in accordance with the Company’s allowance for loan loss methodology. If it is determined that losses are probable on such TDRs, either because of delinquency or other credit quality indicators, the Company establishes specific reserves for these loans.
	Acquisition Accounting for Loans
	The Company accounts for business acquisitions in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 805, Business Combinations, which requires the use of the acquisition method of accounting. All identifiable assets acquired, including loans, are recorded at fair value. The fair value of loans that do not have deteriorated credit quality are accounted for in accordance with ASC 310-20, Nonrefundable Fees and Other Costs, and is represented by the expected cash flows from the portfolio discounted at current market rates. In estimating the cash flows, the Company makes assumptions about the amount and timing of principal and interest payments, estimated prepayments, estimated default rates, estimated loss severities in the event of defaults, and current market rates. The fair value adjustment is amortized over the life of the loan using the effective interest method. The Company accounts for certain acquired loans with deteriorated credit quality under ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality. In accordance with ASC 310-30 and in estimating the fair value of loans with deteriorated credit quality as of the acquisition date, the Company: (a) calculates the contractual amount and timing of undiscounted principal and interest payments (the undiscounted contractual cash flows), and (b) estimates the amount and timing of undiscounted expected principal and interest payments (the undiscounted expected cash flows). The difference between the undiscounted contractual cash flows and the undiscounted expected cash flows is the nonaccretable difference. On the acquisition date, the amount by which the undiscounted expected cash flows exceed the estimated fair value of the loans with deteriorated credit quality is the accretable yield. The accretable yield is recorded into interest income over the estimated lives of the loans using the effective yield method. The accretable yield changes over time as actual and expected cash flows vary from the estimated cash flows at acquisition. Decreases in expected cash flows subsequent to acquisition result in recognition of a provision for loan loss. The accretable yield is measured at each financial reporting date and represents the difference between the remaining undiscounted expected cash flows and the current carrying value of the loans. The remaining undiscounted expected cash flows are calculated at each financial reporting date, based on information currently available. Increases in expected cash flows over those originally estimated increase the accretable yield and are recognized prospectively as interest income. Increases in expected cash flows may also lead to the reduction of any allowance for loan losses recorded after the acquisition. Decreases in expected cash flows compared to those originally estimated decrease the accretable yield and are recognized by recording an allowance for loan losses. As the accretable yield increases or decreases from changes in cash flow expectations, the offset is an increase or decrease to the nonaccretable difference. There is no carryover of allowance for loan losses, as the loans acquired are initially recorded at fair value as of the date of acquisition.
	Allowance for Loan Losses
	The allowance for loan losses represents an estimate that management believes will be adequate to absorb probable incurred losses on existing loans in its portfolio at the balance sheet date. The allowance is based on an evaluation of the collectability of loans and prior loss experience, including both industry and Company specific considerations. While management uses available information to make loan loss allowance evaluations, adjustments to the allowance may be necessary based on changes in economic and other conditions or changes in accounting guidance. See Note 6 for an analysis of the Company’s allowance for loan losses by portfolio and portfolio segment, and credit quality information by class.
	Management has an established methodology to determine the allowance for loan losses that assesses the risks and losses inherent in its portfolio and portfolio segments. The Company utilizes an internally developed model that requires significant judgment to determine the estimation method that fits the credit risk characteristics of the loans in its portfolio and portfolio segments. The allowance for loan losses is established through a provision for loan losses charged to expense. A similar methodology and model is utilized by the Company to calculate a reserve assigned to off-balance sheet commitments, specifically unfunded loan commitments and letters of credit, and any needed reserve is recorded in other liabilities. The appropriateness of the allowance for loan losses is determined in accordance with generally accepted accounting principles.
	The Company’s loan portfolio is disaggregated into portfolio segments for purposes of determining the allowance for loan losses. The Company’s portfolio segments include commercial real estate, consumer real estate, commercial and industrial, and consumer loans. The Company further disaggregates the commercial and consumer real estate portfolio segments into classes for purposes of monitoring and assessing credit quality based on certain risk characteristics. Classes within each commercial real estate portfolio segment include commercial real estate construction and commercial real estate mortgage. Classes within each consumer real estate portfolio segment include consumer real estate construction and consumer real estate mortgage.
	Loans are charged off against the allowance for loan losses when management believes that the collectability of the principal is unlikely. The allowance for loan losses consists of specific and general reserves. The Company determines specific reserves based on the provisions of ASC 310, Receivables. The Company’s allowance for loan losses includes a measure of impairment for those loans specifically identified for evaluation under the topic. This measurement is based on a comparison of the recorded investment in the loan with either the expected cash flows discounted using the loan’s original contractual effective interest rate or the fair value of the collateral underlying certain collateral-dependent loans. Collectability of principal and interest is evaluated in assessing the need for a loss accrual. Loans identified as impaired are individually evaluated periodically for impairment.
	General reserves are based on management’s evaluation of many factors and reflect an estimated measurement of losses related to loans not individually evaluated for impairment. These loans are grouped into portfolio segments. The loss rates are derived from historical loss factors of the Company or the industry sustained on loans according to their risk grade, as well as qualitative and economic factors, and may be adjusted for Company-specific factors. Loss rates are reviewed quarterly and adjusted as management deems necessary based on changing borrower and/or collateral conditions and actual collections and charge-off experience.
	Based on observations made through a qualitative review, management may apply qualitative adjustments to the quantitatively determined loss estimates at a group and/or portfolio segment level as deemed appropriate. Primary qualitative and environmental factors that may not be directly reflected in quantitative estimates include:
	•	Asset quality trends
	•	Changes in lending policies
	•	Trends in the nature and volume of the loan portfolio, including the existence and effect of any portfolio concentrations
	•	Changes in experience and depth of lending staff
	•	National and regional economic trends
	Changes in these factors are considered in determining the directional consistency of changes in the allowance for loan losses. The impact of these factors on the Company’s qualitative assessment of the allowance for loan losses can change from period to period based on management’s assessment to the extent to which these factors are already reflected in historic loss rates. The uncertainty inherent in the estimation process is also considered in evaluating the allowance for loan losses.
	Off-Balance-Sheet
	Credit-Related Financial Instruments
	The Company accounts for its guarantees in accordance with the provisions of ASC 460, Guarantees. In the ordinary course of business, the Company has entered into commitments to extend credit, including commitments under credit card agreements, and standby letters of credit. Such financial instruments are recorded when they are funded.
	Derivative Financial Instruments
	ASC 815, Derivatives and Hedging, requires that all derivatives be recognized as assets or liabilities in the balance sheet at fair value. The Company may enter into derivative contracts to manage exposure to interest rate risk or meet the financing and/or investing needs of its customers.
	In the course of its business operations, the Company is exposed to certain risks, including interest rate, liquidity, and credit risk. The Company manages its risks through the use of derivative financial instruments, primarily through management of exposure due to the receipt or payment of future cash amounts based on interest rates. The Company’s derivative financial instruments manage the differences in the timing, amount, and duration of expected cash receipts and payments.
	Derivatives which are designated and qualify as a hedge of the exposure to variability in expected future cash flows or other types of forecasted transactions are considered cash flow hedges. The Company prepares written hedge documentation for all derivatives which are designated as cash flow hedges. The written hedge documentation includes identification of, among other items, the risk management objective, hedging instrument, hedged item and methodologies for assessing and measuring hedge effectiveness and ineffectiveness, along with support for management’s assertion that the hedge will be highly effective. These methods are consistent with the Company’s approach to managing risk. The Company reports these net in the accompanying consolidated balance sheets when the Company has a master netting arrangement. As of December 31, 2014, there were net amounts reported.
For designated hedging relationships, the Company performs retrospective and prospective effectiveness testing to determine whether the hedging relationship has been highly effective in offsetting changes in cash flows of hedged items and whether the relationship is expected to continue to be highly effective in the future. Assessments of hedge effectiveness and measurements of hedge ineffectiveness are performed at least quarterly. The effective portion of the changes in the fair value of a derivative that is highly effective and that has been designated and qualifies as a cash flow hedge are initially recorded in accumulated other comprehensive income and reclassified to earnings in the same period that the hedged item impacts earnings or when the hedging relationship is terminated; any ineffective portion is recorded in earnings immediately.
Hedge accounting ceases on transactions that are no longer deemed effective, or for which the derivative has been terminated or de-designated. For discontinued cash flow hedges, the unrealized gains and losses recorded in accumulated other comprehensive income would be reclassified to earnings during the period or periods in which the previously designated hedged cash flows affect earnings (straight-line amortization/accretion) unless it was determined that the transaction was probable to not occur, whereby any unrealized gains and losses in accumulated other comprehensive income would be immediately reclassified to earnings. Note 18 describes the derivative instruments currently used by the Company and discloses how these derivatives impact the Company’s financial position and results of operations.
Premises and Equipment
Land is carried at cost. Buildings, furniture, fixtures, and equipment are carried at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated life of each respective type of asset as follows:
	Buildings	40 years
	Furniture, fixtures, and equipment	5	-	15 years
Leasehold improvements are amortized using the straight-line method over the periods of the leases, including options expected to be exercised, or the estimated useful lives, whichever is shorter. Gains and losses on disposition and maintenance and repairs are included in current operations. Rental expense on leased property is recognized on a straight-line basis over the original lease term plus options that management expects to exercise. Fixed rental increases that are determinable are expensed over the lease period, including any option periods which are expected to be exercised, using a straight-line lease expense method.
Other Real Estate
Assets acquired through, or in lieu of, loan foreclosure are held for sale and are recorded at a new cost basis determined at the date of foreclosure as the lower of cost or fair value less estimated cost to sell. Cost is defined as the recorded investment in the loan. Subsequent to foreclosure, valuation allowances are established for any decreases in the estimate of the asset’s fair value or selling costs, but not in excess of its new cost basis. Revenues and expenses from operations and changes in the valuation allowance are included in current earnings.
Goodwill and Other Intangible Assets
Goodwill is accounted for in accordance with ASC 350, Intangibles—Goodwill and Other, and, accordingly, is not amortized but is evaluated at least annually for impairment. As part of its annual impairment testing, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company determines the fair value of a reporting unit is less than its carrying amount using these qualitative factors, the Company compares the fair value of goodwill with its carrying amount and then measures impairment loss by comparing the implied fair value of goodwill with the carrying amount of that goodwill.
Definite-lived intangible assets, which consist of core deposit intangibles, are amortized on a straight-line basis over their useful lives and evaluated at least annually for impairment.
Income Taxes
The Company accounts for income taxes under the liability method. Deferred tax assets and liabilities are established for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities using enacted tax rates expected to be in effect during the year in which the basis differences reverse.
The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires the Company to report information regarding its exposure to various tax positions taken by the Company. The Company has determined whether any tax positions have met the recognition threshold and has measured the Company’s exposure to those tax positions. Management believes that the Company has adequately addressed all relevant tax positions and that there are no unrecorded tax liabilities. Any interest or penalties assessed to the Company are recorded in operating expenses. No interest or penalties from any taxing authorities were recorded in the accompanying consolidated financial statements. Federal, state, and local taxing authorities generally have the right to examine and audit the previous three years of tax returns filed.
The Company is also required to reduce its tax basis of the investment in certain of the projects that generated the Federal NMTC or Federal Historic Rehabilitation tax credits by the amount of the credit generated in that year based on the taxable entity structure of the investee.
Noncontrolling Interests
Noncontrolling interests include $2 thousand at December 31, 2014 and 2013 and $1 thousand at December 31, 2012, of common stock held by unrelated parties in various tax credit-related subsidiaries, which have activities solely related to generating the tax credits.
In 2012, $1.6 million of noncumulative, perpetual preferred stock held by unrelated parties of the Bank was redeemed and noncontrolling interests were reduced by that amount. The stock had been assumed by the Bank in a prior acquisition.
Investments in Real Estate Properties
FNBC CDC invests in real estate properties, which are carried at cost. Costs of construction are capitalized during the construction period and do not include interest. The Company periodically obtains as-is appraisals to determine the recoverability of its investments for which it intends to sell. For properties the Company intends to hold, the Company assesses recoverability based on the cash flows of the underlying properties.
Investments in Tax Credit Entities
As part of its Community Reinvestment Act responsibilities and due to their favorable economics, the Company invests in tax credit-motivated projects. These projects are directed at tax credits issued under Low-Income Housing, Federal Historic Rehabilitation, and Federal New Markets Tax Credits. The Company generates its returns on tax credit motivated projects through the receipt of federal, and if applicable, state tax credits. The federal tax credits are recorded as an offset to the income tax provision in the year that they are earned under federal income tax law – over 10 to 15 years, beginning in the year in which rental activity commences for Low-Income Housing credits, in the year of the issuance of the certificate of occupancy and the property is placed into service for Federal Historic Rehabilitation credits, and over 7 years for Federal NMTC upon the investment of funds into the CDE. These credits, if not used in the tax return for the year of origination, can be carried forward for 20 years.
For Low-Income Housing and Federal Historic Rehabilitation credits, the Company invests in a tax credit entity, usually a limited liability company, which owns the real estate. The Company receives a 99.99% nonvoting interest in the entity for Low-Income Housing investments and 99% for Federal Historic Rehabilitation investments that must be retained during the compliance period for the credits (15 years for Low-Income Housing credits and 5 years for Federal Historic Rehabilitation credits). In most cases, the Company’s interest in the entity is generally reduced from a 99.99% and 99% interest to a 5% to 25% interest at the end of the compliance period. Control of the tax credit entity rests in the .01% and 1% interest general partner, who has the power and authority to make decisions that impact economic performance of the project and is required to oversee and manage the project. Due to the lack of any voting, economic or managerial control and due to the contractual reduction in its ownership, the Company accounts for its investment in Low-Income Housing and Federal Historic Rehabilitation credits by amortizing its investment, beginning in the year of the issuance of the certificate of occupancy and when the property is placed into service, over the compliance or contract period, as management believes any potential residual value in the real estate will have limited value.
For Federal NMTC, a different structure is required by federal tax law. In order to distribute Federal NMTC, the federal government allocates such credits to CDEs. The Company invests in both CDEs formed by unaffiliated parties and in CDEs formed by the Company. Projects must be commercial or real estate operations and are qualified by their location in low- income areas or by their employment of, or service to, low-income citizens. A CDE, in most cases, creates a special-purpose subsidiary for each project through which the credits are allocated and through which the proceeds from the tax credit investor and a leverage lender, if applicable, flow through to the project, which in turn generate the credit. The credits are calculated at 39% of the total CDE allocation to the project at the rate of 5% for the first three years and 6% for the next four years. Federal tax law requires special terms benefiting the qualified project, which can include below-market interest rates. The Company expenses the cost of any benefits provided to the project over the seven-year compliance period. When the Company also has a loan, commonly called a leveraged loan, to the project, it is carried in loans, as the Company has normal credit exposure to the project and is repaid at the end of the compliance period (in general, the debt has no principal payments during the compliance period but the Company may require the project to fund a sinking fund over the compliance period to achieve the same risk reduction effect as if principal is being amortized).
When the Company is the tax credit investor in a CDE formed by an unaffiliated party, it has no control of the applicable CDE or the CDE’s special-purpose subsidiary. When a project is funded through FNBC CDE, the Company consolidates its CDE and the specifically formed special-purpose entities since it maintains control over these entities. As part of the activities of FNBC CDE, the Company makes investments in the CDE for purposes of providing equity to the projects sponsored by the FNBC CDE.
The Company has the risk of credit recapture if the project fails during the compliance period for Low-Income Housing and Federal Historic Rehabilitation transactions. For Federal NMTC transactions, the risk of credit recapture exists if investment requirements are not maintained during the compliance period. Such events, although rare, are accounted for when they occur and no such events have occurred to date.
Variable Interest Entities
VIEs are entities that, in general, either do not have equity investors with voting rights or that have equity investors that do not provide sufficient financial resources for the entity to support its activities. The Company uses VIEs in various legal forms to conduct normal business activities. The Company reviews the structure and activities of VIEs for possible consolidation.
A controlling financial interest in a VIE is present when an enterprise has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits of the VIE that could potentially be significant to the VIE. A VIE often holds financial assets, including loans or receivables, real estate, or other property. The company with a controlling financial interest, known as the primary beneficiary, is required to consolidate the VIE. Noncontrolling variable interests in certain limited partnerships for which it does not absorb a majority of expected losses or receive a majority of expected residual returns are not included in the accompanying consolidated financial statements. Refer to Notes 12 and 13 for further detail.
Stock-Based Compensation Plans
At December 31, 2014 and 2013, the Company had a stock-based employee compensation plan, which provides for the issuance of stock options and restricted stock. The Company accounts for stock-based employee compensation in accordance with the fair value recognition provisions of ASC 718, Compensation—Stock Compensation. Compensation cost is recognized as expense over the service period, which is generally the vesting period of the options and restricted stock. The expense is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occur. As a result, compensation cost for all share-based payments is reflected in net income as part of salaries and employee benefits in the accompanying consolidated statements of income. See Note 24 for additional information on the Company’s stock-based compensation plans.
Earnings Per Share
Basic earnings per common share is computed based upon net income attributable to common shareholders divided by the weighted-average number of common shares outstanding during each period. Diluted earnings per common share is computed based upon net income, adjusted for dilutive participating securities, divided by the weighted-average number of common shares outstanding during each period and adjusted for the effect of dilutive potential common shares calculated using the treasury stock method and the assumed conversion for any dilutive convertible securities. In determining net income attributable to common shareholders, the net income attributable to participating securities is excluded. The Company issued Series C preferred stock in 2011, which is considered a participating security because it shares in any dividends paid to common shareholders. The assumed conversion of the Series C preferred stock is excluded from the calculation of diluted earnings per share due to the fact that the shares are contingently issuable and the contingency still existed at the end of the year.
Comprehensive Income
Accounting principles generally require that recognized revenue, expenses, gains, and losses be included in net income. Although certain changes in assets and liabilities, such as unrealized gains and losses on available for sale securities and cash flow hedges, are reported as a separate component of the equity section of the balance sheet; such items, along with net income, are components of comprehensive income.
Segments
All of the Company’s banking operations are considered by management to be aggregated in one reportable operating segment. Because the overall banking operations comprise substantially all of the consolidated operations and none of the Company’s other subsidiaries, either individually or in the aggregate, meet quantitative materiality thresholds, no separate segment disclosures are presented in the accompanying consolidated financial statements.
Recent Accounting Pronouncements
ASU No. 2014-01
In January 2014, the FASB issued ASU No. 2014-01, Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects, which permits reporting entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). This ASU applies to all reporting entities that invest in qualified affordable housing projects through limited liability entities that are flow-through entities for tax purposes. The provisions of this ASU should be applied retrospectively to all periods presented for periods beginning after December 15, 2014, with early adoption permitted. The Company is evaluating the adoption of this ASU and has not determined the impact on the Company's financial condition or results of operations.
ASU No. 2014-04
In January 2014, the FASB issued ASU No. 2014-04, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure, which clarifies when an insubstance repossession or foreclosure occurs, that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. The ASU requires a creditor to reclassify a collateralized consumer mortgage loan to real estate property upon obtaining legal title to the residential real estate property, or the borrower conveying all interest in the residential real estate property through completion of a deed in lieu of foreclosure or similar legal agreement. The provisions of this ASU are effective for all periods beginning after December 15, 2014. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations.
ASU No. 2014-09
In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 205): An Amendment of the FASB Accounting Standards Codification, which clarifies the principles for recognizing revenue from contracts with customers. The new accounting guidance, which does not apply to financial instruments, is effective on a retrospective basis for annual reporting periods beginning after December 15, 2016, with early adoption not permitted. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.
ASU No. 2014-11
In June 2014, the FASB issued ASU No. 2014-11 Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures, which requires separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty that will result in secured borrowing accounting for the repurchase agreement. The ASU requires new disclosures for repurchase agreements, securities lending transactions and repurchase-to-maturity transactions that are accounted for as secured borrowings. These disclosures include information about the types of assets pledged and the relationship between those assets and the related obligation to return the proceeds. The ASU also requires new disclosures for transfers of financial assets that are accounted for as sales that involve an agreement with the transferee entered into in contemplation of the initial transfer that result in the transferor retaining substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The accounting and disclosure changes are effective for annual periods beginning after December 15, 2014. The Company is evaluating the adoption of this ASU and has not determined the impact on the Company’s financial condition or results of operations.
ASU No. 2014-12
In June 2014, the FASB issued ASU No. 2014-12 Compensation-Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could be Achieved after the Requisite Service Period, which requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is intended to resolve the diverse accounting treatments of these types of awards in practice and is effective for annual and interim periods beginning after December 15, 2015. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.
ASU No. 2014-13
In August 2014, the FASB issued ASU No. 2014-13, Consolidation (Topic 810): Measuring the Financial Assets and Financial Liabilities of a Consolidated Collateralized Financing Entity, which will allow an alternative fair value measurement approach for consolidated collateralized financing entities (CFEs) to eliminate a practice issue that results in measuring the fair value of a CFE’s financial assets at a different amount from the fair value of its financial liabilities even when the financial liabilities have recourse to only the financial assets. The approach would permit the parent company of a consolidated CFE to measure the CFE’s financial assets and financial liabilities based on the more observable of the fair value of the financial assets and the fair value of the financial liabilities. The new accounting guidance is for the annual period ending after December 15, 2015, and for annual periods and interim periods thereafter, with early application permitted as of the beginning of an annual period. The Company does not expect the new guidance to have a material impact on the Company’s financial condition or results of operations.
ASU No. 2014-14
In August 2014, the FASB issued ASU No. 2014-14, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure, which will require creditors to derecognize certain foreclosed government-guaranteed mortgage loans and to recognize a separate other receivable that is measured at the amount the creditor expects to recover from the guarantor, and to treat the guarantee and the receivable as a single unit of account. The new accounting guidance is effective on a prospective or a modified retrospective transition method for annual reporting periods, and interim periods within those annual periods, beginning after December 15, 2014, with early adoption permitted. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.
ASU No. 2014-15
In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which will require management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards in connection with preparing financial statements for each annual and interim reporting period. The new accounting guidance is for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter, with early application permitted. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share
	The following sets forth the computation of basic net income per common share and diluted net income per common share:
		Year Ended December 31,
	(In thousands, except per share data)	2014		2013		2012
	Basic: Income available to common shareholders	$	54,144	$	38,584	$	26,431
	Weighted-average common shares outstanding	18,541		16,204		12,953
	Basic earnings per share	$	2.92	$	2.38	$	2.04
	Diluted: Income attributable to common shareholders	$	54,144	$	38,584	$	26,431
	Weighted-average common shares outstanding	18,541		16,204		12,953
	Effect of dilutive securities:
	Stock options outstanding	389		337		109
	Warrants	119		83		52
	Weighted-average common shares outstanding – assuming dilution	19,049		16,624		13,114
	Diluted earnings per share	$	2.84	$	2.32	$	2.02
	For the year ended December 31, 2012, the calculation of diluted earnings per share outstanding excludes the effects from the assumed exercise of 87,059 shares of warrants and 264,000 shares of stock options outstanding. These amounts would have had an antidilutive effect on earnings per share.

Cash_and_Due_From_Banks

Cash and Due From Banks	12 Months Ended
	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Cash and Due From Banks	Cash and Due From Banks
	The Company is required to maintain reserve requirements with the Federal Reserve Bank. The requirement is dependent upon the Bank’s cash on hand and transaction deposit account balances. The reserve requirements at December 31, 2014 and 2013, were $9.3 million and $10.1 million, respectively.

Investment_in_ShortTerm_Receiv

Investment in Short-Term Receivables	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Investment in Short-Term Receivables	Investment in Short-Term Receivables
	The Company invests in short-term trade receivables purchased on an exchange, which are covered by a repurchase agreement from the seller of the receivables, if not paid within a specified period. Since the receivables are traded on an exchange, the Company has the ability to resell the receivables on the exchange. As of December 31, 2014 and 2013, the Company had $237.1 million and $246.8 million, respectively in purchased receivables.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities
	The amortized cost and market values of investment securities, with gross unrealized gains and losses, as of December 31, 2014 and December 31, 2013, were as follows (in thousands):
		31-Dec-14
		Amortized			Gross			Gross Unrealized Losses								Estimated
		Cost			Unrealized											Market Value
					Gains			Less Than				Greater Than
								One Year				One Year
	Available for sale:
	U.S. government agency securities	$	161,461		$	891		$	—			$	(4,825	)		$	157,527
	U.S. Treasury securities	13,019			—			—				(409		)		12,610
	Municipal securities	12,175			107			(36		)		—				12,246
	Mortgage-backed securities	57,025			635			(137		)		(436		)		57,087
	Corporate bonds	8,263			—			—				(86		)		8,177
		$	251,943		$	1,633		$	(173	)		$	(5,756	)		$	247,647
	Held to maturity:
	Municipal securities	$	41,255		$	2,182		$	(62	)		$	—			$	43,375
	Mortgage-backed securities	47,821			1,098			(208		)		(1,130		)		47,581
		$	89,076		$	3,280		$	(270	)		$	(1,130	)		$	90,956
		31-Dec-13
		Amortized			Gross			Gross Unrealized Losses								Estimated
		Cost			Unrealized											Market Value
					Gains			Less Than				Greater Than
								One Year				One Year
	Available for sale:
	U.S. government agency securities	$	163,964		$	81		$	(10,991	)		$	(1,731	)		$	151,323
	U.S. Treasury securities	13,022			—			(873		)		—				12,149
	Municipal securities	23,240			140			(213		)		—				23,167
	Mortgage-backed securities	57,010			447			(1,897		)		(16		)		55,544
	Corporate bonds	37,023			395			(1,677		)		(205		)		35,536
		$	294,259		$	1,063		$	(15,651	)		$	(1,952	)		$	277,719
	Held to maturity:
	Municipal securities	$	44,294		$	94		$	(398	)		$	—			$	43,990
	Mortgage-backed securities	50,610			12			(3,646		)		—				46,976
		$	94,904		$	106		$	(4,044	)		$	—			$	90,966
	During 2013, the Company transferred securities with a fair value of $95.4 million from available-for-sale to held to maturity. Management determined that it has both the positive intent and ability to hold these securities until maturity. The reclassified securities consisted of municipal and mortgage-backed securities and were transferred due to movements in interest rates. The securities were reclassified at fair value at the time of the transfer and represented a non-cash transaction. Accumulated other comprehensive income included pre-tax unrealized losses of $5.9 million on these securities at the date of the transfer. As of December 31, 2014, $5.2 million of pre-tax unrealized losses on these securities were included in accumulated other comprehensive income. These unrealized losses and offsetting other comprehensive income components are being amortized into net interest income over the remaining life of the related securities as a yield adjustment, resulting in no impact on future net income.
	At December 31, 2014, the Company’s exposure to three investment security issuers individually exceeded 10% of shareholders’ equity (in thousands):
		Amortized			Estimated
		Cost			Market Value
	Federal National Mortgage Association (Fannie Mae)	$	92,205		$	90,366
	Federal Home Loan Bank (FHLB)	74,442			73,623
	Federal Home Loan Mortgage Corporation (Freddie Mac)	55,979			54,875
		$	222,626		$	218,864
	As of December 31, 2014, the Company had 38 securities that were in a loss position. The unrealized losses for each of the 38 securities relate to market interest rate changes. The Company has considered the current market for the securities in a loss position, as well as the severity and duration of the impairments, and expects that the value will recover. As of December 31, 2014, management does not intend to sell these investments until the fair value exceeds amortized cost and it is more likely than not that the Company will not be required to sell debt securities before the anticipated recovery of the amortized cost basis of the security; thus, the impairment is determined not to be other-than-temporary.
	As of December 31, 2013, the Company had 88 securities that were in a loss position. The unrealized losses for each of the 88 securities relate to market interest rate changes. The Company has considered the current market for the securities in a loss position, as well as the severity and duration of the impairments, and expects that the value will recover. As of December 31, 2013, management had both the intent and ability to hold these investments until the fair value exceeds amortized cost; thus, the impairment is determined not to be other-than-temporary. In addition, management does not believe the Company will be required to sell debt securities before the anticipated recovery of the amortized cost basis of the security.
	The amortized cost and estimated market values by contractual maturity of investment securities as of December 31, 2014 and December 31, 2013 are shown in the following table (in thousands). Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.
		31-Dec-14									31-Dec-13
		Weighted		Amortized			Estimated				Weighted			Amortized				Estimated
		Average		Cost			Market Value				Average			Cost				Market Value
		Yield									Yield
	Available for sale:
	Due in one year or less	1.78	%	$	571		$	573			1.39	%		$	12,340			$	12,368
	Due after one year through five years	2.64		51,037			51,916				2.58			64,790				65,038
	Due after five years through ten years	2.02		176,631			172,012				2.12			180,362				168,243
	Due after ten years	3.34		23,704			23,146				3.17			36,767				32,070
	Total securities	2.27	%	$	251,943		$	247,647			2.3	%		$	294,259			$	277,719
	Held to maturity:
	Due in one year or less	3.88	%	$	2,045		$	2,003			1.76	%		$	1,007			$	1,007
	Due after one year through five years	4.16		20,921			21,875				2.6			18,101				17,539
	Due after five years through ten years	3.39		32,618			33,898				3.7			37,591				37,137
	Due after ten years	3.3		33,492			33,180				3.41			38,205				35,283
	Total securities	3.55	%	$	89,076		$	90,956			3.35	%		$	94,904			$	90,966
	Securities with estimated market values of $279.1 million and $204.3 million at December 31, 2014 and December 31, 2013, respectively, were pledged to secure public deposits, securities sold under agreements to repurchase, and long-term borrowings.
	Proceeds from sales of available for sale securities for the years ended December 31, 2014, 2013, and 2012 were $41.7 million, $45.8 million, and $125.4 million, respectively. Gross gains of $0.8 million, $0.5 million, and $4.3 million were realized on these sales for the years ended December 31, 2014, 2013, and 2012, respectively. There were gross losses of $0.6 million and $0.2 for the years ended December 31, 2014 and 2013, respectively, and no gross losses were realized for the year ended December 31, 2012.
	During 2014, the Company sold a municipal security that was classified as held to maturity. The proceeds from the sale were$2.7 million and the Company recorded a gross loss of $0.1 million which was realized on this sale. The Company made the decision to sell the municipal security due to the deteriorating credit worthiness of the issuer. The Company has the ability and intent to hold the remaining securities within the held to maturity portfolio to maturity.
Other Equity Securities
At December 31, 2014 and 2013, the Company included the following securities in other assets, at cost, in the accompanying consolidated balance sheets (in thousands):
	2014			2013
FHLB stock	$	1,347		$	1,099
First National Bankers Bankshares, Inc. (FNBB) stock	600			600
Other investments	5,233			4,853
Total equity securities	$	7,180		$	6,552

Loans

Loans	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Loans	Loans
	Major classifications of loans at December 31, 2014 and December 31, 2013 were as follows (in thousands):
		31-Dec-14				31-Dec-13
	Commercial real estate loans:
	Construction	$	316,492			$	203,369
	Mortgage(1)	1,252,225				1,118,048
		1,568,717				1,321,417
	Consumer real estate loans:
	Construction	10,393				8,986
	Mortgage	131,031				115,307
		141,424				124,293
	Commercial and industrial loans	1,016,414				868,469
	Loans to individuals, excluding real estate	18,316				16,345
	Nonaccrual loans	21,228				16,396
	Other loans	8,165				10,857
		2,774,264				2,357,777
	Less allowance for loan losses	(42,336		)		(32,143		)
	Loans, net	$	2,731,928			$	2,325,634
	-1	Included in commercial real estate loans, mortgage, are owner-occupied real estate loans, of $419.3 million at December 31, 2014 and $364.9 million at December 31, 2013.
	A summary of changes in the allowance for loan losses during the years ended December 31, 2014, 2013, and 2012 is as follows (in thousands):
		2014				2013				2012
	Balance, beginning of period	$	32,143			$	26,977			$	18,122
	Provision charged to operations	12,000				9,800				11,035
	Charge-offs	(1,929		)		(4,769		)		(2,561		)
	Recoveries	122				135				381
	Balance, end of period	$	42,336			$	32,143			$	26,977
	Deferred costs less deferred fees, net of amortization, related to loan origination were $13.8 million and $10.6 million as of December 31, 2014 and 2013, respectively. These amounts are included in the loan balances above.
	In addition to loans issued in the normal course of business, the Company considers overdrafts on customer deposit accounts to be loans and reclassifies these overdrafts to loans in the accompanying consolidated balance sheets. At December 31, 2014 and 2013, overdrafts of $0.7 million and $0.8 million, respectively, had been reclassified to loans receivable.
	Loans with carrying values of $847.0 million were pledged on a blanket lien to secure other borrowings at December 31, 2014. At December 31, 2013, loans with carrying values of $655.1 million on a blanket lien and $29.4 million which were held in custody were pledged to secure other borrowings.
	The allowance for loan losses and recorded investment in loans, including loans acquired with deteriorated credit quality as of the dates indicated are as follows (in thousands):
		31-Dec-14
		Construction				Commercial				Consumer			Commercial			Consumer			Total
						Real Estate				Real Estate			and
													Industrial
	Allowance for loan losses:
	Balance, beginning of period	$	2,790			$	13,780			$	2,656		$	12,677		$	240		$	32,143
	Charge-offs	(18		)		(1,034		)		(63		)	(648		)	(166		)	(1,929		)
	Recoveries	30				—				—			71			21			122
	Provision	1,228				2,219				723			7,714			116			12,000
	Balance, end of period	$	4,030			$	14,965			$	3,316		$	19,814		$	211		$	42,336
	Ending balances:
	Individually evaluated for impairment	$	—			$	3,138			$	—		$	5,889		$	1		$	9,028
	Collectively evaluated for impairment	$	4,030			$	11,827			$	3,316		$	13,925		$	210		$	33,308
	Loans receivable:
	Ending balance-total	$	327,677			$	1,264,371			$	132,950		$	1,030,629		$	18,637		$	2,774,264
	Ending balances:
	Individually evaluated for impairment	$	927			$	13,130			$	2,085		$	15,157		$	259		$	31,558
	Collectively evaluated for impairment	$	326,750			$	1,251,241			$	130,865		$	1,015,472		$	18,378		$	2,742,706
		31-Dec-13
		Construction				Commercial				Consumer			Commercial			Consumer			Total
						Real Estate				Real Estate			and
													Industrial
	Allowance for loan losses:
	Balance, beginning of period	$	2,004			$	10,716			$	2,450		$	11,675		$	132		$	26,977
	Charge-offs	(46		)		(292		)		—			(4,229		)	(202		)	(4,769		)
	Recoveries	—				19				30			68			18			135
	Provision	832				3,337				176			5,163			292			9,800
	Balance, end of period	$	2,790			$	13,780			$	2,656		$	12,677		$	240		$	32,143
	Ending balances:
	Individually evaluated for impairment	$	42			$	1,639			$	183		$	2,091		$	—		$	3,955
	Collectively evaluated for impairment	$	2,748			$	12,141			$	2,473		$	10,586		$	240		$	28,188
	Loans receivable:
	Ending balance-total	$	212,430			$	1,128,181			$	117,653		$	883,111		$	16,402		$	2,357,777
	Ending balances:
Individually evaluated for impairment	$	309			$	9,811			$	2,990		$	4,005		$	—		$	17,115
Collectively evaluated for impairment	$	212,121			$	1,118,370			$	114,663		$	879,106		$	16,402		$	2,340,662
Credit quality indicators on the Company’s loan portfolio, including loans acquired with deteriorated credit quality, as of the dates indicated were as follows (in thousands):
	31-Dec-14
	Pass and				Special				Substandard			Doubtful			Total
	Pass/Watch				Mention
Construction	$	313,987			$	2			$	13,688		$	—		$	327,677
Commercial real estate	1,215,673				1,613				47,085			—			1,264,371
Consumer real estate	128,507				60				4,383			—			132,950
Commercial and industrial	1,005,829				—				24,800			—			1,030,629
Consumer	18,247				7				383			—			18,637
Total loans	$	2,682,243			$	1,682			$	90,339		$	—		$	2,774,264
	December 31, 2013
	Pass and				Special				Substandard			Doubtful			Total
	Pass/Watch				Mention
Construction	$	197,951			$	4			$	14,475		$	—		$	212,430
Commercial real estate	1,073,339				1,720				53,122			—			1,128,181
Consumer real estate	113,037				185				4,431			—			117,653
Commercial and industrial	873,547				17				9,547			—			883,111
Consumer	16,251				9				142			—			16,402
Total loans	$	2,274,125			$	1,935			$	81,717		$	—		$	2,357,777
The table above includes $5.4 million in substandard loans and $1.6 million in special mention loans as of December 31, 2014, which are loans acquired with deteriorated credit quality and accounted for under ASC 310-30. As of December 31, 2013, included in the above table was $7.4 million of substandard loans and $1.6 million of special mention loans which are loans acquired with deteriorated credit quality and accounted for under ASC 310-30.
The above classifications follow regulatory guidelines and can generally be described as follows:
•	Pass and pass/watch loans are of satisfactory quality.
•	Special mention loans have an existing weakness that could cause future impairment, including the deterioration of financial ratios, past due status, questionable management capabilities, and possible reduction in the collateral values.
•	Substandard loans have an existing specific and well-defined weakness that may include poor liquidity and deterioration of financial ratios. The loan may be past due and related deposit accounts may be experiencing overdrafts. Immediate corrective action is necessary.
•	Doubtful loans have specific weaknesses that are severe enough to make collection or liquidation in full highly questionable and improbable.
Age analysis of past due loans, including loans acquired with deteriorated credit quality, as of the dates indicated were as follows (in thousands):
	31-Dec-14
	Greater Than				90 Days and				Total Past			Current Loans			Total Loans
	30 and Fewer				Greater				Due
	Than 90 Days				Past Due
	Past Due
Real estate loans:
Construction	$	97			$	750			$	847		$	326,830		$	327,677
Commercial real estate	2,497				9,545				12,042			1,252,329			1,264,371
Consumer real estate	1,623				1,255				2,878			130,072			132,950
Total real estate loans	4,217				11,550				15,767			1,709,231			1,724,998
Other loans:
Commercial and industrial	159				4,426				4,585			1,026,044			1,030,629
Consumer	564				322				886			17,751			18,637
Total other loans	723				4,748				5,471			1,043,795			1,049,266
Total loans	$	4,940			$	16,298			$	21,238		$	2,753,026		$	2,774,264
	December 31, 2013
	Greater Than				90 Days and				Total Past			Current Loans			Total Loans
	30 and Fewer				Greater				Due
	Than 90 Days				Past Due
	Past Due
Real estate loans:
Construction	$	15			$	75			$	90		$	212,340		$	212,430
Commercial real estate	2,935				7,642				10,577			1,117,604			1,128,181
Consumer real estate	1,260				2,166				3,426			114,227			117,653
Total real estate loans	4,210				9,883				14,093			1,444,171			1,458,264
Other loans:
Commercial and industrial	3,076				1,281				4,357			878,754			883,111
Consumer	488				207				695			15,707			16,402
Total other loans	3,564				1,488				5,052			894,461			899,513
Total loans	$	7,774			$	11,371			$	19,145		$	2,338,632		$	2,357,777
The table above includes $0.6 million of consumer loans past due greater than 30 and fewer than 90 days and $28 thousand of consumer loans 90 days and greater past due, as of December 31, 2014. These loans are cash secured and the Company has rights of offset against the guarantors’ deposit accounts when the loans are 120 days past due.
As of December 31, 2013, consumer loans past due greater than 30 and fewer than 90 days were $0.4 million and consumer loans 90 days and greater past due were $0.2 million. These loans are cash secured and the Company has rights of offset against the guarantors’ deposit accounts when the loans are 120 days past due.
The following is a summary of information pertaining to impaired loans, which consist primarily of nonaccrual loans. This table excludes loans acquired with deteriorated credit quality. Acquired impaired loans are generally not subject to individual evaluation for impairment and are not reported with impaired loans or troubled debt restructurings, even if they would otherwise qualify for such treatment. Impaired loans as of the periods indicated were as follows (in thousands):
	31-Dec-14
	Recorded				Contractual				Related			Average			Interest
	Investment				Balance				Allowance			Recorded			Income
												Investment			Recognized
With no related allowance recorded:
Construction	$	927			$	927			$	—		$	464		$	39
Commercial real estate	7,175				7,453				—			5,718			109
Consumer real estate	2,085				2,097				—			2,029			18
Commercial and industrial	436				498				—			768			22
Consumer	256				256				—			128			6
Total	$	10,879			$	11,231			$	—		$	9,107		$	194
With an allowance recorded:
Construction	$	—			$	—			$	—		$	—		$	—
Commercial real estate	5,955				6,235				3,138			5,753			79
Consumer real estate	—				—				—			509			—
Commercial and industrial	14,721				14,774				5,889			8,814			310
Consumer	3				3				1			2			—
Total	$	20,679			$	21,012			$	9,028		$	15,078		$	389
Total impaired loans:
Construction	$	927			$	927			$	—		$	464		$	39
Commercial real estate	13,130				13,688				3,138			11,471			188
Consumer real estate	2,085				2,097				—			2,538			18
Commercial and industrial	15,157				15,272				5,889			9,582			332
Consumer	259				259				1			130			6
Total	$	31,558			$	32,243			$	9,028		$	24,185		$	583
	31-Dec-13
	Recorded				Contractual				Related			Average			Interest
	Investment				Balance				Allowance			Recorded			Income
												Investment			Recognized
With no related allowance recorded:
Construction	$	—			$	—			$	—		$	24		$	—
Commercial real estate	4,261				4,469				—			3,063			110
Consumer real estate	1,973				1,999				—			1,254			—
Commercial and industrial	1,099				1,116				—			977			40
Total	$	7,333			$	7,584			$	—		$	5,318		$	150
With an allowance recorded:
Construction	$	309			$	309			$	42		$	530		$	23
Commercial real estate	5,550				7,428				1,639			4,445			59
Consumer real estate	1,017				1,046				183			831			21
Commercial and industrial	2,906				2,941				2,091			8,093			10
Total	$	9,782			$	11,724			$	3,955		$	13,899		$	113
Total impaired loans:
Construction	$	309			$	309			$	42		$	554		$	23
Commercial real estate	9,811				11,897				1,639			7,508			169
Consumer real estate	2,990				3,045				183			2,085			21
Commercial and industrial	4,005				4,057				2,091			9,070			50
Total	$	17,115			$	19,308			$	3,955		$	19,217		$	263
Also presented in the above table is the average recorded investment of the impaired loans and the related amount of interest recognized during the time within the period that the impaired loans were impaired. When the ultimate collectability of the total principal of an impaired loan is in doubt and the loan is on nonaccrual status, all payments are applied to principal under the cost recovery method. When the ultimate collectability of the total principal of an impaired loan is not in doubt and the loan is in nonaccrual status, contractual interest is credited to interest income when received under the cash basis method. In the table above, all interest recognized represents cash collected. The average balances are calculated based on the month-end balances of the financing receivables of the period reported.
As of December 31, 2014, there were $28 thousand of cash secured tuition loans that were past due 90 days or more that were still accruing interest, and $0.2 million in cash secured tuition loans that were past due 90 days or more still accruing interest as of December 31, 2013.
A summary of information pertaining to nonaccrual loans as of the periods indicated is as follows (in thousands):
	2014				2013
Nonaccrual loans:
Construction	$	792			$	75
Commercial real estate	12,146				10,133
Consumer real estate	1,919				2,347
Commercial and industrial	6,051				3,784
Consumer	320				57
	$	21,228			$	16,396
As of December 31, 2014 and December 31, 2013, the average recorded investment in nonaccrual loans was $19.6 million and $17.9 million, respectively. The amount of interest income that would have been recognized on nonaccrual loans based on contractual terms was $1.0 million at December 31, 2014 and December 31, 2013. As of December 31, 2014, the Company was not committed to lend additional funds to any customer whose loan was classified as impaired.
ASC 310-30 Loans
During 2011, the Company acquired certain loans from the Federal Deposit Insurance Corporation, as receiver for Central Progressive Bank, that are subject to ASC 310-30. ASC 310-30 provides recognition, measurement, and disclosure requirements for acquired loans that have evidence of deterioration of credit quality since origination for which it is probable, at acquisition, that the Company will be unable to collect all contractual amounts owed. The Company’s allowance for loan losses for all acquired loans subject to ASC 310-30 would reflect only those losses incurred after acquisition.
The following is a summary of changes in the accretable yields of acquired loans as of the years ended December 31, 2014 and 2013 (in thousands):
	2014				2013
Balance, beginning of period	$	170			$	628
Acquisition	—				—
Net transfers from nonaccretable difference to accretable yield	815				45
Accretion	(871		)		(503		)
Balance, end of period	$	114			$	170
Information about the Company’s TDRs as of December 31, 2014 and December 31, 2013, is presented in the following tables (in thousands):
Year Ended December 31, 2014	Current				Greater Than 30				Nonaccrual			Total TDRs
					Days Past Due				TDRs
Real estate loans:
Construction	$	233			$	—			$	—		$	233
Commercial real estate	349				—				1,960			2,309
Consumer real estate	604				—				132			736
Total real estate loans	1,186				—				2,092			3,278
Other loans:
Commercial and industrial	385				—				—			385
Total loans	$	1,571			$	—			$	2,092		$	3,663
Year Ended December 31, 2013	Current				Greater Than 30				Nonaccrual			Total TDRs
					Days Past Due				TDRs
Real estate loans:
Construction	$	309			$	—			$	—		$	309
Commercial real estate	357				—				102			459
Consumer real estate	625				—				136			761
Total real estate loans	1,291				—				238			1,529
Other loans:
Commercial and industrial	337				—				—			337
Total loans	$	1,628			$	—			$	238		$	1,866
The following table provides information on how the TDRs were modified during the years ended December 31, 2014 and 2013 (in thousands):
	2014				2013
Maturity and interest rate adjustment	$	2,536			$	925
Movement to or extension of interest rate-only payments	833				597
Other concessions(1)	294				344
Total	$	3,663			$	1,866
-1	Other concessions include concessions or a combination of concessions, other than maturity extensions and interest rate adjustments.
A summary of information pertaining to modified terms of loans, as of the dates indicated, is as follows (in thousands):
	31-Dec-14
	Number of			Pre-				Post-
	Contracts			Modification				Modification
				Outstanding				Outstanding
				Recorded				Recorded
				Investment				Investment
Troubled debt restructuring:
Construction	4			$	233			$	233
Commercial real estate	3			2,309				2,309
Consumer real estate	3			736				736
Commercial and industrial	2			385				385
	12			$	3,663			$	3,663
	December 31, 2013
	Number of			Pre-Modification				Post-
	Contracts			Outstanding				Modification
				Recorded				Outstanding
				Investment				Recorded
								Investment
Troubled debt restructuring:
Construction	2			$	309			$	309
Commercial real estate	3			459				459
Consumer real estate	3			761				761
Commercial and industrial	1			337				337
	9			$	1,866			$	1,866
None of the performing TDRs defaulted subsequent to the restructuring through the date the financial statements were available to be issued.
As of December 31, 2014 and 2013, the Company was not committed to lend additional funds to any customer whose loan was classified as impaired or as a TDR.

Transfers_and_Servicing_of_Fin

Transfers and Servicing of Financial Assets	12 Months Ended
	Dec. 31, 2014
Transfers and Servicing of Financial Assets [Abstract]
Transfers and Servicing of Financial Assets	Transfers and Servicing of Financial Assets
	Loans serviced for others, consisting primarily of commercial loan participations sold, are not included in the accompanying consolidated balance sheets. The unpaid principal balances of loans serviced for others were $28.1 million and $28.0 million at December 31, 2014 and 2013, respectively.

Premises_and_Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment
	Premises and equipment consisted of the following at December 31 (in thousands):
		2014		2013
	Buildings and leasehold improvements	$	38,569	$	35,765
	Land	10,401		10,399
	Furniture, fixtures, and equipment	15,462		13,773
	Construction in progress	1,663		1,542
	Total premises and equipment	66,095		61,479
	Less accumulated depreciation and amortization	13,214		10,305
	Total premises and equipment, net	$	52,881	$	51,174
	The Company recorded depreciation of $3.0 million for the year ended December 31, 2014 and $2.7 million for each of the years ended December 31, 2013 and 2012.

Other_Real_Estate_Owned

Other Real Estate Owned	12 Months Ended
	Dec. 31, 2014
Real Estate [Abstract]
Other Real Estate Owned	Other Real Estate Owned
	At December 31, 2014 and 2013, the Company had other real estate owned of $5.5 million and $3.7 million, respectively, from real estate acquired by foreclosure.

Goodwill_and_Other_Acquired_In

Goodwill and Other Acquired Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Acquired Intangible Assets	Goodwill and Other Acquired Intangible Assets
	Changes to the carrying amount of goodwill for the years ended December 31, 2014 and 2013 are provided in the following table (in thousands):
	Balance at December 31, 2012	$	4,808
	Goodwill acquired during the year	—
	Balance at December 31, 2013	4,808
	Goodwill acquired during the year	—
	Balance at December 31, 2014	$	4,808
	The Company performs an annual impairment test of goodwill as of October 1, or more often if indicators or conditions are present which require an assessment. The results of this test did not indicate impairment of the Company’s recorded goodwill.
	Intangible assets subject to amortization
	Definite-lived intangible assets had the following carrying values as of December 31 (in thousands):
		2014						2013
		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	Core deposit intangibles	$	4,400	$	1,485	$	2,915	$	4,400	$	883	$	3,517
	Total definite-lived intangible assets	$	4,400	$	1,485	$	2,915	$	4,400	$	883	$	3,517
	The Company’s core deposit intangibles are being amortized over the estimated useful life of 12 years. The Company’s annual amortization expense totaled $0.6 million for the year ended December 31, 2014 and $0.2 million for each of the years ended December 31, 2013, and 2012, respectively.
	The estimated aggregate amortization expense for the core deposit intangible asset is as follows as of December 31, 2014 (in thousands):
	2015-2019	$	367
	2020 and thereafter	1,080

Investments_in_Real_Estate_Pro

Investments in Real Estate Properties	12 Months Ended
	Dec. 31, 2014
Real Estate [Abstract]
Investments in Real Estate Properties	Investments in Real Estate Properties
	FNBC CDC purchases various affordable residential real estate properties in the New Orleans area for the purpose of making improvements to these properties and renting or selling the properties. The Company’s cost basis (including the cost of improvements) in these residential real estate properties totaled $12.8 million and $10.1 million at December 31, 2014 and 2013, respectively. During the years ended December 31, 2014, 2013, and 2012, the Company capitalized costs of $2.6 million, $5.0 million, and $0.9 million, respectively.

Investments_in_Tax_Credit_Enti

Investments in Tax Credit Entities	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
Investments in Tax Credit Entities	Investments in Tax Credit Entities
	Federal NMTC
	Investment in Bank Owned CDE
	The Federal NMTC program is administered by the Community Development Financial Institutions Fund of the U.S. Treasury and is aimed at stimulating economic and community development and job creation in low-income communities. The program provides federal tax credits to investors who make qualified equity investments (QEIs) in a Community Development Entity. The CDE is required to invest the proceeds of each QEI in projects located in or benefiting low-income communities, which are generally defined as those census tracts with poverty rates greater than 20% and/or median family incomes that are less than or equal to 80% of the area median family income. FNBC CDE has received allocations of Federal NMTC, totaling $118.0 million over a three year period beginning in 2011. These allocations generated $46.0 million in tax credits. During June 2014, the Company was notified that FNBC CDE had not been awarded an allocation of Federal NMTC from its 2013 application.
	The credit provided to the investor totals 39% of each QEI in a CDE and is claimed over a seven-year credit allowance period. In each of the first three years, the investor receives a credit equal to 5% of the total amount invested in the project. For each of the remaining four years, the investor receives a credit equal to 6% of the total amount invested in the project. The Company is eligible to receive up to $46.0 million in tax credits over the seven-year credit allowance period, beginning with the period in which the QEI was made, for its QEI of $118.0 million. Through December 31, 2014, FNBC CDE has invested in allocations of $118.0 million, of which $40.0 million of the awards was invested by the Company and $78.0 million was invested by other investors and leverage lenders, which include the Company. Of the $78.0 million invested by other investors and leverage lenders, $17.5 million was invested by the Company as the leverage lender. The Company's investment is eliminated upon consolidation. The Federal NMTC claimed by the Company, with respect to each QEI, remain subject to recapture over each QEI’s credit allowance period upon the occurrence of any of the following:
	•	FNBC CDE does not invest substantially all (defined as a minimum of 85%) of the QEI proceeds in qualified low-income community investments;
	•	FNBC CDE ceases to be a CDE; or
	•	FNBC CDE redeems its QEI investment prior to the end of the current credit allowance period.
	At December 31, 2014 and December 31, 2013, none of the above recapture events had occurred, nor, in the opinion of management, are such events anticipated to occur in the foreseeable future. As of December 31, 2014, FNBC CDE had total assets of $129.8 million, consisting of cash of $4.8 million, loans of $112.3 million and other assets of $12.7 million, with liabilities of $0.4 million and capital of $129.4 million.
	Investments in Non-Bank Owned CDEs
	The Company is also a limited partner in several tax-advantaged limited partnerships and a shareholder in several C corporations whose purpose is to invest in approved Federal NMTC projects through CDEs that are not associated with FNBC CDE. During 2014 and 2013, several of these partnerships that the company was a limited partner in converted to a C corporation. The Company’s ownership in the CDEs did not change based on the conversion. These investments are accounted for using the cost method of accounting and are included in investment in tax credit entities in the accompanying consolidated balance sheets. The limited partnerships and C corporations are considered VIEs. The VIEs have not been consolidated because the Company is not considered the primary beneficiary. All of the Company’s investments in Federal NMTC structures are privately held, and their market values are not readily determinable. Based on the structure of these transactions, the Company expects to recover its investment solely through use of the tax credits that were generated by the investments. As such, the investment in these entities will be amortized on a straight-line basis over the period over which the Company holds its investment (approximately seven years).
	Low-Income Housing Tax Credits
	The Company is a limited partner in several tax-advantaged limited partnerships whose purpose is to invest in approved Low-Income Housing tax credit projects. These investments are accounted for using the cost method of accounting and are included in investments in tax credit entities in the accompanying consolidated balance sheets. The limited partnerships are considered to be VIEs. The VIEs have not been consolidated because the Company is not considered the primary beneficiary. All of the Company’s investments in low-income housing partnerships are evaluated for impairment at the end of each reporting period. Based on the structure of these transactions, the Company expects to recover its remaining investments at December 31, 2014 solely through use of the tax credits that were generated by the investments. As such, the investment in these partnerships will be amortized on a straight-line basis over the period for which the Company maintains its ownership interest in the property (approximately 15 years).
	Federal Historic Rehabilitation Tax Credits
	The Company is a limited partner in several tax-advantaged limited partnerships whose purpose is to invest in approved Federal Historic Rehabilitation tax credit projects. These investments are accounted for using the cost method of accounting and are included in investments in tax credit entities in the accompanying consolidated balance sheets. The limited partnerships are considered to be VIEs. The VIEs have not been consolidated because the Company is not considered the primary beneficiary. All of the Company’s investments in limited partnerships are evaluated for impairment at the end of each reporting period. Based on the structure of these transactions, the Company expects to recover its remaining investments in Federal Historic Rehabilitation Tax Credits at December 31, 2014 solely through use of the tax credits that were generated by the investments. As such, these amounts will be amortized on a straight-line basis over the period during which the Company retains its ownership interest in the tax credit entity (approximately 10 years).
	State NMTC
	Investments in Non-Bank Owned CDEs
	The Company is a limited partner in several tax-advantaged limited partnerships that are CDEs, whose purpose is to invest in approved state projects that are not associated with FNBC CDE. Based on the structure of these transactions, the Company expects to recover its remaining investments at December 31, 2014 in State NMTC through the transfer of its ownership interest to third party investors.
	The tables below set forth the Company's investment in Federal NMTC, State NMTC, Federal Low-Income Housing, Federal Historic Rehabilitation, and State Historic Rehabilitation tax credits, along with the credits expected to be generated through its participation in these programs as of December 31, 2014 and December 31, 2013 (in thousands):
			31-Dec-14
			Investment			Accumulated Amortization				Loans to Investment Funds(1)			Elimination			Net Investment		Tax Benefits Recognized Through December 31, 2013		Tax Benefits Recognized in 2014		Tax Benefits to be Recognized in 2015, and Thereafter		Total Tax Benefits Expected to be Recognized
	NMTC:
	Federal:
	Non-Bank Owned CDEs		$	162,192		$	(15,852	)		$	(120,540	)	$	—		$	25,800	$	27,213	$	9,367	$	25,945	$	62,525
	Bank Owned CDEs(2)		118,000			—				—			(118,000		)	—		10,375		6,115		29,530		46,020
	Bank Owned CDE Equity Investment(3)		5,700			—				—			—			5,700		—		—		—		—
	Total Bank Owned CDEs		123,700			—				—			(118,000		)	5,700		10,375		6,115		29,530		46,020
	State		28,227			—				—			—			28,227		—		—		—		—
	Total NMTC		314,119			(15,852		)		(120,540		)	(118,000		)	59,727		37,588		15,482		55,475		108,545
	Low-Income Housing		43,733			(7,264		)		—			—			36,469		9,546		3,642		42,109		55,297
	Historic Rehabilitation:
	Federal(4)		41,794			(3,412		)		—			—			38,382		17,823		19,321		37,295		74,439
	State		6,335			—				—			—			6,335		—		—		—		—
	Total Historic Rehabilitation		48,129			(3,412		)		—			—			44,717		17,823		19,321		37,295		74,439
	Total		$	405,981		$	(26,528	)		$	(120,540	)	$	(118,000	)	$	140,913	$	64,957	$	38,445	$	134,879	$	238,281
	(1) Interest only loan made to the investment fund during the compliance period for Federal NMTC.
	(2) Through December 31, 2014, FNBC CDE received allocations of Federal NMTC from the CDFI Fund of the U.S. Treasury totaling $118.0 million over a three year period beginning in 2011. These investments are eliminated upon consolidation by the Company.
	(3) The Company made an equity investment of $5.7 million in various Federal NMTC projects. This investment generated Federal NMTC. For its equity investment, the Company is a limited partner and will have the right to share in the activity of the Partnership.
	(4) As of December 31, 2014, the Company had $12.6 million invested in Federal Historic Rehabilitation Tax Credit projects which the Company expects to generate Federal Historic Rehabilitation Tax Credits in 2015 and 2016 when the projects are completed, receive the certificates of occupancy, and the property is placed in service. The amount of tax credits to be received will be determined when the costs are certified.
			31-Dec-13
			Investment			Accumulated Amortization				Loans to Investment Funds(1)			Elimination			Net Investment		Tax Benefits Recognized Through December 31, 2012		Tax Benefits Recognized in 2013		Tax Benefits to be Recognized in 2014, and Thereafter		Total Tax Benefits Expected to be Recognized
	NMTC:
	Federal:
	Non-Bank Owned CDEs		$	155,412		$	(9,328	)		$	(115,590	)	$	—		$	30,494	$	18,889	$	8,324	$	33,362	$	60,575
	Bank Owned CDEs(2)		118,000			—				—			(118,000		)	—		4,475		5,900		35,645		46,020
	Bank Owned CDE Equity Investment(3)		5,700			—				—			—			5,700		—		—		—		—
	Total Bank Owned CDEs		123,700			—				—			(118,000		)	5,700		4,475		5,900		35,645		46,020
	State		24,000			—				—			—			24,000		—		—		—		—
	Total NMTC		303,112			(9,328		)		(115,590		)	(118,000		)	60,194		23,364		14,224		69,007		106,595
	Low-Income Housing		45,072			(5,078		)		—			—			39,994		5,846		3,700		47,438		56,984
	Historic Rehabilitation:
	Federal		13,870			(1,586		)		—			—			12,284		7,326		10,497		—		17,823
	State		5,212			—				—			—			5,212		—		—		—		—
	Total Historic Rehabilitation		19,082			(1,586		)		—			—			17,496		7,326		10,497		—		17,823
	Total		$	367,266		$	(15,992	)		$	(115,590	)	$	(118,000	)	$	117,684	$	36,536	$	28,421	$	116,445	$	181,402
	(1) Interest only loan made to the investment fund during the compliance period for Federal NMTC.
	(2) Through December 31, 2013, FNBC CDE received allocations of Federal NMTC from the CDFI Fund of the U.S. Treasury totaling $118.0 million over a three year period beginning in 2011. These investments are eliminated upon consolidation by the Company.
	(3) The Company made an equity investment of $5.7 million in various Federal NMTC projects. This investment generated Federal NMTC. For its equity investment, the Company is a limited partner and will have the right to share in the activity of the Partnership.
	The amortization of tax credit investments for the years ended December 31, 2014, 2013, and 2012 were as follows (in thousands):
		For the Years Ended
		December 31,
		2014			2013				2012
	Federal NMTC	$	10,048		$	5,923			$	3,094
	Low-Income Housing	2,186			1,900				1,287
Federal Historic Rehabilitation	1,825			816				427
Total amortization	$	14,059		$	8,639			$	4,808
The amount of basis reduction recorded related to the Company's investment in tax credit entities for the years ended December 31, 2014, 2013, and 2012 were as follows (in thousands):
	For the Years Ended
	December 31,
	2014			2013				2012
Federal NMTC	$	1,401		$	2,019			$	2,416
Federal Historic Rehabilitation	246			—				350
Total basis reduction	$	1,647		$	2,019			$	2,766
The Company also made loans to the tax credit related projects. The proceeds from these loans can be utilized for the generation and use of tax credits on the related real estate project or as funding for the tax credit real estate project itself. These loans are subject to the Company's normal underwriting criteria and all loans were performing according to their contractual terms at December 31, 2014. These loans were classified in the Company's loan portfolio at December 31, 2014 and December 31, 2013 as follows (in thousands):
	December 31, 2014			December 31, 2013
Construction	$	80,741		$	10,686
Commercial real estate	67,520			49,017
Commercial and industrial	117,191			105,944
Total loans	$	265,452		$	165,647

Variable_Interest_Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities
	During 2013, the Company entered into a loan workout arrangement with a borrower. The result of this workout arrangement is considered to be a VIE, whereby the Company is considered the primary beneficiary and must consolidate the VIE. The initial recognition of this VIE relationship was accounted for using acquisition accounting. Under acquisition accounting, the assets and liabilities acquired are accounted for at market and intercompany balances are eliminated. The asset acquired from the debtor, which consisted of a net operating loss, is included in the accompanying consolidated balance sheets.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Deposits	Deposits
	Interest-bearing deposits at December 31, 2014 and 2013 consisted of the following (in thousands):
		2014		2013
	Savings deposits	$	49,634	$	53,779
	Money market accounts	1,055,505		655,173
	Negotiable order of withdrawal (NOW) accounts	476,825		511,620
	Certificates of deposit over $250,000	284,262		280,354
	Certificates of deposit under $250,000	890,090		938,801
	Total Deposits	$	2,756,316	$	2,439,727
	The certificates of deposit mature as follows as of December 31, 2014 (in thousands):
	2015	$	632,111
	2016	257,606
	2017	127,775
	2018	110,874
	2019	45,986
	Total certificates of deposit	$	1,174,352

ShortTerm_Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Short-Term Borrowings	Short-Term Borrowings
	The following is a summary of short-term borrowings at December 31 (in thousands):
		2014		2013
	FNBB	$	—	$	8,425
	Total short-term borrowings	$	—	$	8,425
	There were no short-term borrowings as of December 31, 2014. The short-term borrowings at December 31, 2013 consisted of federal funds purchased with a maturity of 1 day and an interest rate of 0.95%. These borrowings were repaid in January 2014.
	The following is a summary of unused lines of credit at December 31 (in thousands):
		2014		2013
	FNBB	$	30,000	$	30,000
	JPMorgan Chase	30,000		30,000
	FHLB	563,213		432,181
	PNC Bank	15,000		15,000
	Comerica	10,000		10,000
	Total unused lines of credit	$	648,213	$	517,181
	The FHLB line of credit at December 31, 2014 was subject to a blanket pledge of $847.0 million of real estate loans. The FHLB line of credit at December 31, 2013 was subject to a blanket pledge of $655.1 million of real estate loans and a custody pledge of $29.4 million of real estate loans.

LongTerm_Borrowings

Long-Term Borrowings	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Borrowings	Long-Term Borrowings
	The following is a summary of long-term borrowings at December 31 (in thousands):
		2014		2013
	FNBB	$	—	$	110
	Credit Suisse Securities (USA) LLC	40,000		55,000
	Total long-term borrowings	$	40,000	$	55,110
	Long-term borrowings as of December 31, 2014 consisted of a borrowing by the Company from Credit Suisse which is in the legal form of a long-term repurchase agreement. During 2014, the $40.0 million borrowing was refinanced and its maturity extended. The $40.0 million borrowing matures on April 1, 2019, and bears interest at a floating rate equal to three-month USD LIBOR plus 1.35%, and was 1.59% at December 31, 2014. The borrowing at December 31, 2013 bears interest at a floating rate equal to 2.83% minus the greater of three-month USD LIBOR less 2.00% or 0%. The interest rate was 2.83% at December 31, 2013. This borrowing is subject to a pledge of mortgage-backed securities with a market value of $61.1 million and $65.9 million at December 31, 2014 and 2013, respectively. During 2014, the $15.0 million borrowing from Credit Suisse matured.
	During 2014, the long-term borrowings from FNBB were paid.
	Principal payments by year on these borrowings are as follows (in thousands):
	2019	$	40,000
	Total long-term borrowings	$	40,000

Repurchase_Agreements

Repurchase Agreements	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Repurchase Agreements	Repurchase Agreements
	Securities sold under agreements to repurchase, which are classified as secured borrowings, generally mature one day after the transaction date. Securities sold under agreements to repurchase are reflected at the amount of cash received in connection with the transaction. The Company may be required to provide additional collateral based on the fair value of the underlying securities. The carrying value of the securities pledged as collateral for the repurchase agreements was $132.7 million and $92.7 million at December 31, 2014 and 2013, respectively.

Derivative_Interest_Rate_Swap_

Derivative - Interest Rate Swap Agreements	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative - Interest Rate Swap Agreements	Derivative - Interest Rate Swap Agreements
	Interest Rate Swaps. During 2014, the Company entered into three delayed interest rate swaps with Counterparty C to manage exposure to future interest rate risk, given the changes in forecasted interest rates, through modification of the Company’s net interest sensitivity to levels deemed to be appropriate. The Company entered into this interest rate swap agreement to convert a portion of its forecasted variable-rate debt to a fixed rate, which is a cash flow hedge of a forecasted transaction. The notional amounts of each of the three derivative contracts are $55.0 million for a total notional amount of $165.0 million. The Company will receive payments from the counterparty at three-month LIBOR and make payments to the counterparty at fixed rates of 2.652%, 2.753%, and 2.793%, respectively, on the $55.0 million notional amounts of each derivative contract. The cash flow payments on the derivatives begin January 2018 and terminate October 2023 for the 2.652% interest rate swap, begin January 2019 and terminate October 2024 for the 2.753% interest rate swap, and begin July 2019 and terminate April 2025 for the 2.793% interest rate swap.
	The Company entered into an interest rate swap agreement in 2012 with Counterparty A to convert a portion of its forecasted variable-rate debt to a fixed rate, which was a cash flow hedge of a forecasted transaction. The total notional amount of the derivative contract was $115.0 million. The Company was to receive payments from the counterparty at three-month LIBOR and make payments to the counterparty at a fixed rate on 2.88% on the notional amount.
	In December 2014, the company terminated the cash flow hedge with Counterparty A as internal forecasts for future interest rates changed since this transaction was initiated. The termination of the cash flow hedge resulted in a loss of $8.0 million which has been reflected in the Company’s operating cash flows and included within accumulated other comprehensive income (loss), net of tax. This loss has not been included in net income as of December 31, 2014 as the Company entered into a new delayed interest rate swap with substantially similar terms (see transaction above with Counterparty C) at the time of termination. The loss will be reclassified from accumulated other comprehensive income (loss) to net income as interest expense as it is amortized over a multi-year period consistent with the original maturity dates of the hedge which began in January 2015 and terminate in January 2022.
	The Company entered into a delayed interest rate swap with Counterparty B in 2013, to manage exposure against the variability in the expected future cash flows attributed to changes in the benchmark interest rate on a portion of its variable-rate debt. The Company entered into this interest rate swap agreement to convert a portion of its variable-rate debt to a fixed rate, which is a cash flow hedge of a forecasted transaction. The total notional amount of the derivative contract is $150.0 million. The Company will receive payments from the counterparty at three-month LIBOR and make payments to the counterparty at a fixed rate of 4.165% on the notional amount. The cash flow payments on the derivative begin December 2016 and terminate September 2023.
	Interest Rate-Prime Swaps. During 2013, the Company entered into four interest rate swaps with Counterparty B to manage exposure against the variability in the expected future cash flows on the designated Prime, Prime plus 1%, Prime plus 1% floored at 5% and Prime plus 1% floored at 5.5% pools of its floating rate loan portfolio (the Prime Hedges). The Company entered into the interest rate swap agreements to hedge the cash flows from these pools of its floating rate loan portfolio, which is expected to offset the variability in the expected future cash flows attributable to the fluctuations in the daily weighted average Wall Street Journal Prime index, which is a cash flow hedge of a forecasted transaction. The notional amount of the contracts are Prime tranche of $30.0 million, Prime plus 1% tranche of $40.0 million, Prime plus 1% floored at 5% tranche of $100.0 million, and Prime plus 1% floored at 5.5% tranche of $80.0 million for a total notional amount of $250.0 million. The Company will receive payments from the counterparty at a fixed rate of interest and pay the counterparty at the Prime rate associated with each tranche on its notional amount. The Prime tranche will receive payments at a fixed rate of 4.70% and pay the counterparty at Prime on the notional amount. The Prime plus 1% tranche will receive payments at a fixed rate of 5.70% and pay the counterparty at Prime plus 1% on the notional amount. The Prime plus 1% floored at 5% tranche will receive payments at a fixed rate of 6.01% and pay the counterparty at Prime plus 1%, floored at 5% on the notional amount. The Prime plus 1% floored at 5.5% tranche will receive payments at a fixed rate of 6.26% and pay the counterparty at Prime plus 1% floored at 5.5% on the notional amount. The cash flow payments on the derivatives began September 2013 and terminate September 2019.
	Information pertaining to outstanding derivative instruments is as follows (in thousands):
				Derivative Assets Fair Value									Derivative Liabilities Fair Value
		Balance Sheet Location		December 31, 2014				December 31, 2013				Balance Sheet Location	December 31, 2014		December 31, 2013
	Derivatives designated as hedging instruments under ASC Topic 815:
	Interest rate swaps - Counterparty A(1)	Other Assets		$	—			$	1,157			Other Liabilities	$	—	$	—
	Interest rate swaps - Counterparty B	Other Assets		—				—				Other Liabilities	15,995		2,046
	Interest rate-prime swaps - Counterparty B	Other Assets		3,042				—				Other Liabilities	—		2,271
	Interest rate swaps - Counterparty C	Other Assets		37				—				Other Liabilities	—		—
				$	3,079			$	1,157				$	15,995	$	4,317
	-1	Hedge was terminated during 2014.
	The Company entered into a master netting arrangement with Counterparty B whereby the delayed interest rate swap and Prime Hedges would be settled net. Net fair values of the Counterparty B delayed interest rate swap and Prime Hedges as of December 31, 2014 and 2013 are as follows (in thousands):
		31-Dec-14
		Gross Amounts Presented in the Balance Sheet				Gross Amounts Not Offset in the Balance Sheet
						Derivatives				Collateral			Net
	Derivatives subject to master netting arrangements:
	Derivative assets:
	Interest rate swaps	$	—			$	—			$	—		$	—
	Interest rate-prime swaps	3,042				—				—			3,042
		$	3,042			$	—			$	—		$	3,042
	Derivative liabilities:
	Interest rate swaps	$	15,995			$	—			$	—		$	15,995
	Interest rate-prime swaps	—				—				—			—
		$	15,995			—				—			$	15,995
	Net derivative liability	$	12,953			$	—			$	—		$	12,953
		31-Dec-13
		Gross Amounts Presented in the Balance Sheet				Gross Amounts Not Offset in the Balance Sheet
						Derivatives				Collateral			Net
	Derivatives subject to master netting arrangements:
	Derivative assets:
	Interest rate swaps	$	—			$	—			$	—		$	—
	Interest rate-prime swaps	—				—				—			—
		$	—			$	—			$	—		$	—
	Derivative liabilities:
	Interest rate swaps	$	2,046			$	—			$	—		$	2,046
	Interest rate-prime swaps	2,271				—				—			2,271
		$	4,317			—				—			$	4,317
	Net derivative liability	$	4,317			$	—			$	—		$	4,317
	Pursuant to the interest rate swap agreements described above with Counterparty B, the Company pledged collateral in the form of investment securities totaling $13.8 million (with a fair value at December 31, 2014 of $14.2 million), which has been presented gross in the Company’s balance sheet. There was no collateral posted from the counterparties to the Company as of December 31, 2014 and 2013.
	Because the swap agreement used to manage interest rate risk has been designated as hedging exposure to variable cash flows of a forecasted transaction, the effective portion of the derivative’s gain or loss is initially reported as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affects earnings or when the hedge is terminated. The ineffective portion of the gain or loss is reported in earnings immediately.
	In applying hedge accounting for derivatives, the Company establishes a method for assessing the effectiveness of the hedging derivative by utilizing the dollar offset approach and a measurement approach for determining the ineffective aspect of the hedge through the variable cash flows methods upon the inception of the hedge. These methods are consistent with Company’s approach to managing risk.
	For interest rate swap agreements that are not designated as hedging instruments, changes in the fair value of the derivatives are recognized in earnings immediately.
	For the years ended December 31, 2014 and 2013, the Company did not reclassify into earnings any gain or loss as a result of the discontinuance of cash flow hedges because it was probable the original forecasted transaction would not occur by the end of the originally specified term. The Company anticipates to reclassify $1.1 million from accumulated other comprehensive income (loss) into interest expense over the next 12 months related to the amortization of the loss incurred on the cash flow hedge terminated in December 2014. The total $8.0 million loss will be reclassified from accumulated other comprehensive income (loss) into interest expense as it is amortized by the effective yield method over a multi-year period consistent with the original maturity dates of the hedge which began in January 2015 and will terminate in January 2022.
	As of December 31, 2014 and 2013, no amounts of gains or losses were reclassified from accumulated comprehensive income (loss), nor have any amounts of gains or losses been recognized due to ineffectiveness of a portion of the derivatives. At December 31, 2014, no amount of the derivatives will mature within the next 12 months. The Company does not expect to reclassify any amount from accumulated other comprehensive income (loss) into interest income over the next 12 months for derivatives that will be settled.
	At December 31, 2014 and 2013, and for the years then ended, information pertaining to the effect of the hedging instruments on the consolidated financial statements is as follows (in thousands):
		Amount of Gain (Loss) Recognized in OCI, net of taxes (Effective Portion)
		As of December 31,
	Derivatives in ASC Topic 815 Cash Flow Hedging Relationships:	2014				2013
	Interest rate swap with Counterparty A(1)	$	(5,946	)		$	5,207
	Interest rate swap and prime swaps with Counterparty B	(5,614		)		(2,806		)
	Interest rate swap with Counterparty C	24				—
	Total	$	(11,536	)		$	2,401
	-1	Hedge was terminated during 2014.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The income tax benefit on the income from operations for the years ended December 31, 2014, 2013, and 2012 was as follows (in thousands):
		2014			2013			2012
	Current tax expense	$	3,436		$	186		$	—
	Deferred tax benefit	(30,412		)	(19,937		)	(7,565		)
	Total tax benefit	$	(26,976	)	$	(19,751	)	$	(7,565	)
	The amount of taxes in the accompanying consolidated statements of income differs from the expected amount using the statutory federal income tax rates primarily due to the effect of various tax credits. An analysis of those differences for the years ended December 31, 2014, 2013, and 2012 are presented below (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Federal tax expense at statutory rates	$	10,015		$	7,406		$	7,481
	Tax credits(1)	(38,445		)	(28,421		)	(17,100		)
	Tax credit-basis reduction	1,647			2,019			2,767
	Other tax credits	(617		)	—			—
	Tax-exempt income	(87		)	(1,070		)	(918		)
	Disallowed interest expense	98			117			99
	Other	413			198			106
	Income tax benefit	$	(26,976	)	$	(19,751	)	$	(7,565	)
	-1	As discussed in Note 12, the Company earns Federal NMTC, Federal Historic Rehabilitation, and Low-Income Housing tax credits, which reduce the Company’s federal income tax liability or creates a carryforward as applicable.
	The components of the Company’s deferred tax assets and liabilities as of December 31 are presented below (in thousands):
		Year Ended December 31,
		2014			2013
	Deferred tax assets:
	Loan loss reserve	$	14,817		$	11,250
	Tax credit carryforwards	94,490			65,216
	NOL carryforward	7,271			7,317
	Stock-based compensation	824			684
	Deferred compensation	91			91
	Securities available for sale	10,615			8,880
	Other real estate	263			250
	Basis difference in assumed liabilities	140			338
	Other	621			373
	Total deferred tax assets	129,132			94,399
	Deferred tax liabilities:
	Fixed assets	7,190			6,546
	Deferred loan costs	6,296			5,157
	Amortizable costs	1,388			1,477
	State tax credits	1,614			1,155
	Investments in tax credit entities	28,625			28,097
	Other	558			776
	Total deferred tax liabilities	45,671			43,208
	Net deferred tax assets	$	83,461		$	51,191
	In the opinion of management, no valuation allowance was required for the net deferred tax assets at December 31, 2014 as the amounts will more likely than not be realized as reductions of future taxable income.
	As of December 31, 2014, the Company’s net operating loss (NOL) carryforwards were $20.8 million with an expiration date of December 2035.
	As of December 31, 2014, the Company’s tax credit carryforwards were $94.5 million with expiration dates beginning December 2030 through December 2034.
	The Company recognized $15.5 million, $14.2 million, and $11.4 million in Federal NMTC in its consolidated income tax provision for the years ended December 31, 2014, 2013, and 2012, respectively. The Company recognized $3.6 million, $3.7 million, and $2.5 million in Low-Income Housing Tax Credits in its consolidated income tax provision for the years ended December 31, 2014, 2013, and 2012, respectively. The Company recognized $19.3 million, $10.5 million, and $3.2 million in Federal Historic Rehabilitation Tax Credits in its consolidated income tax provision for the years ended December 31, 2014, 2013, and 2012, respectively.

Shareholders_Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity
	Senior Preferred Stock
	The Company sold approximately $20.6 million of convertible perpetual preferred stock Series C in 2011. There were no shares of the Company's convertible perpetual preferred stock Series C shares that were converted during 2014. During 2013, the holder of the convertible perpetual preferred stock Series C converted 551,858 shares into shares of the Company’s $1 par common stock. The assumed conversion of the convertible perpetual preferred stock Series C shares outstanding is excluded in the calculation of the Company's diluted earnings per share due to the fact that the shares are contingently issuable and the contingency still existed as of December 31, 2014 and 2013.
	At December 31, 2014, the Series C preferred stock had an aggregate liquidation preference of approximately $4.5 million and qualified as Tier 1 regulatory capital. Each share of Series C preferred stock is convertible at the option of the holder, except in certain circumstances when regulatory approval is necessary, into one share of common stock. The Series C preferred stock ranks pari passu with the common stock with respect to the payment of dividends. The contingency on the Series C preferred stock was in effect at December 31, 2014 and 2013.
	The Company sold approximately $37.9 million of senior noncumulative perpetual preferred stock, Series D in 2011 to the Treasury, pursuant to the Small Business Lending Fund program. At December 31, 2014, the Series D preferred stock had an aggregate liquidation preference of approximately $37.9 million and qualified as Tier 1 regulatory capital.
	The terms of the Series D preferred stock provide for payment of noncumulative dividends on a quarterly basis beginning October 3, 2011. The dividend rate, as a percentage of the liquidation amount, fluctuates, while the Series D preferred stock is outstanding based upon changes in the level of qualified small business lending (QSBL) by the Company from its average level of QSBL at each of the four quarter-ends leading up to June 30, 2010 (Baseline), as follows:
		Dividend Period
		Beginning	Ending	Annualized Dividend Rate
		January 1, 2012	March 31, 2012	1.00%
		April 1, 2012	June 30, 2012	1.00%
		July 1, 2012	31-Dec-13	1.000% to 5.000%
		January 1, 2014	February 3, 2016	1.000% to 7.000%
		February 4, 2016	Redemption	9.00%
	As long as shares of Series D preferred stock remain outstanding, the Company may not pay dividends to common shareholders (nor may the Company repurchase or redeem any shares of common stock) during any quarter in which the Company fails to declare and pay dividends on the Series D preferred stock and for the next three quarters following such failure. In addition, under the terms of the Series D preferred stock, the Company may only declare and pay dividends on common stock (or repurchase shares of common stock) if, after payment of such dividend, the dollar amount of Tier 1 capital would be at least 90% of Tier 1 capital as of August 4, 2011, excluding charge-offs and redemptions of the Series D preferred stock (Tier 1 dividend threshold). Beginning January 1, 2014, the Tier 1 dividend threshold is subject to a reduction based upon the extent by which, if at all, the QSBL at September 30, 2013, has increased over the Baseline. The Company was notified in 2013 that its dividend rate would be 1% from January 1, 2014 until February 3, 2016 because the Company satisfied the lending baseline at September 30, 2013.
	The Company may redeem the Series D preferred stock at any time at the Company’s option, at a redemption price of 100% of the liquidation amount plus accrued but unpaid dividends, subject to the approval of the Company’s primary federal regulatory agency.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income
	The components of accumulated other comprehensive income (loss) and changes in those components are presented in the following table (in thousands):
		Cash Flow			Terminated Cash Flow Hedge (2)			Transfers of			Available for			Total
		Hedges (1)						Available for			Sale
								Sale			Securities
								Securities to
								Held to
								Maturity
	Balance at January 1, 2014	$	(2,054	)	$	—		$	(3,710	)	$	(10,751	)	$	(16,515	)
	Other comprehensive income before income taxes:
	Net change in unrealized gain (loss)	(9,757		)	(7,990		)	—			12,379			(5,368		)
	Reclassification of net gains realized and included in earnings	—			—			—			(135		)	(135		)
	Amortization of unrealized net gain	—			—			547			—			547
	Income tax expense (benefit)	(3,415		)	(2,796		)	191			4,286			(1,734		)
	Balance at December 31, 2014	$	(8,396	)	$	(5,194	)	$	(3,354	)	$	(2,793	)	$	(19,737	)
		Cash Flow			Terminated Cash Flow Hedge (2)			Transfers of			Available for			Total
		Hedges (1)						Available for			Sale
								Sale			Securities
								Securities to
								Held to
								Maturity
	Balance at January 1, 2013	$	(4,455	)	$	—		$	—		$	1,529		$	(2,926	)
	Other comprehensive income before income taxes:
	Net change in unrealized gain (loss)	3,694			—			(5,919		)	(18,576		)	(20,801		)
	Reclassification of net gains realized and included in earnings	—			—			—			(316		)	(316		)
	Amortization of unrealized net gain	—			—			211			—			211
	Income tax expense (benefit)	1,293			—			(1,998		)	(6,612		)	(7,317		)
	Balance at December 31, 2013	$	(2,054	)	$	—		$	(3,710	)	$	(10,751	)	$	(16,515	)
	Balance at January 1, 2012	$	—		$	—		$	—		$	1,795		$	1,795
	Other comprehensive income before income taxes:
	Net change in unrealized gain (loss)	(6,854		)	—			—			3,956			(2,898		)
	Reclassification of net gains realized and included in earnings	—			—			—			(4,324		)	(4,324		)
	Income tax benefit	(2,399		)	—			—			(102		)	(2,501		)
	Balance at December 31, 2012	$	(4,455	)	$	—		$	—		$	1,529		$	(2,926	)
	(1) Balances in the Cash Flow Hedge column represent the net operating changes in all of the Company's cash flow hedge relationships as of the dates above.
	(2) Balances in the Terminated Cash Flow Hedge column represent the net unrealized loss at termination of a certain cash flow hedge relationship. See Note 18 for further explanation on the terminated cash flow hedge.

Capital_Requirements_and_Other

Capital Requirements and Other Regulatory Matters	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Capital Requirements and Other Regulatory Matters	Capital Requirements and Other Regulatory Matters
	Regulatory Capital Requirements
	The Company and the Bank are subject to various regulatory capital requirements administered by the federal and state banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the consolidated financial statements of the Company and the Bank. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and the Bank must meet specific capital guidelines that involve quantitative measures of their assets, liabilities and certain off-balance sheet items. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Prompt corrective action provisions are not applicable to bank holding companies.
	Quantitative measures established by regulation to ensure capital adequacy require the Company and the Bank to maintain minimum amounts and ratios of total and Tier 1 capital to risk-weighted assets and ratios of Tier 1 capital to average assets. Management believes, as of December 31, 2014 and 2013, that the Company and the Bank met all capital adequacy requirements to which they are subject.
	As of December 31, 2014, the Bank was in compliance with all regulatory requirements and the Bank was classified as “well capitalized” for purposes of the Federal Deposit Insurance Corporation's prompt corrective action requirements. To be categorized as well capitalized, an institution must maintain minimum total risk-based, Tier 1 risk-based and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since the notification that management believes have changed that categorization.
	The following tables present the actual capital amounts and regulatory capital ratios for the Company and the Bank as of December 31, 2014 and 2013 (in thousands):
		31-Dec-14
		Actual				For Capital Adequacy				To Be Well Capitalized
						Purposes				Under Prompt Corrective
										Action Provisions
		Amount		Ratio		Amount		Ratio		Amount		Ratio
	Tier 1 leverage capital:
	First NBC Bank Holding Company	$	387,224	10.66	%	$	145,320	4	%	NA		NA
	First NBC Bank	361,078		9.95	%	145,130		4	%	$	181,412	5	%
	Tier 1 risk-based capital:
	First NBC Bank Holding Company	$	387,224	11.59	%	133,644		4	%	NA		NA
	First NBC Bank	361,078		10.82	%	133,528		4	%	$	200,292	6	%
	Total risk-based capital:
	First NBC Bank Holding Company	$	428,962	12.84	%	267,289		8	%	NA		NA
	First NBC Bank	402,816		12.07	%	267,056		8	%	$	333,820	10	%
		31-Dec-13
		Actual				For Capital Adequacy				To Be Well Capitalized
						Purposes				Under Prompt Corrective
										Action Provisions
		Amount		Ratio		Amount		Ratio		Amount		Ratio
	Tier 1 leverage capital:
	First NBC Bank Holding Company	$	375,355	11.76	%	$	127,625	4	%	NA		NA
	First NBC Bank	349,104		10.96	%	127,435		4	%	$	159,294	5	%
	Tier 1 risk-based capital:
	First NBC Bank Holding Company	$	375,355	13.26	%	113,254		4	%	NA		NA
	First NBC Bank	349,104		12.34	%	113,170		4	%	$	169,755	6	%
	Total risk-based capital:
	First NBC Bank Holding Company	$	407,648	14.4	%	226,508		8	%	NA		NA
	First NBC Bank	381,396		13.48	%	226,340		8	%	$	282,924	10	%

Warrants

Warrants	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Warrants	Warrants
	In connection with the financing of the start-up activities of the Company, the organizing shareholders of the Company received warrants for 162,500 shares of common stock with an exercise price of $10 per share. The warrants are exercisable immediately and have an expiration date of 10 years. No charge was made to income in connection with the warrants. During 2014, there were no shares of the organizing shareholders of the Company’s warrants exercised. As of December 31, 2014, a total of 125,000 organizer warrants remained outstanding. In connection with the acquisition of Dryades Bancorp, Inc. in 2010, the Company issued 87,509 warrants at $19.50 per share, there were no shares of these warrants exercised during 2014, and 77,426 remained outstanding as of December 31, 2014.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation
	The Company has various types of stock-based compensation plans. These plans are administered by the Compensation and Human Resources Committee of the Board of Directors, which selects persons eligible to receive awards and approves the number of shares and/or options subject to each award, the terms, conditions, and other provisions of the awards.
	Restricted Stock
	The Company issues restricted stock under the 2006 Plan and 2014 Plan for certain officers and directors. The Company approved the 2014 Plan during May 2014. There were no restricted stock awards issued under the 2014 Plan during the year. These plans authorized the issuance of restricted stock. The plans allow for the issuance of restricted stock awards that may not be sold or otherwise transferred until certain restrictions have lapsed. The unearned compensation related to these awards is amortized over the vesting period of 3 years. The total share-based compensation expense related to the awards is determined based on the market price of the Company's common stock as of the grant date applied to the total number of shares granted and is amortized over the vesting period. There were no shares of restricted stock vested as of December 31, 2014. There was $0.3 million unearned share-based compensation associated with these awards as of December 31, 2014. There were no restricted shares issued during 2013.
	The following table represents unvested restricted stock activity for the year ended December 31, 2014:
			Number			Weighted-Average Grant Date Fair Value
			of Shares
	Balance, beginning of year		—			$	—
	Granted		13,021			34.32
	Forfeited		(129	)		34.35
	Balance, end of year		12,892			$	34.32
	There was $0.1 million in compensation expense that was included in salaries and benefits expense in the accompanying consolidated statements of income for the year ended December 31, 2014. There was no compensation expense included in salaries and benefits in the accompanying consolidated statements of income for the years ended December 31, 2013 and 2012.
	Stock Options
	The Company issues stock options to directors, officers, and other key employees. The option exercise price cannot be less than the fair value of the underlying common stock as of the date of the option grant and the maximum option term cannot exceed 10 years. The stock options granted were issued with vesting periods ranging from 3 to 4 years. At December 31, 2014, there were 1.1 million shares available for future issuance of option or restricted stock awards under approved compensation plans.
	For the years ended December 31, 2014, 2013 and 2012, total stock option compensation expense that is included in salaries and employee benefits expense was $0.6 million, $0.7 million, and $0.5 million, respectively. The related income tax benefit in the accompanying consolidated statements of income was $0.1 million for the year ended December 31, 2014 and $0.2 million for the years ended December 31, 2013 and 2012.
	The Company uses the Black-Scholes option pricing model to estimate the fair value of the stock options awards. The following weighted-average assumptions were used for option awards granted during the years ended December 31 of the periods indicated:
			2014				2013				2012
	Expected dividend yield		—	%			—	%			—	%
	Weighted-average expected volatility		44.53	%			36.68	%			35.33	%
	Weighted-average risk-free interest rate		2.21	%			1.73	%			1.25	%
	Expected option term (in years)		6				6				6.3
	Contractual term (in years)		10				10				10
	Weighted-average grant date fair value	$	15.56			$	5.22			$	5.49
	The assumptions above were based on multiple factors, primarily the historical stock option patterns of a group of publicly traded peer banks based in the southeastern United States.
	At December 31, 2014, there was $1.4 million in unrecognized compensation cost related to stock options which is expected to be recognized over a weighted-average period of 1.7 years.
	The following table represents the activity related to stock options during the periods indicated:
		Number			Weighted-				Weighted-
		of Shares			Average				Average
					Exercise				Remaining
					Price				Contractual
									Term (Years)
	Options outstanding, December 31, 2011	443,658			$	11.11
	Granted	378,692			14.69
	Exercised	—			—
	Forfeited or expired	(13,333	)		14.43
	Options outstanding, December 31, 2012	809,017			11.81
	Granted	139,650			16.16
	Exercised	(76,966	)		10.39
	Forfeited or expired	(16,600	)		15.16
	Options outstanding, December 31, 2013	855,101			13.48
	Granted	38,013			34.32
	Exercised	(57,370	)		12.26
	Forfeited or expired	(1,074	)		22.13
	Options outstanding, December 31, 2014	834,670			$	14.5			6.41
	Options exercisable, December 31, 2012	289,444			$	10.6
	Options exercisable, December 31, 2013	374,535			$	11.94
	Options exercisable, December 31, 2014	522,600			$	12.7			5.57
	The following table presents weighted-average remaining life as of December 31, 2014 for options outstanding within the stated exercise prices:
		Options Outstanding									Options Exercisable
	Exercise Price Range	Number			Weighted-				Weighted-		Number		Weighted-
	Per Share	of Shares			Average				Average		of Shares		Average
					Exercise				Remaining				Exercise
					Price				Life				Price
									(Years)
	$10.00-$12.70	323,294			$	11.33			4.39		323,294		$	11.33
	$14.20-$14.88	342,108			14.68				7.33		157,233		14.59
	$15.88-$23.68	169,268			20.21				8.4		42,073		16.19
	Total Options	834,670			$	14.5			6.41		522,600		$	12.7
	At December 31, 2014, the aggregate intrinsic value of shares underlying outstanding stock options and underlying exercisable stock options was $17.0 million and $11.8 million, respectively. Total intrinsic value of options exercised was $1.2 million for the years ended December 31, 2014 and 2013. There were no options exercised during the year ended December 31, 2012.

Financial_Instruments_With_Off

Financial Instruments With Off-Balance-Sheet Risk	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
Financial Instruments With Off-Balance-Sheet Risk	Financial Instruments With Off-Balance-Sheet Risk
	The Company is a party to various financial instruments with off-balance-sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit, which are recorded when they are funded. Such commitments involve, to varying degrees, elements of credit risk in excess of the amounts recognized in the accompanying consolidated financial statements.
	At December 31, 2014 and 2013, the Company had made various commitments to extend credit of $620.3 million and $375.2 million, respectively. The Company’s management does not anticipate any material loss as a result of these transactions.
	Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being fully drawn upon, the total commitment amounts disclosed above do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if considered necessary upon extension of credit, is based on management’s credit evaluation of the counterparty.
	Standby letters of credit represent commitments by the Company to meet the obligations of certain customers, if called upon. These financial instruments are considered guarantees in accordance with ASC 460. Outstanding standby letters of credit as of December 31, 2014 were $110.6 million and expire between 2015 and 2040. Outstanding standby letters of credit as of December 31, 2013, were $106.5 million and expire between 2014 and 2040. Net unamortized fees related to letters of credit origination were $0.3 million and $0.2 million in 2014 and 2013, respectively. Net unamortized costs related to letters of credit origination were $0.2 million and $0.3 million in 2014 and 2013, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	The Company leases certain branch offices through noncancelable operating leases with terms that range from one to 30 years, with renewal options thereafter. Certain leases have escalation clauses and renewal options ranging from one to 59 years. Rent expense was approximately $3.2 million, $3.3 million, and $3.2 million for the years ended December 31, 2014, 2013, and 2012, respectively.
	At December 31, 2014, the minimum annual rental payments to be made under the noncancelable leases are as follows (in thousands):
	Year ending December 31:
	2015	$	3,387
	2016	3,349
	2017	3,356
	2018	3,035
	2019	2,862
	Thereafter	31,976
		$	47,965
	Off-Balance-Sheet Arrangements
	The Company is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These transactions include commitments to extend credit in the ordinary course of business to approved customers. Generally, loan commitments have been granted on a temporary basis for working capital or commercial real estate financing requirements or may be reflective of loans in various stages of funding. These commitments are recorded on the Company’s financial statements as they are funded. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Loan commitments include unused commitments for open-end lines secured by one to four family residential properties and commercial properties, commitments to fund loans secured by commercial real estate, construction loans, business lines of credit, and other unused commitments. Standby letters of credit are written conditional commitments issued by the Company to guarantee the performance of a customer to a third party. In the event the customer does not perform in accordance with the terms of the agreement with the third party, the Company would be required to fund the commitment. The maximum potential amount of future payments the Company could be required to make is represented by the contractual amount of the commitment. If the commitment is funded, the Company would be entitled to seek recovery from the customer. The Company minimizes its exposure to loss under loan commitments and standby letters of credit by subjecting them to credit approval and monitoring procedures. The effect on the Company’s revenues, expenses, cash flows, and liquidity of the unused portions of these commitments cannot be reasonably predicted because there is no guarantee that the lines of credit will be used.
	The following is a summary of the total notional amount of loan commitments and standby letters of credit outstanding at December 31, 2014 and 2013 (in thousands):
		2014		2013
	Standby letters of credit	$	110,636	$	106,467
	Unused loan commitments	509,665		268,760
	Total	$	620,301	$	375,227

RelatedParty_Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions
	In the ordinary course of business, the Company makes loans to and holds deposits for directors and executive officers of the Company and their associates.
	The amounts of such related-party loans were $64.9 million and $47.8 million at December 31, 2014 and 2013, respectively. During 2014, $40.8 million in related-party loans were funded and $23.7 million were repaid. Also, in the ordinary course of business, the Company makes loans to affiliate entities of the Bank. These loans totaled $41.4 million and $40.2 million as of December 31, 2014 and 2013, respectively. None of the related-party loans and affiliate entity loans were classified as nonaccrual, past due, restructured, or potential problem loans at December 31, 2014 or 2013. The amounts of such related-party deposits were $14.4 million and $17.9 million at December 31, 2014 and 2013, respectively.
	The Company leases a building from a partnership that is owned by two directors of the Company. The Company paid approximately $0.2 million in rent expense related to this lease for the years ended December 31, 2014, 2013, and 2012. The lease also includes options for multiple five-year term extensions beyond the original lease expiration of October 2004, provided there were no defaults of material lease provisions by the lessee. The Company exercised an option to extend the lease for an additional five years in October 2014.

Employee_Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employee Benefits	Employee Benefits
	401(k) Profit-Sharing Plan
	The Company participates in a contributory retirement and savings plan (the Plan), which covers substantially all employees and meets the requirements of Section 401(k) of the Internal Revenue Code. Employer contributions to the Plan are based on the participants’ contributions, with an additional discretionary contribution as determined by the Board of Directors. Company contributions under the Plan were approximately $1.1 million, $1.0 million, and $0.9 million for the years ended December 31, 2014, 2013, and 2012, respectively. The Company pays all expenses associated with the Plan.
	Employee Stock Ownership Plan
	The Company sponsors an employee stock ownership plan (ESOP), which holds 50,000 shares of Company stock, subject to indebtedness utilized to purchase the shares in 2009. The leveraged ESOP allocates shares annually to eligible employee participants pro rata based on compensation. All participants vest in the annual allocations at 20% per year. The Company recognized compensation expense with respect to the ESOP of $0.3 million for the year ended December 31, 2014, and $0.2 million for the years ended December 31, 2013 and 2012. The Company pays all expenses associated with the ESOP.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	ASC 820, Fair Value Measurements and Disclosures, clarifies the principle that fair value should be based on the assumptions that market participants would use when pricing the asset or liability and establishes a fair value hierarchy that prioritizes the inputs used to develop those assumptions and measure fair value. The hierarchy requires companies to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows:
	•	Level 1 – Quoted prices in active markets for identical assets or liabilities.
	•	Level 2 – Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.
	•	Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. This includes certain pricing models, discounted cash flow methodologies, and similar techniques that use significant unobservable inputs.
	A description of the valuation methodologies used for instruments measured at fair value follows, as well as the classification
	of such instruments within the valuation hierarchy.
	Securities are classified within Level 1 when quoted market prices are available in an active market. Inputs include securities that have quoted prices in active markets for identical assets. If quoted market prices are unavailable, fair value is estimated using pricing models or quoted prices of securities with similar characteristics, at which point the securities would be classified within Level 2 of the hierarchy. Examples include certain available for sale securities. The Company’s investment portfolio did not include Level 3 securities as of December 31, 2014 and December 31, 2013.
	The Company has segregated all financial assets and liabilities that are measured at fair value on a recurring basis into the most appropriate level within the fair value hierarchy, based on the inputs used to determine the fair value at the measurement date in the tables below (in thousands):
				31-Dec-14
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Available for sale securities:
	U.S. government agency securities	$	157,527	$	—	$	157,527	$	—
	U.S. Treasury securities	12,610		—		12,610		—
	Municipal securities	12,246		—		12,246		—
	Mortgage-backed securities	57,087		—		57,087		—
	Corporate bonds	8,177		—		8,177		—
		$	247,647	$	—	$	247,647	$	—
	Derivative instruments	37		—		37		—
	Total	$	247,684	$	—	$	247,684	$	—
	Liabilities
	Derivative instruments	$	12,953	$	—	$	12,953	$	—
				December 31, 2013
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Available for sale securities:
	U.S. government agency securities	$	151,323	$	—	$	151,323	$	—
	U.S. Treasury securities	12,149		—		12,149		—
	Municipal securities	23,167		—		23,167		—
	Mortgage-backed securities	55,544		—		55,544		—
	Corporate bonds	35,536		—		35,536		—
		$	277,719	$	—	$	277,719	$	—
	Derivative instruments	1,157		—		1,157		—
	Total	$	278,876	$	—	$	278,876	$	—
	Liabilities
	Derivative instruments	$	4,317	$	—	$	4,317	$	—
	The Company has segregated all financial assets and liabilities that are measured at fair value on a nonrecurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date in the tables below (in thousands):
				31-Dec-14
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Loans	$	20,679	$	—	$	—	$	20,679
	OREO	3,022		—		—		3,022
		$	23,701	$	—	$	—	$	23,701
				December 31, 2013
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
Identical Assets				Inputs		(Level 3)
(Level 1)				(Level 2)
Assets
Loans	$	9,782	$	—	$	—	$	9,782
OREO	2,390		—		—		2,390
	$	12,172	$	—	$	—	$	12,172
In accordance with ASC Topic 310, the Company records loans and other real estate considered impaired at the lower of cost or fair value. Impaired loans, recorded at fair value, are Level 3 assets measured using appraisals from external parties of the collateral, less any prior liens primarily using the market or income approach.
The Company did not record any liabilities at fair value for which measurement of the fair value was made on a nonrecurring basis during the years ended December 31, 2014 and December 31, 2013.
ASC 820 requires the disclosure of the fair value for each class of financial instruments for which it is practicable to estimate. The fair value of a financial instrument is the current amount that would be exchanged between willing parties, other than in a forced liquidation. Fair value is best determined based upon quoted market prices. However, in many instances, there are no quoted market prices for the Company’s various financial instruments. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Accordingly, the fair value estimates may not be realized in an immediate settlement of the instrument. ASC 820 excludes certain financial instruments and all nonfinancial instruments from its disclosure requirements. Accordingly, the aggregate fair value amounts presented may not necessarily represent the underlying fair value of the Company.
The following methods and assumptions were used to estimate the fair value of each class of financial instrument for which it is practicable to estimate that value.
Cash and Cash Equivalents and Short-Term Investments
The carrying amounts of these short-term instruments approximate their fair values and would be classified within Level 1 of the hierarchy.
Investment in Short-Term Receivables
The carrying amounts of these short-term receivables approximate their fair value and would be classified within Level 1 of the hierarchy.
Investment Securities
Securities are classified within Level 1 where quoted market prices are available in the active market. If quoted market prices are unavailable, fair value is estimated using pricing models or quoted prices of securities with similar characteristics, at which point the securities would be classified within Level 2 of the hierarchy. Inputs include securities that have quoted prices in active markets for identical assets.
Loans
For variable-rate loans that reprice frequently and have no significant change in credit risk, fair values are based on carrying values. Fair values for fixed-rate commercial real estate, commercial loans, and consumer loans are estimated using discounted cash flow analyses using interest rates currently being offered for loans with similar terms and borrowers of similar credit quality. Fair value of mortgage loans held for sale is based on commitments on hand from investors or prevailing market rates. The fair value associated with the loans includes estimates related to expected prepayments and the amount and timing of undiscounted expected principal, interest and other cash flows, which would be classified as Level 3 of the hierarchy.
Bank-Owned Life Insurance
The carrying amounts of the bank-owned life insurance policies are recorded at cash surrender value, which approximate their fair values and would be classified within Level 1 of the hierarchy.
Deposits
The fair values disclosed for demand deposits are, by definition, equal to the amount payable on demand at the reporting date (that is, their carrying amounts) and would be categorized within Level 2 of the fair value hierarchy. The carrying amounts of variable-rate, fixed-term money market accounts approximate their fair values at the reporting date. Fair values for fixed-rate certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered on certificates to a schedule of aggregated expected monthly maturities on time deposits. The fair value of the Company’s interest-bearing deposits would, therefore, be categorized within Level 3 of the fair value hierarchy.
Short-Term Borrowings and Repurchase Agreements
The carrying amounts of these short-term instruments approximate their fair values and would be classified within Level 2 of the hierarchy.
Long-Term Borrowings
The fair values of long-term borrowings are estimated using discounted cash flows analyses based on the Company’s current incremental borrowing rates for similar types of borrowing arrangements. The fair value of the Company’s long-term debt would, therefore, be categorized within Level 3 of the fair value hierarchy.
Derivative Instruments
Fair values for interest rate swap agreements are based upon the amounts required to settle the contracts. The derivative instruments are classified within Level 2 of the fair value hierarchy.
The estimated fair values of the Company’s financial instruments were as follows as of the dates indicated (in thousands):
	Fair Value Measurements at December 31, 2014
	Carrying		Total		Level 1		Level 2		Level 3
	Amount
Financial Assets:
Cash and due from banks	$	32,484	$	32,484	$	32,484	$	—	$	—
Short-term investments	18,404		18,404		18,404		—		—
Investment in short-term receivables	237,135		237,135		237,135		—		—
Investment securities available for sale	247,647		247,647		—		247,647		—
Investment securities held to maturity	89,076		90,956		—		90,956		—
Loans and loans held for sale	2,775,886		3,003,280		—		—		3,003,280
Cash surrender value of bank-owned life insurance	47,289		47,289		47,289		—		—
Derivative instruments	37		37		—		37		—
Financial Liabilities:
Deposits, noninterest-bearing	364,534		364,534		—		364,534		—
Deposits, interest-bearing	2,756,316		2,722,134		—		—		2,722,134
Repurchase agreements	117,991		117,991		—		117,991		—
Long-term borrowings	40,000		42,270		—		—		42,270
Derivative instruments	12,953		12,953		—		12,953		—
	Fair Value Measurements at December 31, 2013
	Carrying		Total		Level 1		Level 2		Level 3
	Amount
Financial Assets:
Cash and due from banks	$	28,140	$	28,140	$	28,140	$	—	$	—
Short-term investments	3,502		3,502		3,502		—		—
Investment in short-term receivables	246,817		246,817		246,817		—		—
Investment securities available for sale	277,719		277,719		—		277,719		—
Investment securities held to maturity	94,904		90,966		—		90,966		—
Loans and loans held for sale	2,364,354		2,344,475		—		—		2,344,475
Cash surrender value of bank-owned life insurance	26,187		26,187		26,187		—		—
Derivative instruments	1,157		1,157		—		1,157		—
Financial Liabilities:
Deposits, noninterest-bearing	291,080		291,080		—		291,080		—
Deposits, interest-bearing	2,439,727		2,380,985		—		—		2,380,985
Repurchase agreements	75,957		75,957		—		75,957		—
Short-term borrowings	8,425		8,425		—		8,425		—
Long-term borrowings	55,110		55,616		—		—		55,616
Derivative instruments	4,317		4,317		—		4,317		—

Parent_Company_Only_Financial_

Parent Company Only Financial Statements	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Only Financial Statements	Parent Company Only Financial Statements
	Financial statements of First NBC Bank Holding Company (parent company only) are shown below. The parent company has no significant operating activities.
	Balance Sheets
		December 31,
	(In thousands)	2014			2013
	Assets
	Cash and due from banks	$	23,736		$	23,990
	Goodwill	841			841
	Investments in subsidiaries	409,689			355,068
	Other assets	2,145			2,123
	Total assets	$	436,411		$	382,022
	Liabilities and shareholders’ equity
	Long-term borrowings	$	—		$	110
	Other liabilities	36			53
	Total liabilities	36			163
	Total shareholders’ equity	436,375			381,859
	Total liabilities and shareholders’ equity	$	436,411		$	382,022
	Statements of Income
		Year Ended December 31,
	(In thousands)	2014			2013			2012
	Operating income
	Interest income	$	—		$	—		$	—
	Dividend from bank subsidiary	—			2,000			—
	Total operating income	—			2,000			—
	Operating expense
	Interest expense	3			424			11
	Other expense	1,414			856			431
	Total operating expense	1,417			1,280			442
	Income (loss) before income tax benefit and increase in equity in undistributed earnings of subsidiaries	(1,417		)	720			(442		)
	Income tax benefit	(496		)	(448		)	(155		)
	Income (loss) before equity in undistributed earnings of subsidiaries	(921		)	1,168			(287		)
	Equity in undistributed earnings of subsidiaries	56,510			39,743			29,227
	Net income	55,589			40,911			28,940
	Preferred stock dividends	(379		)	(347		)	(510		)
	Income available to common shareholders	$	55,210		$	40,564		$	28,430
	Statements of Cash Flows
		Year Ended December 31,
	(in thousands)	2014			2013			2012
	Operating activities
	Net income	$	55,589		$	40,911		$	28,940
	Adjustments to reconcile net income to net cash (used in) provided by operating activities:
	Net income of subsidiaries	(56,510		)	(39,743		)	(29,227		)
	Deferred tax benefit	(496		)	(448		)	(155		)
	Stock compensation	333			1,155			97
	Changes in operating assets and liabilities:
	Change in other assets	474			1,481			(1,989		)
	Change in other liabilities	(17		)	50			—
	Net cash (used in) provided by operating activities	(627		)	3,406			(2,334		)
	Investing activities
	Capital contributed to subsidiary, net	—			(67,000		)	(16,600		)
	Net cash used in investing activities	—			(67,000		)	(16,600		)
	Financing activities
	Proceeds from long-term borrowings	—			—			20,000
	Repayment of borrowings	(110		)	(20,110		)	(110		)
	Proceeds from sale of common stock, net of offering costs	862			104,332			1,420
	Dividends paid	(379		)	(347		)	(510		)
	Net cash provided by financing activities	373			83,875			20,800
	Net change in cash, due from banks, and short-term investments	(254		)	20,281			1,866
	Cash, due from banks, and short-term investments at beginning of period	23,990			3,709			1,843
	Cash, due from banks, and short-term investments at end of period	$	23,736		$	23,990		$	3,709

Consolidated_Quarterly_Results

Consolidated Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Consolidated Quarterly Results of Operations (Unaudited)	Consolidated Quarterly Results of Operations (Unaudited)
	(In thousands, except per share data)	First  Quarter			Second			Third			Fourth
					Quarter			Quarter			Quarter
	Year Ended December 31, 2014
	Total interest income	$	35,161		$	37,193		$	38,668		$	38,956
	Total interest expense	10,313			10,643			10,908			10,865
	Net interest income	24,848			26,550			27,760			28,091
	Provision for loan losses	3,000			3,000			3,000			3,000
	Net interest income after provision for loan losses	21,848			23,550			24,760			25,091
	Noninterest income	3,359			2,933			3,034			2,287
	Noninterest expense	17,337			18,568			20,047			22,297
	Income before income taxes	7,870			7,915			7,747			5,081
	Income tax benefit	(4,958		)	(4,784		)	(6,612		)	(10,622		)
	Net income attributable to Company	12,828			12,699			14,359			15,703
	Less preferred stock dividends	(95		)	(95		)	(95		)	(94		)
	Less earnings allocated to participating securities	(246		)	(243		)	(275		)	(302		)
	Income available to common shareholders	$	12,487		$	12,361		$	13,989		$	15,307
	Earnings per common share-basic	$	0.68		$	0.67		$	0.75		$	0.82
	Earnings per common share-diluted	$	0.66		$	0.65		$	0.73		$	0.8
	(In thousands, except per share data)	First Quarter			Second			Third			Fourth
					Quarter			Quarter			Quarter
	Year Ended December 31, 2013
	Total interest income	$	28,580		$	29,034		$	31,973		$	34,437
	Total interest expense	8,893			9,779			10,150			10,326
	Net interest income	19,687			19,255			21,823			24,111
	Provision for loan losses	2,600			2,400			2,400			2,400
	Net interest income after provision for loan losses	17,087			16,855			19,423			21,711
	Noninterest income	2,827			2,738			2,461			5,400
	Noninterest expense	15,643			15,185			17,092			19,422
	Income before income taxes	4,271			4,408			4,792			7,689
	Income tax benefit	(4,013		)	(4,198		)	(5,673		)	(5,867		)
	Net income	8,284			8,606			10,465			13,556
	Less net income attributable to noncontrolling interest	—			—			—			—
	Net income attributable to Company	8,284			8,606			10,465			13,556
	Less preferred stock dividends	(95		)	(95		)	(62		)	(95		)
	Less earnings allocated to participating securities	(538		)	(455		)	(519		)	(468		)
	Income available to common shareholders	$	7,651		$	8,056		$	9,884		$	12,993
	Earnings per common share-basic	$	0.59		$	0.51		$	0.55		$	0.71
	Earnings per common share-diluted	$	0.58		$	0.49		$	0.54		$	0.69

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	Acquisitions
	Acquisition of State-Investors Bank
	On December 30, 2014, the Company entered into a definitive agreement to acquire State Investors Bancorp, Inc. (“State Investors”), the holding company for State-Investors Bank, a full service bank with four offices located in the New Orleans metropolitan area, by means of a merger. The merger agreement has been approved by the boards of directors of the Company and State Investors, and the merger is expected to close in the second quarter of 2015, subject to customary closing conditions, including the receipt of required regulatory approvals and the approval of the shareholders of State Investors. Promptly following the holding company merger, the Company expects to merge the subsidiary banks under the charter of First NBC Bank.
	Under the terms of the merger agreement, shareholders of State Investors will receive $21.25 in cash for each share of State Investors stock owned by them at the effective time of the merger. The merger agreement also provides that holders of options to purchase shares of State Investors common stock will receive, in exchange for their stock options, cash consideration equal to the difference between $21.25 and the exercise price of the option.
	The merger allows the Company to enter into a new section of the New Orleans metropolitan area with a very strong demographic make-up, provides liquidity to allow the Company to fund loan growth, adds approximately $156.0 million in deposits in the New Orleans MSA, and allows the Company to effectively deploy capital.
	Acquisition of Certain Assets and Liabilities of First National Bank of Crestview
	On January 16, 2015, the Company announced an agreement with the Federal Deposit Insurance Corporation (“FDIC”) and purchased certain assets and assumed certain liabilities from the FDIC, as receiver for First National Bank of Crestview, a full-service commercial bank headquartered in Crestview, Florida, which was closed and placed into receivership. Under the agreement, the Company agreed to assume all of the deposit liabilities, and acquire approximately $62.3 million of assets, of the failed bank. The acquired assets included the failed bank's performing loans, substantially all of its investment securities portfolio, and its three banking facilities, with the FDIC retaining the failed bank's other real estate owned. The transaction was effective immediately and did not include a loss-share agreement with the FDIC.
	Private Placement of Subordinated Notes
	Subordinated Notes due 2025
	On February 18, 2015, the Company completed a private placement of $60.0 million in aggregate principal amount of subordinated notes to certain qualified institutional investors. Unless earlier redeemed, the notes mature on February 18, 2025 and bear interest at a fixed rate of 5.75% per annum, payable semiannually, over their term.
	The Company plans to use the net proceeds from the sale of the subordinated notes for general corporate purposes, which may include supporting the continued growth of its business, acquisitions, and the redemption or repayment of other fixed obligations.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations
	First NBC Bank Holding Company (“Company”) is a bank holding company that offers a broad range of financial services through First NBC Bank, a Louisiana state non-member bank, to businesses, institutions, and individuals in southeastern Louisiana and the Mississippi Gulf Coast. The accounting and reporting policies of the Company conform to accounting principles generally accepted in the United States and to prevailing practices within the banking industry.
Principles of Consolidation	Principles of Consolidation
	The accompanying consolidated financial statements include the accounts of the Company and First NBC Bank, and First NBC Bank’s wholly owned subsidiaries, which include First NBC Community Development, LLC (FNBC CDC), First NBC Community Development Fund, LLC (FNBC CDE) (collectively referred to as the Bank) and any variable interest entities (VIE) of which the Company is the primary beneficiary. Substantially all of the VIEs for which the Company is the primary beneficiary relate to tax credit investments. FNBC CDC is a Community Development Corporation formed to construct, purchase, and renovate affordable residential real estate properties in the New Orleans area. FNBC CDE is a Community Development Entity (CDE) formed to apply for and receive allocations of Federal New Markets Tax Credits (NMTC).
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are susceptible to a significant change in the near term are the allowance for loan losses, income tax provision, fair value adjustments, and share-based compensation.
Concentration of Credit Risk	Concentration of Credit Risk
	The Company’s loan portfolio consists of the various types of loans described in Note 6. Real estate or other assets secure most loans. The majority of these loans have been made to individuals and businesses in the Company’s market area of southeastern Louisiana and southern Mississippi, which are dependent on the area economy for their livelihoods and servicing of their loan obligations. The Company does not have any significant concentrations to any one industry or customer.
	The Company maintains deposits in other financial institutions that may, from time to time, exceed the federally insured deposit limits.
Cash and Cash Equivalents	Cash and Cash Equivalents
	For purposes of reporting cash flows, cash and cash equivalents include the amount in the accompanying consolidated balance sheet caption, cash and due from banks, which represents cash on hand and balances due from other financial institutions, as well as the amount in the accompanying consolidated balance sheet caption, short-term investments, which primarily represents federal funds sold with original maturities less than three months.
Investment Securities	Investment Securities
	Investment securities are classified either as held to maturity or available for sale. Management determines the classification of securities when they are purchased.
	Investment securities that the Company has the ability and positive intent to hold to maturity are classified as securities held to maturity and are stated at amortized cost. The amortized cost of debt securities classified as held to maturity or available for sale is adjusted for amortization of premiums and accretion of discounts over the contractual life of the security using the effective interest method or, in the case of mortgage-backed securities, over the estimated life of the security using the effective yield method. Such amortization or accretion is included in interest income on securities.
	Securities that may be sold in response to changes in interest rates, liquidity needs, or asset liability management strategies are classified as securities available for sale. These securities are carried at fair value, with net unrealized gains or losses excluded from earnings and shown as a separate component of shareholders’ equity in accumulated other comprehensive (loss) income, net of income taxes. Any expected credit loss due to the inability to collect all amounts due accordingly to the security’s contractual terms is recognized as a charge against earnings. Any remaining unrealized loss related to other factors is recognized in other comprehensive income, net of taxes.
	Realized gains and losses on both held to maturity securities and available for sale securities are computed based on the specific-identification method. Realized gains and losses and declines in value judged to be other than temporary are included in net securities gains and losses.
	Unrealized losses on securities are evaluated to determine if the losses are temporary, based on various factors, including the cause of the loss, prospects for recovery, projected cash flows, collateral values, credit enhancements and other relevant factors, and management’s intent and ability not to sell the security until the fair value exceeds amortized cost. A charge is recognized against earnings for all or a portion of the impairment if the loss is determined to be other than temporary.
Investment in Short-Term Receivables	Investment in Short-Term Receivables
	The Company invests in short-term receivables which are purchased on an exchange. These short-term receivables have repayment terms of less than a year. The investments are recorded on the consolidated balance sheets at cost plus accreted discount.
Mortgage Loans Held for Sale	Mortgage Loans Held for Sale
	Mortgage loans originated and intended for sale in the secondary market are carried at the lower of cost or estimated fair value, in the aggregate. Net unrealized losses, if any, are recognized through a valuation allowance that is recorded as a charge to income. Loans held for sale have primarily been fixed-rate, single-family residential mortgage loans under contract to be sold in the secondary market. In most cases, loans in this category are sold within 120 days. These loans are sold with the mortgage servicing rights released. Buyers generally have recourse to return a purchased loan to the Company under limited circumstances which may include early payment default, breach of representations or warranties, and documentation deficiencies.
Transfers of Financial Assets	Transfers of Financial Assets
	Transfers of financial assets are accounted for as sales when control over the assets has been surrendered or in the case of a loan participation, a portion of the asset has been surrendered and meets the definition of a "participating interest". Control over transferred assets is deemed to be surrendered when 1) the assets have been isolated from the Company, 2) the transferee obtains the right, free of conditions that constrain it from taking advantage of that right, to pledge or exchange the transferred assets, and 3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity. Should the transfer not meet these three criteria, the transaction is treated as a secured financing.
Loans	Loans
	Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are stated at the principal amount outstanding, net of unamortized fees and costs on originated loans and allowances for loan losses. Loan origination fees and certain direct loan origination costs are deferred and amortized over the lives of the respective loans as a yield adjustment using the effective interest method.
	Interest income on loans is accrued as earned using the interest method over the life of the loan. Interest on loans deemed uncollectible is excluded from income. The accrual of interest is discontinued and reversed against current income once loans become more than 90 days past due or earlier if conditions warrant. The past due status of loans is determined based on the contractual terms. If the decision is made to continue accruing interest on the loan, periodic reviews are made to confirm the accruing status of the loan. When a loan is placed on nonaccrual status, interest accrued and unpaid during prior periods is reversed. Generally, any payments on nonaccrual loans are applied first to outstanding loan principal amounts and then to the recovery of the charged-off loan amounts. Any excess is treated as recovery of lost interest and fees. Loans are returned to accrual status after a minimum of six consecutive monthly payments have been made in a timely manner.
	The Company considers a loan to be impaired when, based upon current information and events, it believes it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. The Company’s impaired loans include troubled debt restructurings (TDRs) and performing and nonperforming loans for which full payment of principal or interest is not expected. The Company calculates a reserve required for impaired loans based on the present value of expected future cash flows discounted using the loan’s effective interest rate or the fair value of the collateral securing the loan.
	Third-party property valuations are obtained at the time of origination for real estate-secured loans. The Company obtains updated appraisals on all impaired loans at least annually. In addition, if an intervening event occurs that, in management’s opinion, would suggest further deterioration in value, the Company obtains an updated appraisal. These policies do not vary based on loan type. Any exposure arising from the deterioration in value of collateral evidenced by the appraisal is recorded as an adjustment to the loan loss reserve in the case of an impaired loan or as an adjustment to income in the case of foreclosed property.
Troubled Debt Restructurings	Troubled Debt Restructurings
	The Company periodically grants concessions to its customers in an attempt to protect as much of its investment as possible and minimize the risk of loss. These concessions may include restructuring the terms of a customer loan, thereby adjusting the customer’s payment requirements. In order to be considered a TDR, the Company must conclude that the restructuring constitutes a concession and the customer is experiencing financial difficulties. The Company defines a concession to a customer as a modification of existing loan terms for economic or legal reasons that it would otherwise not consider. Concessions are typically granted through an agreement with the customer or are imposed by a court of law. Concessions include modifying original loan terms to reduce or defer cash payments required as part of the loan agreement, including but not limited to:
	•	A reduction of the stated interest rate for the remaining original life of the debt
	•	Extension of the maturity date or dates at a stated interest rate lower than the current market rate for new debt with similar risk characteristics
	•	Reduction of the face amount or maturity amount of the debt as stated in the agreement
	•	Reduction of accrued interest receivable on the debt
	In its determination of whether the customer is experiencing financial difficulties, the Company considers numerous indicators, including but not limited to:
	•	Whether the customer is currently in default on its existing loan or is in an economic position where it is probable the customer will be in default on its loan in the foreseeable future without a modification
	•	Whether the customer has declared or is in the process of declaring bankruptcy
	•	Whether there is substantial doubt about the customer’s ability to continue as a going concern
	•	Whether, based on its projections of the customer’s current capabilities, the Company believes the customer’s future cash flows will be insufficient to service the debt, including interest, in accordance with the contractual terms of the existing agreement for the foreseeable future
	•	Whether, without modification, the customer cannot obtain sufficient funds from other sources at an effective interest rate equal to the current market rate for similar debt for a nontroubled debtor
	If the Company concludes that both a concession has been granted and the concession was granted to a customer experiencing financial difficulties, the Company identifies the loan as a TDR. For purposes of the determination of an allowance for loan losses on these TDRs, the loan is reviewed for specific impairment in accordance with the Company’s allowance for loan loss methodology. If it is determined that losses are probable on such TDRs, either because of delinquency or other credit quality indicators, the Company establishes specific reserves for these loans.
Acquisition Accounting for Loans	Acquisition Accounting for Loans
	The Company accounts for business acquisitions in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 805, Business Combinations, which requires the use of the acquisition method of accounting. All identifiable assets acquired, including loans, are recorded at fair value. The fair value of loans that do not have deteriorated credit quality are accounted for in accordance with ASC 310-20, Nonrefundable Fees and Other Costs, and is represented by the expected cash flows from the portfolio discounted at current market rates. In estimating the cash flows, the Company makes assumptions about the amount and timing of principal and interest payments, estimated prepayments, estimated default rates, estimated loss severities in the event of defaults, and current market rates. The fair value adjustment is amortized over the life of the loan using the effective interest method. The Company accounts for certain acquired loans with deteriorated credit quality under ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality. In accordance with ASC 310-30 and in estimating the fair value of loans with deteriorated credit quality as of the acquisition date, the Company: (a) calculates the contractual amount and timing of undiscounted principal and interest payments (the undiscounted contractual cash flows), and (b) estimates the amount and timing of undiscounted expected principal and interest payments (the undiscounted expected cash flows). The difference between the undiscounted contractual cash flows and the undiscounted expected cash flows is the nonaccretable difference. On the acquisition date, the amount by which the undiscounted expected cash flows exceed the estimated fair value of the loans with deteriorated credit quality is the accretable yield. The accretable yield is recorded into interest income over the estimated lives of the loans using the effective yield method. The accretable yield changes over time as actual and expected cash flows vary from the estimated cash flows at acquisition. Decreases in expected cash flows subsequent to acquisition result in recognition of a provision for loan loss. The accretable yield is measured at each financial reporting date and represents the difference between the remaining undiscounted expected cash flows and the current carrying value of the loans. The remaining undiscounted expected cash flows are calculated at each financial reporting date, based on information currently available. Increases in expected cash flows over those originally estimated increase the accretable yield and are recognized prospectively as interest income. Increases in expected cash flows may also lead to the reduction of any allowance for loan losses recorded after the acquisition. Decreases in expected cash flows compared to those originally estimated decrease the accretable yield and are recognized by recording an allowance for loan losses. As the accretable yield increases or decreases from changes in cash flow expectations, the offset is an increase or decrease to the nonaccretable difference. There is no carryover of allowance for loan losses, as the loans acquired are initially recorded at fair value as of the date of acquisition.
Allowance for Loan Losses	Allowance for Loan Losses
	The allowance for loan losses represents an estimate that management believes will be adequate to absorb probable incurred losses on existing loans in its portfolio at the balance sheet date. The allowance is based on an evaluation of the collectability of loans and prior loss experience, including both industry and Company specific considerations. While management uses available information to make loan loss allowance evaluations, adjustments to the allowance may be necessary based on changes in economic and other conditions or changes in accounting guidance. See Note 6 for an analysis of the Company’s allowance for loan losses by portfolio and portfolio segment, and credit quality information by class.
	Management has an established methodology to determine the allowance for loan losses that assesses the risks and losses inherent in its portfolio and portfolio segments. The Company utilizes an internally developed model that requires significant judgment to determine the estimation method that fits the credit risk characteristics of the loans in its portfolio and portfolio segments. The allowance for loan losses is established through a provision for loan losses charged to expense. A similar methodology and model is utilized by the Company to calculate a reserve assigned to off-balance sheet commitments, specifically unfunded loan commitments and letters of credit, and any needed reserve is recorded in other liabilities. The appropriateness of the allowance for loan losses is determined in accordance with generally accepted accounting principles.
	The Company’s loan portfolio is disaggregated into portfolio segments for purposes of determining the allowance for loan losses. The Company’s portfolio segments include commercial real estate, consumer real estate, commercial and industrial, and consumer loans. The Company further disaggregates the commercial and consumer real estate portfolio segments into classes for purposes of monitoring and assessing credit quality based on certain risk characteristics. Classes within each commercial real estate portfolio segment include commercial real estate construction and commercial real estate mortgage. Classes within each consumer real estate portfolio segment include consumer real estate construction and consumer real estate mortgage.
	Loans are charged off against the allowance for loan losses when management believes that the collectability of the principal is unlikely. The allowance for loan losses consists of specific and general reserves. The Company determines specific reserves based on the provisions of ASC 310, Receivables. The Company’s allowance for loan losses includes a measure of impairment for those loans specifically identified for evaluation under the topic. This measurement is based on a comparison of the recorded investment in the loan with either the expected cash flows discounted using the loan’s original contractual effective interest rate or the fair value of the collateral underlying certain collateral-dependent loans. Collectability of principal and interest is evaluated in assessing the need for a loss accrual. Loans identified as impaired are individually evaluated periodically for impairment.
	General reserves are based on management’s evaluation of many factors and reflect an estimated measurement of losses related to loans not individually evaluated for impairment. These loans are grouped into portfolio segments. The loss rates are derived from historical loss factors of the Company or the industry sustained on loans according to their risk grade, as well as qualitative and economic factors, and may be adjusted for Company-specific factors. Loss rates are reviewed quarterly and adjusted as management deems necessary based on changing borrower and/or collateral conditions and actual collections and charge-off experience.
	Based on observations made through a qualitative review, management may apply qualitative adjustments to the quantitatively determined loss estimates at a group and/or portfolio segment level as deemed appropriate. Primary qualitative and environmental factors that may not be directly reflected in quantitative estimates include:
	•	Asset quality trends
	•	Changes in lending policies
	•	Trends in the nature and volume of the loan portfolio, including the existence and effect of any portfolio concentrations
	•	Changes in experience and depth of lending staff
	•	National and regional economic trends
	Changes in these factors are considered in determining the directional consistency of changes in the allowance for loan losses. The impact of these factors on the Company’s qualitative assessment of the allowance for loan losses can change from period to period based on management’s assessment to the extent to which these factors are already reflected in historic loss rates. The uncertainty inherent in the estimation process is also considered in evaluating the allowance for loan losses.
Credit-Related Financial Instruments	Credit-Related Financial Instruments
	The Company accounts for its guarantees in accordance with the provisions of ASC 460, Guarantees. In the ordinary course of business, the Company has entered into commitments to extend credit, including commitments under credit card agreements, and standby letters of credit. Such financial instruments are recorded when they are funded.
Derivative Financial Instruments	Derivative Financial Instruments
	ASC 815, Derivatives and Hedging, requires that all derivatives be recognized as assets or liabilities in the balance sheet at fair value. The Company may enter into derivative contracts to manage exposure to interest rate risk or meet the financing and/or investing needs of its customers.
	In the course of its business operations, the Company is exposed to certain risks, including interest rate, liquidity, and credit risk. The Company manages its risks through the use of derivative financial instruments, primarily through management of exposure due to the receipt or payment of future cash amounts based on interest rates. The Company’s derivative financial instruments manage the differences in the timing, amount, and duration of expected cash receipts and payments.
	Derivatives which are designated and qualify as a hedge of the exposure to variability in expected future cash flows or other types of forecasted transactions are considered cash flow hedges. The Company prepares written hedge documentation for all derivatives which are designated as cash flow hedges. The written hedge documentation includes identification of, among other items, the risk management objective, hedging instrument, hedged item and methodologies for assessing and measuring hedge effectiveness and ineffectiveness, along with support for management’s assertion that the hedge will be highly effective. These methods are consistent with the Company’s approach to managing risk. The Company reports these net in the accompanying consolidated balance sheets when the Company has a master netting arrangement. As of December 31, 2014, there were net amounts reported.
	For designated hedging relationships, the Company performs retrospective and prospective effectiveness testing to determine whether the hedging relationship has been highly effective in offsetting changes in cash flows of hedged items and whether the relationship is expected to continue to be highly effective in the future. Assessments of hedge effectiveness and measurements of hedge ineffectiveness are performed at least quarterly. The effective portion of the changes in the fair value of a derivative that is highly effective and that has been designated and qualifies as a cash flow hedge are initially recorded in accumulated other comprehensive income and reclassified to earnings in the same period that the hedged item impacts earnings or when the hedging relationship is terminated; any ineffective portion is recorded in earnings immediately.
	Hedge accounting ceases on transactions that are no longer deemed effective, or for which the derivative has been terminated or de-designated. For discontinued cash flow hedges, the unrealized gains and losses recorded in accumulated other comprehensive income would be reclassified to earnings during the period or periods in which the previously designated hedged cash flows affect earnings (straight-line amortization/accretion) unless it was determined that the transaction was probable to not occur, whereby any unrealized gains and losses in accumulated other comprehensive income would be immediately reclassified to earnings. Note 18 describes the derivative instruments currently used by the Company and discloses how these derivatives impact the Company’s financial position and results of operations.
Premises and Equipment	Premises and Equipment
	Land is carried at cost. Buildings, furniture, fixtures, and equipment are carried at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated life of each respective type of asset as follows:
		Buildings	40 years
		Furniture, fixtures, and equipment	5	-	15 years
	Leasehold improvements are amortized using the straight-line method over the periods of the leases, including options expected to be exercised, or the estimated useful lives, whichever is shorter. Gains and losses on disposition and maintenance and repairs are included in current operations. Rental expense on leased property is recognized on a straight-line basis over the original lease term plus options that management expects to exercise. Fixed rental increases that are determinable are expensed over the lease period, including any option periods which are expected to be exercised, using a straight-line lease expense method.
Other Real Estate	Other Real Estate
	Assets acquired through, or in lieu of, loan foreclosure are held for sale and are recorded at a new cost basis determined at the date of foreclosure as the lower of cost or fair value less estimated cost to sell. Cost is defined as the recorded investment in the loan. Subsequent to foreclosure, valuation allowances are established for any decreases in the estimate of the asset’s fair value or selling costs, but not in excess of its new cost basis. Revenues and expenses from operations and changes in the valuation allowance are included in current earnings.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets
	Goodwill is accounted for in accordance with ASC 350, Intangibles—Goodwill and Other, and, accordingly, is not amortized but is evaluated at least annually for impairment. As part of its annual impairment testing, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company determines the fair value of a reporting unit is less than its carrying amount using these qualitative factors, the Company compares the fair value of goodwill with its carrying amount and then measures impairment loss by comparing the implied fair value of goodwill with the carrying amount of that goodwill.
	Definite-lived intangible assets, which consist of core deposit intangibles, are amortized on a straight-line basis over their useful lives and evaluated at least annually for impairment.
Income Taxes	Income Taxes
	The Company accounts for income taxes under the liability method. Deferred tax assets and liabilities are established for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities using enacted tax rates expected to be in effect during the year in which the basis differences reverse.
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires the Company to report information regarding its exposure to various tax positions taken by the Company. The Company has determined whether any tax positions have met the recognition threshold and has measured the Company’s exposure to those tax positions. Management believes that the Company has adequately addressed all relevant tax positions and that there are no unrecorded tax liabilities. Any interest or penalties assessed to the Company are recorded in operating expenses. No interest or penalties from any taxing authorities were recorded in the accompanying consolidated financial statements. Federal, state, and local taxing authorities generally have the right to examine and audit the previous three years of tax returns filed.
	The Company is also required to reduce its tax basis of the investment in certain of the projects that generated the Federal NMTC or Federal Historic Rehabilitation tax credits by the amount of the credit generated in that year based on the taxable entity structure of the investee.
Investments in Real Estate Properties	Investments in Real Estate Properties
	FNBC CDC invests in real estate properties, which are carried at cost. Costs of construction are capitalized during the construction period and do not include interest. The Company periodically obtains as-is appraisals to determine the recoverability of its investments for which it intends to sell. For properties the Company intends to hold, the Company assesses recoverability based on the cash flows of the underlying properties.
Investments in Tax Credit Entities	Investments in Tax Credit Entities
	As part of its Community Reinvestment Act responsibilities and due to their favorable economics, the Company invests in tax credit-motivated projects. These projects are directed at tax credits issued under Low-Income Housing, Federal Historic Rehabilitation, and Federal New Markets Tax Credits. The Company generates its returns on tax credit motivated projects through the receipt of federal, and if applicable, state tax credits. The federal tax credits are recorded as an offset to the income tax provision in the year that they are earned under federal income tax law – over 10 to 15 years, beginning in the year in which rental activity commences for Low-Income Housing credits, in the year of the issuance of the certificate of occupancy and the property is placed into service for Federal Historic Rehabilitation credits, and over 7 years for Federal NMTC upon the investment of funds into the CDE. These credits, if not used in the tax return for the year of origination, can be carried forward for 20 years.
	For Low-Income Housing and Federal Historic Rehabilitation credits, the Company invests in a tax credit entity, usually a limited liability company, which owns the real estate. The Company receives a 99.99% nonvoting interest in the entity for Low-Income Housing investments and 99% for Federal Historic Rehabilitation investments that must be retained during the compliance period for the credits (15 years for Low-Income Housing credits and 5 years for Federal Historic Rehabilitation credits). In most cases, the Company’s interest in the entity is generally reduced from a 99.99% and 99% interest to a 5% to 25% interest at the end of the compliance period. Control of the tax credit entity rests in the .01% and 1% interest general partner, who has the power and authority to make decisions that impact economic performance of the project and is required to oversee and manage the project. Due to the lack of any voting, economic or managerial control and due to the contractual reduction in its ownership, the Company accounts for its investment in Low-Income Housing and Federal Historic Rehabilitation credits by amortizing its investment, beginning in the year of the issuance of the certificate of occupancy and when the property is placed into service, over the compliance or contract period, as management believes any potential residual value in the real estate will have limited value.
	For Federal NMTC, a different structure is required by federal tax law. In order to distribute Federal NMTC, the federal government allocates such credits to CDEs. The Company invests in both CDEs formed by unaffiliated parties and in CDEs formed by the Company. Projects must be commercial or real estate operations and are qualified by their location in low- income areas or by their employment of, or service to, low-income citizens. A CDE, in most cases, creates a special-purpose subsidiary for each project through which the credits are allocated and through which the proceeds from the tax credit investor and a leverage lender, if applicable, flow through to the project, which in turn generate the credit. The credits are calculated at 39% of the total CDE allocation to the project at the rate of 5% for the first three years and 6% for the next four years. Federal tax law requires special terms benefiting the qualified project, which can include below-market interest rates. The Company expenses the cost of any benefits provided to the project over the seven-year compliance period. When the Company also has a loan, commonly called a leveraged loan, to the project, it is carried in loans, as the Company has normal credit exposure to the project and is repaid at the end of the compliance period (in general, the debt has no principal payments during the compliance period but the Company may require the project to fund a sinking fund over the compliance period to achieve the same risk reduction effect as if principal is being amortized).
	When the Company is the tax credit investor in a CDE formed by an unaffiliated party, it has no control of the applicable CDE or the CDE’s special-purpose subsidiary. When a project is funded through FNBC CDE, the Company consolidates its CDE and the specifically formed special-purpose entities since it maintains control over these entities. As part of the activities of FNBC CDE, the Company makes investments in the CDE for purposes of providing equity to the projects sponsored by the FNBC CDE.
	The Company has the risk of credit recapture if the project fails during the compliance period for Low-Income Housing and Federal Historic Rehabilitation transactions. For Federal NMTC transactions, the risk of credit recapture exists if investment requirements are not maintained during the compliance period. Such events, although rare, are accounted for when they occur and no such events have occurred to date.
Variable Interest Entities	Variable Interest Entities
	VIEs are entities that, in general, either do not have equity investors with voting rights or that have equity investors that do not provide sufficient financial resources for the entity to support its activities. The Company uses VIEs in various legal forms to conduct normal business activities. The Company reviews the structure and activities of VIEs for possible consolidation.
	A controlling financial interest in a VIE is present when an enterprise has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits of the VIE that could potentially be significant to the VIE. A VIE often holds financial assets, including loans or receivables, real estate, or other property. The company with a controlling financial interest, known as the primary beneficiary, is required to consolidate the VIE. Noncontrolling variable interests in certain limited partnerships for which it does not absorb a majority of expected losses or receive a majority of expected residual returns are not included in the accompanying consolidated financial statements. Refer to Notes 12 and 13 for further detail.
Stock-Based Compensation Plans	Stock-Based Compensation Plans
	At December 31, 2014 and 2013, the Company had a stock-based employee compensation plan, which provides for the issuance of stock options and restricted stock. The Company accounts for stock-based employee compensation in accordance with the fair value recognition provisions of ASC 718, Compensation—Stock Compensation. Compensation cost is recognized as expense over the service period, which is generally the vesting period of the options and restricted stock. The expense is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occur. As a result, compensation cost for all share-based payments is reflected in net income as part of salaries and employee benefits in the accompanying consolidated statements of income. See Note 24 for additional information on the Company’s stock-based compensation plans.
Earnings Per Share	Earnings Per Share
	Basic earnings per common share is computed based upon net income attributable to common shareholders divided by the weighted-average number of common shares outstanding during each period. Diluted earnings per common share is computed based upon net income, adjusted for dilutive participating securities, divided by the weighted-average number of common shares outstanding during each period and adjusted for the effect of dilutive potential common shares calculated using the treasury stock method and the assumed conversion for any dilutive convertible securities. In determining net income attributable to common shareholders, the net income attributable to participating securities is excluded. The Company issued Series C preferred stock in 2011, which is considered a participating security because it shares in any dividends paid to common shareholders. The assumed conversion of the Series C preferred stock is excluded from the calculation of diluted earnings per share due to the fact that the shares are contingently issuable and the contingency still existed at the end of the year.
Comprehensive Income	Comprehensive Income
	Accounting principles generally require that recognized revenue, expenses, gains, and losses be included in net income. Although certain changes in assets and liabilities, such as unrealized gains and losses on available for sale securities and cash flow hedges, are reported as a separate component of the equity section of the balance sheet; such items, along with net income, are components of comprehensive income.
Segments	Segments
	All of the Company’s banking operations are considered by management to be aggregated in one reportable operating segment. Because the overall banking operations comprise substantially all of the consolidated operations and none of the Company’s other subsidiaries, either individually or in the aggregate, meet quantitative materiality thresholds, no separate segment disclosures are presented in the accompanying consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	ASU No. 2014-01
	In January 2014, the FASB issued ASU No. 2014-01, Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects, which permits reporting entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). This ASU applies to all reporting entities that invest in qualified affordable housing projects through limited liability entities that are flow-through entities for tax purposes. The provisions of this ASU should be applied retrospectively to all periods presented for periods beginning after December 15, 2014, with early adoption permitted. The Company is evaluating the adoption of this ASU and has not determined the impact on the Company's financial condition or results of operations.
	ASU No. 2014-04
	In January 2014, the FASB issued ASU No. 2014-04, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure, which clarifies when an insubstance repossession or foreclosure occurs, that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. The ASU requires a creditor to reclassify a collateralized consumer mortgage loan to real estate property upon obtaining legal title to the residential real estate property, or the borrower conveying all interest in the residential real estate property through completion of a deed in lieu of foreclosure or similar legal agreement. The provisions of this ASU are effective for all periods beginning after December 15, 2014. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations.
	ASU No. 2014-09
	In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 205): An Amendment of the FASB Accounting Standards Codification, which clarifies the principles for recognizing revenue from contracts with customers. The new accounting guidance, which does not apply to financial instruments, is effective on a retrospective basis for annual reporting periods beginning after December 15, 2016, with early adoption not permitted. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.
	ASU No. 2014-11
	In June 2014, the FASB issued ASU No. 2014-11 Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures, which requires separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty that will result in secured borrowing accounting for the repurchase agreement. The ASU requires new disclosures for repurchase agreements, securities lending transactions and repurchase-to-maturity transactions that are accounted for as secured borrowings. These disclosures include information about the types of assets pledged and the relationship between those assets and the related obligation to return the proceeds. The ASU also requires new disclosures for transfers of financial assets that are accounted for as sales that involve an agreement with the transferee entered into in contemplation of the initial transfer that result in the transferor retaining substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The accounting and disclosure changes are effective for annual periods beginning after December 15, 2014. The Company is evaluating the adoption of this ASU and has not determined the impact on the Company’s financial condition or results of operations.
	ASU No. 2014-12
	In June 2014, the FASB issued ASU No. 2014-12 Compensation-Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could be Achieved after the Requisite Service Period, which requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is intended to resolve the diverse accounting treatments of these types of awards in practice and is effective for annual and interim periods beginning after December 15, 2015. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.
	ASU No. 2014-13
	In August 2014, the FASB issued ASU No. 2014-13, Consolidation (Topic 810): Measuring the Financial Assets and Financial Liabilities of a Consolidated Collateralized Financing Entity, which will allow an alternative fair value measurement approach for consolidated collateralized financing entities (CFEs) to eliminate a practice issue that results in measuring the fair value of a CFE’s financial assets at a different amount from the fair value of its financial liabilities even when the financial liabilities have recourse to only the financial assets. The approach would permit the parent company of a consolidated CFE to measure the CFE’s financial assets and financial liabilities based on the more observable of the fair value of the financial assets and the fair value of the financial liabilities. The new accounting guidance is for the annual period ending after December 15, 2015, and for annual periods and interim periods thereafter, with early application permitted as of the beginning of an annual period. The Company does not expect the new guidance to have a material impact on the Company’s financial condition or results of operations.
	ASU No. 2014-14
	In August 2014, the FASB issued ASU No. 2014-14, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure, which will require creditors to derecognize certain foreclosed government-guaranteed mortgage loans and to recognize a separate other receivable that is measured at the amount the creditor expects to recover from the guarantor, and to treat the guarantee and the receivable as a single unit of account. The new accounting guidance is effective on a prospective or a modified retrospective transition method for annual reporting periods, and interim periods within those annual periods, beginning after December 15, 2014, with early adoption permitted. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.
	ASU No. 2014-15
	In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which will require management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards in connection with preparing financial statements for each annual and interim reporting period. The new accounting guidance is for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter, with early application permitted. The Company does not expect the new guidance to have a material impact on the Company's financial condition or results of operations.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Estimated Useful Life of Assets	Depreciation is computed using the straight-line method over the estimated life of each respective type of asset as follows:
		Buildings	40 years
		Furniture, fixtures, and equipment	5	-	15 years

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Income Per Common Share	The following sets forth the computation of basic net income per common share and diluted net income per common share:
		Year Ended December 31,
	(In thousands, except per share data)	2014		2013		2012
	Basic: Income available to common shareholders	$	54,144	$	38,584	$	26,431
	Weighted-average common shares outstanding	18,541		16,204		12,953
	Basic earnings per share	$	2.92	$	2.38	$	2.04
	Diluted: Income attributable to common shareholders	$	54,144	$	38,584	$	26,431
	Weighted-average common shares outstanding	18,541		16,204		12,953
	Effect of dilutive securities:
	Stock options outstanding	389		337		109
	Warrants	119		83		52
	Weighted-average common shares outstanding – assuming dilution	19,049		16,624		13,114
	Diluted earnings per share	$	2.84	$	2.32	$	2.02

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Summary of Amortized Cost and Market Values of Investment Securities with Gross Unrealized Gains and Losses	The amortized cost and market values of investment securities, with gross unrealized gains and losses, as of December 31, 2014 and December 31, 2013, were as follows (in thousands):
		31-Dec-14
		Amortized			Gross			Gross Unrealized Losses								Estimated
		Cost			Unrealized											Market Value
					Gains			Less Than				Greater Than
								One Year				One Year
	Available for sale:
	U.S. government agency securities	$	161,461		$	891		$	—			$	(4,825	)		$	157,527
	U.S. Treasury securities	13,019			—			—				(409		)		12,610
	Municipal securities	12,175			107			(36		)		—				12,246
	Mortgage-backed securities	57,025			635			(137		)		(436		)		57,087
	Corporate bonds	8,263			—			—				(86		)		8,177
		$	251,943		$	1,633		$	(173	)		$	(5,756	)		$	247,647
	Held to maturity:
	Municipal securities	$	41,255		$	2,182		$	(62	)		$	—			$	43,375
	Mortgage-backed securities	47,821			1,098			(208		)		(1,130		)		47,581
		$	89,076		$	3,280		$	(270	)		$	(1,130	)		$	90,956
		31-Dec-13
		Amortized			Gross			Gross Unrealized Losses								Estimated
		Cost			Unrealized											Market Value
					Gains			Less Than				Greater Than
								One Year				One Year
	Available for sale:
	U.S. government agency securities	$	163,964		$	81		$	(10,991	)		$	(1,731	)		$	151,323
	U.S. Treasury securities	13,022			—			(873		)		—				12,149
	Municipal securities	23,240			140			(213		)		—				23,167
	Mortgage-backed securities	57,010			447			(1,897		)		(16		)		55,544
	Corporate bonds	37,023			395			(1,677		)		(205		)		35,536
		$	294,259		$	1,063		$	(15,651	)		$	(1,952	)		$	277,719
	Held to maturity:
	Municipal securities	$	44,294		$	94		$	(398	)		$	—			$	43,990
	Mortgage-backed securities	50,610			12			(3,646		)		—				46,976
		$	94,904		$	106		$	(4,044	)		$	—			$	90,966
Summary of Investment Security Issuers	At December 31, 2014, the Company’s exposure to three investment security issuers individually exceeded 10% of shareholders’ equity (in thousands):
		Amortized			Estimated
		Cost			Market Value
	Federal National Mortgage Association (Fannie Mae)	$	92,205		$	90,366
	Federal Home Loan Bank (FHLB)	74,442			73,623
	Federal Home Loan Mortgage Corporation (Freddie Mac)	55,979			54,875
		$	222,626		$	218,864
Summary of Amortized Cost and Estimated Market Values by Contractual Maturity of Investment Securities	The amortized cost and estimated market values by contractual maturity of investment securities as of December 31, 2014 and December 31, 2013 are shown in the following table (in thousands). Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.
		31-Dec-14									31-Dec-13
		Weighted		Amortized			Estimated				Weighted			Amortized				Estimated
		Average		Cost			Market Value				Average			Cost				Market Value
		Yield									Yield
	Available for sale:
	Due in one year or less	1.78	%	$	571		$	573			1.39	%		$	12,340			$	12,368
	Due after one year through five years	2.64		51,037			51,916				2.58			64,790				65,038
	Due after five years through ten years	2.02		176,631			172,012				2.12			180,362				168,243
	Due after ten years	3.34		23,704			23,146				3.17			36,767				32,070
	Total securities	2.27	%	$	251,943		$	247,647			2.3	%		$	294,259			$	277,719
	Held to maturity:
	Due in one year or less	3.88	%	$	2,045		$	2,003			1.76	%		$	1,007			$	1,007
	Due after one year through five years	4.16		20,921			21,875				2.6			18,101				17,539
	Due after five years through ten years	3.39		32,618			33,898				3.7			37,591				37,137
	Due after ten years	3.3		33,492			33,180				3.41			38,205				35,283
	Total securities	3.55	%	$	89,076		$	90,956			3.35	%		$	94,904			$	90,966
Summary of Securities in Other Assets, at Cost	At December 31, 2014 and 2013, the Company included the following securities in other assets, at cost, in the accompanying consolidated balance sheets (in thousands):
		2014			2013
	FHLB stock	$	1,347		$	1,099
	First National Bankers Bankshares, Inc. (FNBB) stock	600			600
	Other investments	5,233			4,853
	Total equity securities	$	7,180		$	6,552

Loans_Tables

Loans (Tables)	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Summary of Major Classifications of Loans	Major classifications of loans at December 31, 2014 and December 31, 2013 were as follows (in thousands):
		31-Dec-14				31-Dec-13
	Commercial real estate loans:
	Construction	$	316,492			$	203,369
	Mortgage(1)	1,252,225				1,118,048
		1,568,717				1,321,417
	Consumer real estate loans:
	Construction	10,393				8,986
	Mortgage	131,031				115,307
		141,424				124,293
	Commercial and industrial loans	1,016,414				868,469
	Loans to individuals, excluding real estate	18,316				16,345
	Nonaccrual loans	21,228				16,396
	Other loans	8,165				10,857
		2,774,264				2,357,777
	Less allowance for loan losses	(42,336		)		(32,143		)
	Loans, net	$	2,731,928			$	2,325,634
	-1	Included in commercial real estate loans, mortgage, are owner-occupied real estate loans, of $419.3 million at December 31, 2014 and $364.9 million at December 31, 2013.
	These loans were classified in the Company's loan portfolio at December 31, 2014 and December 31, 2013 as follows (in thousands):
		December 31, 2014				December 31, 2013
	Construction	$	80,741			$	10,686
	Commercial real estate	67,520				49,017
	Commercial and industrial	117,191				105,944
	Total loans	$	265,452			$	165,647
Summary of Changes in Allowance for Loan Losses	A summary of changes in the allowance for loan losses during the years ended December 31, 2014, 2013, and 2012 is as follows (in thousands):
		2014				2013				2012
	Balance, beginning of period	$	32,143			$	26,977			$	18,122
	Provision charged to operations	12,000				9,800				11,035
	Charge-offs	(1,929		)		(4,769		)		(2,561		)
	Recoveries	122				135				381
	Balance, end of period	$	42,336			$	32,143			$	26,977
Summary of Allowance for Loan Losses and Recorded Investment in Loans	The allowance for loan losses and recorded investment in loans, including loans acquired with deteriorated credit quality as of the dates indicated are as follows (in thousands):
		31-Dec-14
		Construction				Commercial				Consumer			Commercial			Consumer			Total
						Real Estate				Real Estate			and
													Industrial
	Allowance for loan losses:
	Balance, beginning of period	$	2,790			$	13,780			$	2,656		$	12,677		$	240		$	32,143
	Charge-offs	(18		)		(1,034		)		(63		)	(648		)	(166		)	(1,929		)
	Recoveries	30				—				—			71			21			122
	Provision	1,228				2,219				723			7,714			116			12,000
	Balance, end of period	$	4,030			$	14,965			$	3,316		$	19,814		$	211		$	42,336
	Ending balances:
	Individually evaluated for impairment	$	—			$	3,138			$	—		$	5,889		$	1		$	9,028
	Collectively evaluated for impairment	$	4,030			$	11,827			$	3,316		$	13,925		$	210		$	33,308
	Loans receivable:
	Ending balance-total	$	327,677			$	1,264,371			$	132,950		$	1,030,629		$	18,637		$	2,774,264
	Ending balances:
	Individually evaluated for impairment	$	927			$	13,130			$	2,085		$	15,157		$	259		$	31,558
	Collectively evaluated for impairment	$	326,750			$	1,251,241			$	130,865		$	1,015,472		$	18,378		$	2,742,706
		31-Dec-13
		Construction				Commercial				Consumer			Commercial			Consumer			Total
						Real Estate				Real Estate			and
													Industrial
	Allowance for loan losses:
	Balance, beginning of period	$	2,004			$	10,716			$	2,450		$	11,675		$	132		$	26,977
	Charge-offs	(46		)		(292		)		—			(4,229		)	(202		)	(4,769		)
	Recoveries	—				19				30			68			18			135
	Provision	832				3,337				176			5,163			292			9,800
	Balance, end of period	$	2,790			$	13,780			$	2,656		$	12,677		$	240		$	32,143
	Ending balances:
	Individually evaluated for impairment	$	42			$	1,639			$	183		$	2,091		$	—		$	3,955
	Collectively evaluated for impairment	$	2,748			$	12,141			$	2,473		$	10,586		$	240		$	28,188
	Loans receivable:
	Ending balance-total	$	212,430			$	1,128,181			$	117,653		$	883,111		$	16,402		$	2,357,777
	Ending balances:
	Individually evaluated for impairment	$	309			$	9,811			$	2,990		$	4,005		$	—		$	17,115
	Collectively evaluated for impairment	$	212,121			$	1,118,370			$	114,663		$	879,106		$	16,402		$	2,340,662
Summary of Credit Quality Indicators on Company's Loan Portfolio	Credit quality indicators on the Company’s loan portfolio, including loans acquired with deteriorated credit quality, as of the dates indicated were as follows (in thousands):
		31-Dec-14
		Pass and				Special				Substandard			Doubtful			Total
		Pass/Watch				Mention
	Construction	$	313,987			$	2			$	13,688		$	—		$	327,677
	Commercial real estate	1,215,673				1,613				47,085			—			1,264,371
	Consumer real estate	128,507				60				4,383			—			132,950
	Commercial and industrial	1,005,829				—				24,800			—			1,030,629
	Consumer	18,247				7				383			—			18,637
	Total loans	$	2,682,243			$	1,682			$	90,339		$	—		$	2,774,264
		December 31, 2013
		Pass and				Special				Substandard			Doubtful			Total
		Pass/Watch				Mention
	Construction	$	197,951			$	4			$	14,475		$	—		$	212,430
	Commercial real estate	1,073,339				1,720				53,122			—			1,128,181
	Consumer real estate	113,037				185				4,431			—			117,653
	Commercial and industrial	873,547				17				9,547			—			883,111
	Consumer	16,251				9				142			—			16,402
	Total loans	$	2,274,125			$	1,935			$	81,717		$	—		$	2,357,777
Age Analysis of Past Due Loans Including Loans Acquired with Deteriorated Credit Quality	Age analysis of past due loans, including loans acquired with deteriorated credit quality, as of the dates indicated were as follows (in thousands):
		31-Dec-14
		Greater Than				90 Days and				Total Past			Current Loans			Total Loans
		30 and Fewer				Greater				Due
		Than 90 Days				Past Due
		Past Due
	Real estate loans:
	Construction	$	97			$	750			$	847		$	326,830		$	327,677
	Commercial real estate	2,497				9,545				12,042			1,252,329			1,264,371
	Consumer real estate	1,623				1,255				2,878			130,072			132,950
	Total real estate loans	4,217				11,550				15,767			1,709,231			1,724,998
	Other loans:
	Commercial and industrial	159				4,426				4,585			1,026,044			1,030,629
	Consumer	564				322				886			17,751			18,637
	Total other loans	723				4,748				5,471			1,043,795			1,049,266
	Total loans	$	4,940			$	16,298			$	21,238		$	2,753,026		$	2,774,264
		December 31, 2013
		Greater Than				90 Days and				Total Past			Current Loans			Total Loans
		30 and Fewer				Greater				Due
		Than 90 Days				Past Due
		Past Due
	Real estate loans:
	Construction	$	15			$	75			$	90		$	212,340		$	212,430
	Commercial real estate	2,935				7,642				10,577			1,117,604			1,128,181
	Consumer real estate	1,260				2,166				3,426			114,227			117,653
	Total real estate loans	4,210				9,883				14,093			1,444,171			1,458,264
	Other loans:
	Commercial and industrial	3,076				1,281				4,357			878,754			883,111
	Consumer	488				207				695			15,707			16,402
	Total other loans	3,564				1,488				5,052			894,461			899,513
	Total loans	$	7,774			$	11,371			$	19,145		$	2,338,632		$	2,357,777
Summary of Information Pertaining to Impaired Loans	The following is a summary of information pertaining to impaired loans, which consist primarily of nonaccrual loans. This table excludes loans acquired with deteriorated credit quality. Acquired impaired loans are generally not subject to individual evaluation for impairment and are not reported with impaired loans or troubled debt restructurings, even if they would otherwise qualify for such treatment. Impaired loans as of the periods indicated were as follows (in thousands):
		31-Dec-14
		Recorded				Contractual				Related			Average			Interest
		Investment				Balance				Allowance			Recorded			Income
													Investment			Recognized
	With no related allowance recorded:
	Construction	$	927			$	927			$	—		$	464		$	39
	Commercial real estate	7,175				7,453				—			5,718			109
	Consumer real estate	2,085				2,097				—			2,029			18
	Commercial and industrial	436				498				—			768			22
	Consumer	256				256				—			128			6
	Total	$	10,879			$	11,231			$	—		$	9,107		$	194
	With an allowance recorded:
	Construction	$	—			$	—			$	—		$	—		$	—
	Commercial real estate	5,955				6,235				3,138			5,753			79
	Consumer real estate	—				—				—			509			—
	Commercial and industrial	14,721				14,774				5,889			8,814			310
	Consumer	3				3				1			2			—
	Total	$	20,679			$	21,012			$	9,028		$	15,078		$	389
	Total impaired loans:
	Construction	$	927			$	927			$	—		$	464		$	39
	Commercial real estate	13,130				13,688				3,138			11,471			188
	Consumer real estate	2,085				2,097				—			2,538			18
	Commercial and industrial	15,157				15,272				5,889			9,582			332
	Consumer	259				259				1			130			6
	Total	$	31,558			$	32,243			$	9,028		$	24,185		$	583
		31-Dec-13
		Recorded				Contractual				Related			Average			Interest
		Investment				Balance				Allowance			Recorded			Income
													Investment			Recognized
	With no related allowance recorded:
	Construction	$	—			$	—			$	—		$	24		$	—
	Commercial real estate	4,261				4,469				—			3,063			110
	Consumer real estate	1,973				1,999				—			1,254			—
	Commercial and industrial	1,099				1,116				—			977			40
	Total	$	7,333			$	7,584			$	—		$	5,318		$	150
	With an allowance recorded:
	Construction	$	309			$	309			$	42		$	530		$	23
	Commercial real estate	5,550				7,428				1,639			4,445			59
	Consumer real estate	1,017				1,046				183			831			21
	Commercial and industrial	2,906				2,941				2,091			8,093			10
	Total	$	9,782			$	11,724			$	3,955		$	13,899		$	113
	Total impaired loans:
	Construction	$	309			$	309			$	42		$	554		$	23
	Commercial real estate	9,811				11,897				1,639			7,508			169
	Consumer real estate	2,990				3,045				183			2,085			21
	Commercial and industrial	4,005				4,057				2,091			9,070			50
	Total	$	17,115			$	19,308			$	3,955		$	19,217		$	263
Summary of Nonaccrual Loans	A summary of information pertaining to nonaccrual loans as of the periods indicated is as follows (in thousands):
		2014				2013
	Nonaccrual loans:
	Construction	$	792			$	75
	Commercial real estate	12,146				10,133
	Consumer real estate	1,919				2,347
	Commercial and industrial	6,051				3,784
	Consumer	320				57
		$	21,228			$	16,396
Changes in Carrying Amount of Accretable Yield for Purchased Credit Impaired Loans Acquired	The following is a summary of changes in the accretable yields of acquired loans as of the years ended December 31, 2014 and 2013 (in thousands):
		2014				2013
	Balance, beginning of period	$	170			$	628
	Acquisition	—				—
	Net transfers from nonaccretable difference to accretable yield	815				45
	Accretion	(871		)		(503		)
	Balance, end of period	$	114			$	170
Summary of Company's TDRs	Information about the Company’s TDRs as of December 31, 2014 and December 31, 2013, is presented in the following tables (in thousands):
	Year Ended December 31, 2014	Current				Greater Than 30				Nonaccrual			Total TDRs
						Days Past Due				TDRs
	Real estate loans:
	Construction	$	233			$	—			$	—		$	233
	Commercial real estate	349				—				1,960			2,309
	Consumer real estate	604				—				132			736
	Total real estate loans	1,186				—				2,092			3,278
	Other loans:
	Commercial and industrial	385				—				—			385
	Total loans	$	1,571			$	—			$	2,092		$	3,663
	Year Ended December 31, 2013	Current				Greater Than 30				Nonaccrual			Total TDRs
						Days Past Due				TDRs
	Real estate loans:
	Construction	$	309			$	—			$	—		$	309
	Commercial real estate	357				—				102			459
	Consumer real estate	625				—				136			761
	Total real estate loans	1,291				—				238			1,529
	Other loans:
	Commercial and industrial	337				—				—			337
	Total loans	$	1,628			$	—			$	238		$	1,866
Summary of Information on TDRs Modification	The following table provides information on how the TDRs were modified during the years ended December 31, 2014 and 2013 (in thousands):
		2014				2013
	Maturity and interest rate adjustment	$	2,536			$	925
	Movement to or extension of interest rate-only payments	833				597
	Other concessions(1)	294				344
	Total	$	3,663			$	1,866
	-1	Other concessions include concessions or a combination of concessions, other than maturity extensions and interest rate adjustments.
Summary of Information Pertaining to Modified Terms of Loans	A summary of information pertaining to modified terms of loans, as of the dates indicated, is as follows (in thousands):
		31-Dec-14
		Number of			Pre-				Post-
		Contracts			Modification				Modification
					Outstanding				Outstanding
					Recorded				Recorded
					Investment				Investment
	Troubled debt restructuring:
	Construction	4			$	233			$	233
	Commercial real estate	3			2,309				2,309
	Consumer real estate	3			736				736
	Commercial and industrial	2			385				385
		12			$	3,663			$	3,663
		December 31, 2013
		Number of			Pre-Modification				Post-
		Contracts			Outstanding				Modification
					Recorded				Outstanding
					Investment				Recorded
									Investment
	Troubled debt restructuring:
	Construction	2			$	309			$	309
	Commercial real estate	3			459				459
	Consumer real estate	3			761				761
	Commercial and industrial	1			337				337
		9			$	1,866			$	1,866

Premises_and_Equipment_Tables

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of Premises and Equipment	Premises and equipment consisted of the following at December 31 (in thousands):
		2014		2013
	Buildings and leasehold improvements	$	38,569	$	35,765
	Land	10,401		10,399
	Furniture, fixtures, and equipment	15,462		13,773
	Construction in progress	1,663		1,542
	Total premises and equipment	66,095		61,479
	Less accumulated depreciation and amortization	13,214		10,305
	Total premises and equipment, net	$	52,881	$	51,174

Goodwill_and_Other_Acquired_In1

Goodwill and Other Acquired Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Changes to Carrying Amount of Goodwill	Changes to the carrying amount of goodwill for the years ended December 31, 2014 and 2013 are provided in the following table (in thousands):
	Balance at December 31, 2012	$	4,808
	Goodwill acquired during the year	—
	Balance at December 31, 2013	4,808
	Goodwill acquired during the year	—
	Balance at December 31, 2014	$	4,808
Schedule of Definite-lived Intangible Assets Amortization Expense	Definite-lived intangible assets had the following carrying values as of December 31 (in thousands):
		2014						2013
		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	Core deposit intangibles	$	4,400	$	1,485	$	2,915	$	4,400	$	883	$	3,517
	Total definite-lived intangible assets	$	4,400	$	1,485	$	2,915	$	4,400	$	883	$	3,517
Schedule of Finite Lived Intangible Assets Future Amortization Expense	The estimated aggregate amortization expense for the core deposit intangible asset is as follows as of December 31, 2014 (in thousands):
	2015-2019	$	367
	2020 and thereafter	1,080

Investments_in_Tax_Credit_Enti1

Investments in Tax Credit Entities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
Investment Holdings, Schedule of Investments	The tables below set forth the Company's investment in Federal NMTC, State NMTC, Federal Low-Income Housing, Federal Historic Rehabilitation, and State Historic Rehabilitation tax credits, along with the credits expected to be generated through its participation in these programs as of December 31, 2014 and December 31, 2013 (in thousands):
			31-Dec-14
			Investment			Accumulated Amortization				Loans to Investment Funds(1)			Elimination			Net Investment		Tax Benefits Recognized Through December 31, 2013		Tax Benefits Recognized in 2014		Tax Benefits to be Recognized in 2015, and Thereafter		Total Tax Benefits Expected to be Recognized
	NMTC:
	Federal:
	Non-Bank Owned CDEs		$	162,192		$	(15,852	)		$	(120,540	)	$	—		$	25,800	$	27,213	$	9,367	$	25,945	$	62,525
	Bank Owned CDEs(2)		118,000			—				—			(118,000		)	—		10,375		6,115		29,530		46,020
	Bank Owned CDE Equity Investment(3)		5,700			—				—			—			5,700		—		—		—		—
	Total Bank Owned CDEs		123,700			—				—			(118,000		)	5,700		10,375		6,115		29,530		46,020
	State		28,227			—				—			—			28,227		—		—		—		—
	Total NMTC		314,119			(15,852		)		(120,540		)	(118,000		)	59,727		37,588		15,482		55,475		108,545
	Low-Income Housing		43,733			(7,264		)		—			—			36,469		9,546		3,642		42,109		55,297
	Historic Rehabilitation:
	Federal(4)		41,794			(3,412		)		—			—			38,382		17,823		19,321		37,295		74,439
	State		6,335			—				—			—			6,335		—		—		—		—
	Total Historic Rehabilitation		48,129			(3,412		)		—			—			44,717		17,823		19,321		37,295		74,439
	Total		$	405,981		$	(26,528	)		$	(120,540	)	$	(118,000	)	$	140,913	$	64,957	$	38,445	$	134,879	$	238,281
	(1) Interest only loan made to the investment fund during the compliance period for Federal NMTC.
	(2) Through December 31, 2014, FNBC CDE received allocations of Federal NMTC from the CDFI Fund of the U.S. Treasury totaling $118.0 million over a three year period beginning in 2011. These investments are eliminated upon consolidation by the Company.
	(3) The Company made an equity investment of $5.7 million in various Federal NMTC projects. This investment generated Federal NMTC. For its equity investment, the Company is a limited partner and will have the right to share in the activity of the Partnership.
	(4) As of December 31, 2014, the Company had $12.6 million invested in Federal Historic Rehabilitation Tax Credit projects which the Company expects to generate Federal Historic Rehabilitation Tax Credits in 2015 and 2016 when the projects are completed, receive the certificates of occupancy, and the property is placed in service. The amount of tax credits to be received will be determined when the costs are certified.
			31-Dec-13
			Investment			Accumulated Amortization				Loans to Investment Funds(1)			Elimination			Net Investment		Tax Benefits Recognized Through December 31, 2012		Tax Benefits Recognized in 2013		Tax Benefits to be Recognized in 2014, and Thereafter		Total Tax Benefits Expected to be Recognized
	NMTC:
	Federal:
	Non-Bank Owned CDEs		$	155,412		$	(9,328	)		$	(115,590	)	$	—		$	30,494	$	18,889	$	8,324	$	33,362	$	60,575
	Bank Owned CDEs(2)		118,000			—				—			(118,000		)	—		4,475		5,900		35,645		46,020
	Bank Owned CDE Equity Investment(3)		5,700			—				—			—			5,700		—		—		—		—
	Total Bank Owned CDEs		123,700			—				—			(118,000		)	5,700		4,475		5,900		35,645		46,020
	State		24,000			—				—			—			24,000		—		—		—		—
	Total NMTC		303,112			(9,328		)		(115,590		)	(118,000		)	60,194		23,364		14,224		69,007		106,595
	Low-Income Housing		45,072			(5,078		)		—			—			39,994		5,846		3,700		47,438		56,984
	Historic Rehabilitation:
	Federal		13,870			(1,586		)		—			—			12,284		7,326		10,497		—		17,823
	State		5,212			—				—			—			5,212		—		—		—		—
	Total Historic Rehabilitation		19,082			(1,586		)		—			—			17,496		7,326		10,497		—		17,823
	Total		$	367,266		$	(15,992	)		$	(115,590	)	$	(118,000	)	$	117,684	$	36,536	$	28,421	$	116,445	$	181,402
	(1) Interest only loan made to the investment fund during the compliance period for Federal NMTC.
	(2) Through December 31, 2013, FNBC CDE received allocations of Federal NMTC from the CDFI Fund of the U.S. Treasury totaling $118.0 million over a three year period beginning in 2011. These investments are eliminated upon consolidation by the Company.
	(3) The Company made an equity investment of $5.7 million in various Federal NMTC projects. This investment generated Federal NMTC. For its equity investment, the Company is a limited partner and will have the right to share in the activity of the Partnership.
Schedule of Amortization of Credit Investments	The amortization of tax credit investments for the years ended December 31, 2014, 2013, and 2012 were as follows (in thousands):
		For the Years Ended
		December 31,
		2014			2013				2012
	Federal NMTC	$	10,048		$	5,923			$	3,094
	Low-Income Housing	2,186			1,900				1,287
	Federal Historic Rehabilitation	1,825			816				427
	Total amortization	$	14,059		$	8,639			$	4,808
Summary of Basis Reduction Recorded Related to Investments in Tax Credit Entities	The amount of basis reduction recorded related to the Company's investment in tax credit entities for the years ended December 31, 2014, 2013, and 2012 were as follows (in thousands):
		For the Years Ended
		December 31,
		2014			2013				2012
	Federal NMTC	$	1,401		$	2,019			$	2,416
	Federal Historic Rehabilitation	246			—				350
	Total basis reduction	$	1,647		$	2,019			$	2,766
Summary of Major Classifications of Loans	Major classifications of loans at December 31, 2014 and December 31, 2013 were as follows (in thousands):
		31-Dec-14			31-Dec-13
	Commercial real estate loans:
	Construction	$	316,492		$	203,369
	Mortgage(1)	1,252,225			1,118,048
		1,568,717			1,321,417
	Consumer real estate loans:
	Construction	10,393			8,986
	Mortgage	131,031			115,307
		141,424			124,293
	Commercial and industrial loans	1,016,414			868,469
	Loans to individuals, excluding real estate	18,316			16,345
	Nonaccrual loans	21,228			16,396
	Other loans	8,165			10,857
		2,774,264			2,357,777
	Less allowance for loan losses	(42,336		)	(32,143		)
	Loans, net	$	2,731,928		$	2,325,634
	-1	Included in commercial real estate loans, mortgage, are owner-occupied real estate loans, of $419.3 million at December 31, 2014 and $364.9 million at December 31, 2013.
	These loans were classified in the Company's loan portfolio at December 31, 2014 and December 31, 2013 as follows (in thousands):
		December 31, 2014			December 31, 2013
	Construction	$	80,741		$	10,686
	Commercial real estate	67,520			49,017
	Commercial and industrial	117,191			105,944
	Total loans	$	265,452		$	165,647

Deposits_Tables

Deposits (Tables)	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Summary of Scheduled Interest Bearing Deposits	Interest-bearing deposits at December 31, 2014 and 2013 consisted of the following (in thousands):
		2014		2013
	Savings deposits	$	49,634	$	53,779
	Money market accounts	1,055,505		655,173
	Negotiable order of withdrawal (NOW) accounts	476,825		511,620
	Certificates of deposit over $250,000	284,262		280,354
	Certificates of deposit under $250,000	890,090		938,801
	Total Deposits	$	2,756,316	$	2,439,727
Summary of Scheduled Maturities of Time Deposits	The certificates of deposit mature as follows as of December 31, 2014 (in thousands):
	2015	$	632,111
	2016	257,606
	2017	127,775
	2018	110,874
	2019	45,986
	Total certificates of deposit	$	1,174,352

ShortTerm_Borrowings_Tables

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Summary of Short-Term Borrowings	The following is a summary of short-term borrowings at December 31 (in thousands):
		2014		2013
	FNBB	$	—	$	8,425
	Total short-term borrowings	$	—	$	8,425
Summary of Unused Lines of Credit	The following is a summary of unused lines of credit at December 31 (in thousands):
		2014		2013
	FNBB	$	30,000	$	30,000
	JPMorgan Chase	30,000		30,000
	FHLB	563,213		432,181
	PNC Bank	15,000		15,000
	Comerica	10,000		10,000
	Total unused lines of credit	$	648,213	$	517,181

LongTerm_Borrowings_Tables

Long-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Summary of Long-Term Borrowings	The following is a summary of long-term borrowings at December 31 (in thousands):
		2014		2013
	FNBB	$	—	$	110
	Credit Suisse Securities (USA) LLC	40,000		55,000
	Total long-term borrowings	$	40,000	$	55,110
Summary of Principal Payments	Principal payments by year on these borrowings are as follows (in thousands):
	2019	$	40,000
	Total long-term borrowings	$	40,000

Derivative_Interest_Rate_Swap_1

Derivative - Interest Rate Swap Agreements (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	Information pertaining to outstanding derivative instruments is as follows (in thousands):
				Derivative Assets Fair Value									Derivative Liabilities Fair Value
		Balance Sheet Location		December 31, 2014				December 31, 2013				Balance Sheet Location	December 31, 2014		December 31, 2013
	Derivatives designated as hedging instruments under ASC Topic 815:
	Interest rate swaps - Counterparty A(1)	Other Assets		$	—			$	1,157			Other Liabilities	$	—	$	—
	Interest rate swaps - Counterparty B	Other Assets		—				—				Other Liabilities	15,995		2,046
	Interest rate-prime swaps - Counterparty B	Other Assets		3,042				—				Other Liabilities	—		2,271
	Interest rate swaps - Counterparty C	Other Assets		37				—				Other Liabilities	—		—
				$	3,079			$	1,157				$	15,995	$	4,317
	-1	Hedge was terminated during 2014.
Schedule of Derivative Assets Subject to Master Netting Arrangements	Net fair values of the Counterparty B delayed interest rate swap and Prime Hedges as of December 31, 2014 and 2013 are as follows (in thousands):
		31-Dec-14
		Gross Amounts Presented in the Balance Sheet				Gross Amounts Not Offset in the Balance Sheet
						Derivatives				Collateral			Net
	Derivatives subject to master netting arrangements:
	Derivative assets:
	Interest rate swaps	$	—			$	—			$	—		$	—
	Interest rate-prime swaps	3,042				—				—			3,042
		$	3,042			$	—			$	—		$	3,042
	Derivative liabilities:
	Interest rate swaps	$	15,995			$	—			$	—		$	15,995
	Interest rate-prime swaps	—				—				—			—
		$	15,995			—				—			$	15,995
	Net derivative liability	$	12,953			$	—			$	—		$	12,953
		31-Dec-13
		Gross Amounts Presented in the Balance Sheet				Gross Amounts Not Offset in the Balance Sheet
						Derivatives				Collateral			Net
	Derivatives subject to master netting arrangements:
	Derivative assets:
	Interest rate swaps	$	—			$	—			$	—		$	—
	Interest rate-prime swaps	—				—				—			—
		$	—			$	—			$	—		$	—
	Derivative liabilities:
	Interest rate swaps	$	2,046			$	—			$	—		$	2,046
	Interest rate-prime swaps	2,271				—				—			2,271
		$	4,317			—				—			$	4,317
	Net derivative liability	$	4,317			$	—			$	—		$	4,317
Schedule of Derivative Liabilities Subject to Master Netting Arrangements	Net fair values of the Counterparty B delayed interest rate swap and Prime Hedges as of December 31, 2014 and 2013 are as follows (in thousands):
		31-Dec-14
		Gross Amounts Presented in the Balance Sheet				Gross Amounts Not Offset in the Balance Sheet
						Derivatives				Collateral			Net
	Derivatives subject to master netting arrangements:
	Derivative assets:
	Interest rate swaps	$	—			$	—			$	—		$	—
	Interest rate-prime swaps	3,042				—				—			3,042
		$	3,042			$	—			$	—		$	3,042
	Derivative liabilities:
	Interest rate swaps	$	15,995			$	—			$	—		$	15,995
	Interest rate-prime swaps	—				—				—			—
		$	15,995			—				—			$	15,995
	Net derivative liability	$	12,953			$	—			$	—		$	12,953
		31-Dec-13
		Gross Amounts Presented in the Balance Sheet				Gross Amounts Not Offset in the Balance Sheet
						Derivatives				Collateral			Net
	Derivatives subject to master netting arrangements:
	Derivative assets:
	Interest rate swaps	$	—			$	—			$	—		$	—
	Interest rate-prime swaps	—				—				—			—
		$	—			$	—			$	—		$	—
	Derivative liabilities:
	Interest rate swaps	$	2,046			$	—			$	—		$	2,046
	Interest rate-prime swaps	2,271				—				—			2,271
		$	4,317			—				—			$	4,317
	Net derivative liability	$	4,317			$	—			$	—		$	4,317
Schedule of Effect of Hedging Instruments	At December 31, 2014 and 2013, and for the years then ended, information pertaining to the effect of the hedging instruments on the consolidated financial statements is as follows (in thousands):
		Amount of Gain (Loss) Recognized in OCI, net of taxes (Effective Portion)
		As of December 31,
	Derivatives in ASC Topic 815 Cash Flow Hedging Relationships:	2014				2013
	Interest rate swap with Counterparty A(1)	$	(5,946	)		$	5,207
	Interest rate swap and prime swaps with Counterparty B	(5,614		)		(2,806		)
	Interest rate swap with Counterparty C	24				—
	Total	$	(11,536	)		$	2,401
	-1	Hedge was terminated during 2014.

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Summary of Income Tax Benefit on Income from Operations	The income tax benefit on the income from operations for the years ended December 31, 2014, 2013, and 2012 was as follows (in thousands):
		2014			2013			2012
	Current tax expense	$	3,436		$	186		$	—
	Deferred tax benefit	(30,412		)	(19,937		)	(7,565		)
	Total tax benefit	$	(26,976	)	$	(19,751	)	$	(7,565	)
Schedule of Income Taxes Reconciliation with Federal Statutory Rates	The amount of taxes in the accompanying consolidated statements of income differs from the expected amount using the statutory federal income tax rates primarily due to the effect of various tax credits. An analysis of those differences for the years ended December 31, 2014, 2013, and 2012 are presented below (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Federal tax expense at statutory rates	$	10,015		$	7,406		$	7,481
	Tax credits(1)	(38,445		)	(28,421		)	(17,100		)
	Tax credit-basis reduction	1,647			2,019			2,767
	Other tax credits	(617		)	—			—
	Tax-exempt income	(87		)	(1,070		)	(918		)
	Disallowed interest expense	98			117			99
	Other	413			198			106
	Income tax benefit	$	(26,976	)	$	(19,751	)	$	(7,565	)
	-1	As discussed in Note 12, the Company earns Federal NMTC, Federal Historic Rehabilitation, and Low-Income Housing tax credits, which reduce the Company’s federal income tax liability or creates a carryforward as applicable.
Summary of Significant Components of Deferred Tax Assets and Liabilities	The components of the Company’s deferred tax assets and liabilities as of December 31 are presented below (in thousands):
		Year Ended December 31,
		2014			2013
	Deferred tax assets:
	Loan loss reserve	$	14,817		$	11,250
	Tax credit carryforwards	94,490			65,216
	NOL carryforward	7,271			7,317
	Stock-based compensation	824			684
	Deferred compensation	91			91
	Securities available for sale	10,615			8,880
	Other real estate	263			250
	Basis difference in assumed liabilities	140			338
	Other	621			373
	Total deferred tax assets	129,132			94,399
	Deferred tax liabilities:
	Fixed assets	7,190			6,546
	Deferred loan costs	6,296			5,157
	Amortizable costs	1,388			1,477
	State tax credits	1,614			1,155
	Investments in tax credit entities	28,625			28,097
	Other	558			776
	Total deferred tax liabilities	45,671			43,208
	Net deferred tax assets	$	83,461		$	51,191

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Annualized Dividend Rate	The dividend rate, as a percentage of the liquidation amount, fluctuates, while the Series D preferred stock is outstanding based upon changes in the level of qualified small business lending (QSBL) by the Company from its average level of QSBL at each of the four quarter-ends leading up to June 30, 2010 (Baseline), as follows:
		Dividend Period
		Beginning	Ending	Annualized Dividend Rate
		January 1, 2012	March 31, 2012	1.00%
		April 1, 2012	June 30, 2012	1.00%
		July 1, 2012	31-Dec-13	1.000% to 5.000%
		January 1, 2014	February 3, 2016	1.000% to 7.000%
		February 4, 2016	Redemption	9.00%

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive income (loss) and changes in those components are presented in the following table (in thousands):
		Cash Flow			Terminated Cash Flow Hedge (2)			Transfers of			Available for			Total
		Hedges (1)						Available for			Sale
								Sale			Securities
								Securities to
								Held to
								Maturity
	Balance at January 1, 2014	$	(2,054	)	$	—		$	(3,710	)	$	(10,751	)	$	(16,515	)
	Other comprehensive income before income taxes:
	Net change in unrealized gain (loss)	(9,757		)	(7,990		)	—			12,379			(5,368		)
	Reclassification of net gains realized and included in earnings	—			—			—			(135		)	(135		)
	Amortization of unrealized net gain	—			—			547			—			547
	Income tax expense (benefit)	(3,415		)	(2,796		)	191			4,286			(1,734		)
	Balance at December 31, 2014	$	(8,396	)	$	(5,194	)	$	(3,354	)	$	(2,793	)	$	(19,737	)
		Cash Flow			Terminated Cash Flow Hedge (2)			Transfers of			Available for			Total
		Hedges (1)						Available for			Sale
								Sale			Securities
								Securities to
								Held to
								Maturity
	Balance at January 1, 2013	$	(4,455	)	$	—		$	—		$	1,529		$	(2,926	)
	Other comprehensive income before income taxes:
	Net change in unrealized gain (loss)	3,694			—			(5,919		)	(18,576		)	(20,801		)
	Reclassification of net gains realized and included in earnings	—			—			—			(316		)	(316		)
	Amortization of unrealized net gain	—			—			211			—			211
	Income tax expense (benefit)	1,293			—			(1,998		)	(6,612		)	(7,317		)
	Balance at December 31, 2013	$	(2,054	)	$	—		$	(3,710	)	$	(10,751	)	$	(16,515	)
	Balance at January 1, 2012	$	—		$	—		$	—		$	1,795		$	1,795
	Other comprehensive income before income taxes:
	Net change in unrealized gain (loss)	(6,854		)	—			—			3,956			(2,898		)
	Reclassification of net gains realized and included in earnings	—			—			—			(4,324		)	(4,324		)
	Income tax benefit	(2,399		)	—			—			(102		)	(2,501		)
	Balance at December 31, 2012	$	(4,455	)	$	—		$	—		$	1,529		$	(2,926	)
	(1) Balances in the Cash Flow Hedge column represent the net operating changes in all of the Company's cash flow hedge relationships as of the dates above.
	(2) Balances in the Terminated Cash Flow Hedge column represent the net unrealized loss at termination of a certain cash flow hedge relationship. See Note 18 for further explanation on the terminated cash flow hedge.

Capital_Requirements_and_Other1

Capital Requirements and Other Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Summary of Capital Amounts and Ratios	The following tables present the actual capital amounts and regulatory capital ratios for the Company and the Bank as of December 31, 2014 and 2013 (in thousands):
		31-Dec-14
		Actual				For Capital Adequacy				To Be Well Capitalized
						Purposes				Under Prompt Corrective
										Action Provisions
		Amount		Ratio		Amount		Ratio		Amount		Ratio
	Tier 1 leverage capital:
	First NBC Bank Holding Company	$	387,224	10.66	%	$	145,320	4	%	NA		NA
	First NBC Bank	361,078		9.95	%	145,130		4	%	$	181,412	5	%
	Tier 1 risk-based capital:
	First NBC Bank Holding Company	$	387,224	11.59	%	133,644		4	%	NA		NA
	First NBC Bank	361,078		10.82	%	133,528		4	%	$	200,292	6	%
	Total risk-based capital:
	First NBC Bank Holding Company	$	428,962	12.84	%	267,289		8	%	NA		NA
	First NBC Bank	402,816		12.07	%	267,056		8	%	$	333,820	10	%
		31-Dec-13
		Actual				For Capital Adequacy				To Be Well Capitalized
						Purposes				Under Prompt Corrective
										Action Provisions
		Amount		Ratio		Amount		Ratio		Amount		Ratio
	Tier 1 leverage capital:
	First NBC Bank Holding Company	$	375,355	11.76	%	$	127,625	4	%	NA		NA
	First NBC Bank	349,104		10.96	%	127,435		4	%	$	159,294	5	%
	Tier 1 risk-based capital:
	First NBC Bank Holding Company	$	375,355	13.26	%	113,254		4	%	NA		NA
	First NBC Bank	349,104		12.34	%	113,170		4	%	$	169,755	6	%
	Total risk-based capital:
	First NBC Bank Holding Company	$	407,648	14.4	%	226,508		8	%	NA		NA
	First NBC Bank	381,396		13.48	%	226,340		8	%	$	282,924	10	%

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Unvested Restricted Stock Activity	The following table represents unvested restricted stock activity for the year ended December 31, 2014:
			Number			Weighted-Average Grant Date Fair Value
			of Shares
	Balance, beginning of year		—			$	—
	Granted		13,021			34.32
	Forfeited		(129	)		34.35
	Balance, end of year		12,892			$	34.32
Summary of Weighted-Average Assumptions Used for Option Awards Granted	The Company uses the Black-Scholes option pricing model to estimate the fair value of the stock options awards. The following weighted-average assumptions were used for option awards granted during the years ended December 31 of the periods indicated:
			2014				2013				2012
	Expected dividend yield		—	%			—	%			—	%
	Weighted-average expected volatility		44.53	%			36.68	%			35.33	%
	Weighted-average risk-free interest rate		2.21	%			1.73	%			1.25	%
	Expected option term (in years)		6				6				6.3
	Contractual term (in years)		10				10				10
	Weighted-average grant date fair value	$	15.56			$	5.22			$	5.49
Summary of Stock Option Activity	The following table represents the activity related to stock options during the periods indicated:
		Number			Weighted-				Weighted-
		of Shares			Average				Average
					Exercise				Remaining
					Price				Contractual
									Term (Years)
	Options outstanding, December 31, 2011	443,658			$	11.11
	Granted	378,692			14.69
	Exercised	—			—
	Forfeited or expired	(13,333	)		14.43
	Options outstanding, December 31, 2012	809,017			11.81
	Granted	139,650			16.16
	Exercised	(76,966	)		10.39
	Forfeited or expired	(16,600	)		15.16
	Options outstanding, December 31, 2013	855,101			13.48
	Granted	38,013			34.32
	Exercised	(57,370	)		12.26
	Forfeited or expired	(1,074	)		22.13
	Options outstanding, December 31, 2014	834,670			$	14.5			6.41
	Options exercisable, December 31, 2012	289,444			$	10.6
	Options exercisable, December 31, 2013	374,535			$	11.94
	Options exercisable, December 31, 2014	522,600			$	12.7			5.57
Summarized Information About Stock Options Outstanding by Range of Exercise Prices	The following table presents weighted-average remaining life as of December 31, 2014 for options outstanding within the stated exercise prices:
		Options Outstanding									Options Exercisable
	Exercise Price Range	Number			Weighted-				Weighted-		Number		Weighted-
	Per Share	of Shares			Average				Average		of Shares		Average
					Exercise				Remaining				Exercise
					Price				Life				Price
									(Years)
	$10.00-$12.70	323,294			$	11.33			4.39		323,294		$	11.33
	$14.20-$14.88	342,108			14.68				7.33		157,233		14.59
	$15.88-$23.68	169,268			20.21				8.4		42,073		16.19
	Total Options	834,670			$	14.5			6.41		522,600		$	12.7

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Summary of Annual Rental Payments	At December 31, 2014, the minimum annual rental payments to be made under the noncancelable leases are as follows (in thousands):
	Year ending December 31:
	2015	$	3,387
	2016	3,349
	2017	3,356
	2018	3,035
	2019	2,862
	Thereafter	31,976
		$	47,965
Summary of Total Notional Amount of Loan Commitments and Standby Letters of Credit	The following is a summary of the total notional amount of loan commitments and standby letters of credit outstanding at December 31, 2014 and 2013 (in thousands):
		2014		2013
	Standby letters of credit	$	110,636	$	106,467
	Unused loan commitments	509,665		268,760
	Total	$	620,301	$	375,227

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Carrying Value and Fair Value Measurements of Financial Assets and Liabilities on Recurring Basis	The Company has segregated all financial assets and liabilities that are measured at fair value on a recurring basis into the most appropriate level within the fair value hierarchy, based on the inputs used to determine the fair value at the measurement date in the tables below (in thousands):
				31-Dec-14
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Available for sale securities:
	U.S. government agency securities	$	157,527	$	—	$	157,527	$	—
	U.S. Treasury securities	12,610		—		12,610		—
	Municipal securities	12,246		—		12,246		—
	Mortgage-backed securities	57,087		—		57,087		—
	Corporate bonds	8,177		—		8,177		—
		$	247,647	$	—	$	247,647	$	—
	Derivative instruments	37		—		37		—
	Total	$	247,684	$	—	$	247,684	$	—
	Liabilities
	Derivative instruments	$	12,953	$	—	$	12,953	$	—
				December 31, 2013
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Available for sale securities:
	U.S. government agency securities	$	151,323	$	—	$	151,323	$	—
	U.S. Treasury securities	12,149		—		12,149		—
	Municipal securities	23,167		—		23,167		—
	Mortgage-backed securities	55,544		—		55,544		—
	Corporate bonds	35,536		—		35,536		—
		$	277,719	$	—	$	277,719	$	—
	Derivative instruments	1,157		—		1,157		—
	Total	$	278,876	$	—	$	278,876	$	—
	Liabilities
	Derivative instruments	$	4,317	$	—	$	4,317	$	—
Carrying Value and Fair Value Measurements of Financial Assets and Liabilities on Non Recurring Basis	The Company has segregated all financial assets and liabilities that are measured at fair value on a nonrecurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date in the tables below (in thousands):
				31-Dec-14
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Loans	$	20,679	$	—	$	—	$	20,679
	OREO	3,022		—		—		3,022
		$	23,701	$	—	$	—	$	23,701
				December 31, 2013
				Fair Value Measurement Using
		Total		Quoted Prices		Significant		Significant
				in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	Assets
	Loans	$	9,782	$	—	$	—	$	9,782
	OREO	2,390		—		—		2,390
		$	12,172	$	—	$	—	$	12,172
Carrying Value and Fair Value Measurements of Financial Instruments	The estimated fair values of the Company’s financial instruments were as follows as of the dates indicated (in thousands):
		Fair Value Measurements at December 31, 2014
		Carrying		Total		Level 1		Level 2		Level 3
		Amount
	Financial Assets:
	Cash and due from banks	$	32,484	$	32,484	$	32,484	$	—	$	—
	Short-term investments	18,404		18,404		18,404		—		—
	Investment in short-term receivables	237,135		237,135		237,135		—		—
	Investment securities available for sale	247,647		247,647		—		247,647		—
	Investment securities held to maturity	89,076		90,956		—		90,956		—
	Loans and loans held for sale	2,775,886		3,003,280		—		—		3,003,280
	Cash surrender value of bank-owned life insurance	47,289		47,289		47,289		—		—
	Derivative instruments	37		37		—		37		—
	Financial Liabilities:
	Deposits, noninterest-bearing	364,534		364,534		—		364,534		—
	Deposits, interest-bearing	2,756,316		2,722,134		—		—		2,722,134
	Repurchase agreements	117,991		117,991		—		117,991		—
	Long-term borrowings	40,000		42,270		—		—		42,270
	Derivative instruments	12,953		12,953		—		12,953		—
		Fair Value Measurements at December 31, 2013
		Carrying		Total		Level 1		Level 2		Level 3
		Amount
	Financial Assets:
	Cash and due from banks	$	28,140	$	28,140	$	28,140	$	—	$	—
	Short-term investments	3,502		3,502		3,502		—		—
	Investment in short-term receivables	246,817		246,817		246,817		—		—
	Investment securities available for sale	277,719		277,719		—		277,719		—
	Investment securities held to maturity	94,904		90,966		—		90,966		—
	Loans and loans held for sale	2,364,354		2,344,475		—		—		2,344,475
	Cash surrender value of bank-owned life insurance	26,187		26,187		26,187		—		—
	Derivative instruments	1,157		1,157		—		1,157		—
	Financial Liabilities:
	Deposits, noninterest-bearing	291,080		291,080		—		291,080		—
	Deposits, interest-bearing	2,439,727		2,380,985		—		—		2,380,985
	Repurchase agreements	75,957		75,957		—		75,957		—
	Short-term borrowings	8,425		8,425		—		8,425		—
	Long-term borrowings	55,110		55,616		—		—		55,616
	Derivative instruments	4,317		4,317		—		4,317		—

Parent_Company_Only_Financial_1

Parent Company Only Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule Of Balance Sheet	Balance Sheets
		December 31,
	(In thousands)	2014			2013
	Assets
	Cash and due from banks	$	23,736		$	23,990
	Goodwill	841			841
	Investments in subsidiaries	409,689			355,068
	Other assets	2,145			2,123
	Total assets	$	436,411		$	382,022
	Liabilities and shareholders’ equity
	Long-term borrowings	$	—		$	110
	Other liabilities	36			53
	Total liabilities	36			163
	Total shareholders’ equity	436,375			381,859
	Total liabilities and shareholders’ equity	$	436,411		$	382,022
Schedule Of Statement of Income	Statements of Income
		Year Ended December 31,
	(In thousands)	2014			2013			2012
	Operating income
	Interest income	$	—		$	—		$	—
	Dividend from bank subsidiary	—			2,000			—
	Total operating income	—			2,000			—
	Operating expense
	Interest expense	3			424			11
	Other expense	1,414			856			431
	Total operating expense	1,417			1,280			442
	Income (loss) before income tax benefit and increase in equity in undistributed earnings of subsidiaries	(1,417		)	720			(442		)
	Income tax benefit	(496		)	(448		)	(155		)
	Income (loss) before equity in undistributed earnings of subsidiaries	(921		)	1,168			(287		)
	Equity in undistributed earnings of subsidiaries	56,510			39,743			29,227
	Net income	55,589			40,911			28,940
	Preferred stock dividends	(379		)	(347		)	(510		)
	Income available to common shareholders	$	55,210		$	40,564		$	28,430
Schedule Of Statement of Cash Flow	Statements of Cash Flows
		Year Ended December 31,
	(in thousands)	2014			2013			2012
	Operating activities
	Net income	$	55,589		$	40,911		$	28,940
	Adjustments to reconcile net income to net cash (used in) provided by operating activities:
	Net income of subsidiaries	(56,510		)	(39,743		)	(29,227		)
	Deferred tax benefit	(496		)	(448		)	(155		)
	Stock compensation	333			1,155			97
	Changes in operating assets and liabilities:
	Change in other assets	474			1,481			(1,989		)
	Change in other liabilities	(17		)	50			—
	Net cash (used in) provided by operating activities	(627		)	3,406			(2,334		)
	Investing activities
	Capital contributed to subsidiary, net	—			(67,000		)	(16,600		)
	Net cash used in investing activities	—			(67,000		)	(16,600		)
	Financing activities
	Proceeds from long-term borrowings	—			—			20,000
	Repayment of borrowings	(110		)	(20,110		)	(110		)
	Proceeds from sale of common stock, net of offering costs	862			104,332			1,420
	Dividends paid	(379		)	(347		)	(510		)
	Net cash provided by financing activities	373			83,875			20,800
	Net change in cash, due from banks, and short-term investments	(254		)	20,281			1,866
	Cash, due from banks, and short-term investments at beginning of period	23,990			3,709			1,843
	Cash, due from banks, and short-term investments at end of period	$	23,736		$	23,990		$	3,709

Consolidated_Quarterly_Results1

Consolidated Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Data
	(In thousands, except per share data)	First  Quarter			Second			Third			Fourth
					Quarter			Quarter			Quarter
	Year Ended December 31, 2014
	Total interest income	$	35,161		$	37,193		$	38,668		$	38,956
	Total interest expense	10,313			10,643			10,908			10,865
	Net interest income	24,848			26,550			27,760			28,091
	Provision for loan losses	3,000			3,000			3,000			3,000
	Net interest income after provision for loan losses	21,848			23,550			24,760			25,091
	Noninterest income	3,359			2,933			3,034			2,287
	Noninterest expense	17,337			18,568			20,047			22,297
	Income before income taxes	7,870			7,915			7,747			5,081
	Income tax benefit	(4,958		)	(4,784		)	(6,612		)	(10,622		)
	Net income attributable to Company	12,828			12,699			14,359			15,703
	Less preferred stock dividends	(95		)	(95		)	(95		)	(94		)
	Less earnings allocated to participating securities	(246		)	(243		)	(275		)	(302		)
	Income available to common shareholders	$	12,487		$	12,361		$	13,989		$	15,307
	Earnings per common share-basic	$	0.68		$	0.67		$	0.75		$	0.82
	Earnings per common share-diluted	$	0.66		$	0.65		$	0.73		$	0.8
	(In thousands, except per share data)	First Quarter			Second			Third			Fourth
					Quarter			Quarter			Quarter
	Year Ended December 31, 2013
	Total interest income	$	28,580		$	29,034		$	31,973		$	34,437
	Total interest expense	8,893			9,779			10,150			10,326
	Net interest income	19,687			19,255			21,823			24,111
	Provision for loan losses	2,600			2,400			2,400			2,400
	Net interest income after provision for loan losses	17,087			16,855			19,423			21,711
	Noninterest income	2,827			2,738			2,461			5,400
	Noninterest expense	15,643			15,185			17,092			19,422
	Income before income taxes	4,271			4,408			4,792			7,689
	Income tax benefit	(4,013		)	(4,198		)	(5,673		)	(5,867		)
	Net income	8,284			8,606			10,465			13,556
	Less net income attributable to noncontrolling interest	—			—			—			—
	Net income attributable to Company	8,284			8,606			10,465			13,556
	Less preferred stock dividends	(95		)	(95		)	(62		)	(95		)
	Less earnings allocated to participating securities	(538		)	(455		)	(519		)	(468		)
	Income available to common shareholders	$	7,651		$	8,056		$	9,884		$	12,993
	Earnings per common share-basic	$	0.59		$	0.51		$	0.55		$	0.71
	Earnings per common share-diluted	$	0.58		$	0.49		$	0.54		$	0.69

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Estimated Useful Life Asset (Detail)	12 Months Ended
	Dec. 31, 2014
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	40 years
Minimum | Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	5 years
Maximum | Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	15 years

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2013
	Segment
Organization And Significant Accounting Policies [Line Items]
Non-controlling interest	$2,000	$1,000	$2,000
Redemption of on cumulative perpetual preferred stock held by non-controlling interest		$1,600,000
Tax credit Carry forward period (years)	20 years
Tax credit as Percentage of project cost	39.00%
Number of Reportable Segments	1
Minimum
Organization And Significant Accounting Policies [Line Items]
Interest at the end of compliance period (as a percent)	5.00%
Maximum
Organization And Significant Accounting Policies [Line Items]
Interest at the end of compliance period (as a percent)	25.00%
Low- Income Housing credits
Organization And Significant Accounting Policies [Line Items]
Non voting interest (as a percent)	99.99%
Compliance Period (in years)	15 years
Interest percentage for general partners	0.01%
Low- Income Housing credits | Minimum
Organization And Significant Accounting Policies [Line Items]
Federal Tax Credit, Adjustment Period (years)	10 years
Low- Income Housing credits | Maximum
Organization And Significant Accounting Policies [Line Items]
Federal Tax Credit, Adjustment Period (years)	15 years
Historic credits
Organization And Significant Accounting Policies [Line Items]
Non voting interest (as a percent)	99.00%
Compliance Period (in years)	5 years
Interest percentage for general partners	1.00%
Federal NMTC
Organization And Significant Accounting Policies [Line Items]
Federal Tax Credit, Adjustment Period (years)	7 years
Compliance Period (in years)	7 years
First Three Years
Organization And Significant Accounting Policies [Line Items]
Tax credit as Percentage of project cost	5.00%
Next Four Years
Organization And Significant Accounting Policies [Line Items]
Tax credit as Percentage of project cost	6.00%

Earnings_Per_Share_Schedule_of

Earnings Per Share - Schedule of Computation of Basic and Diluted Net Income Per Common Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Basic: Income available to common shareholders	$15,307	$13,989	$12,361	$12,487	$12,993	$9,884	$8,056	$7,651	$54,144	$38,584	$26,431
Weighted-average common shares outstanding									18,541	16,204	12,953
Basic earnings per share (in usd per share)	$0.82	$0.75	$0.67	$0.68	$0.71	$0.55	$0.51	$0.59	$2.92	$2.38	$2.04
Diluted: Income attributable to common shareholders									$54,144	$38,584	$26,431
Weighted-average common shares outstanding									18,541	16,204	12,953
Stock options outstanding (in shares)									389	337	109
Warrants (in shares)									119	83	52
Weighted-average common shares outstanding – assuming dilution									19,049	16,624	13,114
Diluted earnings per share (in usd per share)	$0.80	$0.73	$0.65	$0.66	$0.69	$0.54	$0.49	$0.58	$2.84	$2.32	$2.02

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2014
Earnings Per Share [Abstract]
Warrants outstanding (in shares)	87,059	125,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	264,000

Cash_and_Due_From_Banks_Additi

Cash and Due From Banks - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Cash and Cash Equivalents [Abstract]
Reserve Requirements	$9.30	$10.10

Investment_in_ShortTerm_Receiv1

Investment in Short-Term Receivables - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Receivables [Abstract]
Purchase receivable	$237,135	$246,817

Investment_Securities_Summary_

Investment Securities - Summary of Amortized Cost and Market Values of Investment Securities with Gross Unrealized Gains and Losses (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Available for sale:
Amortized Cost	$251,943	$294,259
Gross Unrealized Gains	1,633	1,063
Gross Unrealized Losses Less Than One Year	-173	-15,651
Gross Unrealized Losses Greater Than One Year	-5,756	-1,952
Estimated Market Value	247,647	277,719
Held to maturity:
Amortized Cost	89,076	94,904
Gross Unrealized Gains	3,280	106
Gross Unrealized Losses Less Than One Year	-270	-4,044
Gross Unrealized Losses Greater Than One Year	-1,130	0
Estimated Market Value	90,956	90,966
U.S. government agency securities
Available for sale:
Amortized Cost	161,461	163,964
Gross Unrealized Gains	891	81
Gross Unrealized Losses Less Than One Year	0	-10,991
Gross Unrealized Losses Greater Than One Year	-4,825	-1,731
Estimated Market Value	157,527	151,323
U.S. Treasury securities
Available for sale:
Amortized Cost	13,019	13,022
Gross Unrealized Gains	0	0
Gross Unrealized Losses Less Than One Year	0	-873
Gross Unrealized Losses Greater Than One Year	-409	0
Estimated Market Value	12,610	12,149
Municipal securities
Available for sale:
Amortized Cost	12,175	23,240
Gross Unrealized Gains	107	140
Gross Unrealized Losses Less Than One Year	-36	-213
Gross Unrealized Losses Greater Than One Year	0	0
Estimated Market Value	12,246	23,167
Held to maturity:
Amortized Cost	41,255	44,294
Gross Unrealized Gains	2,182	94
Gross Unrealized Losses Less Than One Year	-62	-398
Gross Unrealized Losses Greater Than One Year	0	0
Estimated Market Value	43,375	43,990
Mortgage-backed securities
Available for sale:
Amortized Cost	57,025	57,010
Gross Unrealized Gains	635	447
Gross Unrealized Losses Less Than One Year	-137	-1,897
Gross Unrealized Losses Greater Than One Year	-436	-16
Estimated Market Value	57,087	55,544
Held to maturity:
Amortized Cost	47,821	50,610
Gross Unrealized Gains	1,098	12
Gross Unrealized Losses Less Than One Year	-208	-3,646
Gross Unrealized Losses Greater Than One Year	-1,130	0
Estimated Market Value	47,581	46,976
Corporate bonds
Available for sale:
Amortized Cost	8,263	37,023
Gross Unrealized Gains	0	395
Gross Unrealized Losses Less Than One Year	0	-1,677
Gross Unrealized Losses Greater Than One Year	-86	-205
Estimated Market Value	$8,177	$35,536

Investment_Securities_Addition

Investment Securities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Security	Security
Schedule of Held-to-maturity Securities [Line Items]
Transfer of securities with fair value		$95,400,000
Accumulated other comprehensive income included net pre-tax unrealized losses	0	5,919,000	0
Available-for-sale Securities, Gross Unrealized Gain (Loss)	-5,200,000
Number of securities in loss position	38	88
Securities with estimated market values	279,100,000	204,300,000
Proceeds from sales of securities	41,700,000	45,800,000	125,400,000
Gross gains realized	800,000	500,000	4,300,000
Gross losses realized	600,000	200,000	0
Carrying value of sold municipal security	2,650,000	0	0
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Carrying value of sold municipal security	2,700,000
Gross realized gain (loss) from sale of municipal security	($100,000)

Investment_Securities_Summary_1

Investment Securities - Summary of Investment Security Issuers (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Amortized Cost	$251,943	$294,259
Estimated Market Value	247,647	277,719
Investments
Schedule of Investments [Line Items]
Amortized Cost	222,626
Estimated Market Value	218,864
Investments | Federal National Mortgage Association (Fannie Mae)
Schedule of Investments [Line Items]
Amortized Cost	92,205
Estimated Market Value	90,366
Investments | Federal Home Loan Bank (FHLB)
Schedule of Investments [Line Items]
Amortized Cost	74,442
Estimated Market Value	73,623
Investments | Federal Home Loan Mortgage Corporation (Freddie Mac)
Schedule of Investments [Line Items]
Amortized Cost	55,979
Estimated Market Value	$54,875

Investment_Securities_Summary_2

Investment Securities - Summary of Amortized Cost and Estimated Market Values by Contractual Maturity of Investment Securities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]
Weighted average yield, Due in one year or less (as a percent)	1.78%	1.39%
Weighted average yield, Due after one year through five years (as a percent)	2.64%	2.58%
Weighted average yield, Due after five years through ten years (as a percent)	2.02%	2.12%
Weighted average yield, Due after ten years (as a percent)	3.34%	3.17%
Weighted average yield, Total securities (as a percent)	2.27%	2.30%
Weighted average yield, Due in one year or less	3.88%	1.76%
Weighted average yield, Due after one year through five years	4.16%	2.60%
Weighted average yield, Due after five years through ten years	3.39%	3.70%
Weighted average yield, Due after ten years	3.30%	3.41%
Weighted average yield, Total securities	3.55%	3.35%
Amortized Cost, Due in one year or less	$571	$12,340
Amortized Cost, Due after one year through five years	51,037	64,790
Amortized Cost, Due after five years through ten years	176,631	180,362
Amortized Cost, Due after ten years	23,704	36,767
Amortized Cost, Total securities	251,943	294,259
Amortized Cost, Due in one year or less	2,045	1,007
Amortized Cost, Due after one year through five years	20,921	18,101
Amortized Cost, Due after five years through ten years	32,618	37,591
Amortized Cost, Due after ten years	33,492	38,205
Amortized Cost, Total securities	89,076	94,904
Estimated Market Value, Due in one year or less	573	12,368
Estimated Market Value, Due after one year through five years	51,916	65,038
Estimated Market Value, Due after five years through ten years	172,012	168,243
Estimated Market Value, Due after ten years	23,146	32,070
Estimated Market Value	247,647	277,719
Estimated Market Value, Due in one year or less	2,003	1,007
Estimated Market Value, Due after one year through five years	21,875	17,539
Estimated Market Value, Due after five years through ten years	33,898	37,137
Estimated Market Value, Due after ten years	33,180	35,283
Estimated Market Value	$90,956	$90,966

Investment_Securities_Summary_3

Investment Securities - Summary of Securities in Other Assets, at Cost (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Total equity securities	$7,180	$6,552
FHLB stock
Schedule of Investments [Line Items]
Total equity securities	1,347	1,099
First National Bankers Bankshares, Inc. (FNBB) stock
Schedule of Investments [Line Items]
Total equity securities	600	600
Other investments
Schedule of Investments [Line Items]
Total equity securities	$5,233	$4,853

Loans_Summary_of_Major_Classif

Loans - Summary of Major Classifications of Loans (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commercial real estate loans:
Construction	$316,492,000	$203,369,000
Mortgage	1,252,225,000	1,118,048,000
Total commercial real estate loans	1,568,717,000	1,321,417,000
Consumer real estate loans:
Construction	10,393,000	8,986,000
Mortgage	131,031,000	115,307,000
Total consumer real estate loans	141,424,000	124,293,000
Commercial and industrial loans	1,016,414,000	868,469,000
Loans to individuals, excluding real estate	18,316,000	16,345,000
Nonaccrual loans	21,228,000	16,396,000
Other loans	8,165,000	10,857,000
Total Loans	2,774,264,000	2,357,777,000
Less allowance for loan losses	-42,336,000	-32,143,000	-26,977,000	-18,122,000
Loans, net	2,731,928,000	2,325,634,000
Owner Occupied Commercial Real Estate Loan	$419,300,000	$364,900,000

Loans_Summary_of_Changes_in_Al

Loans - Summary of Changes in Allowance for Loan Losses (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				$32,143				$26,977	$32,143	$26,977	$18,122
Provision charged to operations	3,000	3,000	3,000	3,000	2,400	2,400	2,400	2,600	12,000	9,800	11,035
Charge-offs									-1,929	-4,769	-2,561
Recoveries									122	135	381
Balance, end of period	$42,336				$32,143				$42,336	$32,143	$26,977

Loans_Additional_Information_D

Loans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Net of amortization	$13,800,000	$10,600,000
Overdraft	700,000	800,000
Financing Receivable, Recorded Investment, 30 to 90 Days Past Due	4,940,000	7,774,000
Financing Receivable, Equal to Greater than 90 Days Past Due	16,298,000	11,371,000
Average recorded investment in nonaccrual loan	19,600,000	17,900,000
Amount of interest income	1,000,000	1,000,000
Substandard
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans acquired with deteriorated credit quality	5,400,000	7,400,000
Special Mention
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans acquired with deteriorated credit quality	1,600,000	1,600,000
Custody Pledge
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans with carrying value pledged to secure other borrowings	847,000,000	29,400,000
Blanket Lien
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans with carrying value pledged to secure other borrowings		655,100,000
Other Consumer Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Recorded Investment, 30 to 90 Days Past Due	600,000	400,000
Financing Receivable, Equal to Greater than 90 Days Past Due	28,000	200,000
Secured Tuition Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Equal to Greater than 90 Days Past Due	$28,000	$200,000

Loans_Summary_of_Allowance_for

Loans - Summary of Allowance for Loan Losses and Recorded Investment in Loans (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				$32,143				$26,977	$32,143	$26,977	$18,122
Charge-offs									-1,929	-4,769	-2,561
Recoveries									122	135	381
Provision	3,000	3,000	3,000	3,000	2,400	2,400	2,400	2,600	12,000	9,800	11,035
Balance, end of period	42,336				32,143				42,336	32,143	26,977
Individually evaluated for impairment	9,028				3,955				9,028	3,955
Collectively evaluated for impairment	33,308				28,188				33,308	28,188
Ending balance-total	2,774,264				2,357,777				2,774,264	2,357,777
Loans receivable
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance-total	2,774,264				2,357,777				2,774,264	2,357,777
Individually evaluated for impairment	31,558				17,115				31,558	17,115
Collectively evaluated for impairment	2,742,706				2,340,662				2,742,706	2,340,662
Construction
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				2,790				2,004	2,790	2,004
Charge-offs									-18	-46
Recoveries									30	0
Provision									1,228	832
Balance, end of period	4,030				2,790				4,030	2,790
Individually evaluated for impairment	0				42				0	42
Collectively evaluated for impairment	4,030				2,748				4,030	2,748
Ending balance-total	327,677				212,430				327,677	212,430
Construction | Loans receivable
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance-total	327,677				212,430				327,677	212,430
Individually evaluated for impairment	927				309				927	309
Collectively evaluated for impairment	326,750				212,121				326,750	212,121
Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				13,780				10,716	13,780	10,716
Charge-offs									-1,034	-292
Recoveries									0	19
Provision									2,219	3,337
Balance, end of period	14,965				13,780				14,965	13,780
Individually evaluated for impairment	3,138				1,639				3,138	1,639
Collectively evaluated for impairment	11,827				12,141				11,827	12,141
Ending balance-total	1,264,371				1,128,181				1,264,371	1,128,181
Commercial Real Estate | Loans receivable
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance-total	1,264,371				1,128,181				1,264,371	1,128,181
Individually evaluated for impairment	13,130				9,811				13,130	9,811
Collectively evaluated for impairment	1,251,241				1,118,370				1,251,241	1,118,370
Consumer Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				2,656				2,450	2,656	2,450
Charge-offs									-63	0
Recoveries									0	30
Provision									723	176
Balance, end of period	3,316				2,656				3,316	2,656
Individually evaluated for impairment	0				183				0	183
Collectively evaluated for impairment	3,316				2,473				3,316	2,473
Ending balance-total	132,950				117,653				132,950	117,653
Consumer Real Estate | Loans receivable
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance-total	132,950				117,653				132,950	117,653
Individually evaluated for impairment	2,085				2,990				2,085	2,990
Collectively evaluated for impairment	130,865				114,663				130,865	114,663
Commercial and Industrial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				12,677				11,675	12,677	11,675
Charge-offs									-648	-4,229
Recoveries									71	68
Provision									7,714	5,163
Balance, end of period	19,814				12,677				19,814	12,677
Individually evaluated for impairment	5,889				2,091				5,889	2,091
Collectively evaluated for impairment	13,925				10,586				13,925	10,586
Ending balance-total	1,030,629				883,111				1,030,629	883,111
Commercial and Industrial | Loans receivable
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance-total	1,030,629				883,111				1,030,629	883,111
Individually evaluated for impairment	15,157				4,005				15,157	4,005
Collectively evaluated for impairment	1,015,472				879,106				1,015,472	879,106
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				240				132	240	132
Charge-offs									-166	-202
Recoveries									21	18
Provision									116	292
Balance, end of period	211				240				211	240
Individually evaluated for impairment	1				0				1	0
Collectively evaluated for impairment	210				240				210	240
Ending balance-total	18,637				16,402				18,637	16,402
Consumer | Loans receivable
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance-total	18,637				16,402				18,637	16,402
Individually evaluated for impairment	259				0				259	0
Collectively evaluated for impairment	$18,378				$16,402				$18,378	$16,402

Loans_Summary_of_Credit_Qualit

Loans - Summary of Credit Quality Indicators on Company's Loan Portfolio (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]
Total loans	$2,774,264	$2,357,777
Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	327,677	212,430
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,264,371	1,128,181
Consumer Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	132,950	117,653
Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,030,629	883,111
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	18,637	16,402
Pass and Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,682,243	2,274,125
Pass and Pass/Watch | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	313,987	197,951
Pass and Pass/Watch | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,215,673	1,073,339
Pass and Pass/Watch | Consumer Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	128,507	113,037
Pass and Pass/Watch | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,005,829	873,547
Pass and Pass/Watch | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	18,247	16,251
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,682	1,935
Special Mention | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	2	4
Special Mention | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,613	1,720
Special Mention | Consumer Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	60	185
Special Mention | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	17
Special Mention | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	7	9
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	90,339	81,717
Substandard | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	13,688	14,475
Substandard | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	47,085	53,122
Substandard | Consumer Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,383	4,431
Substandard | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Total loans	24,800	9,547
Substandard | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	383	142
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Doubtful | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Doubtful | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Doubtful | Consumer Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Doubtful | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Doubtful | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	$0	$0

Loans_Age_Analysis_of_Past_Due

Loans - Age Analysis of Past Due Loans Including Loans Acquired with Deteriorated Credit Quality (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	$4,940	$7,774
90 Days and Greater Past Due	16,298	11,371
Total Past Due	21,238	19,145
Current Loans	2,753,026	2,338,632
Total Loans	2,774,264	2,357,777
Total real estate loans
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	4,217	4,210
90 Days and Greater Past Due	11,550	9,883
Total Past Due	15,767	14,093
Current Loans	1,709,231	1,444,171
Total Loans	1,724,998	1,458,264
Total other loans
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	723	3,564
90 Days and Greater Past Due	4,748	1,488
Total Past Due	5,471	5,052
Current Loans	1,043,795	894,461
Total Loans	1,049,266	899,513
Construction
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	97	15
90 Days and Greater Past Due	750	75
Total Past Due	847	90
Current Loans	326,830	212,340
Total Loans	327,677	212,430
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	2,497	2,935
90 Days and Greater Past Due	9,545	7,642
Total Past Due	12,042	10,577
Current Loans	1,252,329	1,117,604
Total Loans	1,264,371	1,128,181
Consumer Real Estate
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	1,623	1,260
90 Days and Greater Past Due	1,255	2,166
Total Past Due	2,878	3,426
Current Loans	130,072	114,227
Total Loans	132,950	117,653
Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	159	3,076
90 Days and Greater Past Due	4,426	1,281
Total Past Due	4,585	4,357
Current Loans	1,026,044	878,754
Total Loans	1,030,629	883,111
Consumer
Financing Receivable, Recorded Investment [Line Items]
Greater Than 30 and Fewer Than 90 Days Past Due	564	488
90 Days and Greater Past Due	322	207
Total Past Due	886	695
Current Loans	17,751	15,707
Total Loans	$18,637	$16,402

Loans_Summary_of_Information_P

Loans - Summary of Information Pertaining to Impaired Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	$10,879	$7,333
With no related allowance recorded, Contractual Balance	11,231	7,584
With no related allowance recorded, Related Allowance	0	0
With no related allowance recorded, Average Recorded Investment	9,107	5,318
With no related allowance recorded, Interest Income Recognized	194	150
With an allowance recorded, Recorded Investment	20,679	9,782
With an allowance recorded, Contractual Balance	21,012	11,724
With an allowance recorded, Related Allowance	9,028	3,955
With an allowance recorded, Average Recorded Investment	15,078	13,899
With an allowance recorded, Interest Income Recognized	389	113
Total impaired loans, Recorded Investment	31,558	17,115
Total impaired loans, Contractual Balance	32,243	19,308
Total impaired loans, Related Allowance	9,028	3,955
Total impaired loans, Average Recorded Investment	24,185	19,217
Total impaired loans, Interest Income Recognized	583	263
Construction
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	927	0
With no related allowance recorded, Contractual Balance	927	0
With no related allowance recorded, Related Allowance	0	0
With no related allowance recorded, Average Recorded Investment	464	24
With no related allowance recorded, Interest Income Recognized	39	0
With an allowance recorded, Recorded Investment	0	309
With an allowance recorded, Contractual Balance	0	309
With an allowance recorded, Related Allowance	0	42
With an allowance recorded, Average Recorded Investment	0	530
With an allowance recorded, Interest Income Recognized	0	23
Total impaired loans, Recorded Investment	927	309
Total impaired loans, Contractual Balance	927	309
Total impaired loans, Related Allowance	0	42
Total impaired loans, Average Recorded Investment	464	554
Total impaired loans, Interest Income Recognized	39	23
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	7,175	4,261
With no related allowance recorded, Contractual Balance	7,453	4,469
With no related allowance recorded, Related Allowance	0	0
With no related allowance recorded, Average Recorded Investment	5,718	3,063
With no related allowance recorded, Interest Income Recognized	109	110
With an allowance recorded, Recorded Investment	5,955	5,550
With an allowance recorded, Contractual Balance	6,235	7,428
With an allowance recorded, Related Allowance	3,138	1,639
With an allowance recorded, Average Recorded Investment	5,753	4,445
With an allowance recorded, Interest Income Recognized	79	59
Total impaired loans, Recorded Investment	13,130	9,811
Total impaired loans, Contractual Balance	13,688	11,897
Total impaired loans, Related Allowance	3,138	1,639
Total impaired loans, Average Recorded Investment	11,471	7,508
Total impaired loans, Interest Income Recognized	188	169
Consumer Real Estate
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	2,085	1,973
With no related allowance recorded, Contractual Balance	2,097	1,999
With no related allowance recorded, Related Allowance	0	0
With no related allowance recorded, Average Recorded Investment	2,029	1,254
With no related allowance recorded, Interest Income Recognized	18	0
With an allowance recorded, Recorded Investment	0	1,017
With an allowance recorded, Contractual Balance	0	1,046
With an allowance recorded, Related Allowance	0	183
With an allowance recorded, Average Recorded Investment	509	831
With an allowance recorded, Interest Income Recognized	0	21
Total impaired loans, Recorded Investment	2,085	2,990
Total impaired loans, Contractual Balance	2,097	3,045
Total impaired loans, Related Allowance	0	183
Total impaired loans, Average Recorded Investment	2,538	2,085
Total impaired loans, Interest Income Recognized	18	21
Commercial and Industrial
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	436	1,099
With no related allowance recorded, Contractual Balance	498	1,116
With no related allowance recorded, Related Allowance	0	0
With no related allowance recorded, Average Recorded Investment	768	977
With no related allowance recorded, Interest Income Recognized	22	40
With an allowance recorded, Recorded Investment	14,721	2,906
With an allowance recorded, Contractual Balance	14,774	2,941
With an allowance recorded, Related Allowance	5,889	2,091
With an allowance recorded, Average Recorded Investment	8,814	8,093
With an allowance recorded, Interest Income Recognized	310	10
Total impaired loans, Recorded Investment	15,157	4,005
Total impaired loans, Contractual Balance	15,272	4,057
Total impaired loans, Related Allowance	5,889	2,091
Total impaired loans, Average Recorded Investment	9,582	9,070
Total impaired loans, Interest Income Recognized	332	50
Consumer
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	256
With no related allowance recorded, Contractual Balance	256
With no related allowance recorded, Related Allowance	0
With no related allowance recorded, Average Recorded Investment	128
With no related allowance recorded, Interest Income Recognized	6
With an allowance recorded, Recorded Investment	3
With an allowance recorded, Contractual Balance	3
With an allowance recorded, Related Allowance	1
With an allowance recorded, Average Recorded Investment	2
With an allowance recorded, Interest Income Recognized	0
Total impaired loans, Recorded Investment	259
Total impaired loans, Contractual Balance	259
Total impaired loans, Related Allowance	1
Total impaired loans, Average Recorded Investment	130
Total impaired loans, Interest Income Recognized	$6

Loans_Summary_of_Nonaccrual_Lo

Loans - Summary of Nonaccrual Loans (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Loans Receivable [Line Items]
Nonaccrual loans	$21,228	$16,396
Nonaccrual Loans [Member] | Construction
Loans Receivable [Line Items]
Nonaccrual loans	792	75
Nonaccrual Loans [Member] | Commercial Real Estate
Loans Receivable [Line Items]
Nonaccrual loans	12,146	10,133
Nonaccrual Loans [Member] | Consumer Real Estate
Loans Receivable [Line Items]
Nonaccrual loans	1,919	2,347
Nonaccrual Loans [Member] | Commercial and Industrial
Loans Receivable [Line Items]
Nonaccrual loans	6,051	3,784
Nonaccrual Loans [Member] | Consumer
Loans Receivable [Line Items]
Nonaccrual loans	$320	$57

Loans_Summary_of_Changes_in_Ac

Loans - Summary of Changes in Accretable Yields of Acquired Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	$170	$628
Acquisition	0	0
Net transfers from nonaccretable difference to accretable yield	815	45
Accretion	-871	-503
Balance, end of period	$114	$170

Loans_Summary_of_Companys_TDRs

Loans - Summary of Company's TDRs (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Modifications [Line Items]
Current	$1,571	$1,628
Greater Than 30 Days Past Due	0	0
Nonaccrual TDRs	2,092	238
Total TDRs	3,663	1,866
Total real estate loans
Financing Receivable, Modifications [Line Items]
Current	1,186	1,291
Greater Than 30 Days Past Due	0	0
Nonaccrual TDRs	2,092	238
Total TDRs	3,278	1,529
Total real estate loans | Construction
Financing Receivable, Modifications [Line Items]
Current	233	309
Greater Than 30 Days Past Due	0	0
Nonaccrual TDRs	0	0
Total TDRs	233	309
Total real estate loans | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Current	349	357
Greater Than 30 Days Past Due	0	0
Nonaccrual TDRs	1,960	102
Total TDRs	2,309	459
Total real estate loans | Consumer Real Estate
Financing Receivable, Modifications [Line Items]
Current	604	625
Greater Than 30 Days Past Due	0	0
Nonaccrual TDRs	132	136
Total TDRs	736	761
Commercial and industrial | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Current	385	337
Greater Than 30 Days Past Due	0	0
Nonaccrual TDRs	0	0
Total TDRs	$385	$337

Loans_Summary_of_Information_o

Loans - Summary of Information on TDRs Modification (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Receivables [Abstract]
Maturity and interest rate adjustment	$2,536	$925
Movement to or extension of interest rate-only payments	833	597
Other concessions	294	344
Total TDRs	$3,663	$1,866

Loans_Summary_of_Information_P1

Loans - Summary of Information Pertaining to Modified Terms of Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
	Contract	Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	12	9
Pre- Modification Outstanding Recorded Investment	$3,663	$1,866
Post- Modification Outstanding Recorded Investment	3,663	1,866
Troubled debt restructuring | Construction
Financing Receivable, Modifications [Line Items]
Number of Contracts	4	2
Pre- Modification Outstanding Recorded Investment	233	309
Post- Modification Outstanding Recorded Investment	233	309
Troubled debt restructuring | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	3
Pre- Modification Outstanding Recorded Investment	2,309	459
Post- Modification Outstanding Recorded Investment	2,309	459
Troubled debt restructuring | Consumer Real Estate
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	3
Pre- Modification Outstanding Recorded Investment	736	761
Post- Modification Outstanding Recorded Investment	736	761
Troubled debt restructuring | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	1
Pre- Modification Outstanding Recorded Investment	385	337
Post- Modification Outstanding Recorded Investment	$385	$337

Transfers_and_Servicing_of_Fin1

Transfers and Servicing of Financial Assets - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Transfers and Servicing of Financial Assets [Abstract]
Unpaid principal balances of loans	$28.10	$28

Premises_and_Equipment_Schedul

Premises and Equipment - Schedule of Premises and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Total premises and equipment	$66,095	$61,479
Less accumulated depreciation and amortization	13,214	10,305
Total premises and equipment, net	52,881	51,174
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment	38,569	35,765
Land
Property, Plant and Equipment [Line Items]
Total premises and equipment	10,401	10,399
Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment	15,462	13,773
Construction in progress
Property, Plant and Equipment [Line Items]
Total premises and equipment	$1,663	$1,542

Premises_and_Equipment_Additio

Premises and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Depreciation Expense	$3	$2.70	$2.70

Other_Real_Estate_Owned_Additi

Other Real Estate Owned - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Real Estate [Abstract]
Companies other real estate owned or acquired by foreclosure	$5.50	$3.70

Goodwill_and_Other_Acquired_In2

Goodwill and Other Acquired Intangible Assets - Changes to Carrying Amount of Goodwill (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Beginning Balance	$4,808	$4,808
Goodwill acquired during the year	0	0
Ending Balance	$4,808	$4,808

Goodwill_and_Other_Acquired_In3

Goodwill and Other Acquired Intangible Assets - Schedule of Definite-lived Intangibles Assets Amortization Expense (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Total definite-lived intangible assets, gross	$4,400	$4,400
Accumulated Amortization	1,485	883
Total definite-lived intangible assets, net	2,915	3,517
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Total definite-lived intangible assets, gross	4,400	4,400
Accumulated Amortization	1,485	883
Total definite-lived intangible assets, net	$2,915	$3,517

Goodwill_and_Other_Acquired_In4

Goodwill and Other Acquired Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, estimated useful life (in years)	12 years
Amortization expense, Total	$0.60	$0.20	$0.20

Goodwill_and_Other_Acquired_In5

Goodwill and Other Acquired Intangible Assets - Schedule of Finite Lived Intangible Assets Future Amortization Expense (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]
2015-2019	$367
2020 and thereafter	$1,080

Investments_in_Real_Estate_Pro1

Investments in Real Estate Properties - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Real Estate [Abstract]
Real estate properties at cost	$12.80	$10.10
Capitalized cost	$2.60	$5	$0.90

Investments_in_Tax_Credit_Enti2

Investments in Tax Credit Entities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Investment Income [Line Items]
Generated Tax credits	$14,059,000	$8,639,000	$4,808,000
Tax credit as Percentage of project cost	39.00%
Total assets	3,750,617,000	3,286,617,000
Cash and due from banks	32,484,000	28,140,000
Loans	2,731,928,000	2,325,634,000
Other assets	30,175,000	23,781,000
Liabilities	3,314,243,000	2,904,758,000
Federal
Net Investment Income [Line Items]
Tax credit as Percentage of project cost	39.00%
Credit allowance period (in years)	7 years
Qualified Equity Investments	118,000,000
Federal | Maximum
Net Investment Income [Line Items]
Received allocation amount	46,000,000
Federal NMTC | Federal
Net Investment Income [Line Items]
CDE investments in QEI projects located in low-income communities with poverty rates (as a percent) (greater than)	20.00%
CDE investments in QEI projects located in low-income communities with median family income (as a percent) (less than or equal to)	80.00%
Received allocation amount	118,000,000	118,000,000
Generated Tax credits	46,000,000
Property investment term (in years)	7 years
CDEs | Federal
Net Investment Income [Line Items]
CDE gross amount	118,000,000
Total assets	129,800,000
Cash and due from banks	4,800,000
Loans	112,300,000
Other assets	12,700,000
Liabilities	400,000
Capital	129,400,000
Community Development Fund | Federal
Net Investment Income [Line Items]
Qualified Equity Investment low Income community investment percentage	85.00%
Low-Income Housing tax credits | Federal
Net Investment Income [Line Items]
Property investment term (in years)	15 years
Federal Historic tax credits | Federal
Net Investment Income [Line Items]
Property investment term (in years)	10 years
Due Between One Year And Three Years | Federal
Net Investment Income [Line Items]
Investor receives a credit equal to the total amount invested in the project (as a percent)	5.00%
Due Between Year Four And Year Seven | Federal
Net Investment Income [Line Items]
Investor receives a credit equal to the total amount invested in the project (as a percent)	6.00%
Parent Company
Net Investment Income [Line Items]
Total assets	436,411,000	382,022,000
Cash and due from banks	23,736,000	23,990,000
Other assets	2,145,000	2,123,000
Liabilities	36,000	163,000
Capital	428,962,000	407,648,000
Parent Company | CDEs | Federal
Net Investment Income [Line Items]
CDE gross amount	40,000,000
Other Investors and Leverage Lenders | CDEs | Federal
Net Investment Income [Line Items]
CDE gross amount	78,000,000
Leverage Lender | CDEs | Federal
Net Investment Income [Line Items]
CDE gross amount	$17,500,000

Investments_in_Tax_Credit_Enti3

Investments in Tax Credit Entities - Investment Holdings, Schedule of Investments (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Net Investment Income [Line Items]
Investment	$405,981,000	$367,266,000
Accumulated Amortization	-26,528,000	-15,992,000
Loans to Investment Funds	-120,540,000	-115,590,000
Elimination	-118,000,000	-118,000,000
Net Investment	140,913,000	117,684,000
Tax Benefits Recognized In Prior Year	64,957,000	36,536,000
Tax Benefits Recognized in Current Year	38,445,000	28,421,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter	134,879,000	116,445,000
Total New Market Tax Benefits Expected to be Recognized	238,281,000	181,402,000
Low-Income Housing tax credits
Net Investment Income [Line Items]
Investment	43,733,000	45,072,000
Accumulated Amortization	-7,264,000	-5,078,000
Loans to Investment Funds	0	0
Elimination	0	0
Net Investment	36,469,000	39,994,000
Low Income Housing Tax Benefits Recognized in Prior Year	9,546,000	5,846,000
Low Income Housing Tax Benefits Recognized in Current Year	3,642,000	3,700,000
Low Income Housing Tax Benefits Expected to be Recognized in Future Year and Thereafter	42,109,000	47,438,000
Total Low Income Housing Tax Benefits Expected to be Recognized	55,297,000	56,984,000
Federal Historic tax credits
Net Investment Income [Line Items]
Investment	48,129,000	19,082,000
Accumulated Amortization	-3,412,000	-1,586,000
Loans to Investment Funds	0	0
Elimination	0	0
Net Investment	44,717,000	17,496,000
Tax Benefits Recognized In Prior Year		7,326,000
Tax Benefits Recognized in Current Year		10,497,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter		0
Total New Market Tax Benefits Expected to be Recognized		17,823,000
Historic Rehabilitation Tax Benefits Recognized in Prior Year	17,823,000
Historic Rehabilitation Tax Benefits Recognized in Current Year	19,321,000
Historic Rehabilitation Tax Benefits Expected to be Recognized in Future Year and Thereafter	37,295,000
Total Historic Rehabilitation Tax Benefits Expected to be Recognized	74,439,000
Federal
Net Investment Income [Line Items]
Investment	314,119,000	303,112,000
Accumulated Amortization	-15,852,000	-9,328,000
Loans to Investment Funds	-120,540,000	-115,590,000
Elimination	-118,000,000	-118,000,000
Net Investment	59,727,000	60,194,000
Tax Benefits Recognized In Prior Year	37,588,000	23,364,000
Tax Benefits Recognized in Current Year	15,482,000	14,224,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter	55,475,000	69,007,000
Total New Market Tax Benefits Expected to be Recognized	108,545,000	106,595,000
Federal | Non-Bank Owned CDEs
Net Investment Income [Line Items]
Investment	162,192,000	155,412,000
Accumulated Amortization	-15,852,000	-9,328,000
Loans to Investment Funds	-120,540,000	-115,590,000
Elimination	0	0
Net Investment	25,800,000	30,494,000
Tax Benefits Recognized In Prior Year	27,213,000	18,889,000
Tax Benefits Recognized in Current Year	9,367,000	8,324,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter	25,945,000	33,362,000
Total New Market Tax Benefits Expected to be Recognized	62,525,000	60,575,000
Federal | Bank Owned CDEs
Net Investment Income [Line Items]
Investment	118,000,000	118,000,000
Accumulated Amortization	0	0
Loans to Investment Funds	0	0
Elimination	-118,000,000	-118,000,000
Net Investment	0	0
Tax Benefits Recognized In Prior Year	10,375,000	4,475,000
Tax Benefits Recognized in Current Year	6,115,000	5,900,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter	29,530,000	35,645,000
Total New Market Tax Benefits Expected to be Recognized	46,020,000	46,020,000
Federal | Bank Owned CDE Equity Investment
Net Investment Income [Line Items]
Investment	5,700,000	5,700,000
Accumulated Amortization	0	0
Loans to Investment Funds	0	0
Elimination	0	0
Net Investment	5,700,000	5,700,000
Tax Benefits Recognized In Prior Year	0	0
Tax Benefits Recognized in Current Year	0	0
Tax Benefits Expected to be Recognized in Future Year and Thereafter	0	0
Total New Market Tax Benefits Expected to be Recognized	0	0
Federal | Total Bank Owned CDEs
Net Investment Income [Line Items]
Investment	123,700,000	123,700,000
Accumulated Amortization	0	0
Loans to Investment Funds	0	0
Elimination	-118,000,000	-118,000,000
Net Investment	5,700,000	5,700,000
Tax Benefits Recognized In Prior Year	10,375,000	4,475,000
Tax Benefits Recognized in Current Year	6,115,000	5,900,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter	29,530,000	35,645,000
Total New Market Tax Benefits Expected to be Recognized	46,020,000	46,020,000
Federal | Federal Historic tax credits
Net Investment Income [Line Items]
Investment	41,794,000	13,870,000
Accumulated Amortization	-3,412,000	-1,586,000
Loans to Investment Funds	0	0
Elimination	0	0
Net Investment	38,382,000	12,284,000
Tax Benefits Recognized In Prior Year		7,326,000
Tax Benefits Recognized in Current Year		10,497,000
Tax Benefits Expected to be Recognized in Future Year and Thereafter		0
Total New Market Tax Benefits Expected to be Recognized		17,823,000
Historic Rehabilitation Tax Benefits Recognized in Prior Year	17,823,000
Historic Rehabilitation Tax Benefits Recognized in Current Year	19,321,000
Historic Rehabilitation Tax Benefits Expected to be Recognized in Future Year and Thereafter	37,295,000
Total Historic Rehabilitation Tax Benefits Expected to be Recognized	74,439,000
Federal | Federal NMTC
Net Investment Income [Line Items]
Received allocation amount	118,000,000	118,000,000
Federal | Federal Rehabilitation Tax Credit
Net Investment Income [Line Items]
Net Investment	12,600,000
State
Net Investment Income [Line Items]
Investment	28,227,000	24,000,000
Accumulated Amortization	0	0
Loans to Investment Funds	0	0
Elimination	0	0
Net Investment	28,227,000	24,000,000
Tax Benefits Recognized In Prior Year	0	0
Tax Benefits Recognized in Current Year	0	0
Tax Benefits Expected to be Recognized in Future Year and Thereafter	0	0
Total New Market Tax Benefits Expected to be Recognized	0	0
State | State Rehabilitation Tax Credit
Net Investment Income [Line Items]
Investment	6,335,000	5,212,000
Accumulated Amortization	0	0
Loans to Investment Funds	0	0
Elimination	0	0
Net Investment	6,335,000	5,212,000
Tax Benefits Recognized In Prior Year		0
Tax Benefits Recognized in Current Year		0
Tax Benefits Expected to be Recognized in Future Year and Thereafter		0
Total New Market Tax Benefits Expected to be Recognized		0
Historic Rehabilitation Tax Benefits Recognized in Prior Year	0
Historic Rehabilitation Tax Benefits Recognized in Current Year	0
Historic Rehabilitation Tax Benefits Expected to be Recognized in Future Year and Thereafter	0
Total Historic Rehabilitation Tax Benefits Expected to be Recognized	$0

Investments_in_Tax_Credit_Enti4

Investments in Tax Credit Entities - Schedule of Amortization of Credit Investments (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Investment Income [Line Items]
Investment Tax Credit, Amortization Expense	$14,059	$8,639	$4,808
Federal NMTC
Net Investment Income [Line Items]
Investment Tax Credit, Amortization Expense	10,048	5,923	3,094
Low-Income Housing
Net Investment Income [Line Items]
Investment Tax Credit, Amortization Expense	2,186	1,900	1,287
Federal Historic Rehabilitation
Net Investment Income [Line Items]
Investment Tax Credit, Amortization Expense	$1,825	$816	$427

Investments_in_Tax_Credit_Enti5

Investments in Tax Credit Entities - Summary of Basis Reduction Recorded Related to Investments in Tax Credit Entities (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Investment Income [Line Items]
Reduction in Tax Basis	$1,647	$2,019	$2,766
Federal NMTC
Net Investment Income [Line Items]
Reduction in Tax Basis	1,401	2,019	2,416
Federal Historic Rehabilitation
Net Investment Income [Line Items]
Reduction in Tax Basis	$246	$0	$350

Investments_in_Tax_Credit_Enti6

Investments in Tax Credit Entities - Summary of Major Classifications of Loans (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Net Investment Income [Line Items]
Loans Receivable Real Estate	$265,452	$165,647
Construction
Net Investment Income [Line Items]
Loans Receivable Real Estate	80,741	10,686
Commercial Real Estate
Net Investment Income [Line Items]
Loans Receivable Real Estate	67,520	49,017
Commercial and Industrial
Net Investment Income [Line Items]
Loans Receivable Real Estate	$117,191	$105,944

Deposit_Summary_of_Scheduled_I

Deposit - Summary of Scheduled Interest Bearing Deposits (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
Savings deposits	$49,634	$53,779
Money market accounts	1,055,505	655,173
Negotiable order of withdrawal (NOW) accounts	476,825	511,620
Certificates of deposit over $250,000	284,262	280,354
Certificates of deposit under $250,000	890,090	938,801
Total Deposits	$2,756,316	$2,439,727

Deposit_Summary_of_Scheduled_M

Deposit - Summary of Scheduled Maturities of Time Deposits (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
2015	$632,111
2016	257,606
2017	127,775
2018	110,874
2019	45,986
Total certificates of deposit	$1,174,352

ShortTerm_Borrowings_Summary_o

Short-Term Borrowings - Summary of Short-Term Borrowings (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Line of Credit Facility [Line Items]
Total short-term borrowings	$0	$8,425
FNBB
Line of Credit Facility [Line Items]
Total short-term borrowings	$0	$8,425

ShortTerm_Borrowings_Additiona

Short-Term Borrowings - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014
Short-term Debt [Line Items]
Federal funds interest rate (as a percent)	0.95%
Federal Funds Purchased
Short-term Debt [Line Items]
Federal funds maturity period (days)	1 day
Blanket Pledge | Federal Home Loan Bank (FHLB)
Short-term Debt [Line Items]
FHLB line of credit	655.1	$847
Custody Pledge
Short-term Debt [Line Items]
FHLB line of credit	29.4	847
Custody Pledge | Federal Home Loan Bank (FHLB)
Short-term Debt [Line Items]
FHLB line of credit	29.4

ShortTerm_Borrowings_Summary_o1

Short-Term Borrowings - Summary of Unused Lines of Credit (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Line of Credit Facility [Line Items]
Total unused lines of credit	$648,213	$517,181
FNBB
Line of Credit Facility [Line Items]
Total unused lines of credit	30,000	30,000
JPMorgan Chase
Line of Credit Facility [Line Items]
Total unused lines of credit	30,000	30,000
FHLB
Line of Credit Facility [Line Items]
Total unused lines of credit	563,213	432,181
PNC Bank
Line of Credit Facility [Line Items]
Total unused lines of credit	15,000	15,000
Comerica
Line of Credit Facility [Line Items]
Total unused lines of credit	$10,000	$10,000

LongTerm_Borrowings_Summary_of

Long-Term Borrowings - Summary of Long -Term Borrowings (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Line of Credit Facility [Line Items]
Total long-term borrowings	$40,000	$55,110
FNBB
Line of Credit Facility [Line Items]
Total long-term borrowings	0	110
Credit Suisse Securities (USA) LLC
Line of Credit Facility [Line Items]
Total long-term borrowings	$40,000	$55,000

LongTerm_Borrowings_Additional

Long-Term Borrowings - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Long-term borrowings	40,000,000	55,110,000
Credit Suisse
Line of Credit Facility [Line Items]
Market value of mortgaged securities	61,100,000	65,900,000
Credit Suisse | $40 million borrowing
Line of Credit Facility [Line Items]
Long-term borrowings	40,000,000
Debt instrument interest rate (as a percent)		2.83%
Debt instrument, effective interest rate (as a percentage)	1.59%	2.83%
Credit Suisse | $15 million borrowing
Line of Credit Facility [Line Items]
Long-term borrowings	15,000,000
London Interbank Offered Rate (LIBOR) | Credit Suisse | $40 million borrowing
Line of Credit Facility [Line Items]
Debt instrument interest rate (as a percent)	1.35%	2.00%
Base Rate | Credit Suisse | $40 million borrowing
Line of Credit Facility [Line Items]
Debt instrument interest rate (as a percent)		0.00%

LongTerm_Borrowings_Summary_of1

Long-Term Borrowings - Summary of Principal Payments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]
2019	$40,000
Total long-term borrowings	$40,000	$55,110

Repurchase_Agreements_Addition

Repurchase Agreements - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Equity [Abstract]
Carrying value of securities pledged	$132.70	$92.70

Derivative_Interest_Rate_Swap_2

Derivative - Interest Rate Swap Agreement - Additional Information (Detail) (USD $)	12 Months Ended		1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract	$165,000,000		$165,000,000
Derivative instruments, gain (Loss) Reclassified from Accumulated OCI	0	0
Derivative Instruments, expected gain (Loss) Reclassified from Accumulated OCI	1,100,000
Interest Rate Swap
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract	55,000,000		55,000,000
Other comprehensive income (Loss), Derivatives net of tax			-8,000,000
Prime Swaps
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract		250,000,000
Prime | Prime Swaps
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract		30,000,000
Interest rate swap fixed percentage		4.70%
Prime plus 1% | Prime Swaps
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract		40,000,000
Interest rate swap fixed percentage		5.70%
Debt instrument interest rate (as a percent)		1.00%
Prime plus 1% floored at 5% | Prime Swaps
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract		100,000,000
Interest rate swap fixed percentage		6.01%
Debt instrument interest rate (as a percent)		1.00%
Debt instrument interest floored rate (as a percent)		5.00%
Prime plus 1% floored at 5.5% | Prime Swaps
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract		80,000,000
Interest rate swap fixed percentage		6.26%
Debt instrument interest rate (as a percent)		1.00%
Debt instrument interest floored rate (as a percent)		5.50%
Counterparty C | Interest Rate Swap terminating October 2023
Interest Rate Derivatives Outstanding [Line Items]
Interest rate swap fixed percentage	2.65%		2.65%
Counterparty C | Interest Rate Swap terminating April 2025
Interest Rate Derivatives Outstanding [Line Items]
Interest rate swap fixed percentage	2.75%		2.75%
Counterparty C | Interest Rate Swap terminating October 2025
Interest Rate Derivatives Outstanding [Line Items]
Interest rate swap fixed percentage	2.79%		2.79%
Counterparty A
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract	115,000,000		115,000,000
Interest rate swap fixed percentage	2.88%		2.88%
Counterparty B
Interest Rate Derivatives Outstanding [Line Items]
Notional amount of derivative contract	150,000,000		150,000,000
Interest rate swap fixed percentage	4.17%		4.17%
Financial Instruments Owned and Pledged as Collateral	13,800,000		13,800,000
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	$14,200,000		$14,200,000

Derivative_Interest_Rate_Swap_3

Derivative - Interest Rate Swap Agreements - Schedule of Derivative Instruments (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	$3,042	$0
Derivative Liabilities Fair Value	15,995	4,317
Other Assets
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	3,079	1,157
Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Fair Value	15,995	4,317
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0	0
Derivative Liabilities Fair Value	15,995	2,046
Prime Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	3,042	0
Derivative Liabilities Fair Value	0	2,271
Counterparty A | Interest Rate Swap | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0	1,157
Counterparty A | Interest Rate Swap | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Fair Value	0	0
Counterparty B | Interest Rate Swap | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0	0
Counterparty B | Interest Rate Swap | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Fair Value	15,995	2,046
Counterparty B | Prime Swaps | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	3,042	0
Counterparty B | Prime Swaps | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Fair Value	0	2,271
Counterparty C | Interest Rate Swap | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	37	0
Counterparty C | Interest Rate Swap | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities Fair Value	$0	$0

Derivative_Interest_Rate_Swap_4

Derivative - Interest Rate Swap Agreements - Schedule of Derivative Assets/Liabilities Subject to Master Netting Arrangements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative assets:
Gross Amounts Presented in the Balance Sheet	$3,042	$0
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Net	3,042	0
Derivative Liability [Abstract]
Gross Amounts Presented in the Balance Sheet	15,995	4,317
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	15,995	4,317
Net derivative liability
Gross Amounts Presented in the Balance Sheet	12,953	4,317
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Net	12,953	4,317
Interest Rate Swap
Derivative assets:
Gross Amounts Presented in the Balance Sheet	0	0
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Net	0	0
Derivative Liability [Abstract]
Gross Amounts Presented in the Balance Sheet	15,995	2,046
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	15,995	2,046
Prime Swaps
Derivative assets:
Gross Amounts Presented in the Balance Sheet	3,042	0
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Net	3,042	0
Derivative Liability [Abstract]
Gross Amounts Presented in the Balance Sheet	0	2,271
Gross Amounts Not Offset in the Balance Sheet, Derivatives	0	0
Gross Amounts Not Offset in the Balance Sheet, Collateral	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$0	$2,271

Derivative_Interest_Rate_Swap_5

Derivative - Interest Rate Swap Agreements - Schedule of Effect of Hedging Instruments (Details) (Cash Flow Hedging, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI, net of taxes (Effective Portion)	($11,536)	$2,401
Counterparty A | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI, net of taxes (Effective Portion)	-5,946	5,207
Counterparty B | Interest Rate Swap and Prime Swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI, net of taxes (Effective Portion)	-5,614	-2,806
Counterparty C | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI, net of taxes (Effective Portion)	$24	$0

Income_Taxes_Summary_of_Income

Income Taxes - Summary of Income Tax Benefit on Income from Operations (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Current tax expense									$3,436	$186	$0
Deferred tax benefit									-30,412	-19,937	-7,565
Income tax benefit	($10,622)	($6,612)	($4,784)	($4,958)	($5,867)	($5,673)	($4,198)	($4,013)	($26,976)	($19,751)	($7,565)

Income_Taxes_Schedule_of_Incom

Income Taxes - Schedule of Income Taxes Reconciliation with Federal Statutory Rates (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Federal tax expense at statutory rates									$10,015	$7,406	$7,481
Tax credits									-38,445	-28,421	-17,100
Tax credit-basis reduction									1,647	2,019	2,767
Other tax credits									-617	0	0
Tax-exempt income									-87	-1,070	-918
Disallowed interest expense									98	117	99
Other									413	198	106
Income tax benefit	($10,622)	($6,612)	($4,784)	($4,958)	($5,867)	($5,673)	($4,198)	($4,013)	($26,976)	($19,751)	($7,565)

Income_Taxes_Summary_of_Signif

Income Taxes - Summary of Significant Components of Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Loan loss reserve	$14,817	$11,250
Tax credit carryforwards	94,490	65,216
NOL carryforward	7,271	7,317
Stock-based compensation	824	684
Deferred compensation	91	91
Securities available for sale	10,615	8,880
Other real estate	263	250
Basis difference in assumed liabilities	140	338
Other	621	373
Total deferred tax assets	129,132	94,399
Net deferred tax assets	83,461	51,191
Deferred tax liabilities:
Fixed assets	7,190	6,546
Deferred loan costs	6,296	5,157
Amortizable costs	1,388	1,477
State tax credits	1,614	1,155
Investments in tax credit entities	28,625	28,097
Other	558	776
Total deferred tax liabilities	$45,671	$43,208

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Federal NMTC
Tax Credit Carryforward [Line Items]
Federal NMTC recognized	$15.50	$14.20	$11.40
Low-Income Housing tax credits
Tax Credit Carryforward [Line Items]
Low-Income Housing Tax Credits recognized	3.6	3.7	2.5
Federal Historic tax credits
Tax Credit Carryforward [Line Items]
Federal Historic Rehabilitation Tax Credits recognized	19.3	10.5	3.2
Dec-35
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	20.8
December 2030 Through December 2034
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$94.50

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Aug. 04, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Auction Market Preferred Securities, Stock Series [Line Items]
Common stock par value (in usd per share)		$1	$1
Minimum rate required to declare dividend (as a percent)	90.00%
Expected dividend rate (as a percent)			1.00%
Percentage of redemption price		100.00%
Preferred Stock Series C
Auction Market Preferred Securities, Stock Series [Line Items]
Convertible perpetual preferred stock				$20.60
Convertible preferred stock shares converted (in shares)		0	551,858
Preferred stock aggregate liquidation		4.5
Preferred Stock Series D
Auction Market Preferred Securities, Stock Series [Line Items]
Convertible perpetual preferred stock				37.9
Preferred stock aggregate liquidation		$37.90

Shareholders_Equity_Schedule_o

Shareholders' Equity - Schedule of Annualized Dividend Rate (Detail)	0 Months Ended	12 Months Ended
	Aug. 04, 2011	Dec. 31, 2014
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)	90.00%
January 1, 2012 - March 31, 2012
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		1.00%
April 1, 2012 - June 30, 2012
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		1.00%
July 1, 2012 - December 31, 2013 | Minimum
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		1.00%
July 1, 2012 - December 31, 2013 | Maximum
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		5.00%
January 1, 2014 - February 3, 2016 | Minimum
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		1.00%
January 1, 2014 - February 3, 2016 | Maximum
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		7.00%
February 4, 2016 - Redemption
Preferred Units [Line Items]
Annualized Dividend Rate (as a percent)		9.00%

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	($16,515)	($2,926)	$1,795
Net change in unrealized gain (loss)	-5,368	-20,801	-2,898
Reclassification of net gains realized and included in earnings	-135	-316	-4,324
Amortization of unrealized net gain	547	211
Income tax benefit related to items of other comprehensive losses	-1,734	-7,317	-2,501
Ending balance	-19,737	-16,515	-2,926
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	-2,054	-4,455	0
Net change in unrealized gain (loss)	-9,757	3,694	-6,854
Reclassification of net gains realized and included in earnings	0	0	0
Amortization of unrealized net gain	0	0
Income tax benefit related to items of other comprehensive losses	-3,415	1,293	-2,399
Ending balance	-8,396	-2,054	-4,455
Terminated Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	0	0	0
Net change in unrealized gain (loss)	-7,990	0	0
Reclassification of net gains realized and included in earnings	0	0	0
Amortization of unrealized net gain	0	0
Income tax benefit related to items of other comprehensive losses	-2,796	0	0
Ending balance	-5,194	0	0
Transfers of Available for Sale Securities to Held to Maturity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	-3,710	0	0
Net change in unrealized gain (loss)	0	-5,919	0
Reclassification of net gains realized and included in earnings	0	0	0
Amortization of unrealized net gain	547	211
Income tax benefit related to items of other comprehensive losses	191	-1,998	0
Ending balance	-3,354	-3,710	0
Available for Sale Securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	-10,751	1,529	1,795
Net change in unrealized gain (loss)	12,379	-18,576	3,956
Reclassification of net gains realized and included in earnings	-135	-316	-4,324
Amortization of unrealized net gain	0	0
Income tax benefit related to items of other comprehensive losses	4,286	-6,612	-102
Ending balance	($2,793)	($10,751)	$1,529

Capital_Requirements_and_Other2

Capital Requirements and Other Regulatory Matters - Summary of Capital Amounts and Ratios (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
First NBC Bank Holding Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier one leverage capital, Actual Amount	$387,224	$375,355
Tier one risk based capital, Actual Amount	387,224	375,355
Total risk based capital, Actual Amount	428,962	407,648
Tier one leverage capital, Actual Ratio (as a percent)	10.66%	11.76%
Tier one risk based capital, Actual Ratio (as a percent)	11.59%	13.26%
Total risk based capital, Actual Ratio (as a percent)	12.84%	14.40%
Tier one leverage capital, Capital Adequacy Purposes	145,320	127,625
Tier one risk based capital, Capital Adequacy Purposes	133,644	113,254
Total risk based capital, Capital Adequacy Purposes	267,289	226,508
Tier one leverage capital, Capital Adequacy Purposes Ratio (as a percent)	4.00%	4.00%
Tier one risk based capital, Capital Adequacy Purposes Ratio (as a percent)	4.00%	4.00%
Total risk based capital, Capital Adequacy Purposes Ratio (as a percent)	8.00%	8.00%
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio (as a percent)
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio (as a percent)
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio (as a percent)
First NBC Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier one leverage capital, Actual Amount	361,078	349,104
Tier one risk based capital, Actual Amount	361,078	349,104
Total risk based capital, Actual Amount	402,816	381,396
Tier one leverage capital, Actual Ratio (as a percent)	9.95%	10.96%
Tier one risk based capital, Actual Ratio (as a percent)	10.82%	12.34%
Total risk based capital, Actual Ratio (as a percent)	12.07%	13.48%
Tier one leverage capital, Capital Adequacy Purposes	145,130	127,435
Tier one risk based capital, Capital Adequacy Purposes	133,528	113,170
Total risk based capital, Capital Adequacy Purposes	267,056	226,340
Tier one leverage capital, Capital Adequacy Purposes Ratio (as a percent)	4.00%	4.00%
Tier one risk based capital, Capital Adequacy Purposes Ratio (as a percent)	4.00%	4.00%
Total risk based capital, Capital Adequacy Purposes Ratio (as a percent)	8.00%	8.00%
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount	181,412	159,294
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount	200,292	169,755
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Amount	$333,820	$282,924
Tier one leverage capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio (as a percent)	5.00%	5.00%
Tier one risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio (as a percent)	6.00%	6.00%
Total risk based capital to be Well Capitalized under Prompt Corrective Action Provisions, Ratio (as a percent)	10.00%	10.00%

Warrants_Additional_Informatio

Warrants - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2010	Dec. 31, 2012
Common Stock Warrant [Line Items]
Common stock warrants issued (in shares)	162,500
Common stock warrant exercised (in usd per share)	$10
Warrant expiration period (in years)	10 years
Warrants exercised (in shares)	0
Number of warrants outstanding (in shares)	125,000		87,059
Dryades Bancorp, Inc
Common Stock Warrant [Line Items]
Warrants exercised (in shares)	0
Number of warrants outstanding (in shares)	77,426
Warrants issued (in shares)		87,509
Warrants issued price per share (in usd per share)		$19.50

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period (in years)	3 years
Income tax expense (benefit)	$3,436,000	$186,000	$0
Share-based compensation arrangement by share-based payment award, options, outstanding, intrinsic value	17,000,000
Share-based compensation arrangement by share-based payment award, options, exercisable, intrinsic value	11,800,000
Share-based compensation arrangement by share-based payment award, options, exercised, intrinsic value	1,200,000	1,200,000	0
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	600,000	700,000	500,000
Stock options term (in years)	10 years
Shares available for restricted stock awards under approved compensation plans	1,100,000
Income tax expense (benefit)	-100,000	-200,000	-200,000
Unrecognized compensation cost	1,400,000
Weighted-average period for compensation cost	1 year 8 months 12 days
Minimum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period (in years)	3 years
Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vesting period (in years)	4 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested	0
Unearned share-based compensation	300,000
Restricted shares issued		0
Share based compensation expense	$100,000	$0	$0

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Unvested Restricted Stock Activity (Details) (Restricted Stock, USD $)	12 Months Ended
	Dec. 31, 2014
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock, beginning balance (in shares)	0
Restricted stock, granted (in shares)	13,021
Restricted stock, forfeited (in shares)	-129
Restricted stock, ending balance (in shares)	12,892
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average grant date fair value, beginning balance (in usd per share)	$0
Weighted average grant date fair value, granted (in usd per share)	$34.32
Weighted average grant date fair value, forfeited (in usd per share)	$34.35
Weighted average grant date fair value, ending balance (in usd per share)	$34.32

StockBased_Compensation_Summar1

Stock-Based Compensation - Summary of Weighted-Average Assumptions Used for Option Awards Granted (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Weighted-average expected volatility (as a percent)	44.53%	36.68%	35.33%
Weighted-average risk-free interest rate (as a percent)	2.21%	1.73%	1.25%
Expected option term (in years)	6 years	6 years	6 years 3 months 18 days
Contractual term (in years)	10 years	10 years	10 years
Weighted-average grant date fair value (in usd per share)	$15.56	$5.22	$5.49

StockBased_Compensation_Summar2

Stock-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning balance	855,101	809,017	443,658
Shares, Granted	38,013	139,650	378,692
Shares, Exercised	-57,370	-76,966	0
Shares, Forfeited or expired	-1,074	-16,600	-13,333
Shares Outstanding, Ending balance	834,670	855,101	809,017
Options exercisable	522,600	374,535	289,444
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted- Average Exercise Price, Beginning balance (in usd per share)	$13.48	$11.81	$11.11
Weighted- Average Exercise Price, Granted (in usd per share)	$34.32	$16.16	$14.69
Weighted- Average Exercise Price, Exercised (in usd per share)	$12.26	$10.39	$0
Weighted- Average Exercise Price, Forfeited or expired (in usd per share)	$22.13	$15.16	$14.43
Weighted- Average Exercise Price, Ending balance (in usd per share)	$14.50	$13.48	$11.81
Weighted- Average Exercise Price, Options exercisable	$12.70	$11.94	$10.60
Weighted average remaining contractual term (Years) Options outstanding	6 years 4 months 28 days
Weighted average remaining contractual term (Years) Options exercisable	5 years 6 months 26 days

StockBased_Compensation_Summar3

Stock-Based Compensation - Summarized Information about Stock Options Outstanding by Range of Exercise Prices (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Stock Options [Line Items]
Number of Shares Outstanding	834,670	855,101	809,017	443,658
Weighted Average Exercise Price, Options Outstanding (in usd per share)	$14.50
Weighted Average Remaining Contractual Life, Options Outstanding (in years)	6 years 4 months 28 days
Number of Shares Exercisable	522,600
Weighted Average Exercise Price, Options Exercisable (in usd per share)	$12.70	$11.94	$10.60
August 4, 2011 - September 30, 2011
Schedule Of Stock Options [Line Items]
Range of Exercise Prices, Lower range (in usd per share)	$10
Range of Exercise Prices, Upper range (in usd per share)	$12.70
Number of Shares Outstanding	323,294
Weighted Average Exercise Price, Options Outstanding (in usd per share)	$11.33
Weighted Average Remaining Contractual Life, Options Outstanding (in years)	4 years 4 months 21 days
Number of Shares Exercisable	323,294
Weighted Average Exercise Price, Options Exercisable (in usd per share)	$11.33
October 1, 2011 - December 31, 2011
Schedule Of Stock Options [Line Items]
Range of Exercise Prices, Lower range (in usd per share)	$14.20
Range of Exercise Prices, Upper range (in usd per share)	$14.88
Number of Shares Outstanding	342,108
Weighted Average Exercise Price, Options Outstanding (in usd per share)	$14.68
Weighted Average Remaining Contractual Life, Options Outstanding (in years)	7 years 3 months 29 days
Number of Shares Exercisable	157,233
Weighted Average Exercise Price, Options Exercisable (in usd per share)	$14.59
January 1, 2012 - March 31, 2012
Schedule Of Stock Options [Line Items]
Range of Exercise Prices, Lower range (in usd per share)	$15.88
Range of Exercise Prices, Upper range (in usd per share)	$23.68
Number of Shares Outstanding	169,268
Weighted Average Exercise Price, Options Outstanding (in usd per share)	$20.21
Weighted Average Remaining Contractual Life, Options Outstanding (in years)	8 years 4 months 24 days
Number of Shares Exercisable	42,073
Weighted Average Exercise Price, Options Exercisable (in usd per share)	$16.19

Financial_Instruments_With_Off1

Financial Instruments With Off-Balance-Sheet Risk - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial Instruments [Line Items]
Line of credit facility, amount outstanding	$620.30	$375.20
Standby Letters of Credit
Financial Instruments [Line Items]
Line of credit facility outstanding	110.6	106.5
Net unamortized fees	0.3	0.2
Net unamortized cost	$0.20	$0.30

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leased Assets [Line Items]
Operating lease, rent expense	$3.20	$3.30	$3.20
Minimum
Operating Leased Assets [Line Items]
Operating lease period (in years)	1 year
Renewal option period (in years)	1 year
Maximum
Operating Leased Assets [Line Items]
Operating lease period (in years)	30 years
Renewal option period (in years)	59 years

Commitments_and_Contingencies_2

Commitments and Contingencies - Summary of Annual Rental Payments (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
2015	$3,387
2016	3,349
2017	3,356
2018	3,035
2019	2,862
Thereafter	31,976
Total annual rental payments under noncancelable leases	$47,965

Commitments_and_Contingencies_3

Commitments and Contingencies - Summary of Total Notional Amount of Loan Commitments and Standby Letters of Credit (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
Standby letters of credit	$110,636	$106,467
Unused loan commitments	509,665	268,760
Total	$620,301	$375,227

RelatedParty_Transactions_Addi

Related-Party Transactions - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	building
	director
Related Party Transaction [Line Items]
Related party loans	$64.90	$47.80
Related party loans funded	40.8
Related Party loans repaid	23.7
Related party deposit	14.4	17.9
Affiliated Entity
Related Party Transaction [Line Items]
Loans made to affiliate entities	41.4	40.2
Director | Buildings
Related Party Transaction [Line Items]
Number of buildings leased	1
Number of directors who own the leased property	2
Rent incurred for lease	$0.20	$0.20	$0.20
Operating Leases, Optional Lease Term Extension	5 years

Employee_Benefits_Additional_I

Employee Benefits - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Defined contribution plan, Employer contributions	$1.10	$1	$0.90
Shares purchased under ESOP (in shares)	50,000
Annual allocation percentage	20.00%
ESOP compensation expense	$0.30	$0.20	$0.20

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Carrying Value and Fair Value Measurements of Financial Assets and Liabilities on Recurring Basis (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Available for sale securities	$247,647	$277,719
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
Derivative instruments	0	0
Liabilities
Derivative instruments	0	0
Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	247,647	277,719
Derivative instruments	37	1,157
Liabilities
Derivative instruments	12,953	4,317
Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	0	0
Derivative instruments	0	0
Liabilities
Derivative instruments	0	0
Fair Value, Measurements, Recurring
Assets
Available for sale securities	247,647	277,719
Derivative instruments	37	1,157
Total	247,684	278,876
Liabilities
Derivative instruments	12,953	4,317
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
Derivative instruments	0	0
Total	0	0
Liabilities
Derivative instruments	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	247,647	277,719
Derivative instruments	37	1,157
Total	247,684	278,876
Liabilities
Derivative instruments	12,953	4,317
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	0	0
Derivative instruments	0	0
Total	0	0
Liabilities
Derivative instruments	0	0
U.S. government agency securities
Assets
Available for sale securities	157,527	151,323
U.S. government agency securities | Fair Value, Measurements, Recurring
Assets
Available for sale securities	157,527	151,323
U.S. government agency securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
U.S. government agency securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	157,527	151,323
U.S. government agency securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	0	0
U.S. Treasury securities
Assets
Available for sale securities	12,610	12,149
U.S. Treasury securities | Fair Value, Measurements, Recurring
Assets
Available for sale securities	12,610	12,149
U.S. Treasury securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
U.S. Treasury securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	12,610	12,149
U.S. Treasury securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	0	0
Municipal securities
Assets
Available for sale securities	12,246	23,167
Municipal securities | Fair Value, Measurements, Recurring
Assets
Available for sale securities	12,246	23,167
Municipal securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
Municipal securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	12,246	23,167
Municipal securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	0	0
Mortgage-backed securities
Assets
Available for sale securities	57,087	55,544
Mortgage-backed securities | Fair Value, Measurements, Recurring
Assets
Available for sale securities	57,087	55,544
Mortgage-backed securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
Mortgage-backed securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	57,087	55,544
Mortgage-backed securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	0	0
Corporate bonds
Assets
Available for sale securities	8,177	35,536
Corporate bonds | Fair Value, Measurements, Recurring
Assets
Available for sale securities	8,177	35,536
Corporate bonds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Available for sale securities	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available for sale securities	8,177	35,536
Corporate bonds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Available for sale securities	$0	$0

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments - Carrying Value and Fair Value Measurements of Financial Assets and Liabilities on Non Recurring Basis (Detail) (Fair Value, Measurements, Nonrecurring, USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Loans	$20,679	$9,782
OREO	3,022	2,390
Total	23,701	12,172
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Loans	0	0
OREO	0	0
Total	0	0
Significant Other Observable Inputs (Level 2)
Assets
Loans	0	0
OREO	0	0
Total	0	0
Significant Unobservable Inputs (Level 3)
Assets
Loans	20,679	9,782
OREO	3,022	2,390
Total	$23,701	$12,172

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments - Carrying Value and Fair Value Measurements of Financial Instruments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Assets:
Cash and due from banks	$32,484	$28,140
Short-term investments	18,404	3,502
Investment in short-term receivables	237,135	246,817
Investment securities available for sale	247,647	277,719
Investment securities held to maturity	90,956	90,966
Loans and loans held for sale	1,622	6,577
Cash surrender value of bank-owned life insurance	47,289	26,187
Financial Liabilities:
Deposits, noninterest-bearing	364,534	291,080
Deposits, interest-bearing	2,756,316	2,439,727
Repurchase agreements	117,991	75,957
Short-term borrowings	0	8,425
Long-term borrowings	40,000	55,110
Carrying Amount
Financial Assets:
Cash and due from banks	32,484	28,140
Short-term investments	18,404	3,502
Investment in short-term receivables	237,135	246,817
Investment securities available for sale	247,647	277,719
Investment securities held to maturity	89,076	94,904
Loans and loans held for sale	2,775,886	2,364,354
Cash surrender value of bank-owned life insurance	47,289	26,187
Derivative instruments	37	1,157
Financial Liabilities:
Deposits, noninterest-bearing	364,534	291,080
Deposits, interest-bearing	2,756,316	2,439,727
Repurchase agreements	117,991	75,957
Short-term borrowings		8,425
Long-term borrowings	40,000	55,110
Derivative instruments	12,953	4,317
Total Fair Value
Financial Assets:
Cash and due from banks	32,484	28,140
Short-term investments	18,404	3,502
Investment in short-term receivables	237,135	246,817
Investment securities available for sale	247,647	277,719
Investment securities held to maturity	90,956	90,966
Loans and loans held for sale	3,003,280	2,344,475
Cash surrender value of bank-owned life insurance	47,289	26,187
Derivative instruments	37	1,157
Financial Liabilities:
Deposits, noninterest-bearing	364,534	291,080
Deposits, interest-bearing	2,722,134	2,380,985
Repurchase agreements	117,991	75,957
Short-term borrowings		8,425
Long-term borrowings	42,270	55,616
Derivative instruments	12,953	4,317
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Cash and due from banks	32,484	28,140
Short-term investments	18,404	3,502
Investment in short-term receivables	237,135	246,817
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans and loans held for sale	0	0
Cash surrender value of bank-owned life insurance	47,289	26,187
Derivative instruments	0	0
Financial Liabilities:
Deposits, noninterest-bearing	0	0
Deposits, interest-bearing	0	0
Repurchase agreements	0	0
Short-term borrowings		0
Long-term borrowings	0	0
Derivative instruments	0	0
Significant Other Observable Inputs (Level 2)
Financial Assets:
Cash and due from banks	0	0
Short-term investments	0	0
Investment in short-term receivables	0	0
Investment securities available for sale	247,647	277,719
Investment securities held to maturity	90,956	90,966
Loans and loans held for sale	0	0
Cash surrender value of bank-owned life insurance	0	0
Derivative instruments	37	1,157
Financial Liabilities:
Deposits, noninterest-bearing	364,534	291,080
Deposits, interest-bearing	0	0
Repurchase agreements	117,991	75,957
Short-term borrowings		8,425
Long-term borrowings	0	0
Derivative instruments	12,953	4,317
Significant Unobservable Inputs (Level 3)
Financial Assets:
Cash and due from banks	0	0
Short-term investments	0	0
Investment in short-term receivables	0	0
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans and loans held for sale	3,003,280	2,344,475
Cash surrender value of bank-owned life insurance	0	0
Derivative instruments	0	0
Financial Liabilities:
Deposits, noninterest-bearing	0	0
Deposits, interest-bearing	2,722,134	2,380,985
Repurchase agreements	0	0
Short-term borrowings		0
Long-term borrowings	42,270	55,616
Derivative instruments	$0	$0

Parent_Company_Only_Financial_2

Parent Company Only Financial Statements - Schedule Of Balance Sheet (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Assets
Cash and due from banks	$32,484	$28,140
Goodwill	4,808	4,808	4,808
Other assets	30,175	23,781
Total assets	3,750,617	3,286,617
Liabilities and shareholders’ equity
Long-term borrowings	40,000	55,110
Other liabilities	28,752	27,777
Total liabilities	3,314,243	2,904,758
Total shareholders’ equity	436,374	381,859	248,102	223,516
Total liabilities and equity	3,750,617	3,286,617
First NBC Bank Holding Company
Assets
Cash and due from banks	23,736	23,990
Goodwill	841	841
Investments in subsidiaries	409,689	355,068
Other assets	2,145	2,123
Total assets	436,411	382,022
Liabilities and shareholders’ equity
Long-term borrowings	0	110
Other liabilities	36	53
Total liabilities	36	163
Total shareholders’ equity	436,375	381,859
Total liabilities and equity	$436,411	$382,022

Parent_Company_Only_Financial_3

Parent Company Only Financial Statements - Schedule Of Statement of Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating income
Total operating income	$38,956	$38,668	$37,193	$35,161	$34,437	$31,973	$29,034	$28,580	$149,978	$124,024	$106,457
Operating expense
Total operating expense	10,865	10,908	10,643	10,313	10,326	10,150	9,779	8,893	42,729	39,148	31,666
Income before income taxes	5,081	7,747	7,915	7,870	7,689	4,792	4,408	4,271	28,613	21,160	21,885
Income tax benefit	-10,622	-6,612	-4,784	-4,958	-5,867	-5,673	-4,198	-4,013	-26,976	-19,751	-7,565
Net income					13,556	10,465	8,606	8,284	55,589	40,911	29,450
Income available to common shareholders	15,307	13,989	12,361	12,487	12,993	9,884	8,056	7,651	54,144	38,584	26,431
First NBC Bank Holding Company
Operating income
Interest income									0	0	0
Dividend from bank subsidiary									0	2,000	0
Total operating income									0	2,000	0
Operating expense
Interest expense									3	424	11
Other expense									1,414	856	431
Total operating expense									1,417	1,280	442
Income before income taxes									-1,417	720	-442
Income tax benefit									-496	-448	-155
Income (loss) before equity in undistributed earnings of subsidiaries									-921	1,168	-287
Equity in undistributed earnings of subsidiaries									56,510	39,743	29,227
Net income									55,589	40,911	28,940
Preferred stock dividends									-379	-347	-510
Income available to common shareholders									$55,210	$40,564	$28,430

Parent_Company_Only_Financial_4

Parent Company Only Financial Statements - Schedule Of Statement of Cash Flow (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net income	$55,589	$40,911	$28,940
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Deferred tax benefit	-30,412	-19,937	-7,565
Stock compensation	800	2,124	1,102
Changes in operating assets and liabilities:
Change in other assets	-10,015	-5,168	1,540
Change in other liabilities	-7,661	15,125	-2,758
Net cash provided by operating activities	33,299	89,463	1,198
Investing activities
Net cash used in investing activities	-423,310	-665,076	-454,155
Financing activities
Proceeds from sale of common stock, net of offering costs	1,401	104,332	1,420
Dividends paid	-379	-347	-510
Net cash provided by financing activities	409,257	571,243	421,598
Net change in cash, due from banks, and short-term investments	19,246	-4,370	-31,359
Cash, due from banks, and short-term investments at beginning of period	31,642	36,012	67,371
Cash, due from banks, and short-term investments at end of period	50,888	31,642	36,012
First NBC Bank Holding Company
Operating activities
Net income	55,589	40,911	28,940
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Net income of subsidiaries	-56,510	-39,743	-29,227
Deferred tax benefit	-496	-448	-155
Stock compensation	333	1,155	97
Changes in operating assets and liabilities:
Change in other assets	474	1,481	-1,989
Change in other liabilities	-17	50	0
Net cash provided by operating activities	-627	3,406	-2,334
Investing activities
Capital contributed to subsidiary, net	0	-67,000	-16,600
Net cash used in investing activities	0	-67,000	-16,600
Financing activities
Proceeds from long-term borrowings	0	0	20,000
Repayment of borrowings	-110	-20,110	-110
Proceeds from sale of common stock, net of offering costs	862	104,332	1,420
Dividends paid	-379	-347	-510
Net cash provided by financing activities	373	83,875	20,800
Net change in cash, due from banks, and short-term investments	-254	20,281	1,866
Cash, due from banks, and short-term investments at beginning of period	23,990	3,709	1,843
Cash, due from banks, and short-term investments at end of period	$23,736	$23,990	$3,709

Consolidated_Quarterly_Results2

Consolidated Quarterly Results of Operations - Summary of Quarterly Financial Data (Unaudited) (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Total interest income	$38,956	$38,668	$37,193	$35,161	$34,437	$31,973	$29,034	$28,580	$149,978	$124,024	$106,457
Total interest expense	10,865	10,908	10,643	10,313	10,326	10,150	9,779	8,893	42,729	39,148	31,666
Net interest income	28,091	27,760	26,550	24,848	24,111	21,823	19,255	19,687	107,249	84,876	74,791
Provision for loan losses	3,000	3,000	3,000	3,000	2,400	2,400	2,400	2,600	12,000	9,800	11,035
Net interest income after provision for loan losses	25,091	24,760	23,550	21,848	21,711	19,423	16,855	17,087	95,249	75,076	63,756
Noninterest income	2,287	3,034	2,933	3,359	5,400	2,461	2,738	2,827	11,613	13,426	13,136
Noninterest expense	22,297	20,047	18,568	17,337	19,422	17,092	15,185	15,643	78,249	67,342	55,007
Income before income taxes	5,081	7,747	7,915	7,870	7,689	4,792	4,408	4,271	28,613	21,160	21,885
Income tax benefit	-10,622	-6,612	-4,784	-4,958	-5,867	-5,673	-4,198	-4,013	-26,976	-19,751	-7,565
Net income					13,556	10,465	8,606	8,284	55,589	40,911	29,450
Less net income attributable to noncontrolling interests					0	0	0	0	0	0	-510
Net income attributable to Company	15,703	14,359	12,699	12,828	13,556	10,465	8,606	8,284	55,589	40,911	28,940
Less preferred stock dividends	-94	-95	-95	-95	-95	-62	-95	-95	-379	-347	-510
Less earnings allocated to participating securities	-302	-275	-243	-246	-468	-519	-455	-538	-1,066	-1,980	-1,999
Income available to common shareholders	$15,307	$13,989	$12,361	$12,487	$12,993	$9,884	$8,056	$7,651	$54,144	$38,584	$26,431
Earnings per common share – basic (in usd per share)	$0.82	$0.75	$0.67	$0.68	$0.71	$0.55	$0.51	$0.59	$2.92	$2.38	$2.04
Earnings per common share – diluted (in usd per share)	$0.80	$0.73	$0.65	$0.66	$0.69	$0.54	$0.49	$0.58	$2.84	$2.32	$2.02

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	0 Months Ended
	Dec. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Jan. 16, 2015	Feb. 18, 2015
				facility
Subsequent Event [Line Items]
Senior subordinated notes		$40,000,000	$55,110,000
Subsequent Event
Subsequent Event [Line Items]
Business combination, number of banking facilities acquired				3
Subordinated Note | Senior Notes Due February 2025 | Subsequent Event
Subsequent Event [Line Items]
Senior subordinated notes					60,000,000
Interest rate (as a percent)					5.75%
State-Investors Bank
Subsequent Event [Line Items]
Merger, number of offices owned by entity	4
Merger, amount received per share at the effective time of merger (in usd per share)	$21.25
Merger, addition to deposits in New Orleans MSA	156,000,000
First National Bank of Crestview | Subsequent Event
Subsequent Event [Line Items]
Business combination, assets acquired				62,300,000