Intervest Bancshares (IBCA) 10-Q 4 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 31, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'IBCA	'
Entity Registrant Name	'INTERVEST BANCSHARES CORP	'
Entity Central Index Key	'0000927807	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	22,023,990

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Cash and due from banks	$10,249	$16,689
Federal funds sold and other short-term investments	1,234	8,011
Total cash and cash equivalents	11,483	24,700
Time deposits with banks	4,620	5,370
Securities available for sale, at estimated fair value	305,347	965
Securities held to maturity (estimated fair value of $378,507)	'	383,937
Federal Reserve Bank and Federal Home Loan Bank stock, at cost	7,715	8,244
Loans receivable (net of allowance for loan losses of $26,634 and $27,833, respectively)	1,148,635	1,099,689
Accrued interest receivable	4,665	4,861
Loan fees receivable	2,224	2,298
Premises and equipment, net	4,428	4,056
Foreclosed real estate (net of valuation allowance of $390 and $2,017, respectively)	2,650	10,669
Deferred income tax asset	15,229	18,362
Other assets	4,207	4,645
Total assets	1,511,203	1,567,796
Deposits:	'	'
Noninterest-bearing demand deposit accounts	6,390	5,211
Interest-bearing deposit accounts:	'	'
Checking (NOW) accounts	17,505	17,831
Savings accounts	10,382	10,027
Money market accounts	338,999	367,384
Certificate of deposit accounts	841,048	881,779
Total deposit accounts	1,214,324	1,282,232
Long-term debt - subordinated debentures (capital securities)	56,702	56,702
Accrued interest payable on long term debt	56	868
Accrued interest payable on deposits	850	1,508
Mortgage escrow funds payable	27,531	18,879
Official checks outstanding	3,943	7,335
Other liabilities	1,918	3,281
Total liabilities	1,305,324	1,370,805
STOCKHOLDERS' EQUITY	'	'
Common stock ($1.00 par value; 62,000,000 shares authorized; 22,023,990 and 21,918,623 shares issued and outstanding, respectively)	22,024	21,919
Additional paid-in-capital, common	86,123	88,043
Unearned compensation on restricted common stock awards	-1,597	-1,898
Retained earnings	100,517	88,959
Accumulated other comprehensive loss	-1,188	-32
Total stockholders' equity	205,879	196,991
Total liabilities and stockholders' equity	$1,511,203	$1,567,796

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Securities held to maturity, estimated fair value	'	$378,507
Loans receivable, allowance for loan losses	26,634	27,833
Foreclosed real estate, valuation allowance	$390	$2,017
Common stock, par value	$1	$1
Common stock, shares authorized	62,000,000	62,000,000
Common stock, shares issued	22,023,990	21,918,623
Common stock, shares outstanding	22,023,990	21,918,623

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Earnings (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
INTEREST AND DIVIDEND INCOME	'	'	'	'
Loans receivable	$14,760	$14,486	$43,961	$44,230
Securities	1,141	1,121	3,486	3,213
Other interest-earning assets	15	17	48	53
Total interest and dividend income	15,916	15,624	47,495	47,496
INTEREST EXPENSE	'	'	'	'
Deposits	4,530	6,392	14,209	19,810
Subordinated debentures - capital securities	396	402	1,182	1,277
Total interest expense	4,926	6,794	15,391	21,087
Net interest and dividend income	10,990	8,830	32,104	26,409
Provision (credit) for loan losses	'	250	-1,500	-1,500
Net interest and dividend income after provision (credit) for loan losses	10,990	8,580	33,604	27,909
NONINTEREST INCOME	'	'	'	'
Income from the early repayment of mortgage loans	432	619	2,961	1,909
Income from mortgage lending activities	277	455	869	1,112
Customer service fees	104	100	310	289
Gains from sales of securities available for sale	196	'	196	'
Impairment writedowns on investment securities	'	-273	'	-964
Total noninterest income	1,009	901	4,336	2,346
NONINTEREST EXPENSES	'	'	'	'
Salaries and employee benefits	1,963	1,852	6,105	5,663
Stock compensation for employees and directors	278	229	1,052	731
Occupancy and equipment, net	540	554	1,627	1,632
Data processing	107	97	317	271
Professional fees and services	1,113	327	1,773	1,095
Stationery, printing, supplies, postage and delivery	50	61	211	207
FDIC insurance	192	318	717	1,129
General insurance	150	153	447	455
Director and committee fees	97	85	342	272
Advertising and promotion	7	7	33	17
Real estate activities expense (income), net	117	212	616	-1,120
Provision for real estate losses	'	250	'	955
All other	117	179	488	482
Total noninterest expenses	4,731	4,324	13,728	11,789
Earnings before provision for income taxes	7,268	5,157	24,212	18,466
Provision for income taxes	3,088	2,300	10,452	8,179
Net earnings	4,180	2,857	13,760	10,287
Preferred stock dividend requirements and discount amortization	'	-269	'	-1,057
Net earnings available to common stockholders	$4,180	$2,588	$13,760	$9,230
Basic earnings per common share	$0.19	$0.12	$0.62	$0.42
Diluted earnings per common share	$0.19	$0.12	$0.62	$0.42
Cash dividends per common share	$0.05	'	$0.10	'

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net earnings	$4,180	$2,857	$13,760	$10,287
Securities available for sale:	'	'	'	'
Net unrealized loss arising from transfer from held-to maturity	-2,201	'	-2,201	'
Net unrealized holding gain arising during the period	343	'	360	'
Reclassification for net gain on sales included in net income	-196	'	-196	'
Net unrealized loss on securities available for sale	-2,054	'	-2,037	'
Benefit for income taxes related to net unrealized loss	888	'	881	'
Other comprehensive loss, net of tax	-1,166	'	-1,156	'
Total comprehensive income	$3,014	$2,857	$12,604	$10,287

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (USD $)	Total	Preferred Stock [Member]	Additional Paid-In-Capital, Preferred [Member]	Preferred Stock Discount [Member]	Common Stock [Member]	Additional Paid-In-Capital, Common [Member]	Unearned Compensation - Restricted Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at beginning of period at Dec. 31, 2012	'	$25,000	$24,975,000	($376,000)	$21,590,000	$85,726,000	($715,000)	$79,722,000	'
Balance at beginning of period (in shares) at Dec. 31, 2012	'	25,000	'	'	21,589,589	'	'	'	'
Net earnings	10,287,000	'	'	'	'	'	'	10,287,000	'
Amortization of preferred stock discount	'	'	'	376,000	'	'	'	'	'
Issuance of 92,000 and 465,400 shares of restricted stock	'	'	'	'	331,000	1,157,000	-1,488,000	'	'
Redemption	'	-25,000	-24,975,000	'	'	'	'	'	'
Issuance of shares of restricted stock (in shares)	'	'	'	'	330,700	'	465,400	'	'
Amortization of unearned compensation to compensation expense	'	'	'	'	'	'	756,000	'	'
Redemption (in shares)	'	-25,000	'	'	'	'	'	'	'
Cash dividends declared and paid on preferred stock	'	'	'	'	'	'	'	-5,068,000	'
Issuance of shares upon exercise of stock options	'	'	'	'	15,000	39,000	'	'	'
Discount from redemption of preferred stock	'	'	'	'	'	'	'	187,000	'
Issuance of shares upon exercise of stock options (in shares)	'	'	'	'	14,967	'	'	'	'
Preferred stock discount amortization	-1,057,000	'	'	'	'	'	'	-376,000	'
Forfeiture of shares of restricted stock	'	'	'	'	-19,000	-40,000	'	'	'
Forfeitures of shares of restricted stock issued (in shares)	'	'	'	'	-18,633	'	'	'	'
Excess income tax benefit from equity awards	150,000	'	'	'	'	150,000	'	'	'
Compensation expense related to stock options	'	'	'	'	'	34,000	'	'	'
Total stockholders' equity at end of period at Sep. 30, 2013	192,288,000	'	'	'	21,917,000	87,066,000	-1,447,000	84,752,000	'
Balance at end of period (in shares) at Sep. 30, 2013	21,916,623	'	'	'	21,916,623	'	'	'	'
Balance at beginning of period at Dec. 31, 2013	196,991,000	0	0	0	21,919,000	88,043,000	-1,898,000	88,959,000	-32,000
Balance at beginning of period (in shares) at Dec. 31, 2013	'	'	'	'	21,918,623	'	'	'	'
Net earnings	13,760,000	'	'	'	'	'	'	13,760,000	'
Amortization of preferred stock discount	'	'	'	0	'	'	'	'	'
Net change in accumulated other comprehensive loss	-1,156,000	'	'	'	'	'	'	'	-1,156,000
Issuance of 92,000 and 465,400 shares of restricted stock	'	'	'	'	92,000	612,000	-704,000	'	'
Redemption	'	0	0	'	'	'	'	'	'
Cash dividends declared and paid on common stock	'	'	'	'	'	'	'	-2,202,000	'
Issuance of shares of restricted stock (in shares)	'	'	'	'	92,000	'	92,000	'	'
Amortization of unearned compensation to compensation expense	'	'	'	'	'	'	1,005,000	'	'
Issuance of shares upon exercise of stock options	'	'	'	'	16,000	37,000	'	'	'
Issuance of shares upon exercise of stock options (in shares)	16,667	'	'	'	16,667	'	'	'	'
Forfeiture of shares of restricted stock	'	'	'	'	-3,000	-11,000	'	'	'
Forfeitures of shares of restricted stock issued (in shares)	'	'	'	'	-3,300	'	'	'	'
Excess income tax benefit from equity awards	318,000	'	'	'	'	318,000	'	'	'
Compensation expense related to stock options	'	'	'	'	'	16,000	'	'	'
Repurchase and cancelation of stock warrant	'	'	'	'	'	-2,892,000	'	'	'
Total stockholders' equity at end of period at Sep. 30, 2014	$205,879,000	$0	$0	$0	$22,024,000	$86,123,000	($1,597,000)	$100,517,000	($1,188,000)
Balance at end of period (in shares) at Sep. 30, 2014	22,023,990	0	'	'	22,023,990	'	'	'	'

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parenthetical) (Unearned Compensation - Restricted Common Stock [Member])	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Unearned Compensation - Restricted Common Stock [Member]	'	'
Issuance of shares of restricted stock, shares	92,000	465,400

Condensed_Consolidated_Stateme4

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
OPERATING ACTIVITIES	'	'
Net earnings	$13,760	$10,287
Adjustments to reconcile net earnings to net cash provided by operating activities:	'	'
Depreciation and amortization	218	258
Credit for loan losses	-1,500	-1,500
Provision for real estate losses	'	955
Deferred income tax expense	4,014	7,460
Stock compensation expense	1,052	731
Amortization of deferred debenture offering costs	28	28
Amortization of premiums (accretion) of discounts and deferred loan fees, net	-313	610
Net gain from sales of securities available for sale	-196	'
Net gain from sales of foreclosed real estate	-203	-820
Impairment writedowns on investment securities	'	964
Net decrease in loan fees receivable	74	597
Net decrease in accrued interest payable on borrowed funds	-812	-5,765
Net decrease in official checks outstanding	-3,392	-1,779
Net change in all other assets and liabilities	-114	7,716
Net cash provided by operating activities	12,616	19,742
INVESTING ACTIVITIES	'	'
Repayments of securities held to maturity	66,394	99,705
Purchases of securities held to maturity	-34,752	-75,051
Repayments of securities available for sale	8,841	'
Purchases of securities available for sale	-1,046	-16
Proceeds from sales of securities available for sale	37,384	'
Repayments (purchases) of interest-earning time deposits with banks	750	-200
Purchases of FRB and FHLB stock, net	529	-86
(Originations) repayments of loans receivable, net	-47,586	7,337
Proceeds from sales of foreclosed real estate	8,222	3,569
Purchases of premises and equipment, net	-590	-509
Net cash provided by investing activities	38,146	34,749
FINANCING ACTIVITIES	'	'
Net decrease in deposits	-67,908	-64,216
Net increase in mortgage escrow funds payable	8,652	9,260
Redemption of preferred stock	'	-24,813
Repurchase of common stock warrant from U.S. Treasury	-2,892	'
Cash dividends paid to common stockholders	-2,202	'
Cash dividends paid to preferred stockholders	'	-5,068
Proceeds from issuance of common stock upon exercise of stock options	53	54
Excess income tax benefit from exercise of options and vesting of restricted stock	318	150
Net cash used in financing activities	-63,979	-84,633
Net decrease in cash and cash equivalents	-13,217	-30,142
Cash and cash equivalents at beginning of period	24,700	60,395
Cash and cash equivalents at end of period	11,483	30,253
SUPPLEMENTAL DISCLOSURES	'	'
Cash paid for interest	16,833	27,805
Cash paid for income taxes	5,855	900
Securities held to maturity transferred to available for sale	351,587	'
Net change in unrealized loss on securities available for sale	-1,156	'
Loans transferred to foreclosed real estate	'	3,040
Loans originated to finance sales of foreclosed real estate	'	3,240
Preferred stock dividend requirements and amortization of related discount	'	$1,057

Description_of_Business_and_Su

Description of Business and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Description of Business and Summary of Significant Accounting Policies	'
	Note 1 – Description of Business and Summary of Significant Accounting Policies
	General
	Intervest Bancshares Corporation (“IBC”) is the parent company of Intervest National Bank (“INB”). References in this report to “we,” “us” and “our” refer to these entities on a consolidated basis, unless otherwise specified. For a description of our business, see note 1 to the financial statements in our 2013 Annual Report on Form 10-K (“2013 10-K”). Our accounting and reporting policies conform to U.S. generally accepted accounting principles (GAAP) and general practices within the banking industry and are described in note 1 to the financial statements in our 2013 10-K, as updated by the information in this Form 10-Q.
	Proposed Merger
	On July 31, 2014, IBC and INB entered into a definitive agreement and plan of merger (the “Merger Agreement”) with Bank of the Ozarks, Inc. (“Ozarks”) and its wholly-owned bank subsidiary, Bank of the Ozarks, relating to a proposed merger transaction. The Merger Agreement provides that, upon the terms and subject to the conditions set forth therein, (i) IBC will merge with and into Ozarks, with Ozarks continuing as the surviving corporation (the “Merger”), and (ii) INB will merge with and into Bank of the Ozarks, with Bank of the Ozarks continuing as the surviving bank (the “Bank Merger” and, collectively with the “Merger,” the “Mergers”).
	Subject to the terms and conditions of the Merger Agreement, upon completion of the Merger, each share of IBC’s common stock, issued and outstanding immediately prior to the effective time of the Merger will be converted into the right to receive shares of Ozarks common stock (plus cash in lieu of any fractional share) based on the purchase price of $228.5 million (less the amount paid by IBC to cash out outstanding stock options and stock appreciation rights and to redeem all outstanding stock warrants prior to closing), subject to certain additional purchase price adjustments set forth in the Merger Agreement. The number of Ozarks shares to be issued will be determined based on Ozarks’ 10-day average closing stock price as of the fifth business day prior to the closing date, subject to a minimum and maximum price of $23.95 and $39.91, respectively.
	It is a condition of the Merger that all IBC stock options and stock appreciation rights, whether or not vested, will be cashed out by IBC prior to closing and shares of restricted stock will become fully vested. The foregoing description of the Merger Agreement does not purport to be complete and is qualified in its entirety by reference to the complete text of the Merger Agreement, which was filed as Exhibit 2.1 to IBC’s Current Report on Form 8-K, filed on July 31, 2014.
	The Merger Agreement has been approved by the boards of directors of each of IBC and Ozarks. Subject to the required approval of IBC’s stockholders, requisite regulatory approvals, the effectiveness of the registration statement filed by Ozarks with respect to the stock to be issued in this transaction, and other customary closing conditions, the Merger is expected to be completed by the end of the first quarter of 2015. See note 11 for a discussion of certain litigation in connection with this Merger.
	Principles of Consolidation and Basis of Presentation
	The condensed consolidated financial statements (“financial statements”) in this report have not been audited except for information derived from our audited 2013 consolidated financial statements and notes thereto and should be read in conjunction with our 2013 10-K. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted in this report pursuant to the rules and regulations of the Securities and Exchange Commission.
	Use of Estimates
	In preparing our financial statements, we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosure of contingent liabilities as of the date of the financial statements, and revenues and expenses during the reporting periods. Actual results could differ from those estimates. Estimates that are particularly susceptible to significant change currently relate to the determination of our allowance for loan losses and valuation allowance for real estate losses. These estimates involve a higher degree of complexity and subjectivity and may require assumptions about highly uncertain matters. Current market conditions increase the risk and complexity of the judgments in these estimates. In our opinion, all material adjustments necessary for a fair presentation of our financial condition and results of operations for the interim periods presented in this report have been made. These adjustments are of a normal recurring nature.
	All significant intercompany balances and transactions have been eliminated in consolidation. Our results of operations for the interim periods are not necessarily indicative of results that may be expected for the entire year or any other interim period.
	Stock-Based Compensation
	We recognize the cost of our employee and director services received in exchange for awards of our equity instruments (which are in the form of restricted stock, stock options and cash-settled stock appreciation rights or “SARs”) that vest over time based on the grant-date fair value of the awards. The fair value of restricted stock grants is based on the closing market value of our common stock as reported on the Nasdaq Stock Market on the grant date. The fair value of options and SARs is estimated using the Black-Scholes option-pricing model based on various inputs and assumptions that are described in note 9. Compensation cost, or the grant-date fair value of the awards, related to equity awards is recognized on a straight-line basis over the requisite service period, which is normally the vesting period of the grants.
	For SARs only, fair value is re-measured at the end of each reporting period and amortized as compensation cost over the remaining requisite service period less amounts previously recognized. The SARs represent liability-classified awards that are remeasured to reflect their fair value at each reporting period. After the requisite service period is completed, the SAR’s fair value continues to be remeasured each reporting period until settlement and any increase/decrease in the fair value is immediately recognized as an increase/decrease to our reported stock compensation expense. Upon cash-settlement of a SAR, stock compensation expense is trued-up to equal the SAR’s intrinsic cash value on the date of settlement.
	Stock-based compensation associated with equity awards is recorded as stock compensation expense in the statement of earnings and a corresponding increase to stockholders’ equity as additional paid-in capital for amounts related to restricted stock and stock options, and corresponding increase to accrued stock compensation payable for amounts related to the SARs, which is reported as part of our “other liabilities” in our balance sheet.
	For any excess income tax benefit associated with the vesting of restricted common stock awards and the exercise of stock option awards (calculated as the difference between the fair market value of the stock at the vesting date versus the grant date in the case of stock awards and the difference between the fair market value of the stock at the exercise date versus the exercise price per share in the case of options, multiplied by our effective income tax rate) is recorded as decrease to our income taxes payable and an increase in stockholders’ equity as paid-in capital.
	Recent Accounting Standards Update
	In February 2013, the FASB Issued ASU No. 2013-04, “Obligations Resulting from Joint and Several Liability Arrangements for Which the Total Amount of the Obligation Is Fixed at the Reporting Date”. ASU 2013-04 provides guidance for the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for obligations within the scope of this ASU. We adopted this ASU on January 1, 2014 and it had no impact on our financial statements.
	In July 2013, the FASB issued ASU 2013-11, “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists,” which among other things, requires an unrecognized tax benefit, or a portion of an unrecognized tax benefit, to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except as denoted within the ASU. The amendments in this ASU are effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. We adopted this ASU on January 1, 2014 and it had no impact on our financial statements.
	In January 2014, the FASB issued ASU 2014-04, “Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure”, which is intended to clarify 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 should be derecognized and the real estate recognized. These amendments clarify that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either: (a) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure; or (b) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additional disclosures are required. The amendments are effective for us beginning January 1, 2015.
	In June 2014, FASB issued ASU 2014-11, “Transfers and Servicing – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures.” ASU 2014-11 requires, among other things, two accounting changes. First, the amendments in this update change the accounting for repurchase-to-maturity transactions to secured borrowing accounting. Second, for repurchase financing arrangements, the amendments require separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. ASU 2014-11 is effective for the first interim or annual period beginning after December 15, 2014. The adoption of this guidance is not expected to have any impact on our financial statements.
	In June 2014, FASB issued ASU 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” ASU 2014-12 requires, among other things, that a performance target that affects vesting and could be achieved after the requisite service period be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. ASU 2014-12 is effective for annual reporting periods beginning after December 15, 2015, with early adoption permitted. The adoption of this guidance is not expected to have any impact on our financial statements.

Securities_Held_to_Maturity_an

Securities Held to Maturity and Available for Sale	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Securities Held to Maturity and Available for Sale	'
	Note 2 – Securities Held to Maturity and Available for Sale
	During the quarter ended September 30, 2014, INB’s entire portfolio of securities held to maturity (with a then carrying value of $351.6 million and estimated fair value of $349.4 million) was transferred to the available-for-sale category in order to provide additional flexibility in executing INB’s asset and liability management strategies. At September 30, 2014, we had no securities classified as held to maturity. Due to this transfer, INB cannot classify its securities as held-to-maturity until after September 2016.
	The carrying value (estimated fair value) and amortized cost of securities available for sale are as follows as of the dates indicated:
	($ in thousands)		Number of		Amortized		Gross			Gross		Estimated		Wtd-Avg			Wtd-Avg		Wtd-Avg
			Securities		Cost		Unrealized			Unrealized		Fair		Yield			Expected		Remaining
							Gains			Losses		Value					Life		Maturity
	At September 30, 2014
	U.S. government agencies (1)			125	$	226,361	$	15		$	2,244	$	224,132		1	%		2.9 Yrs		3.5 Yrs
	Residential mortgage-backed (2)			70		79,512		524			346		79,690		1.9	%		4.5 Yrs		13.1 Yrs
	State and municipal			1		530		—			1		529		1.25	%		2.5 Yrs		2.5 Yrs
				196		306,403		539			2,591		304,351		1.23	%		3.3 Yrs		6.0 Yrs
	Mutual fund investment (3)			1		1,038		—			42		996
				197	$	307,441	$	539		$	2,633	$	305,347
	At December 31, 2013
	Mutual fund investment (3)			1	$	1,021		—		$	56	$	965
	The carrying value (amortized cost) and estimated fair value of securities held to maturity are as follows:
	($ in thousands)		Number of		Amortized		Gross			Gross		Estimated		Wtd-Avg			Wtd-Avg		Wtd-Avg
			Securities		Cost		Unrealized			Unrealized		Fair		Yield			Expected		Remaining
							Gains			Losses		Value					Life		Maturity
	At December 31, 2013
	U.S. government agencies (1)			161	$	305,906	$	410		$	4,947	$	301,369		0.94	%		3.0 Yrs		3.8 Yrs
	Residential mortgage-backed (2)			57		77,500		130			1,017		76,613		1.79	%		4.3 Yrs		14.7 Yrs
	State and municipal			1		531		—			6		525		1.25	%		3.2 Yrs		3.3 Yrs
				219	$	383,937	$	540		$	5,970	$	378,507		1.11	%		3.3 Yrs		6.0 Yrs
	-1	Consist of debt obligations of U.S. government sponsored agencies (GSEs) – Federal Home Loan Bank (FHLB), Federal Farm Credit Bank (FFCB), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC), which are federally chartered corporations privately owned by shareholders. GSE securities carry no explicit U.S. government guarantee of creditworthiness. Neither principal nor interest payments are guaranteed by the U.S. government nor do they constitute a debt or obligation of the U.S. government or any of its agencies or instrumentalities other than the applicable GSE. FNMA and FHLMC are under U.S. government conservatorship.
	-2	At September 30, 2014, the portfolio consisted of $11.2 million of Government National Mortgage Association (GNMA) residential pass-through certificates and $68.5 million of residential participation certificates issued by FNMA or FHLMC, compared to $13.6 million and $63.9 million, respectively, at December 31, 2013. The GNMA pass-through certificates are guaranteed as to the payment of principal and interest by the full faith and credit of the U.S. government while the FNMA and FHLMC certificates have an implied guarantee by such agency as to principal and interest payments. Included in this line item are investments in FNMA Delegated Underwriting and Servicing (DUS) mortgage-backed securities (of approximately $16 million at September 30, 2014 and $7.0 million at December 31, 2013) that are backed by eligible multifamily pools that typically contain one loan or single purpose entity.
	-3	The investment represented approximately 93,342 shares at September 30, 2014 and 91,683 shares at December 31, 2013, of an intermediate bond fund that holds securities that are deemed to be qualified under the Community Reinvestment Act.
	The estimated fair values of debt securities with gross unrealized losses segregated between securities that have been in a continuous unrealized loss position for less than twelve months at the respective dates and those that have been in a continuous unrealized loss position for twelve months or longer are summarized as follows:
	($ in thousands)				Less Than Twelve Months					Twelve Months or Longer				Total
			Number of		Estimated		Gross			Estimated		Gross		Estimated			Gross
			Securities		Fair		Unrealized			Fair		Unrealized		Fair			Unrealized
					Value		Losses			Value		Losses		Value			Losses
	At September 30, 2014
	U.S. government agencies			115	$	49,161	$	139		$	158,382	$	2,105	$	207,543		$	2,244
	Residential mortgage-backed			33		15,210		78			20,333		268		35,543			346
	State and municipal			1		529		1			—		—		529			1
				149	$	64,900	$	218		$	178,715	$	2,373	$	243,615		$	2,591
	At December 31, 2013
	U.S. government agencies			130	$	233,930	$	4,791		$	7,344	$	156	$	241,274		$	4,947
	Residential mortgage-backed			41		48,862		987			3,284		30		52,146			1,017
	State and municipal			1		525		6			—		—		525			6
				172	$	283,317	$	5,784		$	10,628	$	186	$	293,945		$	5,970
	All of our investments in debt securities were investment grade rated. The securities had either fixed interest rates or had predetermined scheduled interest rate increases and nearly all had call or prepayment features that allow the issuer to repay all or a portion of the security at par before its stated maturity without penalty. In general, as interest rates rise, the estimated fair value of fixed-rate securities will decrease; as interest rates fall, their value will increase. We generally view changes in fair value caused by changes in interest rates as temporary, which is consistent with our experience. The estimated fair values of securities disclosed in this footnote were obtained from a third-party pricing service that used Level 2 inputs for debt securities and Level 1 inputs for equity securities.
	The following table is a summary of our investments in debt securities at September 30, 2014, by remaining period to contractual maturity (ignoring earlier call dates, if any). The amounts reported in the table also did not consider the effects of possible prepayments or unscheduled repayments. Accordingly, actual maturities may differ from contractual maturities shown in the table.
	($ in thousands)		Amortized		Estimated		Wtd-Avg
			Cost		Fair Value		Yield
	Due in one year or less		$	—	$	—		—	%
	Due after one year through five years			215,795		213,891		0.99
	Due after five years through ten years			42,390		42,053		1.68
	Due after ten years			48,218		48,407		1.94
			$	306,403	$	304,351		1.23	%
	The table below provides a cumulative roll forward of credit losses recognized on securities held to maturity for the periods indicated.
			Quarter Ended				Nine-Months Ended
			September 30,				September 30,
	($ in thousands)		2014		2013		2014			2013
	Balance at beginning of period		$	—	$	4,924	$	—		$	4,233
	Additional credit losses on debt securities for which OTTI was previously recognized			—		273		—			964
	Balance at end of period		$	—	$	5,197	$	—		$	5,197
	During the quarter ended September 30, 2014, proceeds from sales of securities available for sale totaled $37.4 million, resulting in a net realized gain totaling $0.2 million. See note 15 for additional information on sales.

Loans_Receivable

Loans Receivable	9 Months Ended
	Sep. 30, 2014
Receivables [Abstract]	'
Loans Receivable	'
	Note 3 – Loans Receivable
	Major classifications of loans receivable are summarized as follows:
			At September 30, 2014					At December 31, 2013
	($ in thousands)		# of Loans		Amount			# of Loans		Amount
	Loans Secured By Real Estate:
	Commercial loans			426	$	908,697			394	$	838,766
	Multifamily loans			137		200,251			138		210,270
	One to four family loans			17		59,472			20		72,064
	Land loans			6		9,875			5		9,178
				586		1,178,295			557		1,130,278
	All Other Loans:
	Business loans			18		1,004			19		1,061
	Consumer loans			7		138			12		211
				25		1,142			31		1,272
	Loans receivable, gross			611		1,179,437			588		1,131,550
	Deferred loan fees					(4,168	)				(4,028	)
	Loans receivable, net of deferred fees					1,175,269					1,127,522
	Allowance for loan losses					(26,634	)				(27,833	)
	Loans receivable, net				$	1,148,635				$	1,099,689
	Loans 90 days past due and still accruing interest – At September 30, 2014, there were two loans 90 days past due and still accruing totaling $4.0 million, compared to three loans totaling $4.1 million at December 31, 2013.
	Loans on nonaccrual status – At September 30, 2014 and December 31, 2013, there were $22.5 million and $35.9 million of loans, respectively, on nonaccrual status, which included restructured loans (or “TDRs”) of $19.9 million and $33.2 million, respectively. All nonaccrual loans were considered impaired loans.
	TDRs on accrual status - At September 30, 2014 and December 31, 2013, there were $24.7 million and $13.4 million of TDR loans, respectively, classified as accruing TDRs. All of these TDR loans were considered impaired loans.
	Other impaired loans - At September 30, 2014 and December 31, 2013, there was one performing and accruing loan of $7.7 million that was also classified as impaired.
	The tables below summarize certain information regarding our impaired loans as follows:
	($ in thousands)		Recorded Investment by State (1)																		Specific		Total		# of
																					Valuation		Unpaid		Loans
	At September 30, 2014		NY		FL			VA		GA			CT		OH		SD		Total		Allowance (2)		Principal (3)
	Type
	Retail		$	8,106	$	9,005		$	7,677	$	—		$	2,665	$	—	$	—	$	27,453	$	2,456	$	31,150		6
	Office Building			—		14,220			—		8,608			—		—		—		22,828		1,913		22,915		3
	Multifamily			—		3,104			—		—			—		—		—		3,104		590		3,104		2
	Land			—		—			—		—			—		—		1,520		1,520		156		1,520		1
	Totals		$	8,106	$	26,329		$	7,677	$	8,608		$	2,665	$	—	$	1,520	$	54,905	$	5,115	$	58,689		12
	($ in thousands)		Recorded Investment by State (1)																		Specific		Total		# of
																					Valuation		Unpaid		Loans
	At December 31, 2013		NY		FL			VA		GA			CT		OH		SD		Total		Allowance (2)		Principal (3)
	Type
	Retail		$	8,223	$	9,005		$	7,828	$	—		$	2,719	$	1,000	$	—	$	28,775	$	3,052	$	36,216		7
	Office Building			—		14,937			—		8,695			—		—		—		23,632		1,947		23,632		3
	Multifamily			—		3,128			—		—			—		—		—		3,128		594		3,128		2
	Land			—		—			—		—			—		—		1,625		1,625		500		1,625		1
	Totals		$	8,223	$	27,070		$	7,828	$	8,695		$	2,719	$	1,000	$	1,625	$	57,160	$	6,093	$	64,601		13
	-1	Represents unpaid principal less partial principal charge offs and interest received and applied as a reduction of principal in certain cases.
	-2	Represents a specific valuation allowance against the recorded investment, which is included as part of our overall allowance for loan losses. All impaired loans at the dates indicated in the table had a specific valuation allowance.
	-3	Represents contractual unpaid principal balance (shown for informational purposes only). The borrowers are obligated to pay such amounts. However, the ultimate collection by us of such amounts is not assured.
	Other information related to our impaired loans is summarized as follows:
			Quarter Ended					Nine-Months Ended
			September 30,					September 30,
	($ in thousands)		2014		2013			2014		2013
	Average recorded investment in nonaccrual loans		$	21,551	$	39,159		$	30,784	$	41,039
	Total cash basis interest income recognized on nonaccrual loans			304		521			1,281		1,729
	Average recorded investment in accruing TDR loans			26,451		11,423			18,864		14,482
	Total interest income recognized on accruing TDR loans under modified terms			226		152			626		581
	Age analysis of our loan portfolio by segment at September 30, 2014 is summarized as follows:
	($ in thousands)		Total		Current			Past Due		Past Due			Past Due		Total
			Portfolio					31-59		60-89			90 or		Past Due
								Days		Days			more
													Days
	Accruing Loans:
	Commercial real estate		$	888,420	$	886,078		$	—	$	378		$	1,963	$	2,341
	Multifamily			197,990		192,635			—		3,353			2,002		5,355
	One to four family			59,472		59,472			—		—			—		—
	Land			9,875		9,875			—		—			—		—
All other			1,142		1,142			—		—			—		—
Total accruing loans			1,156,899		1,149,202			—		3,731			3,965		7,696
Nonaccrual Loans (1):
Commercial real estate			20,277		13,292			—		4,320			2,665		6,985
Multifamily			2,261		2,261			—		—			—
Total nonaccrual loans			22,538		15,553			—		4,320			2,665		6,985
Total loans		$	1,179,437	$	1,164,755		$	—	$	8,051		$	6,630	$	14,681
-1	The amount of nonaccrual loans in the current column included $19.9 million of TDRs for which payments were being made in accordance with their restructured terms, but the loans were maintained on nonaccrual status in accordance with regulatory guidance. The remaining portion was comprised of one performing and paying loan classified nonaccrual due to concerns regarding the borrower’s ability to continue making payments. Interest income from loan payments received on loans in nonaccrual status is recognized on a cash basis, provided the remaining principal balance is deemed collectible.
Age analysis of our loan portfolio by segment at December 31, 2013 is summarized as follows:
($ in thousands)		Total		Current			Past Due		Past Due			Past Due		Total
		Portfolio					31-59		60-89			90 or		Past
							Days		Days			more		Due
												Days
Accruing Loans:
Commercial real estate		$	802,863	$	796,980		$	1,796	$	—		$	4,087	$	5,883
Multifamily			210,270		209,426			844		—			—		844
One to four family			72,064		72,064			—		—			—		—
Land			9,178		9,178			—		—			—		—
All other			1,272		1,271			1		—			—		1
Total accruing loans			1,095,647		1,088,919			2,641		—			4,087		6,728
Nonaccrual Loans (1):
Commercial real estate			35,903		35,903			—		—			—		—
Total loans		$	1,131,550	$	1,124,822		$	2,641	$	—		$	4,087	$	6,728
-1	The amount of nonaccrual loans in the current column included $33.2 million of TDRs for which payments were being made in accordance with their restructured terms, but the loans were maintained on nonaccrual status in accordance with regulatory guidance. The remaining portion was comprised of certain paying loans classified nonaccrual due to concerns regarding the borrowers’ ability to continue making payments. Interest income from loan payments received on loans in nonaccrual status is recognized on a cash basis, provided the remaining principal balance is deemed collectible.
Information regarding the credit quality of the loan portfolio based on our internally assigned grades follows:
($ in thousands)		Pass		Special Mention			Substandard (1)		Total
At September 30, 2014
Commercial real estate		$	853,979	$	2,236		$	52,482	$	908,697
Multifamily			194,334		2,357			3,560		200,251
One to four family			59,472		—			—		59,472
Land			9,875		—			—		9,875
All other			1,142		—			—		1,142
Total loans		$	1,118,802	$	4,593		$	56,042	$	1,179,437
Allocation of allowance for loan losses		$	21,530	$	141		$	4,963	$	26,634
At December 31, 2013
Commercial real estate		$	772,900	$	3,522		$	62,344	$	838,766
Multifamily			204,298		2,369			3,603		210,270
One to four family			72,064		—			—		72,064
Land			7,553		—			1,625		9,178
All other			1,272		—			—		1,272
Total loans		$	1,058,087	$	5,891		$	67,572	$	1,131,550
Allocation of allowance for loan losses		$	20,720	$	169		$	6,944	$	27,833
-1	Substandard loans consisted of $22.5 million of nonaccrual loans, $22.7 million of accruing TDRs and $10.8 million of other performing loans at September 30, 2014, compared to $35.9 million, $13.1 million and $18.6 million in the same categories, respectively, at December 31, 2013. At September 30, 2014 and December 31, 2013, we also had accruing TDRs of $2.0 million and $0.4 million, respectively, which were rated pass.
The geographic distribution of the loan portfolio by state follows:
($ in thousands)		At September 30, 2014					At December 31, 2013
		Amount		% of Total			Amount		% of Total
New York		$	648,271		55	%	$	670,052		59.3	%
Florida			346,757		29.4			321,812		28.4
North Carolina			28,390		2.4			22,611		2
Georgia			24,249		2.1			18,799		1.7
New Jersey			13,832		1.2			15,650		1.4
Pennsylvania			13,154		1.1			16,898		1.5
Virginia			13,088		1.1			11,491		1
South Carolina			11,426		1			9,223		0.8
Kentucky			8,403		0.7			11,930		1.1
Ohio			7,024		0.6			4,703		0.4
Tennessee			6,691		0.6			5,843		0.5
Connecticut			6,357		0.5			8,429		0.7
Massachusetts			6,016		0.5			—		—
Texas			5,691		0.5			—		—
Michigan			5,473		0.5			5,599		0.5
Utah			5,138		0.5			—		—
Arizona			5,108		0.4			—		—
West Virginia			4,454		0.4			—		—
Indiana			4,191		0.3			2,820		0.2
Illinois			3,608		0.3			—		—
Wisconsin			3,349		0.2			1,790		0.1
California			2,742		0.2			—		—
All other states			6,025		0.5			3,900		0.4
		$	1,179,437		100	%	$	1,131,550		100	%
The distribution of TDRs by accruing versus nonaccruing, by loan type and by geographic distribution follows:
($ in thousands)		At September 30, 2014		At December 31, 2013
Performing – nonaccrual status		$	19,873	$	33,184
Performing – accrual status			24,690		13,429
		$	44,563	$	46,613
Commercial real estate		$	39,939	$	41,860
Multifamily			3,104		3,128
Land			1,520		1,625
		$	44,563	$	46,613
New York		$	8,106	$	8,223
Florida			26,329		27,070
Georgia			8,608		8,695
Ohio			—		1,000
South Dakota			1,520		1,625
		$	44,563	$	46,613

Allowance_for_Loan_Losses

Allowance for Loan Losses	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Allowance for Loan Losses	'
	Note 4 – Allowance for Loan Losses
	Activity in the allowance for loan losses by loan type for the periods indicated is as follows:
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All Other			Total
			Real Estate						Family
	Quarter Ended September 30, 2014
	Balance at beginning of period		$	18,381		$	4,964		$	2,358		$	887		$	8		$	26,598
	Loan chargeoffs			—			—			—			—			—			—
	Loan recoveries			36			—			—			—			—			36
	Provision (credit) for loan losses			17			(139	)		(28	)		150			—			—
	Balance at end of period		$	18,434		$	4,825		$	2,330		$	1,037		$	8		$	26,634
	Nine-Months Ended September 30, 2014
	Balance at beginning of period		$	18,403		$	5,097		$	3,017		$	1,308		$	8		$	27,833
	Loan chargeoffs			—			—			—			—			—			—
	Loan recoveries			287			14			—			—			—			301
	Credit for loan losses			(256	)		(286	)		(687	)		(271	)		—			(1,500	)
	Balance at end of period		$	18,434		$	4,825		$	2,330		$	1,037		$	8		$	26,634
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All Other			Total
			Real Estate						Family
	Quarter Ended September 30, 2013
	Balance at beginning of period		$	17,596		$	5,098		$	2,795		$	956		$	10		$	26,455
	Loan chargeoffs			—			—			—			—			—			—
	Loan recoveries			67			5			—			—			—			72
	Provision (credit) for loan losses			(175	)		212			229			(15	)		(1	)		250
	Balance at end of period		$	17,488		$	5,315		$	3,024		$	941		$	9		$	26,777
	Nine-Months Ended September 30, 2013
	Balance at beginning of period		$	19,051		$	6,881		$	1,120		$	1,043		$	8		$	28,103
	Loan chargeoffs			(1,932	)		(6	)		—			—			—			(1,938	)
	Loan recoveries (1)			947			682			—			483			—			2,112
	Provision (credit) for loan losses			(578	)		(2,242	)		1,904			(585	)		1			(1,500	)
	Balance at end of period		$	17,488		$	5,315		$	3,024		$	941		$	9		$	26,777
	-1	In the first and second quarters of 2013, INB entered into settlement agreements with respect to certain litigation INB had pursued in connection with foreclosure actions it had commenced in 2010 on several of its loans. INB commenced the actions to collect, in one case, insurance proceeds, which it contended had been improperly paid to various third parties, and in another case, damages due to alleged legal malpractice when the loan was originated. As a result of these settlements, INB received net proceeds totaling $2.7 million and $0.1 million in the first and second quarter of 2013, respectively, which was recorded as $1.2 million of recoveries of prior loan charge offs and $1.6 million of recoveries of prior real estate expenses associated with two loans and underlying collateral property.
	The following table sets forth the balances of our loans receivable by segment and impairment evaluation and the allowance for loan losses associated with such loans at September 30, 2014.
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All			Total
			Real Estate						Family						Other
	Loans:
	Individually evaluated for impairment		$	50,281		$	3,104		$	—		$	1,520		$	—		$	54,905
	Collectively evaluated for impairment			858,416			197,147			59,472			8,355			1,142			1,124,532
	Total loans		$	908,697		$	200,251		$	59,472		$	9,875		$	1,142		$	1,179,437
	Allowance for loan losses:
	Individually evaluated for impairment		$	4,369		$	590		$	—		$	156		$	—		$	5,115
	Collectively evaluated for impairment			14,066			4,234			2,330			881			8			21,519
	Total allowance for loan losses		$	18,435		$	4,824		$	2,330		$	1,037		$	8		$	26,634
	The following table sets forth the balances of our loans receivable by segment and impairment evaluation and the allowance for loan losses associated with such loans at December 31, 2013.
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All			Total
			Real Estate						Family						Other
	Loans:
	Individually evaluated for impairment		$	52,407		$	3,128		$	—		$	1,625		$	—		$	57,160
	Collectively evaluated for impairment			786,359			207,142			72,064			7,553			1,272			1,074,390
	Total loans		$	838,766		$	210,270		$	72,064		$	9,178		$	1,272		$	1,131,550
	Allowance for loan losses:
	Individually evaluated for impairment		$	4,999		$	594		$	—		$	500		$	—		$	6,093
	Collectively evaluated for impairment			13,404			4,503			3,017			808			8			21,740
	Total allowance for loan losses		$	18,403		$	5,097		$	3,017		$	1,308		$	8		$	27,833

Foreclosed_Real_Estate_and_Val

Foreclosed Real Estate and Valuation Allowance for Real Estate Losses	9 Months Ended
	Sep. 30, 2014
Banking and Thrift [Abstract]	'
Foreclosed Real Estate and Valuation Allowance for Real Estate Losses	'
	Note 5 – Foreclosed Real Estate and Valuation Allowance for Real Estate Losses
	Real estate acquired through foreclosure by property type is summarized as follows:
			At September 30, 2014					At December 31, 2013
	($ in thousands)		# of Properties		Amount (1)			# of Properties			Amount (1)
	Commercial real estate			1	$	2,650			2		$	3,984
	Multifamily			—		—			1			6,685
				1	$	2,650			3		$	10,669
	-1	Reported net of any associated valuation allowance.
	Activity in the valuation allowance for real estate losses is summarized as follows:
			Quarter Ended					Nine-Months Ended
			September 30,					September 30,
	($ in thousands)		2014		2013			2014			2013
	Valuation allowance at beginning of period		$	390	$	6,044		$	2,017		$	5,339
	Provision for real estate losses			—		250			—			955
	Real estate chargeoffs			—		(4,171	)		(1,627	)		(4,171	)
	Valuation allowance at end of period		$	390	$	2,123		$	390		$	2,123

Deposits

Deposits	9 Months Ended
	Sep. 30, 2014
Banking and Thrift [Abstract]	'
Deposits	'
	Note 6 – Deposits
	Scheduled maturities of certificates of deposit accounts (CDs) were as follows:
		At September 30, 2014					At December 31, 2013
	($ in thousands)	Amount		Wtd-Avg			Amount		Wtd-Avg
				Stated Rate					Stated Rate
	Within one year	$	269,268		1.57	%	$	307,122		1.97	%
	Over one to two years		158,266		1.85			167,323		1.92
	Over two to three years		213,925		1.96			170,956		1.92
	Over three to four years		73,696		1.76			106,700		2.5
	Over four years		125,893		2.11			129,678		2.06
		$	841,048		1.82	%	$	881,779		2.03	%
	CDs of $100,000 or more totaled $465 million at September 30, 2014 and $473 million at December 31, 2013 and included brokered CDs of $68 million and $91 million, respectively. At September 30, 2014, all CDs of $100,000 or more (inclusive of brokered CDs) by remaining maturity were as follows: $113 million due within one year; $85 million due over one to two years; $140 million due over two to three years; $47 million due over three to four years; and $80 million due thereafter. At September 30, 2014, brokered CDs had a weighted-average rate of 2.43% and their remaining maturities were as follows: $5 million due within one year; $8 million due over one to two years; $29 million due over two to three years; $14 million due over three to four years and $12 million due over four years.

Lines_of_Credit

Lines of Credit	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Lines of Credit	'
	Note 7 – Lines of Credit
	At September 30, 2014, INB had $41 million of unsecured credit lines that were cancelable by the lender at any time. As a member of the Federal Home Loan Bank of New York (FHLB) and the Federal Reserve Bank of New York (FRB), INB can borrow from these institutions on a secured basis. At September 30, 2014, INB had available collateral consisting of investment securities and certain loans that could be pledged to support additional total borrowings of approximately $323 million from the FHLB and FRB, if needed. There were no borrowings during the reporting periods in this report.

Subordinated_Debentures_Capita

Subordinated Debentures - Capital Securities	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Subordinated Debentures - Capital Securities	'
	Note 8 – Subordinated Debentures – Capital Securities
	Capital Securities (commonly referred to as trust preferred securities) outstanding are summarized as follows:
		At September 30, 2014							At December 31, 2013
	($ in thousands)	Principal		Accrued		Interest			Principal		Accrued		Interest
				Interest		Rate					Interest		Rate
				Payable							Payable
	Capital Securities II – debentures due September 17, 2033	$	15,464	$	17		3.18	%	$	15,464	$	275		3.19	%
	Capital Securities III – debentures due March 17, 2034		15,464		17		3.02	%		15,464		261		3.03	%
	Capital Securities IV – debentures due September 20, 2034		15,464		14		2.63	%		15,464		223		2.65	%
	Capital Securities V – debentures due December 15, 2036		10,310		8		1.88	%		10,310		109		1.89	%
		$	56,702	$	56				$	56,702	$	868
	The securities are obligations of IBC’s wholly owned statutory business trusts, Intervest Statutory Trust II, III, IV and V, respectively. See note 9 to the financial statements included in our 2013 Annual Report on Form 10-K for additional discussion of the above securities.

Common_Stock_Warrant_and_Equit

Common Stock Warrant and Equity Incentive Plans	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Common Stock Warrant and Equity Incentive Plans	'
	Note 9 – Common Stock Warrant and Equity Incentive Plans
	IBC has shareholder-approved equity incentive plans in place under which stock options, restricted stock and other forms of incentive compensation may be awarded from time to time to officers, employees and directors of IBC and its subsidiary. The maximum number of shares of common stock that may be awarded is 2,250,000. At September 30, 2014, 624,703 shares of common stock were available for award.
	Stock Options and Stock Warrant
	There were no awards of options during the quarterly and nine-month periods ended September 30, 2014 and 2013.
	A summary of outstanding common stock options and warrant and related information follows:
			Exercise Price Per Warrant/Option																					Wtd-Avg.
																								Exercise
	($ in thousands, except per share amounts)		$5.42 (1)			$17.10			$7.50			$4.02			$3.00			$2.55			Total			Price
	Outstanding at December 31, 2013			691,882			110,640			113,990			57,400			32,400			35,133			1,041,445		$	6.64
	Repurchased and cancelled			(691,882	)		—			—			—			—			—			(691,882	)	$	5.42
	Forfeited/expired (2)			—			(600	)		(300	)		(300	)		(300	)		(900	)		(2,400	)	$	7.05
	Options exercised			—			—			(600	)		(2,400	)		(7,500	)		(6,167	)		(16,667	)	$	3.14
	Outstanding at September 30, 2014			—			110,040			113,090			54,700			24,600			28,066			330,496		$	9.37
	Expiration date			—			12/13/17			12/11/18			12/10/19			12/9/20			12/8/21
	Vested and exercisable (3)			—			100	%		100	%		100	%		100	%		67	%		97	%
	Wtd-avg contractual remaining term (in years)			—			3.2			4.2			5.2			6.2			7.2			4.4
	Intrinsic value at September 30, 2014 (4)			—		$	—		$	233		$	303		$	161		$	197		$	894
	-1	The U.S. Department of the Treasury, in connection with IBC’s prior participation in the Capital Purchase Program of TARP, had owned a warrant to purchase 691,882 shares of IBC’s common stock at an exercise price of $5.42 per share. On September 3, 2014, IBC repurchased the warrant for a purchase price of $2.9 million and cancelled the warrant. The purchase price was recorded as a reduction in IBC’s stockholders’ equity.
	-2	Represent options forfeited or expired unexercised.
	-3	The $2.55 options further vest and become 100% exercisable on December 8, 2014. Full vesting may occur earlier upon the occurrence of certain events as defined in the option agreement.
	-4	Intrinsic value was calculated using the closing price of the common stock on September 30, 2014 of $9.56.
	Restricted Stock
	A summary of selected information regarding awards of restricted common stock during the periods covered by this report follows:
	($ in thousands, except per share amounts)
	Grant date of award			1/23/14			1/24/13
	Total restricted shares of stock awarded (1)			92,000			330,700
	Grant date per share fair value (2)		$	7.65		$	4.5
	Total estimated fair value of award		$	703,800		$	1,488,150
	Awards scheduled to vest as follows:
	Jan-14			—			49,566
	Jan-15			30,664			170,888
	Jan-16			30,664			110,246
	Jan-17			30,672			—
				92,000			330,700
	-1	For 2014, awards were as follows: a total of 12,000 shares to five executive officers and a total of 80,000 shares to eight non-employee directors (vesting in three equal installments, with one third on each of the next three anniversary dates of the grant).
	For 2013, awards were as follows: a total of 182,000 shares to five executive officers (vesting in two installments, with two thirds vesting on the second anniversary of the grant and the remaining one third on the third anniversary of the grant); a total of 80,000 shares to eight non-employee directors and 68,700 shares to other officers and employees (vesting in three equal installments, with one third on each of the first three anniversary dates of the grant).
	-2	Fair value of each award was based on the closing market price of IBC’s common stock on the grant date.
	A summary of outstanding restricted common stock and related information follows:
			Price Per Share															Wtd-Avg.
																		Price
			$2.90			$4.50			$7.21			$7.65			Total			Per Share
	Outstanding at December 31, 2013			158,317			279,500			135,500			—			573,317		$	4.7
	Shares granted			—			—			—			92,000			92,000		$	7.65
	Shares forfeited			(500	)		(2,800	)		—			—			(3,300	)	$	4.26
	Shares vested and no longer restricted			(101,035	)		(47,664	)		(75,417	)		—			(224,116	)	$	4.69
	Outstanding at September 30, 2014 (1) (2)			56,782			229,036			60,083			92,000			437,901		$	5.33
	-1	All outstanding shares of restricted common stock at September 30, 2014 were unvested and subject to forfeiture.
	Shares issued at $2.90 vest: 56,782 on January 19, 2015.
	Shares issued at $4.50 vest: 137,264 on January 24, 2015; 91,772 on January 24, 2016.
	Shares issued at $7.21 vest: 14,584 on January 19, 2015; 30,333 on January 24, 2015; 15,166 on January 24, 2016.
	Shares issued at $7.65 vest: 30,664 on January 23, 2015; 30,664 on January 23, 2016; 30,672 on January 23, 2017.
	-2	Vesting is subject to the grantee’s continued employment with us or, in the case of non-employee directors, the grantee’s continued service as our director on the vesting dates. All of the awards are subject to accelerated vesting upon the death or disability of the grantee or upon a change in control of IBC, as defined in the restricted stock award agreements. The record holder of IBC’s restricted shares of common stock possesses all the rights of a holder of our common stock, including the right to receive dividends on the shares when declared and to vote the restricted shares. The restricted shares may not be sold, transferred, pledged, assigned, encumbered, or otherwise alienated or hypothecated until they become fully vested and transferable in accordance with the award agreements.
	Stock Appreciations Rights
	On January 23, 2014, Cash-Settled Stock Appreciation Rights (or “SARs”) were awarded to five executive officers in the total amount of 78,000 shares. The SARs have an exercise price of $7.65 per share, a contractual term of 5 years from the date of grant, upon which they expire, and they vest in three equal installments on the first, second and third anniversaries of the grant date. The SARs are exercisable for thirty days after the holder terminates service to our Company, unless such termination is due to the holder’s death or disability, in which case the SARs are exercisable for one year after termination. The SARs give the executive the right to receive upon exercise, an amount payable in cash equal to the number of shares subject to the SAR that is being exercised multiplied by the excess of (a) the fair market value of a share of our common stock on the date the SAR is exercised, over (b) the exercise price specified in the SAR award agreement, which in the case of this award is $7.65. The estimated fair value of each SAR on the date of grant was $2.28, or a total estimated fair value of $178,000 as calculated using the Black-Scholes option pricing model with the following assumptions used as inputs into the model: expected dividend yield of 1.75%; expected stock volatility of 45%; risk-free interest rate of 0.98% and an expected term of 3.5 years.
	Stock Compensation Expense and Excess Income Tax Benefit
	Stock-based compensation expense related to all equity awards totaled $278,000 and $229,000 for the third quarter of 2014 and 2013, respectively, and $1,052,000 and $731,000 for the nine-months ended September 30, 2014 and 2013, respectively. The expense for the 2014 third quarter and nine-month period included $19,000 and $45,000, respectively, attributable to outstanding cash-settled SARs (all of which were issued in January 2014). At September 30, 2014, pre-tax compensation expense related to all non-vested equity awards not yet recognized totaled $1.8 million and such amount is expected to be recognized in the future over a weighted-average period of approximately 1.7 years.
	Our income taxes payable was reduced by the excess income tax benefit arising from the vesting of restricted common stock awards and the exercise of stock option awards during the reporting periods in this report based on certain criteria as described in note 1 to the financial statements. The tax benefit amounted to $11,000 for the third quarter of 2014 and $5,000 for the third quarter of 2013, and $318,000 and $150,000 for the first nine-months of 2014 and 2013, respectively.

Earnings_Per_Common_Share_and_

Earnings Per Common Share and Common Stock Dividend	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings Per Common Share and Common Stock Dividend	'
	Note 10 – Earnings Per Common Share and Common Stock Dividend
	Net earnings applicable to common stockholders and the weighted-average number of shares used for basic and diluted earnings per common share computations are summarized in the table that follows:
			Quarter Ended				Nine-Months Ended September 30,
			September 30,
			2014		2013		2014		2013
	Basic Earnings Per Common Share:
	Net earnings available to common stockholders		$	4,180,000	$	2,588,000	$	13,760,000	$	9,230,000
	Weighted-Average number of common shares outstanding			22,024,722		21,915,596		22,013,754		21,891,886
	Basic Earnings Per Common Share		$	0.19	$	0.12	$	0.62	$	0.42
	Diluted Earnings Per Common Share:
	Net earnings applicable to common stockholders		$	4,180,000	$	2,588,000	$	13,760,000	$	9,230,000
	Weighted-Average number of common shares outstanding:
	Common shares outstanding			22,024,722		21,915,596		22,013,754		21,891,886
	Potential dilutive shares resulting from exercise of warrants/options (1)			243,523		135,866		192,981		81,064
	Total average number of common shares outstanding used for dilution			22,268,245		22,051,462		22,206,735		21,972,950
	Diluted Earnings Per Common Share		$	0.19	$	0.12	$	0.62	$	0.42
	-1	All outstanding options/warrants to purchase shares of our common stock were considered for the diluted earnings per common share computations and only those that were dilutive (as determined by using the treasury stock method prescribed by GAAP) were included in the computations above. For the quarter and nine-month periods of 2014, outstanding options/warrants to purchase 110,040 shares of common stock were not dilutive because the exercise price of each was above the average market price of our common stock during these periods. For both the quarter and nine-month periods of 2013, 234,430 of options/warrants to purchase common stock were not dilutive because the exercise price of each was above the average market price of our common stock during these periods.
	On April 24, 2014, IBC’s board of directors approved the initiation of a quarterly cash dividend to common stockholders. The initial quarterly dividend declared of $0.05 per common share was paid on May 26, 2014 to stockholders of record at the close of business on May 15, 2014. Although IBC intends to pay a quarterly cash dividend, future dividends are discretionary and subject to the approval of IBC’s board of directors.
	On July 14, 2014, IBC’s board of directors approved a quarterly dividend of $0.05 per common share payable August 26, 2014 to stockholders of record at the close of business on August 15, 2014.

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Contingencies	'
	Note 11 – Contingencies
	We are periodically a party to or otherwise involved in legal proceedings arising in the normal course of business, such as foreclosure proceedings. Based on review and consultation with our legal counsel, we do not believe that there is any pending or threatened proceeding against us, which, if determined adversely, would have a material effect on our business, results of operations, financial position or liquidity, other than litigation discussed below related to our proposed merger with Ozarks, discussed in note 1.
	Litigation Related to the Merger
	On August 7, 2014, a putative class action complaint, captioned GreenTech Research LLC v. Callen, et al. (the “Greentech Action”), was filed in the Supreme Court of the State of New York for New York County, by an entity purporting to be a stockholder IBC (also referred to as Intervest). On August 19, 2014, a putative class action complaint, captioned Sonnenberg v. Intervest Bancshares Corp., et al., was filed in the Supreme Court of the State of New York for New York County, by an entity purporting to be a stockholder of Intervest. Each of the complaints alleges that the directors of Intervest breached their fiduciary duties to Intervest’s stockholders in connection with the merger by approving a transaction pursuant to an allegedly inadequate process that undervalues Intervest and includes preclusive deal protection provisions; and that Intervest and Ozarks allegedly aided and abetted the Intervest directors in breaching their duties to Intervest’s stockholders. The complaints seek court certification of the respective plaintiffs as class representatives and that such proceedings may proceed as stockholder class actions, and various remedies, including enjoining the merger from being consummated in accordance with its agreed-upon terms, rescission or an award of rescissory damages in the event that the merger is consummated, an accounting by the defendants to the plaintiff class for all damages caused by the defendants, recovery of plaintiffs’ costs and attorneys’ and experts’ fees relating to the lawsuit, and such further relief as the court deems just and proper. The individual plaintiffs and the defendants have stipulated to the court that the two actions, as well as any further actions brought in the same court, should be consolidated for further proceedings in the same court in order to minimize expense and promote a more efficient proceeding. On October 14, 2014, the plaintiff in the Greentech Action filed an amended complaint alleging, among other things, inadequacy of the disclosures contained in the proxy statement/prospectus included in the Registration Statement on Form S-4 filed by Ozarks on September 29, 2014. The defendants named in these lawsuits, including Intervest, deny the allegations in the complaints and intend to vigorously defend against these lawsuits. No liability or reserve has been recognized in our consolidated balance sheet at September 30, 2014 with respect to the above matters.

Regulatory_Matters_and_Regulat

Regulatory Matters and Regulatory Capital	9 Months Ended
	Sep. 30, 2014
Banking and Thrift [Abstract]	'
Regulatory Matters and Regulatory Capital	'
	Note 12 – Regulatory Matters and Regulatory Capital
	On March 7, 2014, IBC received notification from the Federal Reserve Bank of New York (the “FRB”) that the written agreement between IBC and the FRB that had been in effect since January 14, 2011 was terminated. As a result, IBC is no longer subject to any regulatory agreement or related restrictions that were described in our 2013 10-K. At September 30, 2014, IBC’s consolidated Tier 1 capital and total capital ratios were 20.84% and 22.10%, respectively, and its leverage capital ratio was 16.92%. At September 30, 2014, INB’s leverage capital ratio, Tier 1 capital and total capital ratios were 16.44%, 20.22% and 21.48%, respectively. At September 30, 2014, we believe that IBC and INB met all regulatory capital adequacy requirements to which they were subject. As of the date of filing of this report, we are not aware of any conditions or events that would have changed the status of such compliance with those requirements at September 30, 2014.

OffBalance_Sheet_Financial_Ins

Off-Balance Sheet Financial Instruments	9 Months Ended
	Sep. 30, 2014
Investments, All Other Investments [Abstract]	'
Off-Balance Sheet Financial Instruments	'
	Note 13 – Off-Balance Sheet Financial Instruments
	INB is party to financial instruments with off-balance sheet risk in the normal course of its business to meet the financing needs of its customers. These instruments can be in the form of commitments to extend credit, unused lines of credit and standby letters of credit, and may involve, to varying degrees, elements of credit and interest rate risk in excess of the amounts recognized in our financial statements. Our maximum exposure to credit risk is represented by the contractual amount of those instruments. Commitments to extend credit are agreements to lend funds to a customer as long as there is no violation of any condition established in the contract. Such commitments generally have fixed expiration dates or other termination clauses and normally require payment of fees to INB. Since some of the commitments are expected to expire without being drawn upon, the total commitment amount does not necessarily represent future cash requirements. We evaluate each customer’s creditworthiness on a case-by-case basis. Standby letters of credit are conditional commitments issued by INB to guarantee the performance of its customer to a third party. The credit risk involved in the underwriting of letters of credit is essentially the same as that involved in originating loans. INB had no standby letters of credit outstanding at September 30, 2014 or December 31, 2013.
	The contractual amounts of off-balance sheet financial instruments are as follows:
	($ in thousands)	At September 30, 2014		At December 31, 2013
	Commitments to extend credit	$	23,134	$	19,386
	Unused lines of credit		787		877
		$	23,921	$	20,263

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Note 14 – Fair Value Measurements
	We use fair value measurements to record fair value adjustments to certain of our assets and to determine our fair value disclosures. In accordance with GAAP, we group our assets and liabilities measured at fair value into three levels (Level 1, 2 and 3), based on the markets in which they are traded and the reliability of the assumptions and inputs that are used to determine their fair value. Level 1 has the highest level of reliability because fair value is based on actively traded markets. See note 20 to the financial statements included in our 2013 10-K for a further discussion of the three valuation levels. At September 30, 2014 and December 31, 2013, we had no liabilities recorded at fair value. At December 31, 2013, we had approximately $1.0 million of assets (comprised of securities available for sale) recorded at fair value (Level 1) on a recurring basis.
	Available-for-sale securities at September 30, 2014 measured at fair value on a recurring basis are summarized below:
	($ in thousands)		Estimated Fair Value			Level 1			Level 2
	U.S. government agencies		$	224,132		$	—		$	224,132
	Residential mortgage-backed			79,690			—			79,690
	State and municipal			529			—			529
	Mutual fund investment			996			996			—
			$	305,347		$	996		$	304,351
	The following tables provide information regarding our assets measured at fair value on a nonrecurring basis.
			Outstanding Carrying Value
			At September 30, 2014			At December 31, 2013
	($ in thousands)		Level 3			Level 3
	Impaired loans (1):
	Commercial real estate		$	50,281		$	52,407
	Multifamily			3,104			3,128
	Land			1,520			1,625
	Total impaired loans			54,905			57,160
	Foreclosed real estate			2,650			10,669
	-1	Outstanding carrying value for impaired loans excludes a specific valuation allowance. See note 4 to the financial statements in this report.
			Accumulated Losses on						Total Losses (Gains) (1)
			Outstanding						Quarter Ended						Nine-Months Ended
			Balance as of:						September 30,						September 30,
	($ in thousands)		Sep 30,			Dec 31,			2014			2013			2014			2013
			2014			2013
	Impaired loans: Commercial real estate		$	7,416		$	11,522		$	(452	)	$	—		$	(918	)	$	823
	Multifamily			591			594			—			(7	)		(17	)		(964	)
	Land			156			500			(5	)		(2	)		(344	)		(23	)
	Total impaired loans			8,163			12,616			(457	)		(9	)		(1,279	)		(164	)
	Impaired securities			—			—			—			273			—			964
	Foreclosed real estate			390			2,017			—			149			(203	)		135
			$	8,553		$	14,633		$	(457	)	$	413		$	(1,482	)	$	935
	-1	Represents total losses or (gains) recognized on all assets measured at fair value on a nonrecurring basis during the period indicated. The losses or (gains) for impaired loans represent the change (before chargeoffs and recoveries) during the period in the corresponding specific valuation allowance, while the losses (gains) for foreclosed real estate represent writedowns in carrying values subsequent to foreclosure (recorded as provisions for real estate losses) adjusted for any recoveries of prior write downs and (gains) or losses from the transfer/sale of properties during the period. The losses on securities represent the total of other than temporary impairment charges, which are recorded as component of noninterest income.
	The following table details changes in assets measured at fair value on a nonrecurring basis for the periods indicated.
	($ in thousands)		Impaired Loans			Foreclosed Real Estate
	Quarter Ended September 30, 2014
	Balance at beginning of period		$	57,821		$	2,650
	Principal repayments/sales			(2,916	)		—
	Balance at end of period		$	54,905		$	2,650
	Nine-Months Ended September 30, 2014
	Balance at beginning of period		$	57,160		$	10,669
	Net new impaired loans			3,466			—
	Principal repayments/sales			(5,721	)		(8,222	)
	Gain from sales			—			203
	Balance at end of period		$	54,905		$	2,650
	The following table details changes in assets measured at fair value on a nonrecurring basis for the periods indicated.
	($ in thousands)		Impaired			Impaired			Foreclosed
			Securities			Loans			Real Estate
	Quarter Ended September 30, 2013
	Balance at beginning of period		$	2,923		$	50,533		$	14,869
	Net new impaired loans			—			514			—
	Other than temporary impairment write downs			(273	)		—			—
	Principal repayments/sales			(46	)		(149	)		(2,701	)
	Writedowns of carrying value subsequent to foreclosure			—			—			(250	)
	Gains from sales			—			—			101
	Balance at end of period		$	2,604		$	50,898		$	12,019
	Nine-Months Ended September 30, 2013
	Balance at beginning of period		$	3,721		$	65,973		$	15,923
	Net new impaired loans			—			8,761			—
	Impaired loans transferred to foreclosed real estate			—			(3,040	)		3,040
	Other than temporary impairment write downs			(964	)		—			—
	Principal repayments/sales			(153	)		(18,858	)		(6,809	)
	Chargeoffs of impaired loans			—			(1,938	)		—
Writedowns of carrying value subsequent to foreclosure			—			—			(1,029	)
Recoveries of prior writedowns			—			—			74
Gains from sales			—			—			820
Balance at end of period		$	2,604		$	50,898		$	12,019
We are required to disclose the estimated fair value of each class of our financial instruments for which it is practicable to estimate, which values are shown in the table that follows. The fair value of a financial instrument is the current estimated amount that would be exchanged between willing parties, other than in a forced liquidation. The fair value estimates are made at a specific point in time based on available information. A discussion regarding the assumptions used to compute the estimated fair values disclosed below can be found in note 20 to the financial statements included our 2013 10-K.
The carrying and estimated fair values of our financial instruments are as follows:
		At September 30, 2014						At December 31, 2013
($ in thousands)		Carrying			Fair			Carrying			Fair
		Value			Value			Value			Value
Financial Assets:
Cash and cash equivalents (1)		$	11,483		$	11,483		$	24,700		$	24,700
Time deposits with banks (1)			4,620			4,620			5,370			5,370
Securities available for sale, net (2)			305,347			305,347			965			965
Securities held to maturity, net (2)			—			—			383,937			378,507
FRB and FHLB stock (3)			7,715			7,715			8,244			8,244
Loans receivable, net (3)			1,148,635			1,161,476			1,099,689			1,100,858
Accrued interest receivable (3)			4,665			4,665			4,861			4,861
Loan fees receivable (3)			2,224			1,765			2,298			1,808
Total Financial Assets		$	1,484,689		$	1,497,071		$	1,530,064		$	1,525,313
Financial Liabilities:
Deposits (3)		$	1,214,324		$	1,229,119		$	1,282,232		$	1,294,690
Borrowed funds plus accrued interest payable (3)			56,758			56,516			57,570			57,260
Accrued interest payable on deposits (3)			850			850			1,508			1,508
Commitments to lend (3)			146			146			408			408
Total Financial Liabilities		$	1,272,078		$	1,286,631		$	1,341,718		$	1,353,866
Net Financial Assets		$	212,611		$	210,440		$	188,346		$	171,447
-1	We consider these fair value measurements to be Level 1.
-2	We consider these fair value measurements to be Level 2, except for $1.0 million at each date (which is considered Level 1).
-3	We consider these fair value measurements to be Level 3.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Note 15 – Subsequent Events
	On October 15, 2014, IBC’s board of directors declared a quarterly cash dividend of $0.05 per common share payable November 24, 2014 to stockholders of record at the close of business on November 14, 2014. During October 2014, sales of available for sale securities were made totaling $77 million, which increased INB’s cash on hand to approximately $90 million at October 31, 2014 for use in funding planned deposit outflow and new loans. A net loss of approximately $0.2 million was recorded on these sales.

Description_of_Business_and_Su1

Description of Business and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
General	'
	General
	Intervest Bancshares Corporation (“IBC”) is the parent company of Intervest National Bank (“INB”). References in this report to “we,” “us” and “our” refer to these entities on a consolidated basis, unless otherwise specified. For a description of our business, see note 1 to the financial statements in our 2013 Annual Report on Form 10-K (“2013 10-K”). Our accounting and reporting policies conform to U.S. generally accepted accounting principles (GAAP) and general practices within the banking industry and are described in note 1 to the financial statements in our 2013 10-K, as updated by the information in this Form 10-Q.
Proposed Merger	'
	Proposed Merger
	On July 31, 2014, IBC and INB entered into a definitive agreement and plan of merger (the “Merger Agreement”) with Bank of the Ozarks, Inc. (“Ozarks”) and its wholly-owned bank subsidiary, Bank of the Ozarks, relating to a proposed merger transaction. The Merger Agreement provides that, upon the terms and subject to the conditions set forth therein, (i) IBC will merge with and into Ozarks, with Ozarks continuing as the surviving corporation (the “Merger”), and (ii) INB will merge with and into Bank of the Ozarks, with Bank of the Ozarks continuing as the surviving bank (the “Bank Merger” and, collectively with the “Merger,” the “Mergers”).
	Subject to the terms and conditions of the Merger Agreement, upon completion of the Merger, each share of IBC’s common stock, issued and outstanding immediately prior to the effective time of the Merger will be converted into the right to receive shares of Ozarks common stock (plus cash in lieu of any fractional share) based on the purchase price of $228.5 million (less the amount paid by IBC to cash out outstanding stock options and stock appreciation rights and to redeem all outstanding stock warrants prior to closing), subject to certain additional purchase price adjustments set forth in the Merger Agreement. The number of Ozarks shares to be issued will be determined based on Ozarks’ 10-day average closing stock price as of the fifth business day prior to the closing date, subject to a minimum and maximum price of $23.95 and $39.91, respectively.
	It is a condition of the Merger that all IBC stock options and stock appreciation rights, whether or not vested, will be cashed out by IBC prior to closing and shares of restricted stock will become fully vested. The foregoing description of the Merger Agreement does not purport to be complete and is qualified in its entirety by reference to the complete text of the Merger Agreement, which was filed as Exhibit 2.1 to IBC’s Current Report on Form 8-K, filed on July 31, 2014.
	The Merger Agreement has been approved by the boards of directors of each of IBC and Ozarks. Subject to the required approval of IBC’s stockholders, requisite regulatory approvals, the effectiveness of the registration statement filed by Ozarks with respect to the stock to be issued in this transaction, and other customary closing conditions, the Merger is expected to be completed by the end of the first quarter of 2015. See note 11 for a discussion of certain litigation in connection with this Merger.
Principles of Consolidation and Basis of Presentation	'
	Principles of Consolidation and Basis of Presentation
	The condensed consolidated financial statements (“financial statements”) in this report have not been audited except for information derived from our audited 2013 consolidated financial statements and notes thereto and should be read in conjunction with our 2013 10-K. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted in this report pursuant to the rules and regulations of the Securities and Exchange Commission.
Use of Estimates	'
	Use of Estimates
	In preparing our financial statements, we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosure of contingent liabilities as of the date of the financial statements, and revenues and expenses during the reporting periods. Actual results could differ from those estimates. Estimates that are particularly susceptible to significant change currently relate to the determination of our allowance for loan losses and valuation allowance for real estate losses. These estimates involve a higher degree of complexity and subjectivity and may require assumptions about highly uncertain matters. Current market conditions increase the risk and complexity of the judgments in these estimates. In our opinion, all material adjustments necessary for a fair presentation of our financial condition and results of operations for the interim periods presented in this report have been made. These adjustments are of a normal recurring nature.
	All significant intercompany balances and transactions have been eliminated in consolidation. Our results of operations for the interim periods are not necessarily indicative of results that may be expected for the entire year or any other interim period.
Stock-Based Compensation	'
	Stock-Based Compensation
	We recognize the cost of our employee and director services received in exchange for awards of our equity instruments (which are in the form of restricted stock, stock options and cash-settled stock appreciation rights or “SARs”) that vest over time based on the grant-date fair value of the awards. The fair value of restricted stock grants is based on the closing market value of our common stock as reported on the Nasdaq Stock Market on the grant date. The fair value of options and SARs is estimated using the Black-Scholes option-pricing model based on various inputs and assumptions that are described in note 9. Compensation cost, or the grant-date fair value of the awards, related to equity awards is recognized on a straight-line basis over the requisite service period, which is normally the vesting period of the grants.
	For SARs only, fair value is re-measured at the end of each reporting period and amortized as compensation cost over the remaining requisite service period less amounts previously recognized. The SARs represent liability-classified awards that are remeasured to reflect their fair value at each reporting period. After the requisite service period is completed, the SAR’s fair value continues to be remeasured each reporting period until settlement and any increase/decrease in the fair value is immediately recognized as an increase/decrease to our reported stock compensation expense. Upon cash-settlement of a SAR, stock compensation expense is trued-up to equal the SAR’s intrinsic cash value on the date of settlement.
	Stock-based compensation associated with equity awards is recorded as stock compensation expense in the statement of earnings and a corresponding increase to stockholders’ equity as additional paid-in capital for amounts related to restricted stock and stock options, and corresponding increase to accrued stock compensation payable for amounts related to the SARs, which is reported as part of our “other liabilities” in our balance sheet.
	For any excess income tax benefit associated with the vesting of restricted common stock awards and the exercise of stock option awards (calculated as the difference between the fair market value of the stock at the vesting date versus the grant date in the case of stock awards and the difference between the fair market value of the stock at the exercise date versus the exercise price per share in the case of options, multiplied by our effective income tax rate) is recorded as decrease to our income taxes payable and an increase in stockholders’ equity as paid-in capital.
Recent Accounting Standards Update	'
	Recent Accounting Standards Update
	In February 2013, the FASB Issued ASU No. 2013-04, “Obligations Resulting from Joint and Several Liability Arrangements for Which the Total Amount of the Obligation Is Fixed at the Reporting Date”. ASU 2013-04 provides guidance for the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for obligations within the scope of this ASU. We adopted this ASU on January 1, 2014 and it had no impact on our financial statements.
	In July 2013, the FASB issued ASU 2013-11, “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists,” which among other things, requires an unrecognized tax benefit, or a portion of an unrecognized tax benefit, to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except as denoted within the ASU. The amendments in this ASU are effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. We adopted this ASU on January 1, 2014 and it had no impact on our financial statements.
	In January 2014, the FASB issued ASU 2014-04, “Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure”, which is intended to clarify 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 should be derecognized and the real estate recognized. These amendments clarify that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either: (a) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure; or (b) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additional disclosures are required. The amendments are effective for us beginning January 1, 2015.
	In June 2014, FASB issued ASU 2014-11, “Transfers and Servicing – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures.” ASU 2014-11 requires, among other things, two accounting changes. First, the amendments in this update change the accounting for repurchase-to-maturity transactions to secured borrowing accounting. Second, for repurchase financing arrangements, the amendments require separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. ASU 2014-11 is effective for the first interim or annual period beginning after December 15, 2014. The adoption of this guidance is not expected to have any impact on our financial statements.
	In June 2014, FASB issued ASU 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” ASU 2014-12 requires, among other things, that a performance target that affects vesting and could be achieved after the requisite service period be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. ASU 2014-12 is effective for annual reporting periods beginning after December 15, 2015, with early adoption permitted. The adoption of this guidance is not expected to have any impact on our financial statements.

Securities_Held_to_Maturity_an1

Securities Held to Maturity and Available for Sale (Tables)	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Carrying Value (Estimated Fair Value) and Amortized Cost of Securities Available for Sale	'
	The carrying value (estimated fair value) and amortized cost of securities available for sale are as follows as of the dates indicated:
	($ in thousands)		Number of		Amortized		Gross			Gross		Estimated		Wtd-Avg			Wtd-Avg		Wtd-Avg
			Securities		Cost		Unrealized			Unrealized		Fair		Yield			Expected		Remaining
							Gains			Losses		Value					Life		Maturity
	At September 30, 2014
	U.S. government agencies (1)			125	$	226,361	$	15		$	2,244	$	224,132		1	%		2.9 Yrs		3.5 Yrs
	Residential mortgage-backed (2)			70		79,512		524			346		79,690		1.9	%		4.5 Yrs		13.1 Yrs
	State and municipal			1		530		—			1		529		1.25	%		2.5 Yrs		2.5 Yrs
				196		306,403		539			2,591		304,351		1.23	%		3.3 Yrs		6.0 Yrs
	Mutual fund investment (3)			1		1,038		—			42		996
				197	$	307,441	$	539		$	2,633	$	305,347
	At December 31, 2013
	Mutual fund investment (3)			1	$	1,021		—		$	56	$	965
	-1	Consist of debt obligations of U.S. government sponsored agencies (GSEs) – Federal Home Loan Bank (FHLB), Federal Farm Credit Bank (FFCB), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC), which are federally chartered corporations privately owned by shareholders. GSE securities carry no explicit U.S. government guarantee of creditworthiness. Neither principal nor interest payments are guaranteed by the U.S. government nor do they constitute a debt or obligation of the U.S. government or any of its agencies or instrumentalities other than the applicable GSE. FNMA and FHLMC are under U.S. government conservatorship.
	-2	At September 30, 2014, the portfolio consisted of $11.2 million of Government National Mortgage Association (GNMA) residential pass-through certificates and $68.5 million of residential participation certificates issued by FNMA or FHLMC, compared to $13.6 million and $63.9 million, respectively, at December 31, 2013. The GNMA pass-through certificates are guaranteed as to the payment of principal and interest by the full faith and credit of the U.S. government while the FNMA and FHLMC certificates have an implied guarantee by such agency as to principal and interest payments. Included in this line item are investments in FNMA Delegated Underwriting and Servicing (DUS) mortgage-backed securities (of approximately $16 million at September 30, 2014 and $7.0 million at December 31, 2013) that are backed by eligible multifamily pools that typically contain one loan or single purpose entity.
	-3	The investment represented approximately 93,342 shares at September 30, 2014 and 91,683 shares at December 31, 2013, of an intermediate bond fund that holds securities that are deemed to be qualified under the Community Reinvestment Act.
Carrying Value (Amortized Cost) and Estimated Fair Value of Securities Held to Maturity	'
	The carrying value (amortized cost) and estimated fair value of securities held to maturity are as follows:
	($ in thousands)		Number of		Amortized		Gross			Gross		Estimated		Wtd-Avg			Wtd-Avg		Wtd-Avg
			Securities		Cost		Unrealized			Unrealized		Fair		Yield			Expected		Remaining
							Gains			Losses		Value					Life		Maturity
	At December 31, 2013
	U.S. government agencies (1)			161	$	305,906	$	410		$	4,947	$	301,369		0.94	%		3.0 Yrs		3.8 Yrs
	Residential mortgage-backed (2)			57		77,500		130			1,017		76,613		1.79	%		4.3 Yrs		14.7 Yrs
	State and municipal			1		531		—			6		525		1.25	%		3.2 Yrs		3.3 Yrs
				219	$	383,937	$	540		$	5,970	$	378,507		1.11	%		3.3 Yrs		6.0 Yrs
	-1	Consist of debt obligations of U.S. government sponsored agencies (GSEs) – Federal Home Loan Bank (FHLB), Federal Farm Credit Bank (FFCB), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC), which are federally chartered corporations privately owned by shareholders. GSE securities carry no explicit U.S. government guarantee of creditworthiness. Neither principal nor interest payments are guaranteed by the U.S. government nor do they constitute a debt or obligation of the U.S. government or any of its agencies or instrumentalities other than the applicable GSE. FNMA and FHLMC are under U.S. government conservatorship.
	-2	At September 30, 2014, the portfolio consisted of $11.2 million of Government National Mortgage Association (GNMA) residential pass-through certificates and $68.5 million of residential participation certificates issued by FNMA or FHLMC, compared to $13.6 million and $63.9 million, respectively, at December 31, 2013. The GNMA pass-through certificates are guaranteed as to the payment of principal and interest by the full faith and credit of the U.S. government while the FNMA and FHLMC certificates have an implied guarantee by such agency as to principal and interest payments. Included in this line item are investments in FNMA Delegated Underwriting and Servicing (DUS) mortgage-backed securities (of approximately $16 million at September 30, 2014 and $7.0 million at December 31, 2013) that are backed by eligible multifamily pools that typically contain one loan or single purpose entity.
	-3	The investment represented approximately 93,342 shares at September 30, 2014 and 91,683 shares at December 31, 2013, of an intermediate bond fund that holds securities that are deemed to be qualified under the Community Reinvestment Act.
Estimated Fair Values of Debt Securities	'
	The estimated fair values of debt securities with gross unrealized losses segregated between securities that have been in a continuous unrealized loss position for less than twelve months at the respective dates and those that have been in a continuous unrealized loss position for twelve months or longer are summarized as follows:
	($ in thousands)				Less Than Twelve Months					Twelve Months or Longer				Total
			Number of		Estimated		Gross			Estimated		Gross		Estimated			Gross
			Securities		Fair		Unrealized			Fair		Unrealized		Fair			Unrealized
					Value		Losses			Value		Losses		Value			Losses
	At September 30, 2014
	U.S. government agencies			115	$	49,161	$	139		$	158,382	$	2,105	$	207,543		$	2,244
	Residential mortgage-backed			33		15,210		78			20,333		268		35,543			346
	State and municipal			1		529		1			—		—		529			1
				149	$	64,900	$	218		$	178,715	$	2,373	$	243,615		$	2,591
	At December 31, 2013
	U.S. government agencies			130	$	233,930	$	4,791		$	7,344	$	156	$	241,274		$	4,947
	Residential mortgage-backed			41		48,862		987			3,284		30		52,146			1,017
	State and municipal			1		525		6			—		—		525			6
				172	$	283,317	$	5,784		$	10,628	$	186	$	293,945		$	5,970
Summary of Investments in Debt Securities	'
	The following table is a summary of our investments in debt securities at September 30, 2014, by remaining period to contractual maturity (ignoring earlier call dates, if any). The amounts reported in the table also did not consider the effects of possible prepayments or unscheduled repayments. Accordingly, actual maturities may differ from contractual maturities shown in the table.
	($ in thousands)		Amortized		Estimated		Wtd-Avg
			Cost		Fair Value		Yield
	Due in one year or less		$	—	$	—		—	%
	Due after one year through five years			215,795		213,891		0.99
	Due after five years through ten years			42,390		42,053		1.68
	Due after ten years			48,218		48,407		1.94
			$	306,403	$	304,351		1.23	%
Credit Losses Recognized on Securities	'
	The table below provides a cumulative roll forward of credit losses recognized on securities held to maturity for the periods indicated.
			Quarter Ended				Nine-Months Ended
			September 30,				September 30,
	($ in thousands)		2014		2013		2014			2013
	Balance at beginning of period		$	—	$	4,924	$	—		$	4,233
	Additional credit losses on debt securities for which OTTI was previously recognized			—		273		—			964
	Balance at end of period		$	—	$	5,197	$	—		$	5,197

Loans_Receivable_Tables

Loans Receivable (Tables)	9 Months Ended
	Sep. 30, 2014
Receivables [Abstract]	'
Major Classifications of Loans Receivable	'
	Major classifications of loans receivable are summarized as follows:
			At September 30, 2014					At December 31, 2013
	($ in thousands)		# of Loans		Amount			# of Loans		Amount
	Loans Secured By Real Estate:
	Commercial loans			426	$	908,697			394	$	838,766
	Multifamily loans			137		200,251			138		210,270
	One to four family loans			17		59,472			20		72,064
	Land loans			6		9,875			5		9,178
				586		1,178,295			557		1,130,278
	All Other Loans:
	Business loans			18		1,004			19		1,061
	Consumer loans			7		138			12		211
				25		1,142			31		1,272
	Loans receivable, gross			611		1,179,437			588		1,131,550
	Deferred loan fees					(4,168	)				(4,028	)
	Loans receivable, net of deferred fees					1,175,269					1,127,522
	Allowance for loan losses					(26,634	)				(27,833	)
	Loans receivable, net				$	1,148,635				$	1,099,689
Summary of Impaired Loans	'
	The tables below summarize certain information regarding our impaired loans as follows:
	($ in thousands)		Recorded Investment by State (1)																		Specific		Total		# of
																					Valuation		Unpaid		Loans
	At September 30, 2014		NY		FL			VA		GA			CT		OH		SD		Total		Allowance (2)		Principal (3)
	Type
	Retail		$	8,106	$	9,005		$	7,677	$	—		$	2,665	$	—	$	—	$	27,453	$	2,456	$	31,150		6
	Office Building			—		14,220			—		8,608			—		—		—		22,828		1,913		22,915		3
	Multifamily			—		3,104			—		—			—		—		—		3,104		590		3,104		2
	Land			—		—			—		—			—		—		1,520		1,520		156		1,520		1
	Totals		$	8,106	$	26,329		$	7,677	$	8,608		$	2,665	$	—	$	1,520	$	54,905	$	5,115	$	58,689		12
	($ in thousands)		Recorded Investment by State (1)																		Specific		Total		# of
																					Valuation		Unpaid		Loans
	At December 31, 2013		NY		FL			VA		GA			CT		OH		SD		Total		Allowance (2)		Principal (3)
	Type
	Retail		$	8,223	$	9,005		$	7,828	$	—		$	2,719	$	1,000	$	—	$	28,775	$	3,052	$	36,216		7
	Office Building			—		14,937			—		8,695			—		—		—		23,632		1,947		23,632		3
	Multifamily			—		3,128			—		—			—		—		—		3,128		594		3,128		2
	Land			—		—			—		—			—		—		1,625		1,625		500		1,625		1
	Totals		$	8,223	$	27,070		$	7,828	$	8,695		$	2,719	$	1,000	$	1,625	$	57,160	$	6,093	$	64,601		13
	-1	Represents unpaid principal less partial principal charge offs and interest received and applied as a reduction of principal in certain cases.
	-2	Represents a specific valuation allowance against the recorded investment, which is included as part of our overall allowance for loan losses. All impaired loans at the dates indicated in the table had a specific valuation allowance.
	-3	Represents contractual unpaid principal balance (shown for informational purposes only). The borrowers are obligated to pay such amounts. However, the ultimate collection by us of such amounts is not assured.
Other Information Related to Impaired Loans	'
	Other information related to our impaired loans is summarized as follows:
			Quarter Ended					Nine-Months Ended
			September 30,					September 30,
	($ in thousands)		2014		2013			2014		2013
	Average recorded investment in nonaccrual loans		$	21,551	$	39,159		$	30,784	$	41,039
	Total cash basis interest income recognized on nonaccrual loans			304		521			1,281		1,729
	Average recorded investment in accruing TDR loans			26,451		11,423			18,864		14,482
	Total interest income recognized on accruing TDR loans under modified terms			226		152			626		581
Age Analysis of Loan Portfolio by Segment	'
	Age analysis of our loan portfolio by segment at September 30, 2014 is summarized as follows:
	($ in thousands)		Total		Current			Past Due		Past Due			Past Due		Total
			Portfolio					31-59		60-89			90 or		Past Due
								Days		Days			more
													Days
	Accruing Loans:
	Commercial real estate		$	888,420	$	886,078		$	—	$	378		$	1,963	$	2,341
	Multifamily			197,990		192,635			—		3,353			2,002		5,355
	One to four family			59,472		59,472			—		—			—		—
	Land			9,875		9,875			—		—			—		—
	All other			1,142		1,142			—		—			—		—
	Total accruing loans			1,156,899		1,149,202			—		3,731			3,965		7,696
	Nonaccrual Loans (1):
	Commercial real estate			20,277		13,292			—		4,320			2,665		6,985
	Multifamily			2,261		2,261			—		—			—
	Total nonaccrual loans			22,538		15,553			—		4,320			2,665		6,985
	Total loans		$	1,179,437	$	1,164,755		$	—	$	8,051		$	6,630	$	14,681
	-1	The amount of nonaccrual loans in the current column included $19.9 million of TDRs for which payments were being made in accordance with their restructured terms, but the loans were maintained on nonaccrual status in accordance with regulatory guidance. The remaining portion was comprised of one performing and paying loan classified nonaccrual due to concerns regarding the borrower’s ability to continue making payments. Interest income from loan payments received on loans in nonaccrual status is recognized on a cash basis, provided the remaining principal balance is deemed collectible.
	Age analysis of our loan portfolio by segment at December 31, 2013 is summarized as follows:
	($ in thousands)		Total		Current			Past Due		Past Due			Past Due		Total
			Portfolio					31-59		60-89			90 or		Past
								Days		Days			more		Due
													Days
	Accruing Loans:
	Commercial real estate		$	802,863	$	796,980		$	1,796	$	—		$	4,087	$	5,883
	Multifamily			210,270		209,426			844		—			—		844
	One to four family			72,064		72,064			—		—			—		—
	Land			9,178		9,178			—		—			—		—
	All other			1,272		1,271			1		—			—		1
	Total accruing loans			1,095,647		1,088,919			2,641		—			4,087		6,728
	Nonaccrual Loans (1):
	Commercial real estate			35,903		35,903			—		—			—		—
	Total loans		$	1,131,550	$	1,124,822		$	2,641	$	—		$	4,087	$	6,728
	-1	The amount of nonaccrual loans in the current column included $33.2 million of TDRs for which payments were being made in accordance with their restructured terms, but the loans were maintained on nonaccrual status in accordance with regulatory guidance. The remaining portion was comprised of certain paying loans classified nonaccrual due to concerns regarding the borrowers’ ability to continue making payments. Interest income from loan payments received on loans in nonaccrual status is recognized on a cash basis, provided the remaining principal balance is deemed collectible.
Information Regarding Credit Quality of Loan Portfolio	'
	Information regarding the credit quality of the loan portfolio based on our internally assigned grades follows:
	($ in thousands)		Pass		Special Mention			Substandard (1)		Total
	At September 30, 2014
	Commercial real estate		$	853,979	$	2,236		$	52,482	$	908,697
	Multifamily			194,334		2,357			3,560		200,251
	One to four family			59,472		—			—		59,472
	Land			9,875		—			—		9,875
	All other			1,142		—			—		1,142
	Total loans		$	1,118,802	$	4,593		$	56,042	$	1,179,437
	Allocation of allowance for loan losses		$	21,530	$	141		$	4,963	$	26,634
	At December 31, 2013
	Commercial real estate		$	772,900	$	3,522		$	62,344	$	838,766
	Multifamily			204,298		2,369			3,603		210,270
	One to four family			72,064		—			—		72,064
	Land			7,553		—			1,625		9,178
	All other			1,272		—			—		1,272
	Total loans		$	1,058,087	$	5,891		$	67,572	$	1,131,550
	Allocation of allowance for loan losses		$	20,720	$	169		$	6,944	$	27,833
	-1	Substandard loans consisted of $22.5 million of nonaccrual loans, $22.7 million of accruing TDRs and $10.8 million of other performing loans at September 30, 2014, compared to $35.9 million, $13.1 million and $18.6 million in the same categories, respectively, at December 31, 2013. At September 30, 2014 and December 31, 2013, we also had accruing TDRs of $2.0 million and $0.4 million, respectively, which were rated pass.
Geographic Distribution of Loan Portfolio	'
	The geographic distribution of the loan portfolio by state follows:
	($ in thousands)		At September 30, 2014					At December 31, 2013
			Amount		% of Total			Amount		% of Total
	New York		$	648,271		55	%	$	670,052		59.3	%
	Florida			346,757		29.4			321,812		28.4
	North Carolina			28,390		2.4			22,611		2
	Georgia			24,249		2.1			18,799		1.7
	New Jersey			13,832		1.2			15,650		1.4
	Pennsylvania			13,154		1.1			16,898		1.5
	Virginia			13,088		1.1			11,491		1
	South Carolina			11,426		1			9,223		0.8
	Kentucky			8,403		0.7			11,930		1.1
	Ohio			7,024		0.6			4,703		0.4
	Tennessee			6,691		0.6			5,843		0.5
	Connecticut			6,357		0.5			8,429		0.7
	Massachusetts			6,016		0.5			—		—
	Texas			5,691		0.5			—		—
	Michigan			5,473		0.5			5,599		0.5
	Utah			5,138		0.5			—		—
	Arizona			5,108		0.4			—		—
	West Virginia			4,454		0.4			—		—
	Indiana			4,191		0.3			2,820		0.2
	Illinois			3,608		0.3			—		—
	Wisconsin			3,349		0.2			1,790		0.1
	California			2,742		0.2			—		—
	All other states			6,025		0.5			3,900		0.4
			$	1,179,437		100	%	$	1,131,550		100	%
Distribution of TDRs by Accruing Versus Nonaccruing, by Segment and by Geographic	'
	The distribution of TDRs by accruing versus nonaccruing, by loan type and by geographic distribution follows:
	($ in thousands)		At September 30, 2014		At December 31, 2013
	Performing – nonaccrual status		$	19,873	$	33,184
	Performing – accrual status			24,690		13,429
			$	44,563	$	46,613
	Commercial real estate		$	39,939	$	41,860
	Multifamily			3,104		3,128
	Land			1,520		1,625
			$	44,563	$	46,613
	New York		$	8,106	$	8,223
	Florida			26,329		27,070
	Georgia			8,608		8,695
	Ohio			—		1,000
	South Dakota			1,520		1,625
			$	44,563	$	46,613

Allowance_for_Loan_Losses_Tabl

Allowance for Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Allowance for Loan Losses by Loan Type	'
	Activity in the allowance for loan losses by loan type for the periods indicated is as follows:
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All Other			Total
			Real Estate						Family
	Quarter Ended September 30, 2014
	Balance at beginning of period		$	18,381		$	4,964		$	2,358		$	887		$	8		$	26,598
	Loan chargeoffs			—			—			—			—			—			—
	Loan recoveries			36			—			—			—			—			36
	Provision (credit) for loan losses			17			(139	)		(28	)		150			—			—
	Balance at end of period		$	18,434		$	4,825		$	2,330		$	1,037		$	8		$	26,634
	Nine-Months Ended September 30, 2014
	Balance at beginning of period		$	18,403		$	5,097		$	3,017		$	1,308		$	8		$	27,833
	Loan chargeoffs			—			—			—			—			—			—
	Loan recoveries			287			14			—			—			—			301
	Credit for loan losses			(256	)		(286	)		(687	)		(271	)		—			(1,500	)
	Balance at end of period		$	18,434		$	4,825		$	2,330		$	1,037		$	8		$	26,634
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All Other			Total
			Real Estate						Family
	Quarter Ended September 30, 2013
	Balance at beginning of period		$	17,596		$	5,098		$	2,795		$	956		$	10		$	26,455
	Loan chargeoffs			—			—			—			—			—			—
	Loan recoveries			67			5			—			—			—			72
	Provision (credit) for loan losses			(175	)		212			229			(15	)		(1	)		250
	Balance at end of period		$	17,488		$	5,315		$	3,024		$	941		$	9		$	26,777
	Nine-Months Ended September 30, 2013
	Balance at beginning of period		$	19,051		$	6,881		$	1,120		$	1,043		$	8		$	28,103
	Loan chargeoffs			(1,932	)		(6	)		—			—			—			(1,938	)
	Loan recoveries (1)			947			682			—			483			—			2,112
	Provision (credit) for loan losses			(578	)		(2,242	)		1,904			(585	)		1			(1,500	)
	Balance at end of period		$	17,488		$	5,315		$	3,024		$	941		$	9		$	26,777
	-1	In the first and second quarters of 2013, INB entered into settlement agreements with respect to certain litigation INB had pursued in connection with foreclosure actions it had commenced in 2010 on several of its loans. INB commenced the actions to collect, in one case, insurance proceeds, which it contended had been improperly paid to various third parties, and in another case, damages due to alleged legal malpractice when the loan was originated. As a result of these settlements, INB received net proceeds totaling $2.7 million and $0.1 million in the first and second quarter of 2013, respectively, which was recorded as $1.2 million of recoveries of prior loan charge offs and $1.6 million of recoveries of prior real estate expenses associated with two loans and underlying collateral property.
Loans Receivable by Segment and Impairment Evaluation and Allowance for Loan Losses	'
	The following table sets forth the balances of our loans receivable by segment and impairment evaluation and the allowance for loan losses associated with such loans at September 30, 2014.
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All			Total
			Real Estate						Family						Other
	Loans:
	Individually evaluated for impairment		$	50,281		$	3,104		$	—		$	1,520		$	—		$	54,905
	Collectively evaluated for impairment			858,416			197,147			59,472			8,355			1,142			1,124,532
	Total loans		$	908,697		$	200,251		$	59,472		$	9,875		$	1,142		$	1,179,437
	Allowance for loan losses:
	Individually evaluated for impairment		$	4,369		$	590		$	—		$	156		$	—		$	5,115
	Collectively evaluated for impairment			14,066			4,234			2,330			881			8			21,519
	Total allowance for loan losses		$	18,435		$	4,824		$	2,330		$	1,037		$	8		$	26,634
	The following table sets forth the balances of our loans receivable by segment and impairment evaluation and the allowance for loan losses associated with such loans at December 31, 2013.
	($ in thousands)		Commercial			Multifamily			One to Four			Land			All			Total
			Real Estate						Family						Other
	Loans:
	Individually evaluated for impairment		$	52,407		$	3,128		$	—		$	1,625		$	—		$	57,160
	Collectively evaluated for impairment			786,359			207,142			72,064			7,553			1,272			1,074,390
	Total loans		$	838,766		$	210,270		$	72,064		$	9,178		$	1,272		$	1,131,550
	Allowance for loan losses:
	Individually evaluated for impairment		$	4,999		$	594		$	—		$	500		$	—		$	6,093
	Collectively evaluated for impairment			13,404			4,503			3,017			808			8			21,740
	Total allowance for loan losses		$	18,403		$	5,097		$	3,017		$	1,308		$	8		$	27,833

Foreclosed_Real_Estate_and_Val1

Foreclosed Real Estate and Valuation Allowance for Real Estate Losses (Tables)	9 Months Ended
	Sep. 30, 2014
Banking and Thrift [Abstract]	'
Summary of Real Estate Acquired through Foreclosure by Property Type	'
	Real estate acquired through foreclosure by property type is summarized as follows:
			At September 30, 2014					At December 31, 2013
	($ in thousands)		# of Properties		Amount (1)			# of Properties			Amount (1)
	Commercial real estate			1	$	2,650			2		$	3,984
	Multifamily			—		—			1			6,685
				1	$	2,650			3		$	10,669
	-1	Reported net of any associated valuation allowance.
Summary of Activity in the Valuation Allowance for Real Estate Losses	'
	Activity in the valuation allowance for real estate losses is summarized as follows:
			Quarter Ended					Nine-Months Ended
			September 30,					September 30,
	($ in thousands)		2014		2013			2014			2013
	Valuation allowance at beginning of period		$	390	$	6,044		$	2,017		$	5,339
	Provision for real estate losses			—		250			—			955
	Real estate chargeoffs			—		(4,171	)		(1,627	)		(4,171	)
	Valuation allowance at end of period		$	390	$	2,123		$	390		$	2,123

Deposits_Tables

Deposits (Tables)	9 Months Ended
	Sep. 30, 2014
Banking and Thrift [Abstract]	'
Scheduled Maturities of Certificates of Deposits	'
	Scheduled maturities of certificates of deposit accounts (CDs) were as follows:
		At September 30, 2014					At December 31, 2013
	($ in thousands)	Amount		Wtd-Avg			Amount		Wtd-Avg
				Stated Rate					Stated Rate
	Within one year	$	269,268		1.57	%	$	307,122		1.97	%
	Over one to two years		158,266		1.85			167,323		1.92
	Over two to three years		213,925		1.96			170,956		1.92
	Over three to four years		73,696		1.76			106,700		2.5
	Over four years		125,893		2.11			129,678		2.06
		$	841,048		1.82	%	$	881,779		2.03	%

Subordinated_Debentures_Capita1

Subordinated Debentures - Capital Securities (Tables)	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Summary of Capital Securities Outstanding	'
	Capital Securities (commonly referred to as trust preferred securities) outstanding are summarized as follows:
		At September 30, 2014							At December 31, 2013
	($ in thousands)	Principal		Accrued		Interest			Principal		Accrued		Interest
				Interest		Rate					Interest		Rate
				Payable							Payable
	Capital Securities II – debentures due September 17, 2033	$	15,464	$	17		3.18	%	$	15,464	$	275		3.19	%
	Capital Securities III – debentures due March 17, 2034		15,464		17		3.02	%		15,464		261		3.03	%
	Capital Securities IV – debentures due September 20, 2034		15,464		14		2.63	%		15,464		223		2.65	%
	Capital Securities V – debentures due December 15, 2036		10,310		8		1.88	%		10,310		109		1.89	%
		$	56,702	$	56				$	56,702	$	868

Common_Stock_Warrant_and_Equit1

Common Stock Warrant and Equity Incentive Plans (Tables)	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Summary of Outstanding Common Stock Options and Warrant	'
	A summary of outstanding common stock options and warrant and related information follows:
			Exercise Price Per Warrant/Option																					Wtd-Avg.
																								Exercise
	($ in thousands, except per share amounts)		$5.42 (1)			$17.10			$7.50			$4.02			$3.00			$2.55			Total			Price
	Outstanding at December 31, 2013			691,882			110,640			113,990			57,400			32,400			35,133			1,041,445		$	6.64
	Repurchased and cancelled			(691,882	)		—			—			—			—			—			(691,882	)	$	5.42
	Forfeited/expired (2)			—			(600	)		(300	)		(300	)		(300	)		(900	)		(2,400	)	$	7.05
	Options exercised			—			—			(600	)		(2,400	)		(7,500	)		(6,167	)		(16,667	)	$	3.14
	Outstanding at September 30, 2014			—			110,040			113,090			54,700			24,600			28,066			330,496		$	9.37
	Expiration date			—			12/13/17			12/11/18			12/10/19			12/9/20			12/8/21
	Vested and exercisable (3)			—			100	%		100	%		100	%		100	%		67	%		97	%
	Wtd-avg contractual remaining term (in years)			—			3.2			4.2			5.2			6.2			7.2			4.4
	Intrinsic value at September 30, 2014 (4)			—		$	—		$	233		$	303		$	161		$	197		$	894
	-1	The U.S. Department of the Treasury, in connection with IBC’s prior participation in the Capital Purchase Program of TARP, had owned a warrant to purchase 691,882 shares of IBC’s common stock at an exercise price of $5.42 per share. On September 3, 2014, IBC repurchased the warrant for a purchase price of $2.9 million and cancelled the warrant. The purchase price was recorded as a reduction in IBC’s stockholders’ equity.
	-2	Represent options forfeited or expired unexercised.
	-3	The $2.55 options further vest and become 100% exercisable on December 8, 2014. Full vesting may occur earlier upon the occurrence of certain events as defined in the option agreement.
	-4	Intrinsic value was calculated using the closing price of the common stock on September 30, 2014 of $9.56.
Summary of Selected Information Regarding Restricted Common Stock Awards made Under Plan	'
	A summary of selected information regarding awards of restricted common stock during the periods covered by this report follows:
	($ in thousands, except per share amounts)
	Grant date of award			1/23/14			1/24/13
	Total restricted shares of stock awarded (1)			92,000			330,700
	Grant date per share fair value (2)		$	7.65		$	4.5
	Total estimated fair value of award		$	703,800		$	1,488,150
	Awards scheduled to vest as follows:
	Jan-14			—			49,566
	Jan-15			30,664			170,888
	Jan-16			30,664			110,246
	Jan-17			30,672			—
				92,000			330,700
	-1	For 2014, awards were as follows: a total of 12,000 shares to five executive officers and a total of 80,000 shares to eight non-employee directors (vesting in three equal installments, with one third on each of the next three anniversary dates of the grant).
Summary of Activity in IBCs Restricted Class A Common Stock	'
	A summary of outstanding restricted common stock and related information follows:
			Price Per Share															Wtd-Avg.
																		Price
			$2.90			$4.50			$7.21			$7.65			Total			Per Share
	Outstanding at December 31, 2013			158,317			279,500			135,500			—			573,317		$	4.7
	Shares granted			—			—			—			92,000			92,000		$	7.65
	Shares forfeited			(500	)		(2,800	)		—			—			(3,300	)	$	4.26
	Shares vested and no longer restricted			(101,035	)		(47,664	)		(75,417	)		—			(224,116	)	$	4.69
	Outstanding at September 30, 2014 (1) (2)			56,782			229,036			60,083			92,000			437,901		$	5.33
	-1	All outstanding shares of restricted common stock at September 30, 2014 were unvested and subject to forfeiture.
	Shares issued at $2.90 vest: 56,782 on January 19, 2015.
	Shares issued at $4.50 vest: 137,264 on January 24, 2015; 91,772 on January 24, 2016.
	Shares issued at $7.21 vest: 14,584 on January 19, 2015; 30,333 on January 24, 2015; 15,166 on January 24, 2016.
	Shares issued at $7.65 vest: 30,664 on January 23, 2015; 30,664 on January 23, 2016; 30,672 on January 23, 2017.
	-2	Vesting is subject to the grantee’s continued employment with us or, in the case of non-employee directors, the grantee’s continued service as our director on the vesting dates. All of the awards are subject to accelerated vesting upon the death or disability of the grantee or upon a change in control of IBC, as defined in the restricted stock award agreements. The record holder of IBC’s restricted shares of common stock possesses all the rights of a holder of our common stock, including the right to receive dividends on the shares when declared and to vote the restricted shares. The restricted shares may not be sold, transferred, pledged, assigned, encumbered, or otherwise alienated or hypothecated until they become fully vested and transferable in accordance with the award agreements.

Earnings_Per_Common_Share_and_1

Earnings Per Common Share and Common Stock Dividend (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Summary of Basic and Diluted Earnings Per Common Share	'
	Net earnings applicable to common stockholders and the weighted-average number of shares used for basic and diluted earnings per common share computations are summarized in the table that follows:
			Quarter Ended				Nine-Months Ended September 30,
			September 30,
			2014		2013		2014		2013
	Basic Earnings Per Common Share:
	Net earnings available to common stockholders		$	4,180,000	$	2,588,000	$	13,760,000	$	9,230,000
	Weighted-Average number of common shares outstanding			22,024,722		21,915,596		22,013,754		21,891,886
	Basic Earnings Per Common Share		$	0.19	$	0.12	$	0.62	$	0.42
	Diluted Earnings Per Common Share:
	Net earnings applicable to common stockholders		$	4,180,000	$	2,588,000	$	13,760,000	$	9,230,000
	Weighted-Average number of common shares outstanding:
	Common shares outstanding			22,024,722		21,915,596		22,013,754		21,891,886
	Potential dilutive shares resulting from exercise of warrants/options (1)			243,523		135,866		192,981		81,064
	Total average number of common shares outstanding used for dilution			22,268,245		22,051,462		22,206,735		21,972,950
	Diluted Earnings Per Common Share		$	0.19	$	0.12	$	0.62	$	0.42
	-1	All outstanding options/warrants to purchase shares of our common stock were considered for the diluted earnings per common share computations and only those that were dilutive (as determined by using the treasury stock method prescribed by GAAP) were included in the computations above. For the quarter and nine-month periods of 2014, outstanding options/warrants to purchase 110,040 shares of common stock were not dilutive because the exercise price of each was above the average market price of our common stock during these periods. For both the quarter and nine-month periods of 2013, 234,430 of options/warrants to purchase common stock were not dilutive because the exercise price of each was above the average market price of our common stock during these periods.

OffBalance_Sheet_Financial_Ins1

Off-Balance Sheet Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Investments, All Other Investments [Abstract]	'
Summary of Contractual Amounts of Off-Balance Sheet Financial Instruments	'
	The contractual amounts of off-balance sheet financial instruments are as follows:
	($ in thousands)	At September 30, 2014		At December 31, 2013
	Commitments to extend credit	$	23,134	$	19,386
	Unused lines of credit		787		877
		$	23,921	$	20,263

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Available-for-sale Securities Measured at Fair Value on a Recurring Basis	'
	Available-for-sale securities at September 30, 2014 measured at fair value on a recurring basis are summarized below:
	($ in thousands)		Estimated Fair Value			Level 1			Level 2
	U.S. government agencies		$	224,132		$	—		$	224,132
	Residential mortgage-backed			79,690			—			79,690
	State and municipal			529			—			529
	Mutual fund investment			996			996			—
			$	305,347		$	996		$	304,351
Assets Measured at Fair Value on a Nonrecurring Basis	'
	The following tables provide information regarding our assets measured at fair value on a nonrecurring basis.
			Outstanding Carrying Value
			At September 30, 2014			At December 31, 2013
	($ in thousands)		Level 3			Level 3
	Impaired loans (1):
	Commercial real estate		$	50,281		$	52,407
	Multifamily			3,104			3,128
	Land			1,520			1,625
	Total impaired loans			54,905			57,160
	Foreclosed real estate			2,650			10,669
	-1	Outstanding carrying value for impaired loans excludes a specific valuation allowance. See note 4 to the financial statements in this report.
			Accumulated Losses on						Total Losses (Gains) (1)
			Outstanding						Quarter Ended						Nine-Months Ended
			Balance as of:						September 30,						September 30,
	($ in thousands)		Sep 30,			Dec 31,			2014			2013			2014			2013
			2014			2013
	Impaired loans: Commercial real estate		$	7,416		$	11,522		$	(452	)	$	—		$	(918	)	$	823
	Multifamily			591			594			—			(7	)		(17	)		(964	)
	Land			156			500			(5	)		(2	)		(344	)		(23	)
	Total impaired loans			8,163			12,616			(457	)		(9	)		(1,279	)		(164	)
	Impaired securities			—			—			—			273			—			964
	Foreclosed real estate			390			2,017			—			149			(203	)		135
			$	8,553		$	14,633		$	(457	)	$	413		$	(1,482	)	$	935
	-1	Represents total losses or (gains) recognized on all assets measured at fair value on a nonrecurring basis during the period indicated. The losses or (gains) for impaired loans represent the change (before chargeoffs and recoveries) during the period in the corresponding specific valuation allowance, while the losses (gains) for foreclosed real estate represent writedowns in carrying values subsequent to foreclosure (recorded as provisions for real estate losses) adjusted for any recoveries of prior write downs and (gains) or losses from the transfer/sale of properties during the period. The losses on securities represent the total of other than temporary impairment charges, which are recorded as component of noninterest income.
Change in Assets Measured at Fair Value on a Nonrecurring Basis	'
	The following table details changes in assets measured at fair value on a nonrecurring basis for the periods indicated.
	($ in thousands)		Impaired Loans			Foreclosed Real Estate
	Quarter Ended September 30, 2014
	Balance at beginning of period		$	57,821		$	2,650
	Principal repayments/sales			(2,916	)		—
	Balance at end of period		$	54,905		$	2,650
	Nine-Months Ended September 30, 2014
	Balance at beginning of period		$	57,160		$	10,669
	Net new impaired loans			3,466			—
	Principal repayments/sales			(5,721	)		(8,222	)
	Gain from sales			—			203
	Balance at end of period		$	54,905		$	2,650
	The following table details changes in assets measured at fair value on a nonrecurring basis for the periods indicated.
	($ in thousands)		Impaired			Impaired			Foreclosed
			Securities			Loans			Real Estate
	Quarter Ended September 30, 2013
	Balance at beginning of period		$	2,923		$	50,533		$	14,869
	Net new impaired loans			—			514			—
	Other than temporary impairment write downs			(273	)		—			—
	Principal repayments/sales			(46	)		(149	)		(2,701	)
	Writedowns of carrying value subsequent to foreclosure			—			—			(250	)
	Gains from sales			—			—			101
	Balance at end of period		$	2,604		$	50,898		$	12,019
	Nine-Months Ended September 30, 2013
	Balance at beginning of period		$	3,721		$	65,973		$	15,923
	Net new impaired loans			—			8,761			—
	Impaired loans transferred to foreclosed real estate			—			(3,040	)		3,040
	Other than temporary impairment write downs			(964	)		—			—
	Principal repayments/sales			(153	)		(18,858	)		(6,809	)
	Chargeoffs of impaired loans			—			(1,938	)		—
	Writedowns of carrying value subsequent to foreclosure			—			—			(1,029	)
	Recoveries of prior writedowns			—			—			74
	Gains from sales			—			—			820
	Balance at end of period		$	2,604		$	50,898		$	12,019
Carrying and Estimated Fair Values of Financial Instruments	'
	The carrying and estimated fair values of our financial instruments are as follows:
			At September 30, 2014						At December 31, 2013
	($ in thousands)		Carrying			Fair			Carrying			Fair
			Value			Value			Value			Value
	Financial Assets:
	Cash and cash equivalents (1)		$	11,483		$	11,483		$	24,700		$	24,700
	Time deposits with banks (1)			4,620			4,620			5,370			5,370
	Securities available for sale, net (2)			305,347			305,347			965			965
	Securities held to maturity, net (2)			—			—			383,937			378,507
	FRB and FHLB stock (3)			7,715			7,715			8,244			8,244
	Loans receivable, net (3)			1,148,635			1,161,476			1,099,689			1,100,858
	Accrued interest receivable (3)			4,665			4,665			4,861			4,861
	Loan fees receivable (3)			2,224			1,765			2,298			1,808
	Total Financial Assets		$	1,484,689		$	1,497,071		$	1,530,064		$	1,525,313
	Financial Liabilities:
	Deposits (3)		$	1,214,324		$	1,229,119		$	1,282,232		$	1,294,690
	Borrowed funds plus accrued interest payable (3)			56,758			56,516			57,570			57,260
	Accrued interest payable on deposits (3)			850			850			1,508			1,508
	Commitments to lend (3)			146			146			408			408
	Total Financial Liabilities		$	1,272,078		$	1,286,631		$	1,341,718		$	1,353,866
	Net Financial Assets		$	212,611		$	210,440		$	188,346		$	171,447
	-1	We consider these fair value measurements to be Level 1.
	-2	We consider these fair value measurements to be Level 2, except for $1.0 million at each date (which is considered Level 1).
	-3	We consider these fair value measurements to be Level 3.

Description_of_Business_and_Su2

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) (Bank of the Ozarks, Inc.[Member], USD $)	1 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jul. 31, 2014
Loans At Acquisition Date [Line Items]	'
Business combination, agreed purchase price	$228.50
Number of days to calculate average closing stock price	'10 days
Minimum [Member]	'
Loans At Acquisition Date [Line Items]	'
Business combination, share price	$23.95
Maximum [Member]	'
Loans At Acquisition Date [Line Items]	'
Business combination, share price	$39.91

Securities_Held_to_Maturity_an2

Securities Held to Maturity and Available for Sale - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
	Securities	Security
	Security
Amortized Cost and Fair Value Debt Securities [Abstract]	'	'
Securities, carrying value	$351,600,000	'
Securities, fair value	349,400,000	'
Number of held to maturity securities	0	219
Proceeds from sale of securities available for sale	37,384,000	'
Net realized gain sale of securities available for sale	$196,000	'

Securities_Held_to_Maturity_an3

Securities Held to Maturity and Available for Sale - Carrying Value (Estimated Fair Value) and Amortized Cost of Securities Available for Sale (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Security		Debt Securities [Member]	Debt Securities [Member]	Debt Securities [Member]	Debt Securities [Member]	Equity Securities [Member]	Equity Securities [Member]
			Security	U.S. government agencies [Member]	Residential mortgage-backed [Member]	State and municipal [Member]	Mutual funds investment [Member]	Mutual funds investment [Member]
				Security	Security	Security	Security	Security
Schedule of Held-to-maturity Securities [Line Items]	'	'	'	'	'	'	'	'
Number of Securities, Available for sale	197	'	196	125	70	1	1	1
Amortized Cost, Available for sale	$307,441	'	$306,403	$226,361	$79,512	$530	$1,038	$1,021
Gross Unrealized Gains, Available for sale	539	'	539	15	524	'	'	'
Gross Unrealized Losses, Available for sale	2,633	'	2,591	2,244	346	1	42	56
Estimated Fair Value, Available for sale	$305,347	$965	$304,351	$224,132	$79,690	$529	$996	$965
Wtd-Avg Yield, Available for sale	1.23%	'	1.23%	1.00%	1.90%	1.25%	'	'
Wtd-Avg Expected Life, Available for sale	'	'	'3 years 3 months 18 days	'2 years 10 months 24 days	'4 years 6 months	'2 years 6 months	'	'
Wtd-Avg Remaining Maturity, Available for sale	'	'	'6 years	'3 years 6 months	'13 years 1 month 6 days	'2 years 6 months	'	'

Securities_Held_to_Maturity_an4

Securities Held to Maturity and Available for Sale - Carrying Value (Amortized Cost) and Estimated Fair Value of Securities Held to Maturity (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2014
	Security	Securities
Schedule of Held-to-maturity Securities [Line Items]	'	'
Number of Securities, Held to maturity	219	0
Amortized Cost, Held to maturity	$383,937	'
Gross Unrealized Gains, Held to maturity	540	'
Gross Unrealized Losses, Held to maturity	5,970	'
Estimated Fair Value, Held to maturity	378,507	'
Wtd-Avg Yield, Held to maturity	1.11%	'
Wtd-Avg Expected Life, Held to maturity	'3 years 3 months 18 days	'
Wtd-Avg Remaining Maturity, Held to maturity	'6 years	'
U.S. government agencies [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Number of Securities, Held to maturity	161	'
Amortized Cost, Held to maturity	305,906	'
Gross Unrealized Gains, Held to maturity	410	'
Gross Unrealized Losses, Held to maturity	4,947	'
Estimated Fair Value, Held to maturity	301,369	'
Wtd-Avg Yield, Held to maturity	0.94%	'
Wtd-Avg Expected Life, Held to maturity	'3 years	'
Wtd-Avg Remaining Maturity, Held to maturity	'3 years 9 months 18 days	'
Residential mortgage-backed [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Number of Securities, Held to maturity	57	'
Amortized Cost, Held to maturity	77,500	'
Gross Unrealized Gains, Held to maturity	130	'
Gross Unrealized Losses, Held to maturity	1,017	'
Estimated Fair Value, Held to maturity	76,613	'
Wtd-Avg Yield, Held to maturity	1.79%	'
Wtd-Avg Expected Life, Held to maturity	'4 years 3 months 18 days	'
Wtd-Avg Remaining Maturity, Held to maturity	'14 years 8 months 12 days	'
State and municipal [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Number of Securities, Held to maturity	1	'
Amortized Cost, Held to maturity	531	'
Gross Unrealized Losses, Held to maturity	6	'
Estimated Fair Value, Held to maturity	$525	'
Wtd-Avg Yield, Held to maturity	1.25%	'
Wtd-Avg Expected Life, Held to maturity	'3 years 2 months 12 days	'
Wtd-Avg Remaining Maturity, Held to maturity	'3 years 3 months 18 days	'

Securities_Held_to_Maturity_an5

Securities Held to Maturity and Available for Sale - Carrying Value (Estimated Fair Value) and Amortized Cost of Securities Available for Sale (Parenthetical) (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Schedule of Held-to-maturity Securities [Line Items]	'	'
Available for sale, Amortized Cost	$305,347	$965
Shares owned in an intermediate bond fund	93,342	91,683
Government National Mortgage Association [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Available for sale, Amortized Cost	11,200	13,600
Federal National Mortgage Association [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Available for sale, Amortized Cost	68,500	63,900
Federal National Mortgage Association Delegated Underwriting and Servicing [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Available for sale, Amortized Cost	$16,000	$7,000

Securities_Held_to_Maturity_an6

Securities Held to Maturity and Available for Sale - Carrying Value (Amortized Cost) and Estimated Fair Value of Securities Held to Maturity (Parenthetical) (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Held-to-maturity Securities [Line Items]	'	'
Held to maturity, Amortized Cost	'	$383,937
Government National Mortgage Association [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Held to maturity, Amortized Cost	11,200	13,600
Federal National Mortgage Association [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Held to maturity, Amortized Cost	68,500	63,900
Federal National Mortgage Association Delegated Underwriting and Servicing [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Held to maturity, Amortized Cost	$16,000	$7,000

Securities_Held_to_Maturity_an7

Securities Held to Maturity and Available for Sale - Estimated Fair Values of Debt Securities (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
	Security	Security
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	149	172
Less Than Twelve Months, Estimated Fair Value	$64,900	$283,317
Less Than Twelve Months, Gross Unrealized Losses	218	5,784
Twelve Months or Longer, Estimated Fair Value	178,715	10,628
Twelve Months or Longer, Gross Unrealized Losses	2,373	186
Total Estimated Fair Value	243,615	293,945
Total Gross Unrealized Losses	2,591	5,970
U.S. government agencies [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	115	130
Less Than Twelve Months, Estimated Fair Value	49,161	233,930
Less Than Twelve Months, Gross Unrealized Losses	139	4,791
Twelve Months or Longer, Estimated Fair Value	158,382	7,344
Twelve Months or Longer, Gross Unrealized Losses	2,105	156
Total Estimated Fair Value	207,543	241,274
Total Gross Unrealized Losses	2,244	4,947
Residential mortgage-backed [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	33	41
Less Than Twelve Months, Estimated Fair Value	15,210	48,862
Less Than Twelve Months, Gross Unrealized Losses	78	987
Twelve Months or Longer, Estimated Fair Value	20,333	3,284
Twelve Months or Longer, Gross Unrealized Losses	268	30
Total Estimated Fair Value	35,543	52,146
Total Gross Unrealized Losses	346	1,017
State and municipal [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	1	1
Less Than Twelve Months, Estimated Fair Value	529	525
Less Than Twelve Months, Gross Unrealized Losses	1	6
Total Estimated Fair Value	529	525
Total Gross Unrealized Losses	$1	$6

Securities_Held_to_Maturity_an8

Securities Held to Maturity and Available for Sale - Summary of Investments in Debt Securities (Detail) (USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'
Due in one year or less, Amortized Cost	$0
Due in one year or less, Estimated Fair Value	0
Due in one year or less, Wtd-Avg Yield	0.00%
Due after one year through five years, Amortized Cost	215,795
Due after one year through five years, Estimated Fair Value	213,891
Due after one year through five years, Wtd-Avg Yield	0.99%
Due after five years through ten years, Amortized Cost	42,390
Due after five years through ten years, Estimated Fair Value	42,053
Due after five years through ten years, Wtd-Avg Yield	1.68%
Due after ten years, Amortized Cost	48,218
Due after ten years, Estimated Fair Value	48,407
Due after ten years, Wtd-Avg Yield	1.94%
Securities held to maturity, Total Amortized Cost	306,403
Estimated Fair Value	$304,351
Securities held to maturity, Wtd-Avg Yield	1.23%

Securities_Held_to_Maturity_an9

Securities Held to Maturity and Available for Sale - Credit Losses Recognized on Securities (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'	'	'	'
Balance at beginning of period	$0	$4,924	$0	$4,233
Additional credit losses on debt securities for which OTTI was previously recognized	0	273	0	964
Balance at end of period	$0	$5,197	$0	$5,197

Loans_Receivable_Major_Classif

Loans Receivable - Major Classification of Loans Receivable (Detail) (USD $)	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	SecurityLoan		SecurityLoan
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	611	'	588	'	'	'
Loans receivable, gross, Amount	$1,179,437	'	$1,131,550	'	'	'
Deferred loan fees	-4,168	'	-4,028	'	'	'
Loans receivable, net of deferred fees	1,175,269	'	1,127,522	'	'	'
Allowance for loan losses	-26,634	-26,598	-27,833	-26,777	-26,455	-28,103
Loans receivable, net	1,148,635	'	1,099,689	'	'	'
Loans Secured by Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	586	'	557	'	'	'
Loans receivable, gross, Amount	1,178,295	'	1,130,278	'	'	'
All Other Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	25	'	31	'	'	'
Loans receivable, gross, Amount	1,142	'	1,272	'	'	'
Commercial Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Allowance for loan losses	-18,434	-18,381	-18,403	-17,488	-17,596	-19,051
Commercial Real Estate [Member] | Loans Secured by Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	426	'	394	'	'	'
Loans receivable, gross, Amount	908,697	'	838,766	'	'	'
Multifamily Loans [Member] | Loans Secured by Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	137	'	138	'	'	'
Loans receivable, gross, Amount	200,251	'	210,270	'	'	'
One to Four Family [Member] | Loans Secured by Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	17	'	20	'	'	'
Loans receivable, gross, Amount	59,472	'	72,064	'	'	'
Land Loans [Member] | Loans Secured by Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	6	'	5	'	'	'
Loans receivable, gross, Amount	9,875	'	9,178	'	'	'
Business Loans [Member] | All Other Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	18	'	19	'	'	'
Loans receivable, gross, Amount	1,004	'	1,061	'	'	'
Consumer Loans [Member] | All Other Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Loans receivable, gross, # of Loans	7	'	12	'	'	'
Loans receivable, gross, Amount	$138	'	$211	'	'	'

Loans_Receivable_Additional_In

Loans Receivable - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
	SecurityLoan	SecurityLoan
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
90 days past due and still accruing interest loan	$6,630,000	$4,087,000
Troubled debt restructured loans	44,563,000	46,613,000
Performing and accruing loans classified as impaired	7,700,000	7,700,000
Performing loans	1	1
Accruing Loans [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of loans, 90 days past due and still accruing	2	3
90 days past due and still accruing interest loan	4,000,000	4,100,000
Troubled debt restructured loans	22,700,000	13,100,000
Troubled debt restructured loans	24,700,000	13,400,000
Nonaccrual Loans [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total loans	22,500,000	35,900,000
Troubled debt restructured loans	22,500,000	35,900,000
Performing loans	1	'
Non-accrual Status [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Troubled debt restructured loans	$19,900,000	$33,200,000

Loans_Receivable_Summary_of_Im

Loans Receivable - Summary of Impaired Loans (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	SecurityLoan	SecurityLoan
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	$54,905	$57,160
Specific Valuation Allowance	5,115	6,093
Total Unpaid Principal	58,689	64,601
# of Loans	12	13
New York [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	8,106	8,223
Florida [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	26,329	27,070
Virginia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	7,677	7,828
Georgia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	8,608	8,695
Connecticut [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	2,665	2,719
Ohio [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	1,000
South Dakota [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	1,520	1,625
Retail [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	27,453	28,775
Specific Valuation Allowance	2,456	3,052
Total Unpaid Principal	31,150	36,216
# of Loans	6	7
Retail [Member] | New York [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	8,106	8,223
Retail [Member] | Florida [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	9,005	9,005
Retail [Member] | Virginia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	7,677	7,828
Retail [Member] | Georgia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Retail [Member] | Connecticut [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	2,665	2,719
Retail [Member] | Ohio [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	1,000
Retail [Member] | South Dakota [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Office Building [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	22,828	23,632
Specific Valuation Allowance	1,913	1,947
Total Unpaid Principal	22,915	23,632
# of Loans	3	3
Office Building [Member] | New York [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Office Building [Member] | Florida [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	14,220	14,937
Office Building [Member] | Virginia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Office Building [Member] | Georgia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	8,608	8,695
Office Building [Member] | Connecticut [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Office Building [Member] | Ohio [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Office Building [Member] | South Dakota [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Multifamily Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	3,104	3,128
Specific Valuation Allowance	590	594
Total Unpaid Principal	3,104	3,128
# of Loans	2	2
Multifamily Loans [Member] | New York [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Multifamily Loans [Member] | Florida [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	3,104	3,128
Multifamily Loans [Member] | Virginia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Multifamily Loans [Member] | Georgia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Multifamily Loans [Member] | Connecticut [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Multifamily Loans [Member] | Ohio [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Multifamily Loans [Member] | South Dakota [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	1,520	1,625
Specific Valuation Allowance	156	500
Total Unpaid Principal	1,520	1,625
# of Loans	1	1
Land [Member] | New York [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member] | Florida [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member] | Virginia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member] | Georgia [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member] | Connecticut [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member] | Ohio [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	'	'
Land [Member] | South Dakota [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Recorded Investment	$1,520	$1,625

Loans_Receivable_Other_Informa

Loans Receivable - Other Information Related to Impaired Loans (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Nonaccrual Loans [Member]	'	'	'	'
Financing Receivable, Modifications [Line Items]	'	'	'	'
Average recorded investment in accruing TDR loans	$21,551	$39,159	$30,784	$41,039
Total cash basis interest income recognized on nonaccrual loans	304	521	1,281	1,729
TDR Loans [Member]	'	'	'	'
Financing Receivable, Modifications [Line Items]	'	'	'	'
Average recorded investment in accruing TDR loans	26,451	11,423	18,864	14,482
Total interest income recognized on accruing TDR loans under modified terms	$226	$152	$626	$581

Loans_Receivable_Age_Analysis_

Loans Receivable - Age Analysis of Loan Portfolio by Segment (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	$1,179,437	$1,131,550
Current	1,164,755	1,124,822
Past Due 31-59 Days	'	2,641
Past Due 60-89 Days	8,051	'
Past Due 90 or more Days	6,630	4,087
Total Past Due	14,681	6,728
Accruing Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	1,156,899	1,095,647
Current	1,149,202	1,088,919
Past Due 31-59 Days	'	2,641
Past Due 60-89 Days	3,731	'
Past Due 90 or more Days	3,965	4,087
Total Past Due	7,696	6,728
Nonaccrual Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	22,538	'
Current	15,553	'
Past Due 31-59 Days	'	'
Past Due 60-89 Days	4,320	'
Past Due 90 or more Days	2,665	'
Total Past Due	6,985	'
Commercial Real Estate [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	908,697	838,766
Commercial Real Estate [Member] | Accruing Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	888,420	802,863
Current	886,078	796,980
Past Due 31-59 Days	'	1,796
Past Due 60-89 Days	378	'
Past Due 90 or more Days	1,963	4,087
Total Past Due	2,341	5,883
Commercial Real Estate [Member] | Nonaccrual Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	20,277	35,903
Current	13,292	35,903
Past Due 31-59 Days	'	'
Past Due 60-89 Days	4,320	'
Past Due 90 or more Days	2,665	'
Total Past Due	6,985	'
Multifamily Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	200,251	210,270
Multifamily Loans [Member] | Accruing Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	197,990	210,270
Current	192,635	209,426
Past Due 31-59 Days	'	844
Past Due 60-89 Days	3,353	'
Past Due 90 or more Days	2,002	'
Total Past Due	5,355	844
Multifamily Loans [Member] | Nonaccrual Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	2,261	'
Current	2,261	'
Past Due 31-59 Days	'	'
Past Due 60-89 Days	'	'
Past Due 90 or more Days	'	'
Total Past Due	'	'
One to Four Family [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	59,472	72,064
One to Four Family [Member] | Accruing Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	59,472	72,064
Current	59,472	72,064
Past Due 31-59 Days	'	'
Past Due 60-89 Days	'	'
Past Due 90 or more Days	'	'
Total Past Due	'	'
Land [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	9,875	9,178
Land [Member] | Accruing Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	9,875	9,178
Current	9,875	9,178
Past Due 31-59 Days	'	'
Past Due 60-89 Days	'	'
Past Due 90 or more Days	'	'
Total Past Due	'	'
All Other [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	1,142	1,272
All Other [Member] | Accruing Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Total Portfolio	1,142	1,272
Current	1,142	1,271
Past Due 31-59 Days	'	1
Past Due 60-89 Days	'	'
Past Due 90 or more Days	'	'
Total Past Due	'	$1

Loans_Receivable_Age_Analysis_1

Loans Receivable - Age Analysis of Loan Portfolio by Segment (Parenthetical) (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
	SecurityLoan	SecurityLoan
Mortgage Loans on Real Estate [Line Items]	'	'
Current	$1,164,755	$1,124,822
Performing loans	1	1
Nonaccrual Loans [Member]	'	'
Mortgage Loans on Real Estate [Line Items]	'	'
Current	$19,900	$33,200
Performing loans	1	'

Loans_Receivable_Information_R

Loans Receivable - Information Regarding Credit Quality of Loan Portfolio (Detail) (USD $)	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	$1,179,437	'	$1,131,550	'	'	'
Allocation of allowance for loan losses	26,634	26,598	27,833	26,777	26,455	28,103
Commercial Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	908,697	'	838,766	'	'	'
Multifamily Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	200,251	'	210,270	'	'	'
Allocation of allowance for loan losses	4,825	4,964	5,097	5,315	5,098	6,881
One to Four Family [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	59,472	'	72,064	'	'	'
Allocation of allowance for loan losses	2,330	2,358	3,017	3,024	2,795	1,120
Land [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	9,875	'	9,178	'	'	'
Allocation of allowance for loan losses	1,037	887	1,308	941	956	1,043
All Other [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	1,142	'	1,272	'	'	'
Allocation of allowance for loan losses	8	8	8	9	10	8
Pass [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	1,118,802	'	1,058,087	'	'	'
Allocation of allowance for loan losses	21,530	'	20,720	'	'	'
Pass [Member] | Commercial Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	853,979	'	772,900	'	'	'
Pass [Member] | Multifamily Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	194,334	'	204,298	'	'	'
Pass [Member] | One to Four Family [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	59,472	'	72,064	'	'	'
Pass [Member] | Land [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	9,875	'	7,553	'	'	'
Pass [Member] | All Other [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	1,142	'	1,272	'	'	'
Special Mention [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	4,593	'	5,891	'	'	'
Allocation of allowance for loan losses	141	'	169	'	'	'
Special Mention [Member] | Commercial Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	2,236	'	3,522	'	'	'
Special Mention [Member] | Multifamily Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	2,357	'	2,369	'	'	'
Special Mention [Member] | One to Four Family [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	'	'	'	'	'	'
Special Mention [Member] | Land [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	'	'	'	'	'	'
Special Mention [Member] | All Other [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	'	'	'	'	'	'
Substandard [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	56,042	'	67,572	'	'	'
Allocation of allowance for loan losses	4,963	'	6,944	'	'	'
Substandard [Member] | Commercial Real Estate [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	52,482	'	62,344	'	'	'
Substandard [Member] | Multifamily Loans [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	3,560	'	3,603	'	'	'
Substandard [Member] | One to Four Family [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	'	'	'	'	'	'
Substandard [Member] | Land [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	'	'	1,625	'	'	'
Substandard [Member] | All Other [Member]	'	'	'	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'	'	'	'
Total loans	'	'	'	'	'	'

Loans_Receivable_Information_R1

Loans Receivable - Information Regarding Credit Quality of Loan Portfolio (Parenthetical) (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]	'	'
Total Financing Receivable by TDRs	$44,563	$46,613
Nonaccrual Loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Total Financing Receivable by TDRs	22,500	35,900
Accruing Loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Total Financing Receivable by TDRs	22,700	13,100
All Other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Total Financing Receivable by TDRs	10,800	18,600
Pass [Member] | Accruing Loans One [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Total Financing Receivable by TDRs	$2,000	$400

Loans_Receivable_Geographic_Di

Loans Receivable - Geographic Distribution of Loan Portfolio (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	$1,179,437	$1,131,550
Total Loan Receivable, % of Total	100.00%	100.00%
New York [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	648,271	670,052
Total Loan Receivable, % of Total	55.00%	59.30%
Florida [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	346,757	321,812
Total Loan Receivable, % of Total	29.40%	28.40%
North Carolina [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	28,390	22,611
Total Loan Receivable, % of Total	2.40%	2.00%
Georgia [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	24,249	18,799
Total Loan Receivable, % of Total	2.10%	1.70%
New Jersey [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	13,832	15,650
Total Loan Receivable, % of Total	1.20%	1.40%
Pennsylvania [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	13,154	16,898
Total Loan Receivable, % of Total	1.10%	1.50%
Virginia [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	13,088	11,491
Total Loan Receivable, % of Total	1.10%	1.00%
South Carolina [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	11,426	9,223
Total Loan Receivable, % of Total	1.00%	0.80%
Kentucky [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	8,403	11,930
Total Loan Receivable, % of Total	0.70%	1.10%
Ohio [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	7,024	4,703
Total Loan Receivable, % of Total	0.60%	0.40%
Tennessee [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	6,691	5,843
Total Loan Receivable, % of Total	0.60%	0.50%
Connecticut [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	6,357	8,429
Total Loan Receivable, % of Total	0.50%	0.70%
Massachusetts [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	6,016	'
Total Loan Receivable, % of Total	0.50%	'
Texas [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	5,691	'
Total Loan Receivable, % of Total	0.50%	'
Michigan [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	5,473	5,599
Total Loan Receivable, % of Total	0.50%	0.50%
Utah [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	5,138	'
Total Loan Receivable, % of Total	0.50%	'
Arizona [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	5,108	'
Total Loan Receivable, % of Total	0.40%	'
West Virginia [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	4,454	'
Total Loan Receivable, % of Total	0.40%	'
Indiana [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	4,191	2,820
Total Loan Receivable, % of Total	0.30%	0.20%
Illinois [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	3,608	'
Total Loan Receivable, % of Total	0.30%	'
Wisconsin [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	3,349	1,790
Total Loan Receivable, % of Total	0.20%	0.10%
California [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	2,742	'
Total Loan Receivable, % of Total	0.20%	'
All Other States [Member]	'	'
Noncancelable Obligations Future Minimum Payments Due [Line Items]	'	'
Total loans	$6,025	$3,900
Total Loan Receivable, % of Total	0.50%	0.40%

Loans_Receivable_Distribution_

Loans Receivable - Distribution of TDRs by Accruing Versus Nonaccruing, by Segment and by Geographic (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	$44,563	$46,613
Total Financing Receivable by TDRs	44,563	46,613
Total Financing Receivable by TDRs	44,563	46,613
New York [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	8,106	8,223
Total Financing Receivable by TDRs	8,106	8,223
Total Financing Receivable by TDRs	8,106	8,223
Florida [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	26,329	27,070
Total Financing Receivable by TDRs	26,329	27,070
Total Financing Receivable by TDRs	26,329	27,070
Georgia [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	8,608	8,695
Total Financing Receivable by TDRs	8,608	8,695
Total Financing Receivable by TDRs	8,608	8,695
Ohio [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	'	1,000
Total Financing Receivable by TDRs	'	1,000
Total Financing Receivable by TDRs	'	1,000
South Dakota [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	1,520	1,625
Total Financing Receivable by TDRs	1,520	1,625
Total Financing Receivable by TDRs	1,520	1,625
Commercial Real Estate [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	39,939	41,860
Total Financing Receivable by TDRs	39,939	41,860
Total Financing Receivable by TDRs	39,939	41,860
Multifamily Loans [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	3,104	3,128
Total Financing Receivable by TDRs	3,104	3,128
Total Financing Receivable by TDRs	3,104	3,128
Land [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	1,520	1,625
Total Financing Receivable by TDRs	1,520	1,625
Total Financing Receivable by TDRs	1,520	1,625
Non-accrual Status [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	19,900	33,200
Total Financing Receivable by TDRs	19,900	33,200
Total Financing Receivable by TDRs	19,900	33,200
Performing [Member] | Non-accrual Status [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	19,873	33,184
Total Financing Receivable by TDRs	19,873	33,184
Total Financing Receivable by TDRs	19,873	33,184
Performing [Member] | Accrual Status [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Total Financing Receivable by TDRs	24,690	13,429
Total Financing Receivable by TDRs	24,690	13,429
Total Financing Receivable by TDRs	$24,690	$13,429

Allowance_for_Loan_Losses_Allo

Allowance for Loan Losses - Allowance for Loan Losses by Loan Type (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
Balance at beginning of period	$26,598	$26,455	$27,833	$28,103
Loan chargeoffs	'	'	'	-1,938
Loan recoveries	36	72	301	2,112
Provision (credit) for loan losses	'	250	-1,500	-1,500
Balance at end of period	26,634	26,777	26,634	26,777
Commercial Real Estate [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
Balance at beginning of period	18,381	17,596	18,403	19,051
Loan chargeoffs	'	'	'	-1,932
Loan recoveries	36	67	287	947
Provision (credit) for loan losses	17	-175	-256	-578
Balance at end of period	18,434	17,488	18,434	17,488
Multifamily Loans [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
Balance at beginning of period	4,964	5,098	5,097	6,881
Loan chargeoffs	'	'	'	-6
Loan recoveries	'	5	14	682
Provision (credit) for loan losses	-139	212	-286	-2,242
Balance at end of period	4,825	5,315	4,825	5,315
One to Four Family [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
Balance at beginning of period	2,358	2,795	3,017	1,120
Loan chargeoffs	'	'	'	'
Loan recoveries	'	'	'	'
Provision (credit) for loan losses	-28	229	-687	1,904
Balance at end of period	2,330	3,024	2,330	3,024
Land [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
Balance at beginning of period	887	956	1,308	1,043
Loan chargeoffs	'	'	'	'
Loan recoveries	'	'	'	483
Provision (credit) for loan losses	150	-15	-271	-585
Balance at end of period	1,037	941	1,037	941
All Other [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
Balance at beginning of period	8	10	8	8
Loan chargeoffs	'	'	'	'
Loan recoveries	'	'	'	'
Provision (credit) for loan losses	'	-1	'	1
Balance at end of period	$8	$9	$8	$9

Allowance_for_Loan_Losses_Allo1

Allowance for Loan Losses - Allowance for Loan Losses by Loan Type (Parenthetical) (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
		SecurityLoan
Receivables [Abstract]	'	'
Net Proceeds of loans	$0.10	$2.70
Recovery of prior loan charge offs	'	1.2
Recovery of prior real estate expenses	'	$1.60
Number of loans associated with recoveries of prior real estate expenses	'	2

Allowance_for_Loan_Losses_Loan

Allowance for Loan Losses - Loans Receivable by Segment and Impairment Evaluation and Allowance for Loan Losses (Detail) (USD $)	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Loans:	'	'	'	'	'	'
Individually evaluated for impairment	$54,905	'	$57,160	'	'	'
Collectively evaluated for impairment	1,124,532	'	1,074,390	'	'	'
Total loans	1,179,437	'	1,131,550	'	'	'
Allowance for loan losses:	'	'	'	'	'	'
Individually evaluated for impairment	5,115	'	6,093	'	'	'
Collectively evaluated for impairment	21,519	'	21,740	'	'	'
Total allowance for loan losses	26,634	26,598	27,833	26,777	26,455	28,103
Commercial Real Estate [Member]	'	'	'	'	'	'
Loans:	'	'	'	'	'	'
Individually evaluated for impairment	50,281	'	52,407	'	'	'
Collectively evaluated for impairment	858,416	'	786,359	'	'	'
Total loans	908,697	'	838,766	'	'	'
Allowance for loan losses:	'	'	'	'	'	'
Individually evaluated for impairment	4,369	'	4,999	'	'	'
Collectively evaluated for impairment	14,066	'	13,404	'	'	'
Total allowance for loan losses	18,435	'	18,403	'	'	'
Multifamily Loans [Member]	'	'	'	'	'	'
Loans:	'	'	'	'	'	'
Individually evaluated for impairment	3,104	'	3,128	'	'	'
Collectively evaluated for impairment	197,147	'	207,142	'	'	'
Total loans	200,251	'	210,270	'	'	'
Allowance for loan losses:	'	'	'	'	'	'
Individually evaluated for impairment	590	'	594	'	'	'
Collectively evaluated for impairment	4,234	'	4,503	'	'	'
Total allowance for loan losses	4,824	'	5,097	'	'	'
One to Four Family [Member]	'	'	'	'	'	'
Loans:	'	'	'	'	'	'
Individually evaluated for impairment	'	'	'	'	'	'
Collectively evaluated for impairment	59,472	'	72,064	'	'	'
Total loans	59,472	'	72,064	'	'	'
Allowance for loan losses:	'	'	'	'	'	'
Individually evaluated for impairment	'	'	'	'	'	'
Collectively evaluated for impairment	2,330	'	3,017	'	'	'
Total allowance for loan losses	2,330	'	3,017	'	'	'
Land [Member]	'	'	'	'	'	'
Loans:	'	'	'	'	'	'
Individually evaluated for impairment	1,520	'	1,625	'	'	'
Collectively evaluated for impairment	8,355	'	7,553	'	'	'
Total loans	9,875	'	9,178	'	'	'
Allowance for loan losses:	'	'	'	'	'	'
Individually evaluated for impairment	156	'	500	'	'	'
Collectively evaluated for impairment	881	'	808	'	'	'
Total allowance for loan losses	1,037	'	1,308	'	'	'
All Other [Member]	'	'	'	'	'	'
Loans:	'	'	'	'	'	'
Individually evaluated for impairment	'	'	'	'	'	'
Collectively evaluated for impairment	1,142	'	1,272	'	'	'
Total loans	1,142	'	1,272	'	'	'
Allowance for loan losses:	'	'	'	'	'	'
Individually evaluated for impairment	'	'	'	'	'	'
Collectively evaluated for impairment	8	'	8	'	'	'
Total allowance for loan losses	$8	'	$8	'	'	'

Foreclosed_Real_Estate_and_Val2

Foreclosed Real Estate and Valuation Allowance for Real Estate Losses - Summary of Real Estate Acquired through Foreclosure by Property Type (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Property	Property
Real Estate Properties [Line Items]	'	'
# of Properties	1	3
Amount	$2,650	$10,669
Commercial Real Estate [Member]	'	'
Real Estate Properties [Line Items]	'	'
# of Properties	1	2
Amount	2,650	3,984
Multifamily Loans [Member]	'	'
Real Estate Properties [Line Items]	'	'
# of Properties	'	1
Amount	'	$6,685

Foreclosed_Real_Estate_and_Val3

Foreclosed Real Estate and Valuation Allowance for Real Estate Losses - Summary of Activity in the Valuation Allowance for Real Estate Losses (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Real Estate [Abstract]	'	'	'	'
Valuation allowance at beginning of period	$390	$6,044	$2,017	$5,339
Provision for real estate losses	'	250	'	955
Real estate chargeoffs	'	-4,171	-1,627	-4,171
Valuation allowance at end of period	$390	$2,123	$390	$2,123

Deposits_Scheduled_Maturities_

Deposits - Scheduled Maturities of Certificates of Deposits (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Time Deposits, Fiscal Year Maturity [Abstract]	'	'
Within one year, Amount	$269,268	$307,122
Over one to two years, Amount	158,266	167,323
Over two to three years, Amount	213,925	170,956
Over three to four years, Amount	73,696	106,700
Over four years, Amount	125,893	129,678
Total certificates of deposit, Amount	$841,048	$881,779
Within one year, Wtd-Avg Stated Rate	1.57%	1.97%
Over one to two years, Wtd-Avg Stated Rate	1.85%	1.92%
Over two to three years, Wtd-Avg Stated Rate	1.96%	1.92%
Over three to four years, Wtd-Avg Stated Rate	1.76%	2.50%
Over four years, Wtd-Avg Stated Rate	2.11%	2.06%
Total certificates of deposit, Wtd-Avg Stated Rate	1.82%	2.03%

Deposits_Additional_Informatio

Deposits - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Assets Sold under Agreements to Repurchase [Line Items]	'	'
CDs of $100,000 or more	$465,000,000	$473,000,000
Brokered certificate deposits amount	68,000,000	91,000,000
Due within one year	269,268,000	307,122,000
Due over one to two years	158,266,000	167,323,000
Due over two to three years	213,925,000	170,956,000
Due over three to four years	73,696,000	106,700,000
Due thereafter	125,893,000	129,678,000
CDs of $100,000 or More [Member]	'	'
Assets Sold under Agreements to Repurchase [Line Items]	'	'
Due within one year	113,000,000	'
Due over one to two years	85,000,000	'
Due over two to three years	140,000,000	'
Due over three to four years	47,000,000	'
Due thereafter	80,000,000	'
Brokered CDs [Member]	'	'
Assets Sold under Agreements to Repurchase [Line Items]	'	'
Due within one year	5,000,000	'
Due over one to two years	8,000,000	'
Due over two to three years	29,000,000	'
Due over three to four years	14,000,000	'
Due thereafter	$12,000,000	'
Brokered certificates deposits weighted average rate	2.43%	'

Lines_of_Credit_Additional_Inf

Lines of Credit - Additional Information (Detail) (Federal Home Loan Bank of New York and Federal Reserve Bank of New York [Member], USD $)	Sep. 30, 2014
Federal Home Loan Bank of New York and Federal Reserve Bank of New York [Member]	'
Federal Home Loan Bank Advances Type Of Fhlb Advances [Line Items]	'
Unsecured credit lines	$41,000,000
Additional total borrowings from FHLB and FRB	323,000,000
Borrowings	$0

Subordinated_Debentures_Capita2

Subordinated Debentures - Capital Securities - Summary of Capital Securities Outstanding (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Principal	$56,702	$56,702
Accrued Interest Payable	56	868
Capital Securities II [Member]	'	'
Debt Instrument [Line Items]	'	'
Principal	15,464	15,464
Accrued Interest Payable	17	275
Interest Rate	3.18%	3.19%
Capital Securities III [Member]	'	'
Debt Instrument [Line Items]	'	'
Principal	15,464	15,464
Accrued Interest Payable	17	261
Interest Rate	3.02%	3.03%
Capital Securities IV [Member]	'	'
Debt Instrument [Line Items]	'	'
Principal	15,464	15,464
Accrued Interest Payable	14	223
Interest Rate	2.63%	2.65%
Capital Securities V [Member]	'	'
Debt Instrument [Line Items]	'	'
Principal	10,310	10,310
Accrued Interest Payable	8	109
Interest Rate	1.88%	1.89%
Capital Securities [Member]	'	'
Debt Instrument [Line Items]	'	'
Principal	56,702	56,702
Accrued Interest Payable	$56	$868

Common_Stock_Warrant_and_Equit2

Common Stock Warrant and Equity Incentive Plans - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Executive Officers [Member]

Cash-Settled Stock Appreciation Rights (SARs) [Member]

Cash-Settled Stock Appreciation Rights (SARs) [Member]

Stock Appreciation Right [Member]

Stock Appreciation Right [Member]

Long Term Incentive Plan [Member]

Long Term Incentive Plan [Member]

Long Term Incentive Plan [Member]

Long Term Incentive Plan [Member]

Installment

Installment

Executive Officers [Member]

Executives

Executives

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum number of shares of common stock that may be awarded

'

'

'

'

'

'

'

'

'

2,250,000

'

2,250,000

'

Common stock were available for award

'

'

'

'

'

'

'

'

'

624,703

'

624,703

'

Issuance of common stock option

'

'

'

'

'

'

'

'

'

0

0

0

0

Shares Awarded

'

'

'

'

'

'

'

'

78,000

'

'

'

'

Number of participants

'

'

'

'

5

'

'

'

5

'

'

'

'

Number of installments

'

'

'

'

2

'

'

3

'

'

'

'

'

Contractual term

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

Exercise price of option

'

'

'

'

'

'

'

$7.65

'

'

'

'

'

Estimated fair value per option

'

'

'

'

'

'

'

$2.28

'

'

'

'

'

Estimated fair value of SARs

'

'

'

'

'

'

'

$178,000

'

'

'

'

'

Expected dividend yield

'

'

'

'

'

'

'

1.75%

'

'

'

'

'

Expected stock volatility

'

'

'

'

'

'

'

45.00%

'

'

'

'

'

Risk-free interest rate

'

'

'

'

'

'

'

0.98%

'

'

'

'

'

Expected term in years

'

'

'

'

'

'

'

'3 years 6 months

'

'

'

'

'

Stock-based compensation expense

278,000

229,000

1,052,000

731,000

'

19,000

45,000

'

'

'

'

'

'

Pre-tax, stock-based compensation cost related to all nonvested awards of options and restricted stock not yet recognized

1,800,000

'

1,800,000

'

'

'

'

'

'

'

'

'

'

Options and restricted stock not yet recognized and will be recognized over a weighted-average period

'

'

'1 year 8 months 12 days

'

'

'

'

'

'

'

'

'

'

Net tax benefit

$11,000

$5,000

$318,000

$150,000

'

'

'

'

'

'

'

'

'

Common_Stock_Warrant_and_Equit3

Common Stock Warrant and Equity Incentive Plans - Summary of Outstanding Common Stock Options and Warrant (Detail) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Beginning Outstanding	1,041,445
Repurchased and cancelled	-691,882
Forfeited/expired	-2,400
Options exercised	-16,667
Ending Outstanding	330,496
Vested and exercisable	97.00%
Wtd-avg contractual remaining term (in years)	'4 years 4 months 24 days
Intrinsic value at September 30, 2014	$894
Wtd-Avg Exercise Price, Beginning Outstanding	$6.64
Wtd-Avg Exercise Price, Repurchased and cancelled	$5.42
Wtd-Avg Exercise Price, Forfeited/expired	$7.05
Wtd-Avg Exercise Price, Options exercised	$3.14
Wtd-Avg Exercise Price, Ending Outstanding	$9.37
Exercise Price Per Warrant/Option $5.42 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price Per Warrant/Option	$5.42
Beginning Outstanding	691,882
Repurchased and cancelled	-691,882
Forfeited/expired	0
Options exercised	0
Ending Outstanding	0
Vested and exercisable	0.00%
Intrinsic value at September 30, 2014	0
Exercise Price Per Warrant/Option $17.10 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price Per Warrant/Option	$17.10
Beginning Outstanding	110,640
Repurchased and cancelled	0
Forfeited/expired	-600
Options exercised	0
Ending Outstanding	110,040
Expiration date	13-Dec-17
Vested and exercisable	100.00%
Wtd-avg contractual remaining term (in years)	'3 years 2 months 12 days
Intrinsic value at September 30, 2014	0
Exercise Price Per Warrant/Option $7.50 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price Per Warrant/Option	$7.50
Beginning Outstanding	113,990
Repurchased and cancelled	0
Forfeited/expired	-300
Options exercised	-600
Ending Outstanding	113,090
Expiration date	11-Dec-18
Vested and exercisable	100.00%
Wtd-avg contractual remaining term (in years)	'4 years 2 months 12 days
Intrinsic value at September 30, 2014	233
Exercise Price Per Warrant/Option $4.02 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price Per Warrant/Option	$4.02
Beginning Outstanding	57,400
Repurchased and cancelled	0
Forfeited/expired	-300
Options exercised	-2,400
Ending Outstanding	54,700
Expiration date	10-Dec-19
Vested and exercisable	100.00%
Wtd-avg contractual remaining term (in years)	'5 years 2 months 12 days
Intrinsic value at September 30, 2014	303
Exercise Price Per Warrant/Option $3.00 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price Per Warrant/Option	$3
Beginning Outstanding	32,400
Repurchased and cancelled	0
Forfeited/expired	-300
Options exercised	-7,500
Ending Outstanding	24,600
Expiration date	9-Dec-20
Vested and exercisable	100.00%
Wtd-avg contractual remaining term (in years)	'6 years 2 months 12 days
Intrinsic value at September 30, 2014	161
Exercise Price Per Warrant/Option $2.55 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price Per Warrant/Option	$2.55
Beginning Outstanding	35,133
Repurchased and cancelled	0
Forfeited/expired	-900
Options exercised	-6,167
Ending Outstanding	28,066
Expiration date	8-Dec-21
Vested and exercisable	67.00%
Wtd-avg contractual remaining term (in years)	'7 years 2 months 12 days
Intrinsic value at September 30, 2014	$197

Common_Stock_Warrant_and_Equit4

Common Stock Warrant and Equity Incentive Plans - Summary of Outstanding Common Stock Options and Warrant (Parenthetical) (Detail) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of warrants purchased	330,496	1,041,445
Payment for repurchase of warrants	$2,892	'
Vested and exercisable	97.00%	'
Calculated intrinsic value	$9.56	'
Exercise Price Per Warrant/Option $5.42 [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of warrants purchased	0	691,882
Exercise Price Per Warrant/Option	$5.42	'
Payment for repurchase of warrants	$2,900	'
Vested and exercisable	0.00%	'
Price Per Share $2.55 [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Exercise Price Per Warrant/Option	$2.55	'
Vested and exercisable	100.00%	'

Common_Stock_Warrant_and_Equit5

Common Stock Warrant and Equity Incentive Plans - Summary of Selected Information Regarding Restricted Common Stock Awards made Under Plan (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Grant date of award, Stock Grant	23-Jan-14	24-Jan-13
Total restricted shares of stock awarded	92,000	330,700
Grant date per share fair value	$7.65	$4.50
Total estimated fair value of award	$703,800	$1,488,150
Awards scheduled to vest as follows:	'	'
Awards scheduled to vest, Stock Grant	92,000	330,700
January 2014 [Member]	'	'
Awards scheduled to vest as follows:	'	'
Awards scheduled to vest, Stock Grant	'	49,566
January 2015 [Member]	'	'
Awards scheduled to vest as follows:	'	'
Awards scheduled to vest, Stock Grant	30,664	170,888
January 2016 [Member]	'	'
Awards scheduled to vest as follows:	'	'
Awards scheduled to vest, Stock Grant	30,664	110,246
January 2017 [Member]	'	'
Awards scheduled to vest as follows:	'	'
Awards scheduled to vest, Stock Grant	30,672	'

Common_Stock_Warrant_and_Equit6

Common Stock Warrant and Equity Incentive Plans - Summary of Selected Information Regarding Restricted Common Stock Awards made Under Plan (Parenthetical) (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
	Installment	Installment
Executive Officers [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of participants	'	5
Number of installments	'	2
Restricted stock awards vesting in second anniversary of the grant	'	66.67%
Restricted stock awards vesting in third anniversary of the grant	'	33.33%
Non-employee Directors [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of participants	'	8
Restricted stock awards vesting in first anniversary of the grant	'	33.33%
Restricted stock awards vesting in second anniversary of the grant	'	33.33%
Restricted stock awards vesting in third anniversary of the grant	'	33.33%
Other Officers and Employees [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of installments	3	3
Restricted stock awards vesting in first anniversary of the grant	33.33%	33.33%
Restricted stock awards vesting in second anniversary of the grant	33.33%	33.33%
Restricted stock awards vesting in third anniversary of the grant	33.33%	33.33%
Restricted Common Stock [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Shares Awarded	92,000	'
Restricted Common Stock [Member] | Executive Officers [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Shares Awarded	12,000	182,000
Number of participants	5	'
Restricted Common Stock [Member] | Non-employee Directors [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Shares Awarded	80,000	80,000
Number of participants	8	'
Restricted Common Stock [Member] | Other Officers and Employees [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Shares Awarded	'	68,700

Common_Stock_Warrant_and_Equit7

Common Stock Warrant and Equity Incentive Plans - Summary of Activity in IBCs Restricted Class A Common Stock (Detail) (Restricted Common Stock [Member], USD $)	9 Months Ended
	Sep. 30, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Beginning Outstanding	573,317
Shares granted	92,000
Shares forfeited	-3,300
Shares vested and no longer restricted	-224,116
Ending Outstanding	437,901
Wtd-Avg price outstanding, Beginning Balance	$4.70
Wtd-Avg price , Shares granted	$7.65
Wtd-Avg price, Shares forfeited	$4.26
Wtd-Avg price , Shares vested and no longer restricted	$4.69
Wtd-Avg price outstanding, Ending Balance	$5.33
Price Per Share $2.90 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Price Per Share	$2.90
Beginning Outstanding	158,317
Shares granted	'
Shares forfeited	-500
Shares vested and no longer restricted	-101,035
Ending Outstanding	56,782
Price Per Share $4.50 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Price Per Share	$4.50
Beginning Outstanding	279,500
Shares granted	'
Shares forfeited	-2,800
Shares vested and no longer restricted	-47,664
Ending Outstanding	229,036
Price Per Share $7.21 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Price Per Share	$7.21
Beginning Outstanding	135,500
Shares granted	'
Shares forfeited	'
Shares vested and no longer restricted	-75,417
Ending Outstanding	60,083
Price Per Share $7.65 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Price Per Share	$7.65
Beginning Outstanding	'
Shares granted	92,000
Shares forfeited	'
Shares vested and no longer restricted	'
Ending Outstanding	92,000

Common_Stock_Warrant_and_Equit8

Common Stock Warrant and Equity Incentive Plans - Summary of Activity in IBCs Restricted Class A Common Stock (Parenthetical) (Detail) (Restricted Common Stock [Member], USD $)	9 Months Ended
	Sep. 30, 2014
Price Per Share $2.90 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Exercise Price Per Warrant/Option	$2.90
Price Per Share $4.50 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Exercise Price Per Warrant/Option	$4.50
Price Per Share $7.21 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Exercise Price Per Warrant/Option	$7.21
Price Per Share $7.65 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Exercise Price Per Warrant/Option	$7.65
January 19, 2015 [Member] | Price Per Share $2.90 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 1	56,782
January 19, 2015 [Member] | Price Per Share $7.21 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 1	14,584
January 24, 2015 [Member] | Price Per Share $4.50 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 1	137,264
January 24, 2015 [Member] | Price Per Share $7.21 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 2	30,333
January 24, 2016 [Member] | Price Per Share $4.50 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 2	91,772
January 24, 2016 [Member] | Price Per Share $7.21 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 3	15,166
January 23, 2015 [Member] | Price Per Share $7.65 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 1	30,664
January 23, 2016 [Member] | Price Per Share $7.65 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 2	30,664
January 23, 2017 [Member] | Price Per Share $7.65 [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Restricted common stock will vest on date 3	30,672

Earnings_Per_Common_Share_and_2

Earnings Per Common Share and Common Stock Dividend - Summary of Basic and Diluted Earnings Per Common Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic Earnings Per Common Share:	'	'	'	'
Net earnings available to common stockholders	$4,180	$2,588	$13,760	$9,230
Weighted-Average number of common shares outstanding	22,024,722	21,915,596	22,013,754	21,891,886
Basic earnings per common share	$0.19	$0.12	$0.62	$0.42
Diluted Earnings Per Common Share:	'	'	'	'
Net earnings applicable to common stockholders	$4,180	$2,588	$13,760	$9,230
Weighted-Average number of common shares outstanding:	'	'	'	'
Common shares outstanding	22,024,722	21,915,596	22,013,754	21,891,886
Potential dilutive shares resulting from exercise of warrants /options	243,523	135,866	192,981	81,064
Total average number of common shares outstanding used for dilution	22,268,245	22,051,462	22,206,735	21,972,950
Diluted earnings per common share	$0.19	$0.12	$0.62	$0.42

Earnings_Per_Common_Share_and_3

Earnings Per Common Share and Common Stock Dividend - Summary of Basic and Diluted Earnings Per Common Share (Parenthetical) (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]	'	'	'	'
Outstanding options/warrants to purchase, shares	110,040	234,430	110,040	234,430

Earnings_Per_Common_Share_and_4

Earnings Per Common Share and Common Stock Dividend - Additional Information (Detail) (USD $)	0 Months Ended
	Jul. 14, 2014	Apr. 24, 2014
Earnings Per Share [Abstract]	'	'
Dividend declared per share	$0.05	$0.05
Dividend payment date	26-Aug-14	26-May-14
Dividend record date	15-Aug-14	15-May-14

Contingencies_Additional_Infor

Contingencies - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Liability or reserve recognized from litigation related to merger	$0

Regulatory_Matters_and_Regulat1

Regulatory Matters and Regulatory Capital - Additional Information (Detail)	Sep. 30, 2014
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]	'
Tier 1 capital ratio	20.84%
Tier 1 Total capital ratios	22.10%
Leverage capital ratio	16.92%
INB [Member]	'
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]	'
Tier 1 capital ratio	16.44%
Tier 1 Total capital ratios	20.22%
Leverage capital ratio	21.48%

OffBalance_Sheet_Financial_Ins2

Off-Balance Sheet Financial Instruments - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Off Balance Sheet Financial Instruments [Abstract]	'	'
Standby letters of credit	$0	$0

OffBalance_Sheet_Financial_Ins3

Off-Balance Sheet Financial Instruments - Summary of Contractual Amounts of Off-Balance Sheet Financial Instruments (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]	'	'
Off-balance sheet financial instruments, contractual amount	$23,921	$20,263
Commitments to Extend Credit [Member]	'	'
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]	'	'
Off-balance sheet financial instruments, contractual amount	23,134	19,386
Unused Lines of Credit [Member]	'	'
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]	'	'
Off-balance sheet financial instruments, contractual amount	$787	$877

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available for sale, net	$305,347,000	$965,000
Fair Value Measurement, Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available for sale, net	996,000	'
Fair Value Measurement, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available for sale, net	'	1,000,000
Liabilities that were recorded at fair value	$0	$0

Fair_Value_Measurements_Availa

Fair Value Measurements - Available-for-sale Securities Measured at Fair Value on a Recurring Basis (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	$305,347	$965
Debt Securities [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	304,351	'
Debt Securities [Member] | U.S. government agencies [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	224,132	'
Debt Securities [Member] | Residential mortgage-backed [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	79,690	'
Debt Securities [Member] | State and municipal [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	529	'
Equity Securities [Member] | Mutual funds investment [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	996	965
Fair Value Measurement, Level 1 [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	996	'
Fair Value Measurement, Level 1 [Member] | Debt Securities [Member] | U.S. government agencies [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Fair Value Measurement, Level 1 [Member] | Debt Securities [Member] | Residential mortgage-backed [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Fair Value Measurement, Level 1 [Member] | Debt Securities [Member] | State and municipal [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Fair Value Measurement, Level 1 [Member] | Equity Securities [Member] | Mutual funds investment [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	996	'
Fair Value Measurement, Level 2 [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	304,351	'
Fair Value Measurement, Level 2 [Member] | Debt Securities [Member] | U.S. government agencies [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	224,132	'
Fair Value Measurement, Level 2 [Member] | Debt Securities [Member] | Residential mortgage-backed [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	79,690	'
Fair Value Measurement, Level 2 [Member] | Debt Securities [Member] | State and municipal [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	529	'
Fair Value Measurement, Level 2 [Member] | Equity Securities [Member] | Mutual funds investment [Member]	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'
Available for sale securities	'	'

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets Measured at Fair Value on a Nonrecurring Basis (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Accumulated Losses on Outstanding Balance	$8,553	'	$8,553	'	$14,633
Total Losses (Gains)	-457	413	-1,482	935	'
Foreclosed Real Estate [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Accumulated Losses on Outstanding Balance	390	'	390	'	2,017
Total Losses (Gains)	'	149	-203	135	'
Impaired Securities [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Total Losses (Gains)	'	273	'	964	'
Impaired Loans [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Accumulated Losses on Outstanding Balance	8,163	'	8,163	'	12,616
Total Losses (Gains)	-457	-9	-1,279	-164	'
Impaired Loans [Member] | Commercial Real Estate [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Accumulated Losses on Outstanding Balance	7,416	'	7,416	'	11,522
Total Losses (Gains)	-452	'	-918	823	'
Impaired Loans [Member] | Multifamily Loans [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Accumulated Losses on Outstanding Balance	591	'	591	'	594
Total Losses (Gains)	'	-7	-17	-964	'
Impaired Loans [Member] | Land [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Accumulated Losses on Outstanding Balance	156	'	156	'	500
Total Losses (Gains)	-5	-2	-344	-23	'
Fair Value Measurement, Level 3 [Member] | Foreclosed Real Estate [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Outstanding Carrying Value	2,650	'	2,650	'	10,669
Fair Value Measurement, Level 3 [Member] | Impaired Loans [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Outstanding Carrying Value	54,905	'	54,905	'	57,160
Fair Value Measurement, Level 3 [Member] | Impaired Loans [Member] | Commercial Real Estate [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Outstanding Carrying Value	50,281	'	50,281	'	52,407
Fair Value Measurement, Level 3 [Member] | Impaired Loans [Member] | Multifamily Loans [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Outstanding Carrying Value	3,104	'	3,104	'	3,128
Fair Value Measurement, Level 3 [Member] | Impaired Loans [Member] | Land [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Outstanding Carrying Value	$1,520	'	$1,520	'	$1,625

Fair_Value_Measurements_Change

Fair Value Measurements - Change in Assets Measured at Fair Value on a Nonrecurring Basis (Detail) (Assets Measured at Fair Value on a Nonrecurring Basis [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Impaired Securities [Member]	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Balance at beginning of period	'	$2,923	'	$3,721
Other than temporary impairment write downs	'	-273	'	-964
Principal repayments/sales	'	-46	'	-153
Balance at end of period	'	2,604	'	2,604
Impaired Loans [Member]	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Balance at beginning of period	57,821	50,533	57,160	65,973
Net new impaired loans	'	514	3,466	8,761
Impaired loans transferred to foreclosed real estate	'	'	'	-3,040
Principal repayments/sales	-2,916	-149	-5,721	-18,858
Chargeoffs of impaired loans	'	'	'	-1,938
Gain from sales	'	'	'	'
Balance at end of period	54,905	50,898	54,905	50,898
Foreclosed Real Estate [Member]	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Balance at beginning of period	2,650	14,869	10,669	15,923
Net new impaired loans	'	'	'	'
Impaired loans transferred to foreclosed real estate	'	'	'	3,040
Principal repayments/sales	'	-2,701	-8,222	-6,809
Writedowns of carrying value subsequent to foreclosure	'	-250	'	-1,029
Recoveries of prior writedowns	'	'	'	74
Gain from sales	'	101	203	820
Balance at end of period	$2,650	$12,019	$2,650	$12,019

Fair_Value_Measurements_Carryi

Fair Value Measurements - Carrying and Estimated Fair Values of Financial Instruments (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Financial Assets:	'	'
Securities held to maturity, net	'	$378,507,000
Time deposits with banks	4,620,000	5,370,000
Securities available for sale, net	305,347,000	965,000
Securities held to maturity, net	'	383,937,000
Fair Value Measurement, Level 1 [Member]	'	'
Financial Assets:	'	'
Securities held to maturity, net	1,000,000	'
Securities available for sale, net	996,000	'
Fair Value Measurement, Level 2 [Member]	'	'
Financial Assets:	'	'
Securities available for sale, net	304,351,000	'
Fair Value [Member]	'	'
Financial Assets:	'	'
Total Financial Assets	1,497,071,000	1,525,313,000
Financial Liabilities:	'	'
Total Financial Liabilities	1,286,631,000	1,353,866,000
Net Financial Assets	210,440,000	171,447,000
Fair Value [Member] | Fair Value Measurement, Level 1 [Member]	'	'
Financial Assets:	'	'
Cash and cash equivalents	11,483,000	24,700,000
Time deposits with banks	4,620,000	5,370,000
Securities available for sale, net	305,347,000	965,000
Fair Value [Member] | Fair Value Measurement, Level 2 [Member]	'	'
Financial Assets:	'	'
Securities held to maturity, net	'	378,507,000
Fair Value [Member] | Fair Value Measurement, Level 3 [Member]	'	'
Financial Assets:	'	'
FRB and FHLB stock	7,715,000	8,244,000
Loans receivable, net	1,161,476,000	1,100,858,000
Accrued interest receivable	4,665,000	4,861,000
Loan fees receivable	1,765,000	1,808,000
Financial Liabilities:	'	'
Deposits	1,229,119,000	1,294,690,000
Borrowed funds plus accrued interest payable	56,516,000	57,260,000
Accrued interest payable on deposits	850,000	1,508,000
Commitments to lend	146,000	408,000
Carrying Value [Member]	'	'
Financial Assets:	'	'
Cash and cash equivalents	11,483,000	24,700,000
Time deposits with banks	4,620,000	5,370,000
Securities available for sale, net	305,347,000	965,000
Securities held to maturity, net	'	383,937,000
FRB and FHLB stock	7,715,000	8,244,000
Loans receivable, net	1,148,635,000	1,099,689,000
Accrued interest receivable	4,665,000	4,861,000
Loan fees receivable	2,224,000	2,298,000
Total Financial Assets	1,484,689,000	1,530,064,000
Financial Liabilities:	'	'
Deposits	1,214,324,000	1,282,232,000
Borrowed funds plus accrued interest payable	56,758,000	57,570,000
Accrued interest payable on deposits	850,000	1,508,000
Commitments to lend	146,000	408,000
Total Financial Liabilities	1,272,078,000	1,341,718,000
Net Financial Assets	$212,611,000	$188,346,000

Fair_Value_Measurements_Carryi1

Fair Value Measurements - Carrying and Estimated Fair Values of Financial Instruments (Parenthetical) (Detail) (USD $)	Dec. 31, 2013	Sep. 30, 2014
In Thousands, unless otherwise specified		Fair Value Measurement, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Securities held to maturity, net	$378,507	$1,000

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	0 Months Ended		3 Months Ended	9 Months Ended	0 Months Ended
	Jul. 14, 2014	Apr. 24, 2014	Sep. 30, 2014	Sep. 30, 2014	Oct. 31, 2014	Oct. 15, 2014
					Subsequent Event [Member]	Subsequent Event [Member]
Subsequent Event [Line Items]	'	'	'	'	'	'
Cash dividend	$0.05	$0.05	'	'	'	$0.05
Cash dividend payment date	26-Aug-14	26-May-14	'	'	'	24-Nov-14
Cash dividend record date	15-Aug-14	15-May-14	'	'	'	14-Nov-14
Available for sale of securities	'	'	'	$37,384,000	$77,000,000	'
Increased cash through sale of securities	'	'	'	'	90,000,000	'
Net loss of sale of securities	'	'	$196,000	$196,000	$200,000	'