First Commonwealth Financial (FCF) 10-K 14 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Mar. 13, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	FCF
Entity Registrant Name	FIRST COMMONWEALTH FINANCIAL CORP /PA/
Entity Central Index Key	712,537
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		89,099,100
Entity Public Float			$ 807,350,876

CONSOLIDATED STATEMENTS OF FINA

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Assets
Cash and due from banks	$ 91,033,000	$ 66,644,000
Interest-bearing bank deposits	24,644,000	2,808,000
Securities available for sale, at fair value	(778,612,000)	(886,560,000)
Securities held to maturity, at amortized cost, (Fair value $368,618 at December 31, 2016 and $382,341 at December 31, 2015)	372,513,000	384,324,000
Other investments	36,498,000	62,952,000
Loans held for sale	7,052,000	5,763,000
Loans:
Portfolio loans	4,879,347,000	4,683,750,000
Allowance for credit losses	(50,185,000)	(50,812,000)
Net loans	4,829,162,000	4,632,938,000
Premises and equipment, net	67,534,000	63,454,000
Other real estate owned	6,805,000	9,398,000
Goodwill	186,483,000	164,500,000
Amortizing intangibles, net	12,013,000	1,231,000
Bank owned life insurance	187,021,000	182,601,000
Other assets	84,648,000	103,717,000
Total assets	6,684,018,000	6,566,890,000
Deposits (all domestic):
Noninterest-bearing	1,268,786,000	1,116,689,000
Interest-bearing	3,678,622,000	3,079,205,000
Total deposits	4,947,408,000	4,195,894,000
Short-term borrowings	867,943,000	1,510,825,000
Subordinated debentures	72,167,000	72,167,000
Other long-term debt	8,749,000	9,314,000
Total long-term debt	80,916,000	81,481,000
Other liabilities	37,822,000	59,144,000
Total liabilities	5,934,089,000	5,847,344,000
Shareholders’ Equity
Preferred stock, $1 par value per share, 3,000,000 shares authorized, none issued	0	0
Common stock, $1 par value per share, 200,000,000 shares authorized; 105,563,455 shares issued as of December 31, 2016 and 2015; and 89,007,077 and 88,961,268 shares outstanding at December 31, 2016 and 2015, respectively	105,563,000	105,563,000
Additional paid-in capital	366,426,000	365,981,000
Retained earnings	412,764,000	378,081,000
Accumulated other comprehensive (loss) income, net	(7,027,000)	(2,386,000)
Treasury stock (16,556,378 and 16,602,187 shares at December 31, 2016 and 2015, respectively)	(127,797,000)	(127,693,000)
Total shareholders’ equity	749,929,000	719,546,000
Total liabilities and shareholders’ equity	$ 6,684,018,000	$ 6,566,890,000

CONSOLIDATED STATEMENTS OF FIN3

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities held to maturity, fair value	$ 368,618	$ 382,341
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	3,000,000	3,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	105,563,455	105,563,455
Common stock, shares outstanding (in shares)	89,007,077	88,961,268
Treasury stock, shares (in shares)	16,556,378	16,602,187

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest Income
Interest and fees on loans	$ 185,344	$ 172,819	$ 171,196
Interest and dividends on investments:
Taxable interest	27,919	26,807	28,767
Interest exempt from federal income taxes	1,498	997	311
Dividends	2,826	3,434	1,895
Interest on bank deposits	27	14	12
Total interest income	217,614	204,071	202,181
Interest Expense
Interest on deposits	7,523	7,474	12,453
Interest on short-term borrowings	8,076	5,018	2,449
Interest on subordinated debentures	2,635	2,329	2,292
Interest on other long-term debt	345	774	1,307
Total interest expense	18,579	15,595	18,501
Net Interest Income	199,035	188,476	183,680
Provision for credit losses	18,480	14,948	11,196
Net Interest Income after Provision for Credit Losses	180,555	173,528	172,484
Noninterest Income
Net securities gains (losses)	617	(153)	550
Trust income	5,366	5,834	6,000
Service charges on deposit accounts	15,869	15,319	15,661
Insurance and retail brokerage commissions	7,964	8,522	6,483
Income from bank owned life insurance	5,381	5,412	5,502
Gain on sale of mortgage loans	4,086	2,421	440
Card related interchange income	14,955	14,501	14,222
Derivative, Gain (Loss) on Derivative, Net	219	(274)	(345)
Swap Fee Income	2,359	847	511
Other income	6,372	7,041	7,279
Total noninterest income	64,599	61,325	60,859
Noninterest Expense
Salaries and employee benefits	87,125	89,161	87,223
Net occupancy	13,150	13,712	13,119
Furniture and equipment	11,624	10,737	17,812
Data processing	7,429	6,123	6,124
Advertising and promotion	2,601	2,638	2,953
Pennsylvania shares tax	3,825	4,693	3,776
Intangible amortization	547	605	631
Collection and repossession	2,250	2,826	2,754
Other professional fees and services	3,915	4,034	3,986
FDIC insurance	3,903	4,014	4,054
Gain (Loss) on Sale of Assets and Asset Impairment Charges	1,155	3,112	1,595
Loss on sale or write-down of assets	(1,411)	(1,855)	(4,556)
Litigation and operational losses	1,420	2,119	6,786
Conversion related	0	0	1,788
Merger and acquisition related	3,173	922	0
Other operating expenses	17,808	19,178	18,609
Total noninterest expense	159,925	163,874	171,210
Income before income taxes	85,229	70,979	62,133
Income tax provision	25,639	20,836	17,680
Net Income	$ 59,590	$ 50,143	$ 44,453
Average Shares Outstanding (in shares)	88,851,573	89,356,767	93,114,654
Average Shares Outstanding Assuming Dilution (in shares)	88,851,573	89,356,767	93,114,654
Per Share Data:
Basic Earnings Per Share (in dollars per share)	$ 0.67	$ 0.56	$ 0.48
Diluted Earnings Per Share (in dollars per share)	0.67	0.56	0.48
Cash Dividends Declared per Common Share (in dollars per share)	$ 0.28	$ 0.28	$ 0.28

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 59,590	$ 50,143	$ 44,453
Other comprehensive (loss) income, before tax (benefit) expense:
Unrealized holding (losses) gains on securities arising during the period	(6,304)	2,798	25,153
Less: reclassification adjustment for (gains) losses on securities included in net income	(617)	153	(550)
Unrealized holding (losses) gains on derivatives arising during the period	(479)	450	472
Reclassification adjustment for gains on derivatives included in net income	(70)	(49)	(10)
Unrealized gains (losses) for postretirement obligation:
Transition obligation	0	0	0
Net gain (loss)	331	(102)	(313)
Total other comprehensive (loss) income, before income tax (benefit) expense	(7,139)	3,250	24,752
Income tax (benefit) expense related to items of other comprehensive (loss) income	(2,498)	1,137	8,663
Comprehensive Income	$ 54,949	$ 52,256	$ 60,542

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), net [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2013	$ 711,697	$ 105,563	$ 365,333	$ 334,748	$ (20,588)	$ (73,359)
Beginning balance, Shares Outstanding at Dec. 31, 2013		95,245,215
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	44,453			44,453
Total other comprehensive (loss) Income	16,089				16,089
Cash dividends declared	(26,174)			(26,174)
Discount on dividend reinvestment plan purchases	(65)		(65)
Treasury stock acquired	(30,956)					(30,956)
Treasury stock acquired, Shares Outstanding		(3,636,634)
Treasury stock reissued	192		35	0		157
Treasury stock reissued, Shares Outstanding		21,960
Restricted stock	909	$ 0	312	0		597
Restricted stock, Shares Outstanding		92,487
Ending balance at Dec. 31, 2014	716,145	$ 105,563	365,615	353,027	(4,499)	(103,561)
Ending balance, Shares Outstanding at Dec. 31, 2014		91,723,028
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	50,143			50,143
Total other comprehensive (loss) Income	2,113				2,113
Cash dividends declared	(25,089)			(25,089)
Treasury stock acquired	(25,383)					(25,383)
Treasury stock acquired, Shares Outstanding		(2,918,066)
Treasury stock reissued	192		32	0		160
Treasury stock reissued, Shares Outstanding		20,936
Restricted stock	1,425	$ 0	334	0		1,091
Restricted stock, Shares Outstanding		135,370
Ending balance at Dec. 31, 2015	$ 719,546	$ 105,563	365,981	378,081	(2,386)	(127,693)
Ending balance, Shares Outstanding at Dec. 31, 2015	88,961,268	88,961,268
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 59,590			59,590
Total other comprehensive (loss) Income	(4,641)				(4,641)
Cash dividends declared	(24,907)			(24,907)
Treasury stock acquired	(864)					(864)
Treasury stock acquired, Shares Outstanding		(98,687)
Treasury stock reissued	216		39	0		177
Treasury stock reissued, Shares Outstanding		23,148
Restricted stock	989	$ 0	406	0		583
Restricted stock, Shares Outstanding		121,348
Ending balance at Dec. 31, 2016	$ 749,929	$ 105,563	$ 366,426	$ 412,764	$ (7,027)	$ (127,797)
Ending balance, Shares Outstanding at Dec. 31, 2016	89,007,077	89,007,077

CONSOLIDATED STATEMENTS OF CHA7

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Dividends Declared per Common Share (in dollars per share)	$ 0.28	$ 0.28	$ 0.28

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net Income	$ 59,590	$ 50,143	$ 44,453
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	18,480	14,948	11,196
Deferred Income Taxes and Tax Credits	5,713	12,653	4,862
Depreciation and amortization	7,116	7,640	13,721
Net (gains) losses on securities and other assets	(5,257)	(729)	2,832
Net amortization of premiums and discounts on securities	4,524	2,793	2,233
Net amortization of premiums and discounts on long-term debt	0	0	(37)
Income from increase in cash surrender value of bank owned life insurance	(5,325)	(5,412)	(5,275)
Payments for Origination of Mortgage Loans Held-for-sale	(133,278)	(86,576)	(17,697)
Proceeds from Sale of Mortgage Loans Held-for-sale	136,037	85,718	15,598
(Increase) decrease in interest receivable	(577)	(41)	542
Decrease in interest payable	(272)	(103)	(404)
(Increase) decrease in income taxes payable	(589)	(354)	1,860
Other—net	3,111	(7,929)	8,253
Net cash provided by operating activities	89,273	72,751	82,137
Transactions with securities held to maturity:
Proceeds from maturities and redemptions	54,057	9,358	0
Purchases	(45,188)	(380,877)	0
Transactions with securities available for sale:
Proceeds from sales	55,744	88,054	132,868
Proceeds from maturities and redemptions	168,237	373,228	242,895
Purchases	(128,916)	(24,150)	(339,649)
Purchases of FHLB stock	(37,326)	(65,605)	(40,920)
Proceeds from the redemption of FHLB stock	63,780	48,029	31,819
Proceeds from bank owned life insurance	467	378	2,080
Proceeds from the sale of loans	18,612	3,018	3,112
Proceeds from sales of other assets	7,765	6,407	12,882
Acquisition, net of cash acquired	479,469	(3,533)	(3,042)
Net increase in loans	(135,436)	(191,853)	(195,120)
Payments for Purchase of Other Assets	(430)	0	0
Purchases of premises and equipment	(7,061)	(4,887)	(10,980)
Net cash provided by (used in) investing activities	493,774	(142,433)	(164,055)
Financing Activities
Net decrease in federal funds purchased	(4,000)	(5,000)	(7,000)
Net (decrease) increase in other short-term borrowings	(638,882)	409,949	486,261
Net increase (decrease) in deposits	132,180	(209,928)	(288,352)
Repayments of other long-term debt	(565)	(80,145)	(59,889)
Proceeds from issuance of long-term debt	0	0	5,000
Discount on dividend reinvestment plan purchases	0	0	(65)
Dividends paid	(24,907)	(25,089)	(26,174)
Proceeds from reissuance of treasury stock	216	192	192
Purchase of treasury stock	(864)	(25,383)	(30,956)
Net cash (used in) provided by financing activities	(536,822)	64,596	79,017
Net increase (decrease) in cash and cash equivalents	46,225	(5,086)	(2,901)
Cash and cash equivalents at January 1	69,452	74,538	77,439
Cash and cash equivalents at December 31	$ 115,677	$ 69,452	$ 74,538

Statement of Accounting Policie

Statement of Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Statement of Accounting Policies	Statement of Accounting Policies General The following summary of accounting and reporting policies is presented to aid the reader in obtaining a better understanding of the consolidated financial statements of First Commonwealth Financial Corporation and its subsidiaries (“First Commonwealth”) contained in this report. The financial information is presented in accordance with generally accepted accounting principles and general practice for financial institutions in the United States of America. In preparing financial statements, management is required to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, these estimates and assumptions affect revenues and expenses in the financial statements and as such, actual results could differ from those estimates. Through its subsidiaries, which include a commercial bank and an insurance agency, First Commonwealth provides a full range of loan, deposit, trust, insurance and personal financial planning services primarily to individuals and small to middle market businesses in fifteen counties in central and western Pennsylvania as well as in central and northern Ohio. First Commonwealth has determined that it has one business segment. First Commonwealth is subject to regulations of certain state and federal agencies. These regulatory agencies periodically examine First Commonwealth for adherence to laws and regulations. Basis of Presentation The accompanying Consolidated Financial Statements include the accounts of First Commonwealth previously defined above. All material intercompany transactions have been eliminated in consolidation. Equity investments of less than a majority but at least 20% ownership are accounted for by the equity method and classified as “Other assets.” Earnings on these investments are reflected in “Other income” on the Consolidated Statements of Income, as appropriate, in the period earned. Securities Debt securities that First Commonwealth has the positive intent and ability to hold to maturity are classified as securities held to maturity and are reported at amortized cost adjusted for amortization of premium and accretion of discount on a level yield basis. Debt and equity securities that are bought and held principally for the purpose of selling them in the near term are to be classified as trading securities and reported at fair value, with unrealized gains and losses included in earnings. Debt and equity securities not classified as either held-to-maturity securities or trading securities are classified as securities available for sale and are reported at fair value, with unrealized gains and losses that are not related to impairment excluded from earnings and reported as a component of other comprehensive income, which is included in shareholders’ equity, net of deferred taxes. First Commonwealth has securities classified as held to maturity and available for sale and does not engage in trading activities. First Commonwealth utilizes the specific identification method to determine the net gain or loss on debt securities and the average cost method to determine the net gain or loss on the equity securities. First Commonwealth conducts a comprehensive review of the investment portfolio on a quarterly basis to determine whether other-than-temporary impairment has occurred. Issuer-specific securities whose market values have fallen below their book values are initially selected for more in-depth analysis based on the percentage decline in value and duration of the decline. Issuer-specific securities include obligations of U.S. Government agencies and sponsored enterprises, single issue trust preferred securities, corporate debentures and obligations of states and political subdivisions. Further analysis of these securities includes a review of research reports, analysts’ recommendations, credit rating changes, news stories, annual reports, impact of interest rate changes and any other relevant information pertaining to the affected security. Pooled trust preferred collateralized debt obligations are measured by evaluating all relevant credit and structural aspects, determining appropriate performance assumptions and performing a discounted cash flow analysis. This evaluation includes detailed credit, performance and structural evaluations for each piece of collateral. Other factors in the pooled trust preferred collateralized debt obligations valuation include terms of the structure, the cash flow waterfall (for both interest and principal), the over collateralization and interest coverage tests and events of default/liquidation. Based on this review, a determination is made on a case by case basis as to a potential impairment. Declines in the fair value of individual securities below their cost that are not expected to be recovered will result in write-downs of the individual securities to their fair value. The related write-downs are included in earnings as impairment losses. Mortgage Loans Held for Sale Certain residential mortgage loans are originated for sale in the secondary mortgage loan market with the majority sold with servicing rights released. These loans are classified as loans held for sale and are carried at the lower of cost or estimated market value on an aggregate basis. Market value is determined on the basis of rates obtained in the respective secondary market for the type of loan held for sale. Loans are generally sold at a premium or discount from the carrying amount of the loan. Such premium or discount is recognized at the date of sale. Gain or loss on the sale of loans is recorded in non-interest income at the time consideration is received and all other criteria for sales treatment have been met. Loans Loans are carried at the principal amount outstanding. Interest is accrued as earned. Loans held for sale are carried at the lower of cost or fair value determined on an individual basis. First Commonwealth considers a loan to be past due and still accruing interest when payment of interest or principal is contractually past due but the loan is both well secured and in the process of collection. For installment, mortgage, term and other loans with amortizing payments that are scheduled monthly, 90 days past due is reached when four monthly payments are due and unpaid. For demand, time and other multi-payment obligations with payments scheduled other than monthly, delinquency status is calculated using number of days instead of number of payments. Revolving credit loans, including personal credit lines and home equity lines, are considered to be 90 days past due when the borrower has not made the minimum payment for four monthly cycles. A loan is placed in nonaccrual status when, based on current information and events, it is probable that First Commonwealth will be unable to fully collect principal or interest due according to the contractual terms of the loan. A loan is also placed in nonaccrual status when, based on regulatory definitions, the loan is maintained on a “cash basis” due to the weakened financial condition of the borrower. When a determination is made to place a loan in nonaccrual status, all accrued and unpaid interest is reversed. Nonaccrual loans are restored to accrual status when, based on a sustained period of repayment by the borrower in accordance with the contractual terms of the loan, First Commonwealth expects repayment of the remaining contractual principal and interest or when the loan otherwise becomes well-secured and in the process of collection. First Commonwealth considers a loan to be a troubled debt restructured loan when the loan terms have been renegotiated to provide a reduction or deferral of principal or interest as a result of the financial difficulties experienced by the borrower, who could not obtain comparable terms from alternate financing sources. A loan is considered to be impaired when, based on current information and events, it is probable that First Commonwealth will be unable to collect principal or interest that is due in accordance with contractual terms of the loan. Impaired loans include nonaccrual loans and troubled debt restructured loans. Loan impairment is measured based on the present value of expected cash flows discounted at the loan’s effective interest rate or, as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. For loans other than those that First Commonwealth expects repayment through liquidation of the collateral, when the remaining recorded investment in the impaired loan is less than or equal to the present value of the expected cash flows, income is applied as a reduction to loan principal rather than interest income. Loans deemed uncollectible are charged off through the allowance for credit losses. Factors considered in assessing ultimate collectibility include past due status, financial condition of the borrower, collateral values and debt covenants including secondary sources of repayment by guarantors. Payments received on previously charged off loans are recorded as recoveries in the allowance for credit losses. Acquired loans are recorded at estimated fair value on the date of acquisition with no carryover of the related allowance for credit losses. The fair value of acquired loans is determined by estimating the principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The estimated fair value considers factors such as loan term, internal risk rating, delinquency status, prepayment rates, estimated value of the underlying collateral and the current interest rate environment. Loan Fees Loan origination and commitment fees, net of associated direct costs, are deferred and the net amount is amortized as an adjustment to the related loan yield on the interest method, generally over the contractual life of the related loans or commitments. Other Real Estate Owned Real estate, other than bank premises, is recorded at fair value less estimated selling costs at the time of acquisition. After that time, other real estate is carried at the lower of cost or fair value less estimated costs to sell. Fair value is determined based on an independent appraisal. Expenses related to holding the property and rental income earned on the property are generally reflected in earnings in the current period. Depreciation is not recorded on the other real estate owned properties. Allowance for Credit Losses First Commonwealth maintains an allowance for credit losses at a level deemed sufficient to absorb losses that are inherent in the loan portfolio. First Commonwealth’s management determines and reviews with the Board of Directors the adequacy of the allowance on a quarterly basis to ensure that the provision for credit losses has been charged against earnings in an amount necessary to maintain the allowance at a level that is appropriate based on management’s assessment of probable estimated losses. First Commonwealth’s methodology for assessing the appropriateness of the allowance for credit losses consists of several key elements. These elements include an assessment of individual problem loans, delinquency and loss experience trends and other relevant factors, all of which may be susceptible to significant changes. The major loan classifications used in the allowance for credit losses calculation include pass, other assets especially mentioned (“OAEM”), substandard and doubtful. Additional information related to these credit quality categories is provided in Note 10, "Loans and Allowance for Credit Losses." First Commonwealth consistently applies the following comprehensive methodology and procedure for determining the allowance for credit losses. All impaired credits in excess of $100 thousand are individually reviewed quarterly. A specific reserve is established for impaired loans that is equal to the total amount of probable unconfirmed losses for the impaired loans that are reviewed. Based on this reserve as a percentage of reviewed loan balances, a reserve is also established for the impaired loan balances that are not individually reviewed. The allowance calculation uses historical charge-off trends to estimate probable unconfirmed losses for each loan category. A multiplier known as the emergence factor is applied to the historical loss rates for non-criticized loans. The emergence factor is calculated by loan category and represents the average time period from when a loss is incurred until the bank experiences a charge-off against the loan. Before applying the adjusted historical loss experience percentages, loan balances are reduced by the portion of the loan balances which are subject to guarantee by a government agency. An additional component of the allowance is determined by management based on a qualitative analysis of certain factors related to portfolio risks and economic conditions. Factors considered by management include employment trends, macroeconomic trends, commercial real estate trends, lending practices, ability and experience of the credit staff, the overall lending environment and external factors such as the regulatory environment and competition. Portfolio risks include unusual changes or recent trends in specific portfolios such as unexpected changes in the trends or levels of delinquency. No matter how detailed an analysis of potential credit losses is performed, these estimates are inherently imprecise. Management must make estimates using assumptions and information that is often subjective and changes rapidly. Loans acquired with evidence of credit deterioration were evaluated and not considered to be significant. The premium or discount estimated through the loan fair value calculation is recognized into interest income on a level yield or straight-line basis over the remaining contractual life of the loans. Additional credit deterioration on acquired loans, in excess of the original credit discount embedded in the fair value determination on the date of acquisition, will be recognized in the allowance for credit losses through the provision for loan losses. Allowance for Off-Balance Sheet Credit Exposures First Commonwealth maintains an allowance for off-balance sheet credit exposure at a level deemed sufficient to absorb losses that are inherent to off-balance sheet credit risk. Management determines the adequacy of the allowance on a quarterly basis, charging the provision against earnings in an amount necessary to maintain the allowance at a level that is appropriate based on management’s assessment of probable estimated losses. The Company’s methodology for assessing the appropriateness of the allowance for off-balance sheet credit exposure consists of analysis of historical usage trends as well as loss history and probability of default rates related to the off-balance sheet category. The calculation begins with historical usage trends related to lines of credit as well as letters of credit and then utilizes those figures to determine the probable usage of available lines. These values are then adjusted by a determined probability of default as well as a loss given default. This amount is adjusted quarterly and reported as part of other operating expenses on the Consolidated Statements of Income. Bank Owned Life Insurance First Commonwealth and the banks that First Commonwealth has acquired have purchased insurance on the lives of certain groups of employees. The policies accumulate asset values to meet future liabilities, including the payment of employee benefits such as health care. Increases in the cash surrender value are recorded as non-interest income in the Consolidated Statements of Income. Under some of these policies, the beneficiaries receive a portion of the death benefit. The net present value of the future death benefits scheduled to be paid to the beneficiaries was $3.3 million and $3.7 million as of December 31, 2016 and 2015 , respectively, and is reflected in "Other Liabilities" on the Consolidated Statements of Financial Condition. Premises and Equipment Premises and equipment are carried at cost less accumulated depreciation on First Commonwealth’s Consolidated Statements of Financial Condition. Depreciation is computed on the straight-line and accelerated methods over the estimated useful life of the asset. A straight-line depreciation method was used for substantially all furniture and equipment. The straight-line depreciation method was used for buildings and improvements. Charges for maintenance and repairs are expensed as incurred. Leasehold improvements are expensed over the term of the lease or the estimated useful life of the improvement, whichever is shorter. Software costs are amortized on a straight-line basis over a period not to exceed seven years. Business Combinations Business combinations are accounted for by using the acquisition method of accounting. Under the acquisition method, identifiable assets acquired and liabilities assumed at the acquisition date are measured at their fair values as of that date, and are recognized separately from goodwill. The difference between the purchase price and the fair value of the net assets acquired is recorded as goodwill. Results of operations of the acquired entities are included in the consolidated statement of income from the date of acquisition. Acquisition costs are expensed when incurred. Goodwill Intangible assets resulting from acquisitions under the purchase method of accounting consist of goodwill and other intangible assets (see “Other Intangible Assets” section below). Goodwill is not amortized and is subject to at least annual assessments for impairment by applying a fair value based test. First Commonwealth reviews goodwill annually and again at any quarter-end if a material event occurs during the quarter that may affect goodwill. If goodwill testing is required, an assessment of qualitative factors can be completed before performing the two step goodwill impairment test. If an assessment of qualitative factors determines it is more likely than not that the fair value of a reporting unit exceeds its carrying amount, then the two step goodwill impairment test is not required. Goodwill is evaluated for potential impairment by determining if our fair value has fallen below carrying value. Other Intangible Assets Other intangible assets consist of core deposits and customer lists obtained through acquisitions. Core deposit intangibles are amortized over their estimated lives using the present value of the benefit of the core deposits and straight-line methods of amortization. Customer list intangibles are amortized over the expected lives using expected cash flows based on retention of the customer base. These intangibles are evaluated for impairment on an annual basis and when events or changes in circumstances indicate that the carrying amount may not be recoverable. Accounting for the Impairment of Long-Lived Assets First Commonwealth reviews long-lived assets, such as premises and equipment and intangibles, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. These changes in circumstances may include a significant decrease in the market value of an asset or the extent or manner in which an asset is used. If there is an indication that the carrying amount of an asset may not be recoverable, future undiscounted cash flows expected to result from the use of the asset are estimated. If the sum of the expected cash flows is less than the carrying value of the asset, a loss is recognized for the difference between the carrying value and fair value of the asset. Long-lived assets classified as held for sale are measured at the lower of their carrying amount or fair value less cost to sell. Depreciation or amortization is discontinued on long-lived assets classified as held for sale. Income Taxes First Commonwealth records taxes in accordance with the asset and liability method of FASB ASC Topic 740, “Income Taxes,” whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities and their respective tax bases given the provisions of the enacted tax laws. Deferred tax assets are reduced, if necessary, by the amount of such benefits that are more likely than not expected to be realized based upon available evidence. In accordance with FASB ASC Topic 740, interest or penalties incurred for taxes will be recorded as a component of noninterest expense. Comprehensive Income Disclosures “Other Comprehensive Income” (comprehensive income, excluding net income) includes the after-tax effect of changes in unrealized holding gains and losses on available-for-sale securities, changes in the funded status of defined benefit postretirement plans and changes in the fair value of the effective portion of cash flow hedges. Comprehensive income is reported in the accompanying Consolidated Statements of Comprehensive Income, net of tax. Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks, federal funds sold and interest-bearing bank deposits. Generally, federal funds are sold for one-day periods. Derivatives and Hedging Activities First Commonwealth accounts for derivative instruments and hedging activities in accordance with FASB ASC Topic 815, “Derivatives and Hedging.” All derivatives are evaluated at inception as to whether or not they are hedging or non-hedging activities, and appropriate documentation is maintained to support the final determination. First Commonwealth recognizes all derivatives as either assets or liabilities on the Consolidated Statements of Financial Condition and measures those instruments at fair value. For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in OCI. When the cash flows associated with the hedged item are realized, the gain or loss included in OCI is recognized in the Consolidated Statement of Income. When First Commonwealth purchases a portion of a commercial loan that has an existing interest rate swap, it enters a Risk Participation Agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to First Commonwealth as a result of the risk participation agreement is offset by credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties. Management periodically reviews contracts from various functional areas of First Commonwealth to identify potential derivatives embedded within selected contracts. As of December 31, 2016 , First Commonwealth has interest derivative positions that are not designated as hedging instruments. See Note 7, “Derivatives,” for a description of these instruments. Earnings Per Common Share Basic earnings per share excludes dilution and is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity. For all periods presented, the dilutive effect on average shares outstanding is the result of compensatory stock options outstanding and unvested restricted stock grants. Fair Value Measurements In accordance with FASB ASC Topic 820, “Fair Value Measurements and Disclosures,” First Commonwealth groups financial assets and financial liabilities measured at fair value into three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: • Level 1—Valuations for assets and liabilities traded in active exchange markets, such as the New York Stock Exchange. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities. • Level 2—Valuations for assets and liabilities traded in less active dealer or broker markets. Valuations are obtained for identical or comparable assets or liabilities from alternative pricing sources with reasonable levels of price transparency. Level 2 securities include U.S. Government securities issued by Agencies and Sponsored Enterprises, Obligations of States and Political Subdivisions, certain corporate securities, FHLB stock, loans held for sale, interest rate derivatives that include interest rate swaps, risk participation agreements and foreign currency contracts, certain other real estate owned and certain impaired loans. • Level 3—Valuations for assets and liabilities that are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and not based on market exchange, dealer or broker traded transactions. If the inputs used to provide the evaluation are unobservable and/or there is very little, if any, market activity for the security or similar securities, the securities would be considered Level 3 securities. Level 3 valuations incorporate certain assumptions and projections in determining the fair value assigned to such assets or liabilities. The assets included in Level 3 are pooled trust preferred collateralized debt obligations, nonmarketable equity investments, certain other real estate owned and certain impaired loans. In general, fair values of financial instruments are based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon pricing models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and our creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. See Note 18 “Fair Values of Assets and Liabilities” for additional information.

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers (Topic 606) ” . In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers (Topic 606)", with an original effective date for annual reporting periods beginning after December 15, 2016. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2015-14 deferred the effective date of ASU 2014-09 to annual periods and interim periods within those annual periods beginning after December 15, 2017. We are currently evaluating the potential impact of ASU 2015-14 on our financial statements. In January 2016, the FASB issued ASU 2016-1, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments, (vi) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and (viii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. ASU 2016-1 will be effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, and is not expected to have a significant impact on our financial statements In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)," requiring the recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. Lessor accounting under the new guidance remains largely unchanged as it is substantially equivalent to existing guidance for sales-type leases, direct financing leases, and operating leases. Leveraged leases have been eliminated, although lessors can continue to account for existing leveraged leases using the current accounting guidance. All entities will classify leases to determine how to recognize lease-related revenue and expense. Quantitative and qualitative disclosures will be required by lessees and lessors to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. All entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. We are currently evaluating the potential impact of ASU 2016-02 on our financial statements. In March 2016, FASB issued ASU No. 2016-05, "Derivatives and Hedging (Topic 815)," which clarifies that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under Topic 815 does not, in and of itself, require de-designation of that hedging relationship provided that all other hedge accounting criteria continue to be met. This ASU is effective for public entities beginning after December 15, 2016, and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on First Commonwealth’s financial condition or results of operations. In March 2016, FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718) - Improvements to Employee Share-Based Payment Accounting.” This update requires all income tax effects of awards to be recognized in the income statement when the awards vest or are settled. It also allows an employer to repurchase more of an employee’s shares than it can today for tax withholding purposes without triggering liability accounting and to make a policy election for forfeitures as they occur. The guidance is effective for public business entities for fiscal years beginning after December 15, 2016, and interim periods within those years. The adoption of this ASU is not expected to have a material impact on First Commonwealth’s financial condition or results of operations. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments,” which amends the guidance for recognizing credit losses from an “incurred loss” methodology that delays recognition of credit losses until it is probable a loss has been incurred to an expected credit loss methodology. The guidance requires the use of the modified retrospective transition method by means of a cumulative-effect adjustment to equity as of the beginning of the period in which the guidance is adopted. The standard is effective for the Company as of January 1, 2020. Management is currently evaluating the impact of the amended guidance on First Commonwealth’s financial condition or results of operations. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230),” which provides guidance on eight specific cash flow issues: 1. debt prepayment or extinguishment costs; 2. settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates; 3. contingent consideration payments made after a business combination; 4. proceeds from the settlement of insurance claims; 5. proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; 6. distributions received from equity method investees; 7. beneficial interests in securitizations transactions; and 8. separately identifiable cash flows and application of the predominance principle. This ASU provides additional guidance for these eight issues, reducing current and potential diversity in practice. This standard is effective for the Company as of January 1, 2018. Management is currently evaluating the impact of the amended guidance on First Commonwealth’s financial condition or results of operations.

Supplemental Comprehensive Inco

Supplemental Comprehensive Income Disclosures	12 Months Ended
	Dec. 31, 2016
Supplemental Comprehensive Income Disclosures [Abstract]
Supplemental Comprehensive Income Disclosures	Supplemental Comprehensive Income Disclosures The following table identifies the related tax effects allocated to each component of other comprehensive income in the Consolidated Statements of Comprehensive Income as of December 31 . Reclassification adjustments related to securities available for sale are included in the “ Net securities gains (losses) ” line in the Consolidated Statements of Income and reclassification adjustments related to losses on derivatives are included in the "Other operating expenses" line in the Consolidated Statements of Income. 2016 2015 2014 Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount (dollars in thousands) Unrealized gains (losses) on securities: Unrealized holding (losses) gains on securities arising during the period $ (6,304 ) $ 2,206 $ (4,098 ) $ 2,798 $ (978 ) $ 1,820 $ 25,153 $ (8,803 ) $ 16,350 Reclassification adjustment for (gains) losses on securities included in net income (617 ) 216 (401 ) 153 (54 ) 99 (550 ) 193 (357 ) Total unrealized (losses) gains on securities (6,921 ) 2,422 (4,499 ) 2,951 (1,032 ) 1,919 24,603 (8,610 ) 15,993 Unrealized gains (losses) on derivatives: Unrealized holding (losses) gains on derivatives arising during the period (479 ) 168 (311 ) 450 (158 ) 292 472 (165 ) 307 Reclassification adjustment for gains on derivatives included in net income (70 ) 24 (46 ) (49 ) 17 (32 ) (10 ) 3 (7 ) Total unrealized (losses) gains on derivatives (549 ) 192 (357 ) 401 (141 ) 260 462 (162 ) 300 Unrealized gains (losses) for postretirement obligations: Transition obligation — — — — — — — — — Net gain (loss) 331 (116 ) 215 (102 ) 36 (66 ) (313 ) 109 (204 ) Total unrealized gains (losses) for postretirement obligations 331 (116 ) 215 (102 ) 36 (66 ) (313 ) 109 (204 ) Total other comprehensive (loss) income $ (7,139 ) $ 2,498 $ (4,641 ) $ 3,250 $ (1,137 ) $ 2,113 $ 24,752 $ (8,663 ) $ 16,089 The following table details the change in components of OCI for the year-ended December 31: 2016 Securities Available for Sale Derivatives Post-Retirement Obligation Accumulated Other Comprehensive Income (dollars in thousands) Balance at January 1 $ (2,956 ) $ 560 $ 10 $ (2,386 ) Other comprehensive loss before reclassification adjustment (4,098 ) (311 ) (4,409 ) Amounts reclassified from accumulated other comprehensive income (loss) (401 ) (46 ) (447 ) Net gain 215 215 Net other comprehensive loss during the period (4,499 ) (357 ) 215 (4,641 ) Balance at December 31 $ (7,455 ) $ 203 $ 225 $ (7,027 ) 2015 Securities Available for Sale Derivatives Post-Retirement Obligation Accumulated Other Comprehensive Income (dollars in thousands) Balance at January 1 $ (4,875 ) $ 300 $ 76 $ (4,499 ) Other comprehensive income before reclassification adjustment 1,820 292 2,112 Amounts reclassified from accumulated other comprehensive income (loss) 99 (32 ) 67 Net gain (66 ) (66 ) Net other comprehensive income during the period 1,919 260 (66 ) 2,113 Balance at December 31 $ (2,956 ) $ 560 $ 10 $ (2,386 ) 2014 Securities Available for Sale Derivatives Post-Retirement Obligation Accumulated Other Comprehensive Income (dollars in thousands) Balance at January 1 $ (20,868 ) $ — $ 280 $ (20,588 ) Other comprehensive income before reclassification adjustment 16,350 307 16,657 Amounts reclassified from accumulated other comprehensive income (loss) (357 ) (7 ) (364 ) Net gain (204 ) (204 ) Net other comprehensive income during the period 15,993 300 (204 ) 16,089 Balance at December 31 $ (4,875 ) $ 300 $ 76 $ (4,499 )

Supplemental Cash Flow Disclosu

Supplemental Cash Flow Disclosures	12 Months Ended
	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Disclosures	Supplemental Cash Flow Disclosures The following table presents information related to cash paid during the year for interest and income taxes as well as detail on non-cash investing and financing activities for the years ended December 31 : 2016 2015 2014 (dollars in thousands) Cash paid during the period for: Interest $ 19,208 $ 15,818 $ 18,943 Income taxes 19,950 8,331 10,700 Non-cash investing and financing activities: Loans transferred to other real estate owned and repossessed assets 4,824 8,257 5,061 Fair value of loans transferred from held to maturity to available for sale 18,758 3,196 3,035 Gross (decrease) increase in market value adjustment to securities available for sale (6,919 ) 2,949 24,601 Gross (decrease) increase in market value adjustment to securities derivatives (549 ) 401 472 Investments redeemed, not settled 3,769 — — Investments committed to purchase, not settled — 694 — Net (liabilities) assets acquired through acquisition (501,516 ) 463 — Proceeds from death benefit on bank-owned life insurance not received 437 — — Contribution of premises — — 682

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The following table summarizes the composition of the weighted-average common shares (denominator) used in the basic and diluted earnings per share computation for the years ending December 31 : 2016 2015 2014 Weighted average common shares issued 105,563,455 105,563,455 105,563,455 Average treasury shares (16,605,461 ) (16,045,900 ) (12,294,217 ) Average unearned nonvested shares (106,421 ) (160,788 ) (154,584 ) Weighted average common shares and common stock equivalents used to calculate basic earnings per share 88,851,573 89,356,767 93,114,654 Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share — — — Weighted average common shares and common stock equivalents used to calculate diluted earnings per share 88,851,573 89,356,767 93,114,654 The following table shows the number of shares and the price per share related to common stock equivalents that were not included in the computation of diluted earnings per share for the years ended December 31 , because to do so would have been anti-dilutive. 12/31/2016 12/31/2015 12/31/2014 Price Range Price Range Price Range Shares From To Shares From To Shares From To Stock Options — $ — $ — — $ — $ — 15,000 $ 14.55 $ 14.55 Restricted Stock 67,920 8.38 13.96 92,002 6.82 9.84 106,977 5.26 9.26

Cash and Due from Banks

Cash and Due from Banks	12 Months Ended
	Dec. 31, 2016
Cash and Due from Banks [Abstract]
Cash and Due from Banks	Cash and Due from Banks Regulations of the Board of Governors of the Federal Reserve System impose uniform reserve requirements on all depository institutions with transaction accounts, such as checking accounts and NOW accounts. Reserves are maintained in the form of vault cash or balances held with the Federal Reserve Bank. First Commonwealth Bank maintained average balances of $5.1 million during 2016 and $4.6 million during 2015 with the Federal Reserve Bank.

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives Derivatives Not Designated as Hedging Instruments First Commonwealth is a party to interest rate derivatives that are not designated as hedging instruments. These derivatives relate to interest rate swaps that First Commonwealth enters into with customers to allow customers to convert variable rate loans to a fixed rate. First Commonwealth pays interest to the customer at a floating rate on the notional amount and receives interest from the customer at a fixed rate for the same notional amount. At the same time the interest rate swap is entered into with the customer, an offsetting interest rate swap is entered into with another financial institution. First Commonwealth pays the other financial institution interest at the same fixed rate on the same notional amount as the swap entered into with the customer, and receives interest from the financial institution for the same floating rate on the same notional amount. The changes in the fair value of the swaps offset each other, except for the credit risk of the counterparties, which is determined by taking into consideration the risk rating, probability of default and loss given default for all counterparties. We have twenty-six risk participation agreements with financial institution counterparties for interest rate swaps related to loans in which we are a participant. The risk participation agreements provide credit protection to the financial institution should the borrower fail to perform on its interest rate derivative contract with the financial institution. We have eight risk participation agreements with financial institution counterparties for interest rate swaps related to loans in which we are the lead bank. The risk participation agreement provides credit protection to us should the borrower fail to perform on its interest rate derivative contract with us. First Commonwealth is also party to interest rate caps that are not designated as hedging instruments. These derivatives relate to contracts that First Commonwealth enters into with loan customers providing a maximum interest rate on their variable rate loan. At the same time the interest rate cap is entered into with the customer, First Commonwealth enters into an offsetting interest rate cap with another financial institution. The notional amount and maximum interest rate on both interest cap contracts are identical. The fee received, less the estimate of the loss for the credit exposure, was recognized in earnings at the time of the transaction. Derivatives Designated as Hedging Instruments The Company has entered into four interest rate swap contracts which were designated as cash flow hedges. The interest rate swaps have a total notional amount of $200.0 million , $85.0 million with an original maturity of three years and $115.0 million with an original maturity of four years . The Company's risk management objective for these hedges is to reduce its exposure to variability in expected future cash flows related to interest payments on commercial loans benchmarked to the 1-month LIBOR rate. Therefore, the interest rate swaps convert the interest payments on the first $200.0 million of 1-month LIBOR based commercial loans into fixed rate payments. The periodic net settlement of interest rate swaps is recorded as an adjustment to "Interest and fees on loans" in the Consolidated Statement of Income. For the years ended December 31, 2016 and 2015 , interest income was increased by $1.6 million and $2.0 million , respectively, as a result of these interest rate swaps. Changes in the fair value of the effective portion of cash flow hedges are reported in OCI. When the cash flows associated with the hedged item are realized, the gain or loss included in OCI is recognized in Interest and fees on loans, the same line item in the Consolidated Statement of Income as the income on the hedged items. The cash flow hedges were highly effective at December 31, 2016 , 2015 and 2014.and changes in the fair value attributed to hedge ineffectiveness were not material. The following table depicts the credit value adjustment recorded related to the notional amount of derivatives outstanding as well as the notional amount of risk participation agreements participated to other banks at December 31 : 2016 2015 (dollars in thousands) Derivatives not Designated as Hedging Instruments Credit value adjustment $ (317 ) $ (542 ) Notional Amount: Interest rate derivatives 345,102 276,860 Interest rate caps 14,762 22,793 Risk participation agreements 174,213 126,612 Sold credit protection on risk participation agreements (40,281 ) (20,383 ) Derivatives Designated as Hedging Instruments Fair value adjustment (443 ) 922 Notional Amount - Interest rate derivatives 200,000 200,000 The table below presents the amount representing the change in the fair value of derivative assets and derivative liabilities attributable to credit risk included in “Other income” on the Consolidated Statements of Income for the years ended December 31 : 2016 2015 2014 (dollars in thousands) Non-hedging interest rate derivatives: Increase (decrease) in other income $ 219 $ (274 ) $ (345 ) Hedging interest rate derivatives: Increase in interest income 1,627 2,049 330 Increase in other income 70 64 10 The fair value of our derivatives is included in a table in Note 18, “Fair Values of Assets and Liabilities,” in the line items “Other assets” and “Other liabilities.”

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities Securities Available for Sale Below is an analysis of the amortized cost and fair values of securities available for sale at December 31 : 2016 2015 Amortized Gross Gross Estimated Amortized Gross Gross Estimated (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 15,143 $ 1,481 $ (7 ) $ 16,617 $ 20,034 $ 2,071 $ (13 ) $ 22,092 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 683,601 4,557 (11,305 ) 676,853 778,476 7,983 (8,882 ) 777,577 Mortgage-Backed Securities – Commercial 1 — — 1 28 — — 28 Other Government-Sponsored Enterprises 16,700 — (69 ) 16,631 19,201 2 (85 ) 19,118 Obligations of States and Political Subdivisions 27,075 195 (41 ) 27,229 27,066 532 — 27,598 Corporate Securities 5,903 416 — 6,319 1,897 422 — 2,319 Pooled Trust Preferred Collateralized Debt Obligations 39,989 427 (7,124 ) 33,292 42,239 916 (7,497 ) 35,658 Total Debt Securities 788,412 7,076 (18,546 ) 776,942 888,941 11,926 (16,477 ) 884,390 Equities 1,670 — — 1,670 2,170 — — 2,170 Total Securities Available for Sale $ 790,082 $ 7,076 $ (18,546 ) $ 778,612 $ 891,111 $ 11,926 $ (16,477 ) $ 886,560 Mortgage backed securities include mortgage backed obligations of U.S. Government agencies and obligations of U.S. Government-sponsored enterprises. These obligations have contractual maturities ranging from less than one year to approximately 30 years with lower anticipated lives to maturity due to prepayments. All mortgage backed securities contain a certain amount of risk related to the uncertainty of prepayments of the underlying mortgages. Interest rate changes have a direct impact upon prepayment speeds; therefore, First Commonwealth uses computer simulation models to test the average life and yield volatility of all mortgage backed securities under various interest rate scenarios to monitor the potential impact on earnings and interest rate risk positions. Expected maturities will differ from contractual maturities because issuers may have the right to call or repay obligations with or without call or prepayment penalties. Other fixed income securities within the portfolio also contain prepayment risk. During 2016, a gain of $0.6 million was recognized due to the early redemption of a pooled trust preferred security with a book value of $3.1 million. This security was redeemed due to an election by the senior note holders to liquidate the trust. In 2015, a $0.3 million loss was recognized on the sale of approximately $75.0 million of low-yielding U.S. government agency securities. Proceeds from the sale of these securities were reinvested into higher yielding mortgage-backed securities. The amortized cost and estimated fair value of debt securities available for sale at December 31, 2016 , by contractual maturity, are shown below: Amortized Estimated (dollars in thousands) Due within 1 year $ 3,300 $ 3,292 Due after 1 but within 5 years 17,397 17,343 Due after 5 but within 10 years 27,075 27,229 Due after 10 years 41,895 35,607 89,667 83,471 Mortgage-Backed Securities (a) 698,745 693,471 Total Debt Securities $ 788,412 $ 776,942 (a) Mortgage Backed Securities include an amortized cost of $15.1 million and a fair value of $16.6 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $683.6 million and a fair value of $676.9 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac. Proceeds from sales, gross gains (losses) realized on sales, maturities and other-than-temporary impairment charges related to securities available for sale were as follows for the years ended December 31 : 2016 2015 2014 (dollars in thousands) Proceeds from sales $ 55,744 $ 88,054 $ 132,868 Gross (losses) gains realized: Sales Transactions: Gross gains $ 305 $ — $ 291 Gross losses (277 ) (284 ) (243 ) 28 (284 ) 48 Maturities and impairment Gross gains 589 131 502 Gross losses — — — Other-than-temporary impairment — — — 589 131 502 Net gains and impairment $ 617 $ (153 ) $ 550 Securities available for sale with an approximate fair value of $445.8 million and $416.1 million were pledged as of December 31, 2016 and 2015 , respectively, to secure public deposits and for other purposes required or permitted by law. Securities Held to Maturity Below is an analysis of the amortized cost and fair values of debt securities held to maturity at December 31:. 2016 2015 Amortized Gross Gross Estimated Amortized Gross Gross Estimated (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 4,297 $ — $ (4 ) $ 4,293 $ 4,775 $ — $ (7 ) $ 4,768 Mortgage-Backed Securities – Commercial 34,444 — (561 ) 33,883 16,843 — (247 ) 16,596 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 280,430 5 (2,527 ) 277,908 315,609 30 (1,824 ) 313,815 Mortgage-Backed Securities – Commercial 14,675 — (142 ) 14,533 15,187 — (178 ) 15,009 Obligations of States and Political Subdivisions 38,667 55 (721 ) 38,001 31,910 301 (58 ) 32,153 Total Securities Held to Maturity $ 372,513 $ 60 $ (3,955 ) $ 368,618 $ 384,324 $ 331 $ (2,314 ) $ 382,341 The amortized cost and estimated fair value of debt securities held to maturity at December 31, 2016 , by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Amortized Estimated (dollars in thousands) Due within 1 year $ — $ — Due after 1 but within 5 years 2,636 2,615 Due after 5 but within 10 years 31,893 31,384 Due after 10 years 4,138 4,002 38,667 38,001 Mortgage-Backed Securities (a) 333,846 330,617 Total Debt Securities $ 372,513 $ 368,618 (a) Mortgage Backed Securities include an amortized cost of $38.7 million and a fair value of $38.2 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $295.1 million and a fair value of $292.4 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac. Securities held to maturity with an amortized cost of $119.2 million and $45.7 million were pledged as of December 31, 2016 and 2015 , respectively, to secure public deposits for other purposes required or permitted by law.

Impairment of Investment Securi

Impairment of Investment Securities	12 Months Ended
	Dec. 31, 2016
Impairment of Investment Securities Disclosure [Abstract]
Impairment of Investment Securities	Impairment of Investment Securities Securities Available for Sale As required by FASB ASC Topic 320, “Investments—Debt and Equity Securities,” credit related other-than-temporary impairment on debt securities is recognized in earnings while non-credit related other-than-temporary impairment on debt securities not expected to be sold is recognized in other comprehensive income (“OCI”). During the years ended December 31, 2016 , 2015 and 2014 , no other-than-temporary impairment charges were recognized. First Commonwealth utilizes the specific identification method to determine the net gain or loss on debt securities and the average cost method to determine the net gain or loss on equity securities. We review our investment portfolio on a quarterly basis for indications of impairment. This review includes analyzing the length of time and the extent to which the fair value has been lower than the cost, the financial condition and near-term prospects of the issuer, including any specific events which may influence the operations of the issuer and whether we are more likely than not to sell the security. We evaluate whether we are more likely than not to sell debt securities based upon our investment strategy for the particular type of security and our cash flow needs, liquidity position, capital adequacy, tax position and interest rate risk position. In addition, the risk of future other-than-temporary impairment may be influenced by additional bank failures, weakness in the U.S. economy, changes in real estate values and additional interest deferrals in our pooled trust preferred collateralized debt obligations. Our pooled trust preferred collateralized debt obligations are beneficial interests in securitized financial assets within the scope of FASB ASC Topic 325, “Investments—Other,” and are therefore evaluated for other-than-temporary impairment using management’s best estimate of future cash flows. If these estimated cash flows determine it is probable that an adverse change in cash flows has occurred, then other-than-temporary impairment would be recognized in accordance with FASB ASC Topic 320. There is a risk that First Commonwealth will record other-than-temporary impairment charges in the future. See Note 18, “Fair Values of Assets and Liabilities,” for additional information. The following table presents the gross unrealized losses and estimated fair values at December 31, 2016 for both available for sale and held to maturity securities by investment category and time frame for which the securities have been in a continuous unrealized loss position: Less Than 12 Months 12 Months or More Total Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 4,898 $ (11 ) $ — $ — $ 4,898 $ (11 ) Mortgage-Backed Securities – Commercial 33,883 (561 ) — — 33,883 (561 ) Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 670,708 (11,630 ) 56,200 (2,202 ) 726,908 (13,832 ) Mortgage-Backed Securities – Commercial 14,534 (142 ) — — 14,534 (142 ) Other Government-Sponsored Enterprises 16,632 (69 ) — — 16,632 (69 ) Obligations of States and Political Subdivisions 33,277 (762 ) — — 33,277 (762 ) Pooled Trust Preferred Collateralized Debt Obligations — — 28,952 (7,124 ) 28,952 (7,124 ) Total Securities $ 773,932 $ (13,175 ) $ 85,152 $ (9,326 ) $ 859,084 $ (22,501 ) At December 31, 2016 , pooled trust preferred collateralized debt obligations accounted for 32% of unrealized losses due to changes in interest rates and the illiquid market for this type of investment. Fixed income securities issued by U.S. Government-sponsored enterprises comprised 62% of total unrealized losses due to changes in market interest rates. Government agencies and obligations of state and political subdivisions each account for 3% of total unrealized losses as a result of changes in market interest rates. At December 31, 2016 , there were 122 debt securities in an unrealized loss position. There were no equity securities in an unrealized loss position at December 31, 2016 . The following table presents the gross unrealized losses and estimated fair value at December 31, 2015 for both available for sale and held to maturity securities by investment category and time frame for which the securities had been in a continuous unrealized loss position: Less Than 12 Months 12 Months or More Total Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 6,798 $ (20 ) $ — $ — $ 6,798 $ (20 ) Mortgage-Backed Securities – Commercial 16,596 (247 ) — — 16,596 (247 ) Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 436,011 (3,293 ) 263,119 (7,413 ) 699,130 (10,706 ) Mortgage-Backed Securities – Commercial 15,009 (178 ) — — 15,009 (178 ) Other Government-Sponsored Enterprises 12,316 (85 ) — — 12,316 (85 ) Obligations of States and Political Subdivisions 7,208 (58 ) — — 7,208 (58 ) Pooled Trust Preferred Collateralized Debt Obligations — — 29,957 (7,497 ) 29,957 (7,497 ) Total Securities $ 493,938 $ (3,881 ) $ 293,076 $ (14,910 ) $ 787,014 $ (18,791 ) As of December 31, 2016 , our corporate securities had an amortized cost and estimated fair value of $5.9 million and $6.3 million , respectively, and were comprised of debt for large regional banks. At December 31, 2015 , these securities had an amortized cost of $1.9 million and estimated fair value of $2.3 million . There were no corporate securities in an unrealized loss position as of December 31, 2016 and 2015 . When unrealized losses exist, management reviews each of the issuer’s asset quality, earnings trend and capital position, to determine whether issues in an unrealized loss position were other-than-temporarily impaired. All interest payments on the corporate securities are being made as contractually required. As of December 31, 2016 , the book value of our pooled trust preferred collateralized debt obligations totaled $40.0 million with an estimated fair value of $33.3 million , which includes securities comprised of 259 banks and other financial institutions. All of our pooled securities are mezzanine tranches, two of which have no senior class remaining in the issue. The credit ratings on all of the issues are below investment grade. At the time of initial issue, the subordinated tranches ranged in size from approximately 7% to 35% of the total principal amount of the respective securities and no more than 5% of any pooled security consisted of a security issued by any one institution. As of December 31, 2016 , after taking into account management’s best estimates of future interest deferrals and defaults, two of our securities had no excess subordination in the tranches we own and six of our securities had excess subordination which ranged from 2% to 80% of the current performing collateral. The following table provides additional information related to our pooled trust preferred collateralized debt obligations as of December 31, 2016 : Deal Class Book Estimated Fair Unrealized Moody’s/ Number Deferrals Excess (dollars in thousands) Pre TSL IV Mezzanine $ 1,830 $ 1,360 $ (470 ) B1/BB 6 18.05 % 59.78 % Pre TSL VIII Mezzanine 1,963 2,053 90 C/C 28 44.37 0.00 Pre TSL IX Mezzanine 2,412 1,952 (460 ) B1/C 37 27.83 12.79 Pre TSL X Mezzanine 1,738 1,986 248 Caa1/C 42 31.58 2.17 Pre TSL XII Mezzanine 5,890 4,817 (1,073 ) B3/C 64 24.54 0.00 Pre TSL XIII Mezzanine 12,949 10,900 (2,049 ) Ba3/C 54 11.21 55.77 Pre TSL XIV Mezzanine 12,995 9,923 (3,072 ) B1/CC 52 12.78 31.90 MMCap I Mezzanine 212 301 89 Ca/C 8 58.11 80.31 Total $ 39,989 $ 33,292 $ (6,697 ) Lack of liquidity in the market for trust preferred collateralized debt obligations, below investment grade credit rating and market uncertainties related to the financial industry are factors contributing to the impairment on these securities. In October 2016, the Company received notice that the Senior note holders of Pre TSL VII elected to liquidate all assets of the trust. The sale of the assets occurred in the fourth quarter of 2016 and the redemption was completed in the first quarter of 2017. A gain of $0.6 million related to this liquidation was recognized in 2016 and an additional gain of $0.7 million will be recorded in the first quarter of 2017. All of the Company's pooled trust preferred securities are included in the non-exclusive list issued by the regulatory agencies and therefore are not considered covered funds under the Volcker Rule. On a quarterly basis we evaluate our debt securities for other-than-temporary impairment. For the years ended December 31, 2016 , 2015 and 2014 there were no credit related other-than-temporary impairment charges recognized on our pooled trust preferred collateralized debt obligations. When evaluating these investments we determine a credit related portion and a non-credit related portion of other-than-temporary impairment. The credit related portion is recognized in earnings and represents the difference between book value and the present value of future cash flows. The non-credit related portion is recognized in OCI and represents the difference between the fair value of the security and the amount of credit related impairment. A discounted cash flow analysis provides the best estimate of credit related other-than-temporary impairment for these securities. Additional information related to the discounted cash flow analysis follows: Our pooled trust preferred collateralized debt obligations are measured for other-than-temporary impairment within the scope of FASB ASC Topic 325 by determining whether it is probable that an adverse change in estimated cash flows has occurred. Determining whether there has been an adverse change in estimated cash flows from the cash flows previously projected involves comparing the present value of remaining cash flows previously projected against the present value of the cash flows estimated at December 31, 2016 . We consider the discounted cash flow analysis to be our primary evidence when determining whether credit related other-than-temporary impairment exists. Results of a discounted cash flow test are significantly affected by other variables such as the estimate of future cash flows, credit worthiness of the underlying banks and determination of probability of default of the underlying collateral. The following provides additional information for each of these variables: • Estimate of Future Cash Flows—Cash flows are constructed in an INTEX cash flow model which includes each deal’s structural features. Projected cash flows include prepayment assumptions, which are dependent on the issuer's asset size and coupon rate. For collateral issued by financial institutions over $15 billion in asset size with a coupon over 7% , a 100% prepayment rate is assumed. Financial institutions over $15 billion with a coupon of 7% or under are assigned a prepayment rate of 40% for two years and 2% thereafter. Financial institutions with assets between $2 billion and $15 billion with coupons over 7% are assigned a 5% prepayment rate. For financial institutions below $2 billion , if the coupon is over 10% , a prepayment rate of 5% is assumed and for all other issuers, there is no prepayment assumption incorporated into the cash flows. The modeled cash flows are then used to estimate if all the scheduled principal and interest payments of our investments will be returned. • Credit Analysis—A quarterly credit evaluation is performed for each of the 259 banks comprising the collateral across the various pooled trust preferred securities. Our credit evaluation considers all evidence available to us and includes the nature of the issuer’s business, its years of operating history, corporate structure, loan composition, loan concentrations, deposit mix, asset growth rates, geographic footprint and local economic environment. Our analysis focuses on profitability, return on assets, shareholders’ equity, net interest margin, credit quality ratios, operating efficiency, capital adequacy and liquidity. • Probability of Default—A probability of default is determined for each bank and is used to calculate the expected impact of future deferrals and defaults on our expected cash flows. Each bank in the collateral pool is assigned a probability of default for each year until maturity. Currently, any bank that is in default is assigned a 100% probability of default and a 0% projected recovery rate. All other banks in the pool are assigned a probability of default based on their unique credit characteristics and market indicators with a 10% projected recovery rate. For the majority of banks currently in deferral we assume the bank continues to defer and will eventually default and therefore a 100% probability of default is assigned. However, for some deferring collateral there is the possibility that they become current on interest or principal payments at some point in the future and in those cases a probability that the deferral will ultimately cure is assigned. The probability of default is updated quarterly. As of December 31, 2016 , default probabilities for performing collateral ranged from 0.33% to 75% . Our credit evaluation provides a basis for determining deferral and default probabilities for each underlying piece of collateral. Using the results of the credit evaluation, the next step of the process is to look at pricing of senior debt or credit default swaps for the issuer (or where such information is unavailable, for companies having similar credit profiles as the issuer). The pricing of these market indicators provides the information necessary to determine appropriate default probabilities for each bank. In addition to the above factors, our evaluation of impairment also includes a stress test analysis which provides an estimate of excess subordination for each tranche. We stress the cash flows of each pool by increasing current default assumptions to the level of defaults which results in an adverse change in estimated cash flows. This stressed breakpoint is then used to calculate excess subordination levels for each pooled trust preferred security. The results of the stress test allows management to identify those pools that are at a greater risk for a future break in cash flows so that we can monitor banks in those pools more closely for potential deterioration of credit quality. Our cash flow analysis as of December 31, 2016 , indicates that no credit related other-than-temporary impairment has occurred on our pooled trust preferred securities during the year ended December 31, 2016 . Based upon the analysis performed by management, it is probable that two of our pooled trust preferred securities are expected to experience contractual principal and interest shortfalls and therefore appropriate other-than-temporary impairment charges were recorded in prior periods. These securities are identified in the table on page 69 with 0% “Excess Subordination as a % of Current Performing Collateral.” For the remaining securities in the table, our analysis as of December 31, 2016 indicates that it is probable that we will collect all contractual principal and interest payments. For five of those securities, PreTSL IX, PreTSL X, PreTSL XIII, PreTSL XIV and MMCap I, other-than-temporary impairment charges were recorded in prior periods; however, due to improvement in the expected cash flows of these securities, it is now probable that all contractual payments will be received. During 2008, 2009 and 2010, other-than-temporary impairment charges were recognized on all of our pooled trust preferred securities, except for PreTSL IV. Our cash flow analysis as of December 31, 2016 , for all of these impaired securities indicates that it is now probable we will collect principal and interest in excess of what was estimated at the time other-than-temporary impairment charges were recorded. This change can be attributed to improvement in the underlying collateral for these securities and has resulted in the present value of estimated future principal and interest payments exceeding the securities' current book value. The excess for each bond of the present value of future cash flows over our current book value ranges from 19% to 119% and will be recognized as an adjustment to yield over the remaining life of these securities. The excess subordination recognized as an adjustment to yield is reflected in the following table as increases in cash flows expected to be collected. The table below provides a cumulative roll forward of credit losses recognized in earnings for debt securities held and not intended to be sold for the years ended December 31: 2016 2015 2014 (dollars in thousands) Balance, beginning (a) $ 24,851 $ 26,246 $ 27,543 Credit losses on debt securities for which other-than-temporary impairment was not previously recognized — — — Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized — — — Increases in cash flows expected to be collected, recognized over the remaining life of the security (b) (1,124 ) (1,177 ) (1,297 ) Reduction for debt securities called during the period (6,671 ) (218 ) — Balance, ending $ 17,056 $ 24,851 $ 26,246 (a) The beginning balance represents credit related losses included in other-than-temporary impairment charges recognized on debt securities in prior periods. (b) Represents the increase in cash flows recognized either as principal payments or interest income during the period. For the years ended December 31, 2016 , 2015 and 2014 , there was no impairment recognized on equity securities. On a quarterly basis, management evaluates equity securities for other-than-temporary impairment. As part of this evaluation we review the severity and duration of decline in estimated fair value, research reports, analysts’ recommendations, credit rating changes, news stories, annual reports, regulatory filings, impact of interest rate changes and other relevant information. There were no equity securities in an unrealized loss position as of December 31, 2016 and 2015 . In the table above, the $6.7 million reduction in cumulative credit losses in 2016 related to debt securities being called as a result of the early redemption of PreTSL VII. The senior note holders of this bond elected to liquidate all assets of the trust. Our book value before redemption was $3.1 million and at the time of redemption a gain of $0.6 million was recognized. Other Investments As a member of the FHLB, First Commonwealth is required to purchase and hold stock in the FHLB to satisfy membership and borrowing requirements. The level of stock required to be held is dependent on the amount of First Commonwealth's mortgage related assets and outstanding borrowings with the FHLB. This stock is restricted in that it can only be sold to the FHLB or to another member institution, and all sales of FHLB stock must be at par. As a result of these restrictions, FHLB stock is unlike other investment securities insofar as there is no trading market for FHLB stock and the transfer price is determined by FHLB membership rules and not by market participants. As of December 31, 2016 and 2015 , our FHLB stock totaled $36.5 million and $63.0 million , respectively and is included in “Other investments” on the Consolidated Statements of Financial Condition. FHLB stock is held as a long-term investment and its value is determined based on the ultimate recoverability of the par value. First Commonwealth evaluates impairment quarterly and has concluded that the par value of its investment in FHLB stock will be recovered. Accordingly, no impairment charge was recorded on these securities for the year ended December 31, 2016 .

Loans and Allowance for Credit

Loans and Allowance for Credit Losses	12 Months Ended
	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Abstract]
Loans and Allowance for Credit Losses	Loans and Allowance for Credit Losses The following table provides outstanding balances related to each of our loan types as of December 31 : 2016 2015 Originated Loans Acquired Loans Total Loans Total Loans (dollars in thousands) Commercial, financial, agricultural and other $ 1,131,148 $ 8,399 $ 1,139,547 $ 1,150,906 Real estate construction 217,840 1,781 219,621 220,736 Residential real estate 1,165,851 63,341 1,229,192 1,224,465 Commercial real estate 1,717,043 25,167 1,742,210 1,479,000 Loans to individuals 546,589 2,188 548,777 608,643 Total loans $ 4,778,471 $ 100,876 $ 4,879,347 $ 4,683,750 Credit Quality Information As part of the on-going monitoring of credit quality within the loan portfolio, the following credit worthiness categories are used in grading our loans: Pass Acceptable levels of risk exist in the relationship. Includes all loans not classified as OAEM, substandard or doubtful. Other Assets Especially Mentioned (OAEM) Potential weaknesses that deserve management’s close attention. The potential weaknesses may result in deterioration of the repayment prospects or weaken the Bank’s credit position at some future date. The credit risk may be relatively minor, yet constitute an undesirable risk in light of the circumstances surrounding the specific credit. No loss of principal or interest is expected. Substandard Well-defined weakness or a weakness that jeopardizes the repayment of the debt. A loan may be classified as substandard as a result of deterioration of the borrower’s financial condition and repayment capacity. Loans for which repayment plans have not been met or collateral equity margins do not protect the Company may also be classified as substandard. Doubtful Loans with the characteristics of substandard loans with the added characteristic that collection or liquidation in full, on the basis of presently existing facts and conditions, is highly improbable. The use of creditworthiness categories to grade loans permits management’s use of migration analysis to estimate a portion of credit risk. The Company’s internal creditworthiness grading system provides a measurement of credit risk based primarily on an evaluation of the borrower’s cash flow and collateral. Movements between these rating categories provide a predictive measure of credit losses and therefore assists in determining the appropriate level for the loan loss reserves. Category ratings are reviewed each quarter, at which time management analyzes the results, as well as other external statistics and factors related to loan performance. Loans that migrate towards higher risk rating levels generally have an increased risk of default, whereas loans that migrate toward lower risk ratings generally will result in a lower risk factor being applied to those related loan balances. The following tables represent our credit risk profile by creditworthiness category for the years ended December 31 : 2016 Commercial, financial, agricultural and other Real estate construction Residential real estate Commercial real estate Loans to individuals Total (dollars in thousands) Originated loans Pass $ 1,038,844 $ 217,565 $ 1,152,511 $ 1,691,220 $ 546,316 $ 4,646,456 Non-Pass OAEM 27,387 275 5,923 7,596 — 41,181 Substandard 64,917 — 7,417 18,227 273 90,834 Doubtful — — — — — — Total Non-Pass 92,304 275 13,340 25,823 273 132,015 Total $ 1,131,148 $ 217,840 $ 1,165,851 $ 1,717,043 $ 546,589 $ 4,778,471 Acquired Loans Pass $ 7,591 $ 1,781 $ 62,919 $ 24,043 $ 2,185 $ 98,519 Non-Pass OAEM 486 — — — — 486 Substandard 322 — 422 1,124 3 1,871 Doubtful — — — — — — Total Non-Pass 808 — 422 1,124 3 2,357 Total $ 8,399 $ 1,781 $ 63,341 $ 25,167 $ 2,188 $ 100,876 2015 Commercial, financial, agricultural and other Real estate construction Residential real estate Commercial real estate Loans to individuals Total (dollars in thousands) Pass $ 1,074,858 $ 220,267 $ 1,209,606 $ 1,436,714 $ 608,342 $ 4,549,787 Non-Pass OAEM 11,825 442 5,244 30,012 — 47,523 Substandard 64,223 27 9,615 12,274 301 86,440 Doubtful — — — — — — Total Non-Pass 76,048 469 14,859 42,286 301 133,963 Total $ 1,150,906 $ 220,736 $ 1,224,465 $ 1,479,000 $ 608,643 $ 4,683,750 Portfolio Risks The credit quality of our loan portfolio can potentially represent significant risk to our earnings, capital, regulatory agency relationships, investment community and shareholder returns. First Commonwealth devotes a substantial amount of resources managing this risk primarily through our credit administration department that develops and administers policies and procedures for underwriting, maintaining, monitoring and collecting activities. Credit administration is independent of lending departments and oversight is provided by the credit committee of the First Commonwealth Board of Directors. Total gross charge-offs for the years ended December 31, 2016 and 2015 were $26.3 million and $18.9 million , respectively. Criticized loans have been evaluated when determining the appropriateness of the allowance for credit losses, which we believe is adequate to absorb losses inherent to the portfolio as of December 31, 2016 . However, changes in economic conditions, interest rates, borrower financial condition, delinquency trends or previously established fair values of collateral factors could significantly change those judgmental estimates. Age Analysis of Past Due Loans by Segment The following tables delineate the aging analysis of the recorded investments in past due loans as of December 31 . Also included in these tables are loans that are 90 days or more past due and still accruing because they are well-secured and in the process of collection. 2016 30 - 59 60 - 89 90 days Nonaccrual Total past Current Total (dollars in thousands) Originated Loans Commercial, financial, agricultural and other $ 2,380 $ 171 $ 75 $ 17,928 $ 20,554 $ 1,110,594 $ 1,131,148 Real estate construction 183 — — — 183 217,657 217,840 Residential real estate 4,133 1,089 995 5,792 12,009 1,153,842 1,165,851 Commercial real estate 265 327 57 3,443 4,092 1,712,951 1,717,043 Loans to individuals 1,640 776 970 273 3,659 542,930 546,589 Total $ 8,601 $ 2,363 $ 2,097 $ 27,436 $ 40,497 $ 4,737,974 $ 4,778,471 Acquired Loans Commercial, financial, agricultural and other $ 486 $ — $ — $ — $ 486 $ 7,913 $ 8,399 Real estate construction — — — — — 1,781 1,781 Residential real estate 148 39 34 422 643 62,698 63,341 Commercial real estate — — — 162 162 25,005 25,167 Loans to individuals 1 7 — 3 11 2,177 2,188 Total $ 635 $ 46 $ 34 $ 587 $ 1,302 $ 99,574 $ 100,876 2015 30 - 59 60 - 89 90 days Nonaccrual Total past Current Total (dollars in thousands) Commercial, financial, agricultural and other $ 364 $ 49 $ 129 $ 23,653 $ 24,195 $ 1,126,711 $ 1,150,906 Real estate construction 280 — — 28 308 220,428 220,736 Residential real estate 4,175 1,055 1,315 6,500 13,045 1,211,420 1,224,465 Commercial real estate 781 — 65 6,223 7,069 1,471,931 1,479,000 Loans to individuals 2,998 774 946 301 5,019 603,624 608,643 Total $ 8,598 $ 1,878 $ 2,455 $ 36,705 $ 49,636 $ 4,634,114 $ 4,683,750 Nonaccrual Loans The previous tables summarize nonaccrual loans by loan segment. The Company generally places loans on nonaccrual status when the full and timely collection of interest or principal becomes uncertain, when part of the principal balance has been charged off and no restructuring has occurred, or the loans reach a certain number of days past due. Generally, loans 90 days or more past due are placed on nonaccrual status, except for consumer loans which are placed in nonaccrual status at 150 days past due. When a loan is placed on nonaccrual, the accrued unpaid interest receivable is reversed against interest income and all future payments received are applied as a reduction to the loan principal. Generally, the loan is returned to accrual status when (a) all delinquent interest and principal become current under the terms of the loan agreement or (b) the loan is both well-secured and in the process of collection and collectability is no longer in doubt. Impaired Loans Management considers loans to be impaired when, based on current information and events, it is determined that the Company will not be able to collect all amounts due according to the loan contract, including scheduled interest payments. Determination of impairment is treated the same across all loan categories. When management identifies a loan as impaired, the impairment is measured based on the present value of expected future cash flows, discounted at the loan’s effective interest rate, except when the sole source or repayment for the loan is the operation or liquidation of collateral. When the loan is collateral dependent, the appraised value less estimated cost to sell is utilized. If management determines the value of the impaired loan is less than the recorded investment in the loan, impairment is recognized through an allowance estimate or a charge-off to the allowance. Troubled debt restructured loans on accrual status are considered to be impaired loans. When the ultimate collectability of the total principal of an impaired loan is in doubt and the loan is on nonaccrual status, all payments are applied to principal, under the cost recovery method. When the ultimate collectability of the total principal of an impaired loan is not in doubt and the loan is on nonaccrual status, contractual interest is credited to interest income when received under the cash basis method. There were no impaired loans held for sale at December 31, 2016 and December 31, 2015 and no gains were recognized on sales of impaired loans during the year ended December 31, 2016. Sales of impaired loans during the year ended December 31, 2015 resulted in gains of $0.4 million . Significant nonaccrual loans as of December 31, 2016 , included the following: • A $7.6 million relationship of commercial industrial loans to a steel and aluminum servicing company. These loans were originated in 2011 and were placed in nonaccrual status during the first quarter of 2016. During the year ended December 31, 2016 , charge-offs of $4.2 million related to this relationship were recorded. The collateral valuation completed in the fourth quarter of 2016 incorporated certain estimates obtained in the first quarter of 2016. • A $3.3 million relationship of commercial industrial loans to a local energy company. These loans were originated from 2008 to 2011 and were placed in nonaccrual status during the third quarter of 2013. Two of these loans were modified resulting in TDR classification: one loan totaling $1.0 million was modified in 2012, and the other loan totaling $2.3 million was modified in 2014. During the year ended December 31, 2016 , chargeoffs of $1.3 million related to this relationship were recorded. A gas reserve study was obtained in March 2016 and was internally updated in December 2016 for adjustments to the pricing forecast and production estimates. All other collateral was valued in December 2016. • A $3.1 million relationship of commercial industrial loans to a gear manufacturer. These loans were originated in 2013 and were placed in nonaccrual status during the third quarter of 2015. Charge-offs of $0.5 million related to this relationship were recognized during the year ended December 31, 2016 . A valuation of the collateral was completed during the fourth quarter of 2016. The following tables include the recorded investment and unpaid principal balance for impaired loans with the associated allowance amount, if applicable, as of December 31, 2016 and 2015 . Also presented are the average recorded investment in impaired loans and the related amount of interest recognized while the loan was considered impaired for the years ended December 31, 2016 , 2015 and 2014 . Average balances are calculated based on month-end balances of the loans for the period reported and are included in the table below based on its period end allowance position. 2016 Recorded Unpaid Related Average Interest (dollars in thousands) Originated Loans: With no related allowance recorded: Commercial, financial, agricultural and other $ 9,549 $ 15,369 $ 23,146 $ 576 Real estate construction — — 4 44 Residential real estate 10,873 13,004 10,957 312 Commercial real estate 5,765 6,905 6,718 170 Loans to individuals 382 507 409 15 Subtotal 26,569 35,785 41,234 1,117 With an allowance recorded: Commercial, financial, agricultural and other 13,423 19,226 $ 2,530 13,885 99 Real estate construction — — — — — Residential real estate 424 475 164 241 4 Commercial real estate 810 810 434 555 25 Loans to individuals — — — — — Subtotal 14,657 20,511 3,128 14,681 128 Total $ 41,226 $ 56,296 $ 3,128 $ 55,915 $ 1,245 Acquired Loans: With no related allowance recorded: Commercial, financial, agricultural and other $ — $ — $ — $ — Real estate construction — — — — Residential real estate 406 480 406 — Commercial real estate 162 162 162 — Loans to individuals 3 3 3 — Subtotal 571 645 571 — With an allowance recorded: Commercial, financial, agricultural and other — — $ — — — Real estate construction — — — — — Residential real estate 16 16 16 16 — Commercial real estate — — — — — Loans to individuals — — — — — Subtotal 16 16 16 16 — Total $ 587 $ 661 $ 16 $ 587 $ — 2015 Recorded Unpaid Related Average Interest With no related allowance recorded: Commercial, financial, agricultural and other $ 11,344 $ 15,673 $ 17,692 $ 216 Real estate construction 28 117 95 — Residential real estate 9,952 11,819 10,635 172 Commercial real estate 7,562 9,449 7,890 90 Loans to individuals 421 507 338 4 Subtotal 29,307 37,565 36,650 482 With an allowance recorded: Commercial, financial, agricultural and other 20,132 22,590 $ 6,952 7,731 129 Real estate construction — — — — — Residential real estate 461 672 51 403 — Commercial real estate 944 1,008 42 674 4 Loans to individuals — — — — — Subtotal 21,537 24,270 7,045 8,808 133 Total $ 50,844 $ 61,835 $ 7,045 $ 45,458 $ 615 2014 Average Interest (dollars in thousands) With no related allowance recorded: Commercial, financial, agricultural and other $ 11,536 $ 133 Real estate construction 1,190 19 Residential real estate 11,592 210 Commercial real estate 8,830 98 Loans to individuals 308 4 Subtotal 33,456 464 With an allowance recorded: Commercial, financial, agricultural and other 15,797 143 Real estate construction — — Residential real estate 357 14 Commercial real estate 184 4 Loans to individuals — — Subtotal 16,338 161 Total $ 49,794 $ 625 Unfunded commitments related to nonperforming loans were $1.8 million and $0.1 million at December 31, 2016 and 2015 , respectively. After consideration of available collateral related to these commitments, a reserve of $12 thousand and $13 thousand was established for these off balance sheet exposures at December 31, 2016 and 2015 , respectively. Troubled debt restructured loans are those loans whose terms have been renegotiated to provide a reduction or deferral of principal or interest as a result of the financial difficulties experienced by the borrower, who could not obtain comparable terms from alternate financing sources. The following table provides detail as to the total troubled debt restructured loans and total commitments outstanding on troubled debt restructured loans as of December 31 : 2016 2015 2014 (dollars in thousands) Troubled debt restructured loans Accrual status $ 13,790 $ 14,139 $ 12,584 Nonaccrual status 11,569 12,360 16,952 Total $ 25,359 $ 26,499 $ 29,536 Commitments Unused lines of credit 358 3,252 4,120 The following tables provide detail, including specific reserve and reasons for modification, related to loans identified as troubled debt restructurings during the years ending December 31 : 2016 Type of Modification Number Extend Modify Modify Total Post- Specific (dollars in thousands) Commercial, financial, agricultural and other 5 $ 23 $ 6,318 $ 3,854 $ 10,195 $ 6,210 $ 317 Residential real estate 39 107 214 2,619 2,940 2,698 124 Commercial real estate 8 1,368 — 25 1,393 1,271 59 Loans to individuals 13 23 82 25 130 96 — Total 65 $ 1,521 $ 6,614 $ 6,523 $ 14,658 $ 10,275 $ 500 2015 Type of Modification Number Extend Modify Modify Total Post- Specific (dollars in thousands) Commercial, financial, agricultural and other 12 $ 1,751 $ 3,195 $ 4,527 $ 9,473 $ 8,823 $ 1,330 Residential real estate 32 — 296 1,414 1,710 1,575 2 Commercial real estate 1 — — 464 464 389 — Loans to individuals 16 3 167 35 205 169 — Total 61 $ 1,754 $ 3,658 $ 6,440 $ 11,852 $ 10,956 $ 1,332 2014 Type of Modification Number Extend Modify Modify Total Post- Specific (dollars in thousands) Commercial, financial, agricultural and other 9 $ 5,487 $ — $ 14,529 $ 20,016 $ 13,785 $ 4,665 Residential real estate 52 — 629 1,797 2,426 2,062 — Commercial real estate 1 — — 8 8 6 — Loans to individuals 15 — 103 47 150 114 — Total 77 $ 5,487 $ 732 $ 16,381 $ 22,600 $ 15,967 $ 4,665 The troubled debt restructurings included in the above tables are also included in the impaired loan tables provided earlier in this footnote. Loans defined as modified due to a change in rate include loans that were modified for a change in rate as well as a reamortization of the principal and an extension of the maturity. For the years ended December 31, 2016 , 2015 and 2014 , $6.6 million , $3.7 million and $0.6 million , respectively, of total rate modifications represent loans with modifications to the rate as well as payment due to reamortization. A troubled debt restructuring is considered to be in default when a restructured loan is 90 days or more past due. The following table provides information related to restructured loans that were considered to be in default during the year ending December 31 : 2016 2015 2014 Number of Recorded Number of Recorded Number of Recorded (dollars in thousands) Residential real estate 4 $ 313 3 $ 97 2 $ 7 Commercial real estate — — — — 1 6 Total 4 $ 313 3 $ 97 3 $ 13 The following tables provide detail related to the allowance for credit losses for the years ended December 31 . 2016 Commercial, Real estate Residential Commercial Loans to Total (dollars in thousands) Allowance for credit losses: Beginning Balance on Originated Loans $ 31,035 $ 887 $ 2,606 $ 11,924 $ 4,360 $ 50,812 Charge-offs (19,603 ) — (1,189 ) (570 ) (4,943 ) (26,305 ) Recoveries 4,164 562 481 1,522 469 7,198 Provision (credit) 20,378 (872 ) 594 (6,257 ) 4,618 18,461 Ending Balance on Originated Loans 35,974 577 2,492 6,619 4,504 50,166 Ending Balance on Acquired Loans (1) — — 19 — — 19 Total Ending Balance $ 35,974 $ 577 $ 2,511 $ 6,619 $ 4,504 $ 50,185 Ending balance: individually evaluated for impairment $ 2,530 $ — $ 180 $ 434 $ — $ 3,144 Ending balance: collectively evaluated for impairment 33,444 577 2,331 6,185 4,504 47,041 Loans: Ending balance 1,139,547 219,621 1,229,192 1,742,210 548,777 4,879,347 Ending balance: individually evaluated for impairment 22,325 — 5,875 5,468 — 33,668 Ending balance: collectively evaluated for impairment 1,117,222 219,621 1,223,317 1,736,742 548,777 4,845,679 (1) Amount reflects provision expense and ending allowance balance for loans acquired in 2016 as part of the purchase of FirstMerit branches. 2015 Commercial, Real estate Residential Commercial Loans to Total (dollars in thousands) Allowance for credit losses: Beginning Balance $ 29,627 $ 2,063 $ 3,664 $ 11,881 $ 4,816 $ 52,051 Charge-offs (11,429 ) (8 ) (1,539 ) (1,538 ) (4,354 ) (18,868 ) Recoveries 1,097 84 587 229 684 2,681 Provision (credit) 11,740 (1,252 ) (106 ) 1,352 3,214 14,948 Ending Balance $ 31,035 $ 887 $ 2,606 $ 11,924 $ 4,360 $ 50,812 Ending balance: individually evaluated for impairment $ 6,952 $ — $ 51 $ 42 $ — $ 7,045 Ending balance: collectively evaluated for impairment 24,083 887 2,555 11,882 4,360 43,767 Loans: Ending balance 1,150,906 220,736 1,224,465 1,479,000 608,643 4,683,750 Ending balance: individually evaluated for impairment 30,767 — 6,099 7,143 — 44,009 Ending balance: collectively evaluated for impairment 1,120,139 220,736 1,218,366 1,471,857 608,643 4,639,741 2014 Commercial, Real estate Residential Commercial Loans to Total (dollars in thousands) Allowance for credit losses: Beginning Balance $ 22,663 $ 6,600 $ 7,727 $ 11,778 $ 5,457 $ 54,225 Charge-offs (8,911 ) (296 ) (3,153 ) (1,148 ) (3,964 ) (17,472 ) Recoveries 734 1,340 650 612 766 4,102 Provision (credit) 15,141 (5,581 ) (1,560 ) 639 2,557 11,196 Ending Balance $ 29,627 $ 2,063 $ 3,664 $ 11,881 $ 4,816 $ 52,051 Ending balance: individually evaluated for impairment $ 9,304 $ — $ 56 $ 101 $ — $ 9,461 Ending balance: collectively evaluated for impairment 20,323 2,063 3,608 11,780 4,816 42,590 Loans: Ending balance 1,052,109 120,785 1,226,344 1,405,256 652,814 4,457,308 Ending balance: individually evaluated for impairment 33,332 193 7,127 7,790 — 48,442 Ending balance: collectively evaluated for impairment 1,018,777 120,592 1,219,217 1,397,466 652,814 4,408,866

Commitments and Letters of Cred

Commitments and Letters of Credit	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Letters of Credit	Commitments and Letters of Credit First Commonwealth is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financial needs of its customers. These financial instruments include commitments to extend credit, standby letters of credit and commercial letters of credit. Those instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the Consolidated Statements of Financial Condition. First Commonwealth’s exposure to credit loss in the event of nonperformance by the other party of the financial instrument for commitments to extend credit, standby letters of credit and commercial letters of credit is represented by the contract or notional amount of those instruments. First Commonwealth uses the same credit policies for underwriting all loans, including these commitments and conditional obligations. As of December 31, 2016 and 2015 , First Commonwealth did not own or trade other financial instruments with significant off-balance sheet risk including derivatives such as futures, forwards, option contracts and the like, although such instruments may be appropriate to use in the future to manage interest rate risk. See Note 7, “Derivatives,” for a description of interest rate derivatives entered into by First Commonwealth. Standby letters of credit and commercial letters of credit are conditional commitments issued by First Commonwealth to guarantee the performance of a customer to a third party. The contract or notional amount of these instruments reflects the maximum amount of future payments that First Commonwealth could be required to pay under the guarantees if there were a total default by the guaranteed parties, without consideration for possible recoveries under recourse provisions or from collateral held or pledged. In addition, many of these commitments are expected to expire without being drawn upon; therefore, the total commitment amounts do not necessarily represent future cash requirements. The following table identifies the notional amount of those instruments at December 31 : 2016 2015 (dollars in thousands) Financial instruments whose contract amounts represent credit risk: Commitments to extend credit $ 1,733,820 $ 1,643,187 Financial standby letters of credit 18,108 17,843 Performance standby letters of credit 26,630 26,497 Commercial letters of credit 1,301 1,672 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. First Commonwealth evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by First Commonwealth upon extension of credit, is based on management’s credit evaluation of the counterparty. Collateral that is held varies but may include accounts receivable, inventory, property, plant and equipment, and residential and income-producing commercial properties. The notional amounts outstanding at December 31, 2016 include amounts issued in 2016 of $0.4 million in financial standby letters of credit and $3.0 million in performance standby letters of credit. There were $0.2 million commercial letters of credit issued during 2016 . A liability of $0.2 million has been recorded as of December 31, 2016 and 2015 , which represents the estimated fair value of letters of credit issued. The fair value of letters of credit is estimated based on the unrecognized portion of fees received at the time the commitment was issued. Unused commitments and letters of credit provide exposure to future credit loss in the event of nonperformance by the borrower or guaranteed parties. Management’s evaluation of the credit risk in these commitments resulted in the recording of a liability of $4.1 million and $4.4 million as of December 31, 2016 and 2015 , respectively. This liability is reflected in “ Other liabilities ” in the Consolidated Statements of Financial Condition. The credit risk evaluation incorporated probability of default, loss given default and estimated utilization for the next twelve months for each loan category and the letters of credit.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment Premises and equipment are described as follows: Estimated Useful Life 2016 2015 (dollars in thousands) Land Indefinite $ 13,679 $ 12,185 Buildings and improvements 10-50 years 80,364 77,086 Leasehold improvements 5-40 years 15,871 14,518 Furniture and equipment 3-7 years 61,324 59,463 Software 3-7 years 36,077 34,472 Subtotal 207,315 197,724 Less accumulated depreciation and amortization 139,781 134,270 Total premises and equipment $ 67,534 $ 63,454 Depreciation related to premises and equipment included in noninterest expense for the years ended December 31, 2016 , 2015 and 2014 amounted to $7.5 million , $7.2 million and $13.2 million , respectively. First Commonwealth leases various premises and assorted equipment under non-cancellable agreements. Total future minimal rental commitments at December 31, 2016 , were as follows: Premises Equipment (dollars in thousands) 2017 $ 3,844 $ 10 2018 3,559 — 2019 3,137 — 2020 2,556 — 2021 2,265 — Thereafter 9,693 — Total $ 25,054 $ 10 Included in the lease commitments above is $202 thousand in lease payments to be paid under a sale-leaseback arrangement. The sale-leaseback transaction occurred in 2005 and resulted in a gain of $297 thousand on the sale of a branch that is being recognized over the 15 year lease term through 2020. Increases in utilities and taxes that may be passed on to the lessee under the terms of various lease agreements are not reflected in the above table. However, certain lease agreements provide for increases in rental payments based upon historical increases in the consumer price index or the lessor’s cost of operating the facility, and are included in the minimum lease commitments. Additionally, the table above includes rent expense that is recognized for rent holidays and during construction periods. Total lease expense amounted to $3.7 million in 2016 and $2.9 million in 2015 and 2014 .

Goodwill and Other Amortizing I

Goodwill and Other Amortizing Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill Disclosure [Abstract]
Goodwill and Other Amortizing Intangible Assets	Goodwill and Other Amortizing Intangible Assets FASB ASC Topic 350-20, “Intangibles—Goodwill and Other,” requires an annual valuation of the fair value of a reporting unit that has goodwill and a comparison of the fair value to the book value of equity to determine whether the goodwill has been impaired. Goodwill is also required to be tested on an interim basis if an event or circumstance indicates that it is more likely than not that an impairment loss has been incurred. When triggering events or circumstances indicate goodwill testing is required, an assessment of qualitative factors can be completed before performing the two step goodwill impairment test. ASU 2011-8 provides that if an assessment of qualitative factors determines it is more likely than not that the fair value of a reporting unit exceeds its carrying amount, then the two step goodwill impairment test is not required. We consider First Commonwealth to be one reporting unit. The carrying amount of goodwill as of December 31, 2016 and 2015 was $186.5 million and $164.5 million , respectively. The $22.0 million increase in goodwill during the year ended December 31, 2016 is a result of the acquisition of thirteen First Merit branches. No impairment charges on goodwill or other intangible assets were incurred in 2016 , 2015 or 2014 . We test goodwill for impairment as of November 30th each year and again at any quarter-end if any material events occur during a quarter that may affect goodwill. An assessment of qualitative factors was completed as of November 30, 2016 and December 31, 2016 and indicated that it is more likely than not that the fair value of First Commonwealth's goodwill exceeds its carrying amount; therefore, the two step goodwill impairment test was not considered necessary. The assessment of qualitative factors considered historical and projected financial performance, macroeconomic factors such as the Company's access to capital, the general business climate and changes in the banking industry as well as market considerations such as geographic expansion, new product offerings and the regulatory environment. As of December 31, 2016 , goodwill was not considered impaired; however, changing economic conditions that may adversely affect our performance, the fair value of our assets and liabilities, our stock price could result in impairment, which could adversely affect earnings in future periods. Management will continue to monitor events that could impact this conclusion in the future. FASB ASC Topic 350, “Intangibles—Other,” also requires that an acquired intangible asset be separately recognized if the benefit of the intangible asset is obtained through contractual or other legal rights, or if the asset can be sold, transferred, licensed, rented or exchanged, regardless of the acquirer’s intent to do so. The following table summarizes other intangible assets: Gross Intangible Assets Accumulated Amortization Net Intangible Assets (dollars in thousands) December 31, 2016 Customer deposit intangibles $ 30,471 $ (18,998 ) $ 11,473 Customer list intangible $ 984 $ (444 ) $ 540 Total other intangible assets $ 31,455 $ (19,442 ) $ 12,013 December 31, 2015 Customer deposit intangibles $ 19,142 $ (18,619 ) $ 523 Customer list intangible $ 984 $ (276 ) $ 708 Total other intangible assets $ 20,126 $ (18,895 ) $ 1,231 Core deposits are amortized over their expected lives using the present value of the benefit of the core deposits and straight-line methods of amortization. The core deposits have a remaining amortization period of 9.9 years and a weighted average amortization period of approximately 10.0 years. In the table above, the change in the gross customer deposit intangible from December 31, 2015 to December 31, 2016 is due to the acquisition of thirteen branches from FirstMerit Bank, NA, resulting in $11.3 million in core deposit intangibles. The customer list intangible represents the estimated value of the customer base for an insurance agency acquired in 2014. These amounts are amortized over their expected lives using expected cash flows based on retention of the customer base. The customer list intangible has a remaining amortization period and a weighted average amortization period of 12.8 years. First Commonwealth recognized amortization expense on other intangible assets of $0.5 million , $0.6 million , and $0.6 million for the years ended December 31, 2016 , 2015 and 2014 , respectively. The following presents the estimated amortization expense of core deposit intangibles and the customer intangible list: Core Deposit Intangibles Customer List Intangible Total (dollars in thousands) 2017 $ 2,133 $ 129 $ 2,262 2018 1,923 99 2,022 2019 1,709 77 1,786 2020 1,443 59 1,502 2021 1,234 45 1,279 Thereafter 3,031 131 3,162 Total $ 11,473 $ 540 $ 12,013

Interest-Bearing Deposits

Interest-Bearing Deposits	12 Months Ended
	Dec. 31, 2016
Deposits [Abstract]
Interest-Bearing Deposits	Interest-Bearing Deposits Components of interest-bearing deposits at December 31 were as follows: 2016 2015 (dollars in thousands) Interest-bearing demand deposits $ 114,043 $ 86,365 Savings deposits 2,972,747 2,390,607 Time deposits 591,832 602,233 Total interest-bearing deposits $ 3,678,622 $ 3,079,205 Interest-bearing deposits at December 31, 2016 and 2015 , include allocations from interest-bearing demand deposit accounts of $779.2 million and $580.8 million , respectively, into savings which includes money market accounts. These reallocations are based on a formula and have been made to reduce First Commonwealth’s reserve requirement in compliance with regulatory guidelines. Included in time deposits at December 31, 2016 and 2015 , were certificates of deposit in denominations of $100 thousand or more of $145.4 million and $157.7 million , respectively. Interest expense related to certificates of deposit in denominations of $100 thousand or greater amounted to $1.2 million in 2016 , $1.8 million in 2015 and $3.7 million in 2014 . Included in time deposits at December 31, 2016 , were certificates of deposit with the following scheduled maturities (dollars in thousands): 2017 $ 319,298 2018 133,754 2019 66,121 2020 33,859 2021 and thereafter 38,800 Total $ 591,832

Short-term Borrowings

Short-term Borrowings	12 Months Ended
	Dec. 31, 2016
Short-term Debt [Abstract]
Short-term Borrowings	Short-term Borrowings Short-term borrowings at December 31 were as follows: 2016 2015 2014 Ending Average Average Ending Average Average Ending Average Average (dollars in thousands) Federal funds purchased $ — $ 6,887 0.60 % $ 4,000 $ 14,832 0.36 % $ 9,000 $ 11,691 0.36 % Borrowings from FHLB 748,000 1,265,932 0.61 1,400,000 1,117,522 0.42 945,000 644,651 0.31 Securities sold under agreements to repurchase 119,943 114,918 0.23 106,825 120,177 0.23 151,876 159,051 0.24 Total $ 867,943 $ 1,387,737 0.58 $ 1,510,825 $ 1,252,531 0.40 $ 1,105,876 $ 815,393 0.30 Maximum total at any month-end $ 1,530,678 $ 1,510,825 $ 1,105,876 Weighted average rate at year-end 0.63 % 0.53 % 0.30 % Interest expense on short-term borrowings for the years ended December 31 is detailed below: 2016 2015 2014 (dollars in thousands) Federal funds purchased $ 41 $ 54 $ 42 Borrowings from FHLB 7,765 4,684 2,019 Securities sold under agreements to repurchase 270 280 388 Total interest on short-term borrowings $ 8,076 $ 5,018 $ 2,449

Subordinated Debentures

Subordinated Debentures	12 Months Ended
	Dec. 31, 2016
Disclosure Subordinated Debentures [Abstract]
Subordinated Debentures	Subordinated Debentures Subordinated Debentures outstanding at December 31 are as follows: 2016 2015 Due Amount Rate Amount Rate (dollars in thousands) Owed to: First Commonwealth Capital Trust II 2034 $ 30,929 LIBOR + 2.85 $ 30,929 LIBOR + 2.85 First Commonwealth Capital Trust III 2034 41,238 LIBOR + 2.85 41,238 LIBOR + 2.85 Total $ 72,167 $ 72,167 First Commonwealth currently has two trusts, First Commonwealth Capital Trust II and First Commonwealth Capital Trust III, of which 100% of the common equity is owned by First Commonwealth. The trusts were formed for the purpose of issuing company obligated mandatorily redeemable capital securities to third-party investors and investing the proceeds from the sale of the capital securities solely in junior subordinated debt securities (“subordinated debentures”) of First Commonwealth. The subordinated debentures held by each trust are the sole assets of the trust. Interest on the debentures issued to First Commonwealth Capital Trust III is paid quarterly at a floating rate of LIBOR + 2.85% which is reset quarterly. Subject to regulatory approval, First Commonwealth may redeem the debentures, in whole or in part, at its option on any interest payment date at a redemption price equal to 100% of the principal amount of the debentures, plus accrued and unpaid interest to the date of the redemption. Deferred issuance costs of $630 thousand are being amortized on a straight-line basis over the term of the securities. Interest on the debentures issued to First Commonwealth Capital Trust II is paid quarterly at a floating rate of LIBOR + 2.85% , which is reset quarterly. Subject to regulatory approval, First Commonwealth may redeem the debentures, in whole or in part, at its option at a redemption price equal to 100% of the principal amount of the debentures, plus accrued and unpaid interest to the date of the redemption. Deferred issuance costs of $471 thousand are being amortized on a straight-line basis over the term of the securities.

Other Long-term Debt

Other Long-term Debt	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Other Long-term Debt	Other Long-term Debt Other long-term debt at December 31 follows: 2016 2015 Amount Weighted Amount Weighted (dollars in thousands) Borrowings from FHLB due: 2016 $ 563 3.82 % 2017 $ 586 3.83 % 585 3.83 2018 609 3.83 607 3.83 2019 633 3.84 631 3.83 2020 658 3.84 659 3.84 2021 684 3.84 Thereafter 5,579 3.81 6,269 3.81 Total $ 8,749 $ 9,314 The weighted average contractual rate reflects the rate due to creditors. There are no purchase accounting adjustments related to long-term debt in 2016 or 2015 . Therefore, the weighted average effective rate of long-term debt is equal to the weighted average contractual rate of long-term debt. All of First Commonwealth’s Federal Home Loan Bank stock, along with an interest in mortgage loans and residential mortgage backed securities, has been pledged as collateral with the Federal Home Loan Bank of Pittsburgh. Capital securities included in total long-term debt on the Consolidated Statements of Financial Condition are excluded from the above, but are described in Note 16, “Subordinated Debentures.”

Fair Values of Assets and Liabi

Fair Values of Assets and Liabilities	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Values of Assets and Liabilities	Fair Values of Assets and Liabilities FASB ASC Topic 820, “Fair Value Measurements and Disclosures,” requires disclosures for non-financial assets and non-financial liabilities, except for items that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually). All non-financial assets are included either as a separate line item on the Consolidated Statements of Financial Condition or in the “Other assets” category of the Consolidated Statements of Financial Condition. Currently, First Commonwealth does not have any non-financial liabilities to disclose. FASB ASC Topic 825, “Financial Instruments,” permits entities to irrevocably elect to measure select financial instruments and certain other items at fair value. The unrealized gains and losses are required to be included in earnings each reporting period for the items that fair value measurement is elected. First Commonwealth has elected not to measure any existing financial instruments at fair value under FASB ASC Topic 825; however, in the future we may elect to adopt this guidance for select financial instruments. In accordance with FASB ASC Topic 820, First Commonwealth groups financial assets and financial liabilities measured at fair value in three levels, based on the principal markets in which the assets and liabilities are transacted and the observability of the data points used to determine fair value. These levels are: • Level 1—Valuations for assets and liabilities traded in active exchange markets, such as the New York Stock Exchange (“NYSE”). Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities. • Level 2—Valuations for assets and liabilities traded in less active dealer or broker markets. Valuations are obtained for identical or comparable assets or liabilities from alternative pricing sources with reasonable levels of price transparency. Level 2 includes Obligations of U.S. Government securities issued by Agencies and Sponsored Enterprises, Obligations of States and Political Subdivisions, certain corporate securities, FHLB stock, loans held for sale, interest rate derivatives (including interest rate swaps, interest rate caps and risk participation agreements), certain other real estate owned and certain impaired loans. Level 2 investment securities are valued by a recognized third party pricing service using observable inputs. The model used by the pricing service varies by asset class and incorporates available market, trade and bid information as well as cash flow information when applicable. Because many fixed-income investment securities do not trade on a daily basis, the model uses available information such as benchmark yield curves, benchmarking of like investment securities, sector groupings and matrix pricing. The model will also use processes such as an option-adjusted spread to assess the impact of interest rates and to develop prepayment estimates. Market inputs normally used in the pricing model include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including market research publications. Management validates the market values provided by the third party service by having another recognized pricing service price 100% of the securities on an annual basis and a random sample of securities each quarter, monthly monitoring of variances from prior period pricing and, on a monthly basis, evaluating pricing changes compared to expectations based on changes in the financial markets. Other Investments are comprised of FHLB stock whose estimated fair value is based on its par value. Additional information on FHLB stock is provided in Note 9, “Impairment of Investment Securities.” Loans held for sale include residential mortgage loans originated for sale in the secondary mortgage market. The estimated fair value for these loans was determined on the basis of rates obtained in the respective secondary market. Interest rate derivatives are reported at estimated fair value utilizing Level 2 inputs and are included in Other assets and Other liabilities in the Consolidated Statements of Financial Condition. These consist of interest rate swaps where there is no significant deterioration in the counterparties' (loan customers') credit risk since origination of the interest rate swap as well as interest rate caps and risk participation agreements. First Commonwealth values its interest rate swap and cap positions using a yield curve by taking market prices/rates for an appropriate set of instruments. The set of instruments currently used to determine the U.S. Dollar yield curve includes cash LIBOR rates from overnight to one year, Eurodollar futures contracts and swap rates from one year to thirty years. These yield curves determine the valuations of interest rate swaps. Interest rate derivatives are further described in Note 7, “Derivatives.” For purposes of potential valuation adjustments to our derivative positions, First Commonwealth evaluates the credit risk of its counterparties as well as our own credit risk. Accordingly, we have considered factors such as the likelihood of default, expected loss given default, net exposures and remaining contractual life, among other things, in determining if any estimated fair value adjustments related to credit risk are required. We review our counterparty exposure quarterly, and when necessary, appropriate adjustments are made to reflect the exposure. We also utilize this approach to estimate our own credit risk on derivative liability positions. In 2016 and 2015 , we have not realized any losses due to a counterparty's inability to pay any net uncollateralized position. The estimated fair value for other real estate owned included in Level 2 is determined by either an independent market based appraisal less estimated costs to sell or an executed sales agreement. • Level 3—Valuations for assets and liabilities that are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and not based on market exchange, dealer or broker traded transactions. If the inputs used to provide the valuation are unobservable and/or there is very little, if any, market activity for the security or similar securities, the securities would be considered Level 3 securities. Level 3 valuations incorporate certain assumptions and projections in determining the fair value assigned to such assets or liabilities. The assets included in Level 3 are pooled trust preferred collateralized debt obligations, non-marketable equity investments, certain interest rate derivatives, certain impaired loans and certain other real estate. Our pooled trust preferred collateralized debt obligations are collateralized by the trust preferred securities of individual banks, thrifts and bank holding companies in the United States. There has been little or no active trading in these securities since 2009; therefore it was more appropriate to determine estimated fair value using a discounted cash flow analysis. Detail on the process for determining the appropriate cash flows for this analysis is provided in Note 9 “Impairment of Investment Securities.” The discount rate applied to the cash flows is determined by evaluating the current market yields for comparable corporate and structured credit products along with an evaluation of the risks associated with the cash flows of the comparable security. Due to the fact that there is no active market for the pooled trust preferred collateralized debt obligations, one key reference point is the market yield for the single issue trust preferred securities issued by banks and thrifts for which there is more activity than for the pooled securities. Adjustments are then made to reflect the credit and structural differences between these two security types. Management validates the estimated fair value of the pooled trust preferred collateralized debt obligations by monitoring the performance of the underlying collateral, discussing the discount rate, cash flow assumptions and general market trends with the specialized third party and confirming changes in the underlying collateral to the trustee reports. Management’s monitoring of the underlying collateral includes deferrals of interest payments, payment defaults, cures of previously deferred interest payments, any regulatory filings or actions and general news related to the underlying collateral. Management also evaluates fair value changes compared to expectations based on changes in the interest rates used in determining the discount rate and general financial markets. The estimated fair value of the non-marketable equity investments included in Level 3 is based on par value. The estimated fair value of limited partnership investments included in Level 3 is based on par value. For interest rate derivatives included in Level 3, the fair value incorporates credit risk by considering such factors as likelihood of default and expected loss given default based on the credit quality of the underlying counterparties (loan customers). In accordance with ASU 2011-4, the following table provides information related to quantitative inputs and assumptions used in Level 3 fair value measurements. Fair Value Valuation Technique Unobservable Inputs Range / (weighted Pooled Trust Preferred Securities $ 33,292 Discounted Cash Flow Probability of default 0.00% - 100% (10.67%) Prepayment rates 0.00% - 72.66% (4.15%) Discount rates 5.25% - 12.00% (a) Equities 1,670 Par Value N/A N/A Impaired Loans 2,281 (b) Gas Reserve study Discount rate 10.00% Gas per MCF $1.63 - $3.38 (c) Oil per BBL/d $40.97 - $56.16 (c) 9,303 (b) Discounted Cash Flow Discount Rate 1.90% - 4.68% Limited Partnership Investments 930 Par Value N/A N/A (a) incorporates spread over the risk free rate related primarily to credit quality and illiquidity of securities. (b) the remainder of impaired loans valued using Level 3 inputs are not included in this disclosure as the values of those loans are based on bankruptcy agreement documentation. (c) unobservable inputs are defined as follows: MCF—million cubic feet; BBL/d—barrels per day. The significant unobservable inputs used in the fair value measurement of pooled trust preferred securities are the probability of default, discount rates and prepayment rates. Significant increases in the probability of default or discount rate used would result in a decrease in the estimated fair value of these securities, while decreases in these variables would result in higher fair value measurements. In general, a change in the assumption of probability of default is accompanied by a directionally similar change in the discount rate. In most cases, increases in the prepayment rate assumptions would result in a higher estimated fair value for these securities while decreases would provide for a lower value. The direction of this change is somewhat dependent on the structure of the investment and the amount of the investment tranches senior to our position. The discount rate is the significant unobservable input used in the fair value measurement of impaired loans. Significant increases in this rate would result in a decrease in the estimated fair value of the loans, while a decrease in this rate would result in a higher fair value measurement. Other unobservable inputs in the fair value measurement of impaired loans relate to gas, oil and natural gas prices. Increases in these rates would result in an increase in the estimated fair value of the loans, while a decrease in these prices would result in a lower fair value measurement. The tables below present the balances of assets and liabilities measured at fair value on a recurring basis at December 31: 2016 Level 1 Level 2 Level 3 Total (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities—Residential $ — $ 16,617 $ — $ 16,617 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities—Residential — 676,853 — 676,853 Mortgage-Backed Securities—Commercial — 1 — 1 Other Government-Sponsored Enterprises — 16,631 — 16,631 Obligations of States and Political Subdivisions — 27,229 — 27,229 Corporate Securities — 6,319 — 6,319 Pooled Trust Preferred Collateralized Debt Obligations — — 33,292 33,292 Total Debt Securities — 743,650 33,292 776,942 Equities — — 1,670 1,670 Total Securities Available for Sale — 743,650 34,962 778,612 Other Investments — 36,498 — 36,498 Loans Held for Sale — 7,052 — 7,052 Other Assets (a) — 6,089 930 7,019 Total Assets $ — $ 793,289 $ 35,892 $ 829,181 Other Liabilities (a) $ — $ 5,972 $ — $ 5,972 Total Liabilities $ — $ 5,972 $ — $ 5,972 (a) Hedging and non-hedging interest rate derivatives and limited partnership investments 2015 Level 1 Level 2 Level 3 Total (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities—Residential $ — $ 22,092 $ — $ 22,092 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities—Residential — 777,577 — 777,577 Mortgage-Backed Securities—Commercial — 28 — 28 Other Government-Sponsored Enterprises — 19,118 — 19,118 Obligations of States and Political Subdivisions — 27,598 — 27,598 Corporate Securities — 2,319 — 2,319 Pooled Trust Preferred Collateralized Debt Obligations — — 35,658 35,658 Total Debt Securities — 848,732 35,658 884,390 Equities — — 2,170 2,170 Total Securities Available for Sale — 848,732 37,828 886,560 Other Investments — 62,952 — 62,952 Loans Held for Sale — 5,763 — 5,763 Other Assets (a) — 11,273 — 11,273 Total Assets $ — $ 928,720 $ 37,828 $ 966,548 Other Liabilities (a) $ — $ 10,829 $ — $ 10,829 Total Liabilities $ — $ 10,829 $ — $ 10,829 (a) Non-hedging interest rate derivatives The changes in Level 3 assets and liabilities measured at fair value on a recurring basis are summarized as follows for the year ended December 31, 2016 : Pooled Trust Equities Other Total (dollars in thousands) Balance, beginning of year $ 35,658 $ 2,170 $ — $ 37,828 Total gains or losses Included in earnings 589 — — 589 Included in other comprehensive income 850 — — 850 Purchases, issuances, sales, and settlements Purchases — 36 394 430 Issuances — — — — Sales — — — — Settlements (3,805 ) — — (3,805 ) Transfers from Level 3 — (536 ) — (536 ) Transfers into Level 3 — — 536 536 Balance, end of year $ 33,292 $ 1,670 $ 930 $ 35,892 There are no gains or losses included in earnings for the period that are attributable to the change in realized gains (losses) relating to assets held at December 31, 2016 . During the year ended December 31, 2016 , $0.5 million in investments in limited partnerships were moved from other equity securities to other assets constituting the transfers into and out of Level 3. There were no transfers between fair value Levels 1 and 2. The changes in Level 3 assets and liabilities measured at fair value on a recurring basis are summarized as follows for the year ended December 31, 2015 : Pooled Trust Equities Other Total (dollars in thousands) Balance, beginning of year $ 28,999 $ 1,420 $ — $ 30,419 Total gains or losses Included in earnings 111 — — 111 Included in other comprehensive income 7,608 — — 7,608 Purchases, issuances, sales, and settlements Purchases — 750 — 750 Issuances — — — — Sales — — — — Settlements (1,060 ) — — (1,060 ) Transfers from Level 3 — — — — Transfers into Level 3 — — — — Balance, end of year $ 35,658 $ 2,170 $ — $ 37,828 There are no gains or losses included in earnings for the period that are attributable to the change in realized gains (losses) relating to assets held at December 31, 2015 . During 2015 , there were no transfers between fair value Levels 1, 2 or 3. The tables below present the balances of assets measured at fair value on a nonrecurring basis at December 31 and total gains and losses realized on these assets during the year ended December 31: 2016 Level 1 Level 2 Level 3 Total Total (dollars in thousands) Impaired loans $ — $ 18,679 $ 19,990 $ 38,669 $ (9,032 ) Other real estate owned — 7,566 — 7,566 (703 ) Total Assets $ — $ 26,245 $ 19,990 $ 46,235 $ (9,735 ) 2015 Level 1 Level 2 Level 3 Total Total (dollars in thousands) Impaired loans $ — $ 30,979 $ 12,820 $ 43,799 $ (9,098 ) Other real estate owned — 10,039 8 10,047 (1,693 ) Total Assets $ — $ 41,018 $ 12,828 $ 53,846 $ (10,791 ) Impaired loans over $100 thousand are individually reviewed to determine the amount of each loan considered to be at risk of noncollection. The fair value for impaired loans that are collateral based is determined by reviewing real property appraisals, equipment valuations, accounts receivable listings and other financial information. A discounted cash flow analysis is performed to determine fair value for impaired loans when an observable market price or a current appraisal is not available. For real estate secured loans, First Commonwealth’s loan policy requires updated appraisals be obtained at least every twelve months on all impaired loans with balances of $250 thousand and over. For real estate secured loans with balances under $250 thousand , we rely on broker price opinions. For non-real estate secured assets, the Company normally relies on third party valuations specific to the collateral type. The fair value for other real estate owned, determined by either an independent market based appraisal less estimated costs to sell or an executed sales agreement, is classified as Level 2. The fair value for other real estate owned determined using an internal valuation is classified as Level 3. Other real estate owned has a current carrying value of $6.8 million as of December 31, 2016 and consisted primarily of commercial real estate properties in Pennsylvania. We review whether events and circumstances subsequent to a transfer to other real estate owned have occurred that indicate the balance of those assets may not be recoverable. If events and circumstances indicate further impairment, we will record a charge to the extent that the carrying value of the assets exceed their fair values, less estimated costs to sell, as determined by valuation techniques appropriate in the circumstances. Certain other assets and liabilities, including goodwill, core deposit intangibles and customer list intangibles are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. Additional information related to this measurement is provided in Note 13 “Goodwill and Other Amortizing Intangible Assets.” There were no other assets or liabilities measured at fair value on a nonrecurring basis during 2016 . FASB ASC Topic 825-10, “Transition Related to FSP FAS 107-1” and APB 28-1, “Interim Disclosures about Fair Value of Financial Instruments,” requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or nonrecurring basis. The methodologies for estimating the fair value of financial assets and financial liabilities that are measured at fair value on a recurring or nonrecurring basis are as discussed above. The methodologies for other financial assets and financial liabilities are discussed below. Cash and due from banks and interest bearing bank deposits : The carrying amounts for cash and due from banks and interest-bearing bank deposits approximate the estimated fair values of such assets. Securities : Fair values for available for sale and held to maturity securities are based on quoted market prices, if available. If quoted market prices are not available, fair values are based on quoted market prices of comparable instruments. Pooled trust preferred collateralized debt obligation values are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and are not based on market exchange, dealer or broker traded transactions. These valuations incorporate certain assumptions and projections in determining the fair value assigned to each instrument. The carrying value of other investments, which includes FHLB stock, is considered a reasonable estimate of fair value. Loans held for sale : The estimated fair value of loans held for sale is based on market bids obtained from potential buyers. Loans: The fair values of all loans are estimated by discounting the estimated future cash flows using interest rates currently offered for loans with similar terms to borrowers of similar credit quality adjusted for past due and nonperforming loans, which is not an exit price under FASB ASC Topic 820, “Fair Value Measurements and Disclosures.” Off-balance sheet instruments : Many of First Commonwealth’s off-balance sheet instruments, primarily loan commitments and standby letters of credit, are expected to expire without being drawn upon; therefore, the commitment amounts do not necessarily represent future cash requirements. FASB ASC Topic 460, “Guarantees,” clarified that a guarantor is required to recognize, at the inception of a guarantee, a liability for the fair value of the obligation undertaken in issuing the guarantee. The carrying amount and estimated fair value for standby letters of credit was $0.2 million at both December 31, 2016 and 2015 . See Note 11, “Commitments and Letters of Credit,” for additional information. Deposit liabilities : The estimated fair value of demand deposits, savings accounts and money market deposits is the amount payable on demand at the reporting date because of the customers' ability to withdraw funds immediately. The carrying value of variable rate time deposit accounts and certificates of deposit approximate the fair value at the report date. Also, fair values of fixed rate time deposits for both periods are estimated by discounting the future cash flows using interest rates currently being offered and a schedule of aggregated expected maturities. Short-term borrowings : The fair values of borrowings from the FHLB were estimated based on the estimated incremental borrowing rate for similar types of borrowings. The carrying amounts of other short-term borrowings, such as federal funds purchased and securities sold under agreement to repurchase, were used to approximate fair value due to the short-term nature of the borrowings. Long-term debt and subordinated debt : The fair value of long-term debt and subordinated debt is estimated by discounting the future cash flows using First Commonwealth’s estimate of the current market rate for similar types of borrowing arrangements. The following table presents carrying amounts and estimated fair values of First Commonwealth’s financial instruments at December 31: 2016 Fair Value Measurements Using: Carrying Total Level 1 Level 2 Level 3 (dollars in thousands) Financial assets Cash and due from banks $ 91,033 $ 91,033 $ 91,033 $ — $ — Interest-bearing deposits 24,644 24,644 24,644 — — Securities available for sale 778,612 778,612 — 743,650 34,962 Securities held to maturity 372,513 368,618 — 368,618 — Other investments 36,498 36,498 — 36,498 — Loans held for sale 7,052 7,052 — 7,052 — Loans 4,879,347 4,878,254 — 18,679 4,859,575 Financial liabilities Deposits 4,947,408 4,949,714 — 4,949,714 — Short-term borrowings 867,943 867,667 — 867,667 — Long-term debt 8,749 9,169 — 9,169 — Subordinated debt 72,167 65,656 — — 65,656 2015 Fair Value Measurements Using: Carrying Total Level 1 Level 2 Level 3 (dollars in thousands) Financial assets Cash and due from banks $ 66,644 $ 66,644 $ 66,644 $ — $ — Interest-bearing deposits 2,808 2,808 2,808 — — Securities available for sale 886,560 886,560 — 848,732 37,828 Securities held to maturity 384,324 382,341 — 382,341 — Other investments 62,952 62,952 — 62,952 — Loans held for sale 5,763 5,763 — 5,763 — Loans 4,683,750 4,690,852 — 30,979 4,659,873 Financial liabilities Deposits 4,195,894 4,198,817 — 4,198,817 — Short-term borrowings 1,510,825 1,510,718 — 1,510,718 — Long-term debt 9,314 9,834 — 9,834 — Subordinated debt 72,167 62,794 — — 62,794

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax provision for the years ended December 31 is as follows: 2016 2015 2014 (dollars in thousands) Current tax provision Federal $ 19,879 $ 8,610 $ 12,661 State 154 68 157 Total current tax provision 20,033 8,678 12,818 Deferred tax provision (benefit): Federal 5,846 12,158 4,862 State (240 ) — — Total deferred tax provision 5,606 12,158 4,862 Total tax provision $ 25,639 $ 20,836 $ 17,680 The statutory to effective tax rate reconciliation for the years ended December 31 is as follows: 2016 2015 2014 Amount % of Amount % of Amount % of (dollars in thousands) Tax at statutory rate $ 29,830 35 % $ 24,843 35 % $ 21,747 35 % Increase (decrease) resulting from: Income from bank owned life insurance (1,883 ) (2 ) (1,894 ) (3 ) (1,926 ) (3 ) Tax-exempt interest income, net (2,434 ) (3 ) (2,232 ) (3 ) (2,133 ) (4 ) Tax credits — — (61 ) — (134 ) — Other 126 — 180 — 126 — Total tax provision $ 25,639 30 % $ 20,836 29 % $ 17,680 28 % The total tax provision for financial reporting differs from the amount computed by applying the statutory federal income tax rate to income before taxes. First Commonwealth ordinarily generates an annual effective tax rate that is less than the statutory rate of 35% due to benefits resulting from tax-exempt interest, income from bank owned life insurance and tax benefits associated with low income housing tax credits. The consistent level of tax benefits that reduce First Commonwealth’s tax rate below the 35% statutory rate produced an annual effective tax rate of 30% , 29% and 28% for the years ended December 31, 2016 , 2015 and 2014 , respectively. The tax effects of temporary differences between the financial statement carrying amounts and the tax bases of assets and liabilities that represent significant portions of the deferred tax assets and liabilities at December 31 are presented below: 2016 2015 (dollars in thousands) Deferred tax assets: Allowance for credit losses $ 17,616 $ 17,784 Postretirement benefits other than pensions 611 641 Alternative minimum tax credit carryforward — 5,065 Litigation reserve 106 — Unrealized loss on securities available for sale 3,905 1,291 Writedown of other real estate owned 1,266 1,087 Deferred compensation 1,966 2,113 Accrued interest on nonaccrual loans 1,701 1,452 Other-than-temporary impairment of securities 88 89 Depreciation of assets — 879 Accrued incentives 2,627 1,629 Unfunded loan commitment allowance 1,452 1,557 Accrued severance 102 808 Basis difference in assets acquired 296 417 Loan origination fees and costs 290 141 Deferred rent 1,285 1,258 Other 1,084 1,105 Total deferred tax assets 34,395 37,316 Deferred tax liabilities: Income from unconsolidated subsidiary (623 ) (619 ) Depreciation of assets (28 ) — Other (429 ) (337 ) Total deferred tax liabilities (1,080 ) (956 ) Net deferred tax asset $ 33,315 $ 36,360 Management assesses all available positive and negative evidence to estimate if sufficient future taxable income will be generated to utilize the existing deferred tax assets. Based on on our evaluation, of December 31, 2016 , management has determined that no valuation allowance is necessary for the deferred tax assets because it is more likely than not that these assets will be realized through a carry-back to taxable income in prior years, future reversals of existing temporary differences, and through future taxable income. In accordance with FASB ASC Topic 740-10, “Accounting for Uncertainty in Income Taxes," the Company has no material unrecognized tax benefits or accrued interest and penalties as of December 31, 2016. We do not expect the total amount of unrecognized tax benefits to significantly increase in the next twelve months. The Company records interest and penalties on unrecognized tax benefits as a component of noninterest expense. First Commonwealth is subject to routine audits of our tax returns by the Internal Revenue Service ("IRS") as well as all states in which we conduct business. During 2015, the IRS completed an examination of our 2013 federal tax return. The examination was closed with no adjustments. Generally, tax years prior to the year ended December 31, 2013 are no longer open to examination by federal and state taxing authorities.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Retirement Plans	Retirement Plans First Commonwealth has a savings plan pursuant to the provisions of section 401(k) of the Internal Revenue code. Effective January 1, 2013, a participating employee can receive a maximum matching contribution of 6% of their compensation. In addition, each participating employee may contribute up to 80% of their eligible compensation to the plan. The 401(k) plan expense was $2.5 million in 2016 , $2.7 million in 2015 , and $2.6 million in 2014 . First Commonwealth maintains a Non-Qualified Deferred Compensation Plan ( “ NQDC Plan ” ) to provide deferred compensation for those employees whose total annual or annualized Plan compensation for a calendar year is at least $110,000 . The NQDC Plan provides participants whose maximum retirement contribution is limited by IRS rules to defer additional compensation. Participants in the NQDC Plan are eligible to defer (on a pre-tax basis) from 1% to 25% of their eligible Plan compensation. There was no NQDC Plan expense in 2016 , 2015 and 2014 . Select employees from former acquisitions were covered by postretirement benefit plans which provide medical and life insurance coverage. The measurement date for these plans was December 31. Postretirement Benefits Other than Pensions from Prior Acquisitions Net periodic benefit cost of these plans for the years ended December 31, was as follows: 2016 2015 2014 (dollars in thousands) Service cost $ — $ — $ — Interest cost on projected benefit obligation 67 62 62 Amortization of transition obligation — — — Gain amortization (7 ) (4 ) (29 ) Net periodic benefit cost $ 60 $ 58 $ 33 The following table sets forth the change in the benefit obligation and plan assets as of December 31: 2016 2015 (dollars in thousands) Change in Benefit Obligation Benefit obligation at beginning of year $ 1,815 $ 1,822 Service cost — — Interest cost 67 62 Amendments — — Actuarial loss (gain) (337 ) 98 Net benefits paid (151 ) (167 ) Benefit obligation at end of year 1,394 1,815 Change in Plan Assets Fair value of plan assets at beginning of year — — Actual return on plan assets — — Employer contributions 151 167 Net benefits paid (151 ) (167 ) Fair value of plan assets at end of year — — Funded Status at End of Year 1,394 1,815 Unrecognized transition obligation — — Unrecognized net gain 345 15 Amounts recognized in retained earnings $ 1,739 $ 1,830 As of December 31, the funded status of the plan is: 2016 2015 (dollars in thousands) Amounts Recognized in the Statement of Financial Condition as Other liabilities $ 1,394 $ 1,815 The following table sets forth the amounts recognized in accumulated other comprehensive income that have not yet been recognized as components of net periodic benefit costs as of December 31: 2016 2015 2014 (dollars in thousands) Amounts recognized in accumulated other comprehensive income, net of tax: Net (gain) loss $ (225 ) $ (10 ) $ (76 ) Transition obligation — — — Total $ (225 ) $ (10 ) $ (76 ) Weighted-average assumptions used to determine the benefit obligation as of December 31 are as follows: 2016 2015 2014 Weighted-average Assumptions Discount rate 3.74 % 3.88 % 3.61 % Health care cost trend: Initial 6.00 % 6.25 % 6.50 % Health care cost trend: Ultimate 4.75 % 4.75 % 4.75 % Year ultimate reached 2022 2022 2022 Weighted-average assumptions used to determine the net benefit costs as of December 31 are as follows: 2016 2015 2014 Weighted Average Assumptions for Net Periodic Cost Discount rate 3.88 % 3.61 % 4.01 % Health care cost trend: Initial 6.25 % 6.50 % 6.75 % Health care cost trend: Ultimate 4.75 % 4.75 % 4.75 % Year ultimate reached 2022 2022 2022 Corridor 10.00 % 10.00 % 10.00 % Recognition period for gains and losses 11.0 11.0 10.0 The Medicare Prescription Drug, Improvement and Modernization Act of 2003 (the “Act”) introduced a prescription drug benefit under Medicare Part D and a federal subsidy to sponsors of retiree health care benefit plans that provide a prescription drug benefit that is at least actuarially equivalent to Medicare Part D. The postretirement plans of First Commonwealth are provided through insurance coverage; therefore, First Commonwealth will not receive a direct federal subsidy. The preceding measures of the accumulated postretirement benefit cost assume that First Commonwealth will not receive the subsidy due to the relatively small number of retirees. The health care cost trend rate assumption can have a significant impact on the amounts reported for this plan. A one-percentage-point change in assumed health care cost trend rates would have the following effects: One-Percentage- One-Percentage- (dollars in thousands) Effect on postretirement benefit obligation $ 44 $ (40 ) Effect on total of service and interest cost components 3 (3 ) As of December 31, 2016 , the projected benefit payments for the next ten years are as follows: Projected Benefit (dollars in thousands) 2017 $ 174 2018 162 2019 137 2020 130 2021 123 2022 - 2026 500 The projected payments were calculated using the same assumptions as those used to calculate the benefit obligations included in this note. The estimated costs that will be amortized from accumulated other comprehensive income into net periodic cost for 2017 are as follows (dollars in thousands): Postretirement (dollars in thousands) Net gain $ 21 Transition obligation — Total $ 21

Incentive Compensation Plan

Incentive Compensation Plan	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Incentive Compensation Plan	Incentive Compensation Plan On January 20, 2009, the Board of Directors of the Company adopted, with shareholder approval, the First Commonwealth Financial Corporation Incentive Compensation Plan. This plan allows for shares of common stock to be issued to employees, directors, and consultants of the Company and its subsidiaries as an incentive to aid in the financial success of the Company. The shares can be issued as options, stock appreciation rights, performance share or unit awards, dividend or dividend equivalent rights, stock awards, restricted stock awards, or other annual incentive awards. Up to 5,000,000 shares of stock can be awarded under this plan, of which 3,673,796 shares were still eligible for awards as of December 31, 2016 . Restricted Stock The following provides detail on the restricted stock awards which were issued and outstanding in 2016 , 2015 and 2014 in order to retain and attract key employees. The grant date fair value of the restricted stock awards is equal to the price of First Commonwealth’s common stock on grant date. Grant Date Shares issued Grant Price Vesting Date Number of Equal Vesting Periods December 19, 2016 15,000 $ 13.96 December 19, 2019 3 September 30, 2016 10,000 10.09 September 30, 2019 1 September 19, 2016 33,000 10.02 September 19, 2019 3 June 7, 2016 10,000 9.34 June 7, 2019 1 March 1, 2016 10,000 8.84 March 1, 2019 1 March 1, 2016 5,000 8.84 March 1, 2019 1 March 1, 2016 20,000 8.84 March 1, 2019 1 February 18, 2016 18,348 8.43 December 31, 2016 1 June 26, 2015 1,000 9.84 June 26, 2018 1 February 20, 2015 10,000 8.45 February 20, 2018 1 February 20, 2015 34,200 8.45 December 31, 2015 1 February 5, 2015 50,000 8.55 February 5, 2018 1 January 29, 2015 20,170 7.93 December 31, 2015 1 January 15, 2015 20,000 8.38 January 15, 2017 1 November 17, 2014 3,500 9.26 November 17, 2017 1 April 8, 2014 27,500 8.89 April 8, 2017 3 March 24, 2014 46,000 9.18 March 24, 2017 1 March 4, 2014 5,000 8.75 March 4, 2017 1 January 1, 2014 12,626 8.82 December 31, 2014 1 August 16, 2013 3,000 7.57 August 16, 2016 1 May 31, 2013 45,000 7.21 May 31, 2016 3 March 1, 2013 10,000 7.35 March 1, 2016 1 February 24, 2012 34,000 5.96 December 31, 2014 1 February 24, 2012 90,000 5.96 February 24, 2015 1 January 1, 2012 100,000 5.26 January 1, 2016 4 November 21, 2011 10,000 4.41 November 21, 2014 1 April 1, 2011 25,000 6.82 April 1, 2016 1 Compensation expense related to restricted stock was $3.2 million , $1.4 million and $1.0 million in 2016 , 2015 and 2014 , respectively. As of December 31, 2016 , there was $3.8 million of unrecognized compensation cost related to unvested restricted stock awards granted. A summary of the status of First Commonwealth’s unvested service-based restricted stock awards as of December 31 and changes for the years ended on those dates is presented below: 2016 2015 2014 Shares Weighted Shares Weighted Shares Weighted Outstanding, beginning of the year 231,834 $ 8.01 265,000 $ 7.08 271,000 $ 6.07 Granted 121,348 9.88 135,370 8.41 94,626 9.03 Vested (105,514 ) 7.04 (168,536 ) 6.87 (98,487 ) 6.18 Forfeited — — — — (2,139 ) 5.96 Outstanding, end of the year 247,668 9.34 231,834 8.01 265,000 7.08 The following provides detail on restricted stock awards estimated to be granted on a performance award basis during 2016 , 2015 and 2014 . These plans were previously approved by the Board of Directors. Grant Date Target Share Award Performance Period (years) Award if threshold met Award if targets are met Award if superior met Award if threshold not achieved Vesting After Performance Period (years) Final vesting January 17, 2011 54,166 3 40 % 100 % 200 % — % 1 January 17, 2014 February 24, 2012 68,000 3 40 % 100 % 200 % — % 1 December 31, 2015 January 28, 2013 128,611 3 40 % 100 % 200 % — % 1 December 31, 2016 January 27, 2014 125,000 3 40 % 100 % 200 % — % 0 December 31, 2016 January 26, 2015 125,000 3 40 % 100 % 200 % — % 0 December 31, 2017 December 30, 2015 60,000 5 0 December 31, 2020 February 18, 2016 160,650 3 40 % 100 % 200 % — % 0 December 31, 2018 The following table summarizes the estimated unvested target share awards for the Plans as of December 31: 2016 2015 2014 Outstanding, beginning of the year 320,705 284,000 250,777 Granted 176,936 185,000 126,389 Issued (18,348 ) (34,200 ) (12,626 ) Forfeited (52,697 ) (114,095 ) (80,540 ) Outstanding, end of the year 426,596 320,705 284,000 The estimated unvested target awards for the Plans have an estimated fair value of $14.18 per share for each year based on the closing price of Company stock as of December 31, 2016 .

Contingent Liabilities

Contingent Liabilities	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	Contingent Liabilities Legal proceedings First Commonwealth and its subsidiaries are subject in the normal course of business to various pending and threatened legal proceedings in which claims for monetary damages are asserted. As of December 31, 2016, management, after consultation with legal counsel, does not anticipate that the aggregate ultimate liability arising out of litigation pending or threatened against First Commonwealth or its subsidiaries will be material to First Commonwealth’s consolidated financial position. On at least a quarterly basis, First Commonwealth assesses its liabilities and contingencies in connection with such legal proceedings. For those matters where it is probable that First Commonwealth will incur losses and the amounts of the losses can be reasonably estimated, First Commonwealth records an expense and corresponding liability in its consolidated financial statements. To the extent the pending or threatened litigation could result in exposure in excess of that liability, the amount of such excess is not currently estimable. Although not considered probable, the range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability (if any), is between $0 and $7 million . Although First Commonwealth does not believe that the outcome of pending litigation will be material to First Commonwealth’s consolidated financial position, it cannot rule out the possibility that such outcomes will be material to the consolidated results of operations and cash flows for a particular reporting period in the future. First Commonwealth Financial Corporation and First Commonwealth Bank were named defendants in an action commenced August 27, 2015 by eight named plaintiffs that is pending in the Court of Common Pleas of Jefferson County, Pennsylvania. The plaintiffs allege that the Bank repossessed motor vehicles, sold the vehicles and sought to collect deficiency balances in a manner that did not comply with the notice requirements of the Pennsylvania Uniform Commercial Code (UCC), charged inappropriate costs and fees, including storage costs for dates that a repossessed vehicle was not in storage, and wrongly filed forms with the Department of Motor Vehicles asserting that the Bank had complied with applicable laws relating to the repossession of the vehicles. The plaintiffs seek to pursue the action as a class action on behalf of the named plaintiffs and other similarly situated plaintiffs who had their automobiles repossessed and seek to recover damages under the UCC and the Pennsylvania Fair Credit Extension Uniformity Act. First Commonwealth and the Bank contest the plaintiffs’ allegations and intend to oppose class certification. The Bank has also asserted counterclaims for breach of contract, set-off and recoupment against the plaintiffs, individually, and as representatives of the putative class. As set forth in the preceding paragraph, all current litigation matters, including this action, are believed to be within the range of reasonably possible losses for such matters in the aggregate set forth above.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Some of First Commonwealth’s directors, executive officers, principal shareholders and their related interests had transactions with the subsidiary bank in the ordinary course of business. All deposit and loan transactions were made on substantially the same terms, such as collateral and interest rates, as those prevailing at the time for comparable transactions. In the opinion of management, these transactions do not involve more than the normal risk of collectibility nor do they present other unfavorable features. It is anticipated that similar transactions will be entered into in the future. The following is an analysis of loans to related parties (dollars in thousands): December 31, 2015 $ 1,139 Advances 800 Repayments (775 ) December 31, 2016 $ 1,164

Regulatory Restrictions and Cap

Regulatory Restrictions and Capital Adequacy	12 Months Ended
	Dec. 31, 2016
Regulatory Capital Requirements [Abstract]
Regulatory Restrictions and Capital Adequacy	Regulatory Restrictions and Capital Adequacy The amount of funds available to the parent from its subsidiary bank is limited by restrictions imposed on all depository institutions by banking regulation that restricts and limits the payment of dividends and the ability of depository institutions to engage in transactions, including lending transactions and asset purchases, with affiliates. First Commonwealth and First Commonwealth Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators which, if undertaken, could have a direct material effect on First Commonwealth’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, First Commonwealth and First Commonwealth Bank must meet specific capital guidelines that involve quantitative measures of First Commonwealth’s assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. First Commonwealth’s capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weighting and other factors. First Commonwealth maintains capital to absorb unexpected losses. In order to provide assurance that our capital levels are adequate for our risk exposure we test our capital position under several stress scenarios on an annual basis. This analysis is subject to Board of Director review and approval. Our most recent capital stress test was completed in September 2016. Effective January 1, 2015, the Company became subject to new regulatory risk-based capital rules adopted by the federal banking agencies implementing Basel III. The most significant changes include higher minimum capital requirements, as the minimum Tier I capital ratio increased from 4.0% to 6.0% , and a new common equity Tier I capital ratio was established with a minimum level of 4.5% . Additionally, the new rules improve the quality of capital by providing stricter eligibility criteria for regulatory capital instruments and provide for a phase-in, beginning January 1, 2016, of a capital conservation buffer of 2.5% of risk-weighted assets. This buffer provides a requirement to hold common equity Tier 1 capital above the minimum risk-based capital requirements, resulting in an effective common equity Tier I risk-weighted asset minimum ratio of 7% on a fully phased-in basis. The Basel III Rules also permit banking organizations with less than $15.0 billion in assets to retain, through a one-time election, the exclusion of accumulated other comprehensive income from regulatory capital. The Company elected to retain this treatment, which reduces the volatility of regulatory capital levels. As of December 31, 2016 and 2015 , First Commonwealth and First Commonwealth Bank met all capital adequacy requirements to which they are subject and was considered well-capitalized under the regulatory rules, all on a fully phased-in basis. To be considered well-capitalized, the Company must maintain minimum Total risk-based capital, Tier I risk-based capital, Tier I leverage ratio and Common equity tier I risk-based capital as set forth in the table below: Actual Minimum Capital Required - Basel III Phase-In Schedule Minimum Capital Required - Basel III Fully Phased-In Required to be Considered Well Capital Ratio Capital Ratio Capital Ratio Capital Ratio (dollars in thousands) As of December 31, 2016 Total Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 687,554 12.28 % $ 483,034 8.63 % $ 588,042 10.50 % $ 560,040 10.00 % First Commonwealth Bank 617,076 11.06 481,248 8.63 585,867 10.50 557,969 10.00 Tier I Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 633,262 11.31 % $ 371,026 6.63 % $ 476,034 8.50 % $ 448,032 8.00 % First Commonwealth Bank 562,784 10.09 369,654 6.63 474,273 8.50 446,375 8.00 Tier I Capital to Average Assets First Commonwealth Financial Corporation $ 633,262 9.83 % $ 257,776 4.00 % $ 257,776 4.00 % $ 322,220 5.00 % First Commonwealth Bank 562,784 8.79 256,214 4.00 256,214 4.00 320,268 5.00 Common Equity Tier I to Risk Weighted Assets First Commonwealth Financial Corporation $ 563,262 10.06 % $ 287,020 5.13 % $ 392,028 7.00 % $ 364,026 6.50 % First Commonwealth Bank 562,784 10.09 285,959 5.13 390,578 7.00 362,680 6.50 Actual Minimum Capital Required - Basel III Phase-In Schedule Minimum Capital Required - Basel III Fully Phased-In Required to be Considered Well Capital Ratio Capital Ratio Capital Ratio Capital Ratio (dollars in thousands) As of December 31, 2015 Total Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 682,199 12.25 % $ 445,650 8.00 % $ 584,915 10.50 % $ 557,062 10.00 % First Commonwealth Bank 656,244 11.78 445,642 8.00 584,905 10.50 557,052 10.00 Tier I Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 626,939 11.25 % $ 334,237 6.00 % $ 473,503 8.50 % $ 445,650 8.00 % First Commonwealth Bank 600,984 10.79 334,231 6.00 473,494 8.50 445,642 8.00 Tier I Capital to Average Assets First Commonwealth Financial Corporation $ 626,939 9.85 % $ 254,631 4.00 % $ 254,631 4.00 % $ 318,289 5.00 % First Commonwealth Bank 600,984 9.46 254,095 4.00 254,095 4.00 317,618 5.00 Common Equity Tier I to Risk Weighted Assets First Commonwealth Financial Corporation $ 556,939 10.00 % $ 250,678 4.50 % $ 389,944 7.00 % $ 362,091 6.50 % First Commonwealth Bank 535,814 9.62 250,673 4.50 389,937 7.00 362,084 6.50

Capital

Capital	12 Months Ended
	Dec. 31, 2016
Disclosure Capital Additional Information [Abstract]
Capital	Capital On June 19, 2012 First Commonwealth announced a $50.0 million common stock repurchase program. On January 29, 2013, January 28, 2014, January 27, 2015 and on February 17, 2016, additional share repurchase programs were authorized for up to $25.0 million in shares of the Company’s common stock for each of the four repurchase programs. During 2016, the Company had purchased 45,612 shares at an average price of $8.46 per share under the program. The repurchase program was suspended in July 2016 as a result of the acquisition of thirteen branches in northern Ohio which management believes represents a better use of capital for shareholder. Repurchases under all programs resulted in a total of 16,665,735 shares repurchased at an average price of $7.55 per share.

Acquisition

Acquisition	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisition	Acquisition In October 2016, we entered into an agreement and plan of merger to acquire DCB Financial Corp and its banking subsidiary, The Delaware County Bank and Trust Company, with approximately $550 million in total assets, $477 million in total deposits, $388 million in total loans and nine full-service banking offices in the Columbus MSA. This merger is expected to be completed in the second quarter of 2017. On December 2, 2016, the Company completed the acquisition of thirteen branches from FirstMerit Bank, NA receiving $476.6 million in cash. This acquisition further expands the Company's market into northern Ohio and included the purchase of $105.6 million in loans and $619.7 million in deposits. On October 1, 2015, the Company completed the acquisition of Columbus, Ohio based First Community Bank for $14.75 million cash. Upon closing of the transaction, First Community Bank merged into First Commonwealth Bank. First Community Bank operated four branch locations which after the merger operate under the First Commonwealth name. The acquisition expanded the Company’s market into the central Ohio area. The table below summarizes the net assets acquired (at fair value) and consideration transferred in connection with the FirstMerit Bank, NA, acquisition (dollars in thousands): Consideration Received Cash received $ (476,555 ) Total consideration received $ (476,555 ) Fair Value of Assets Acquired Cash and cash equivalents 2,914 Loans 102,097 Premises and other equipment 4,562 Core deposit intangible 11,330 Other assets 294 Total assets acquired 121,197 Fair Value of Liabilities Assumed Deposits 619,729 Other Liabilities 70 Total liabilities assumed 619,799 Total Fair Value of Identifiable Net Assets (498,602 ) Goodwill $ 22,047 The goodwill of $22.0 million arising from the acquisition consists largely of the synergies and economies of scale expected from combining the operations of the Company with the branches acquired from FirstMerit Bank, NA. The goodwill for this transaction is expected to be deducted over a 15 year period for income tax purposes. We acquired $105.6 million in total loans and recognized a net combined yield and credit market adjustment of $3.5 million . Costs related to the acquisition totaled $3.2 million . These amounts were expensed as incurred and are recorded as a merger and acquisition related expense in the Consolidated Statements of Income. The table below summarizes the net assets acquired (at fair value) and consideration transferred in connection with the First Community acquisition (dollars in thousands): Consideration Paid Cash Paid to shareholders $ 14,750 Total consideration paid $ 14,750 Fair Value of Assets Acquired Cash and cash equivalents 11,217 Investment Securities 25,980 FHLB Stock 832 Loans 61,173 Premises and other equipment 1,801 Core deposit intangible 172 Other real estate 816 Other assets 1,115 Total assets acquired 103,106 Fair Value of Liabilities Assumed Deposits 90,311 Other Liabilities 1,115 Total liabilities assumed 91,426 Total Fair Value of Identifiable Net Assets 11,680 Goodwill $ 3,070 We acquired $62.5 million in gross loans and recognized a net combined yield and credit market adjustment of $1.3 million . Costs related to the acquisition totaled $0.9 million . These amounts were expensed as incurred and are recorded as a merger and acquisition related expense in the Consolidated Statements of Income. The Company determined that both of these acquisitions constitute a business combination as defined in FASB ASC Topic 805, “Business Combinations.” Accordingly, as of the date of the acquisition, the Company recorded the assets acquired and liabilities assumed at fair value. The Company determined fair values in accordance with the guidance provided in FASB ASC Topic 820, “Fair Value Measurements and Disclosures.” Acquired loans were recorded at fair value with no carryover of the related allowance for loan losses. Fair value is established by discounting the expected future cash flows with a market discount rate for like maturities and risk instruments. At the date of acquisition, none of the loans were accounted for under the guidance of ASC Topic 310-30, “Receivables-Loans and Debt Securities Acquired with Deteriorated Credit Quality.”

Condensed Financial Information

Condensed Financial Information of First Commonwealth Financial Corporation (parent company only)	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Financial Information of First Commonwealth Financial Corporation (parent company only)	Condensed Financial Information of First Commonwealth Financial Corporation (parent company only) Statements of Financial Condition December 31, 2016 2015 (dollars in thousands) Assets Cash $ 30,387 $ 10,003 Loans 19 22 Investment in subsidiaries 770,214 719,073 Investment in unconsolidated subsidiary trusts 2,185 2,182 Investment in jointly-owned company 9,042 8,978 Premises and equipment, net 3,793 3,780 Receivable from subsidiaries 33 441 Dividends receivable from subsidiaries 4,662 714 Other assets 2,453 47,631 Total assets $ 822,788 $ 792,824 Liabilities and Shareholders’ Equity Accrued expenses and other liabilities $ 692 $ 1,111 Subordinated debentures payable 72,167 72,167 Shareholders’ equity 749,929 719,546 Total liabilities and shareholders’ equity $ 822,788 $ 792,824 Statements of Income For the years ended December 31, 2016 2015 2014 (dollars in thousands) Interest and dividends $ 1 $ 1 $ 1 Dividends from subsidiaries 55,510 49,917 49,207 Interest expense (2,635 ) (2,357 ) (2,335 ) Other income 83 232 1,251 Operating expense (4,700 ) (4,989 ) (6,766 ) Income (loss) before taxes and equity in undistributed (loss) earnings of subsidiaries 48,259 42,804 41,358 Applicable income tax benefits 2,515 2,528 2,968 Income before equity in undistributed (loss) earnings of subsidiaries 50,774 45,332 44,326 Equity in undistributed earnings (loss) of subsidiaries 8,816 4,811 127 Net income $ 59,590 $ 50,143 $ 44,453 For the years ended December 31, Statements of Cash Flow 2016 2015 2014 (dollars in thousands) Operating Activities Net income $ 59,590 $ 50,143 $ 44,453 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 355 493 2,150 Net gain (loss) on sales of assets — 240 — Decrease (increase) in prepaid income taxes 7,380 (6,993 ) (487 ) Undistributed equity in subsidiaries (8,816 ) (4,811 ) (127 ) Other net 7,759 10,753 13,077 Net cash provided by operating activities 66,268 49,825 59,066 Investing Activities Net change in loans 3 2 3 Purchases of premises and equipment — 54 (47 ) Proceeds from sale of other assets (332 ) — 13 Proceeds from dissolution of subsidiary 27,017 — — Investment in subsidiaries (47,017 ) — — Net cash (used in) provided by investing activities (20,329 ) 56 (31 ) Financing Activities Discount on dividend reinvestment plan purchases — — (65 ) Dividends paid (24,907 ) (25,089 ) (26,174 ) Proceeds from reissuance of treasury stock 216 192 192 Purchase of treasury stock (864 ) (25,383 ) (30,956 ) Net cash used in financing activities (25,555 ) (50,280 ) (57,003 ) Net increase (decrease) in cash 20,384 (399 ) 2,032 Cash at beginning of year 10,003 10,402 8,370 Cash at end of year $ 30,387 $ 10,003 $ 10,402 Cash dividends declared per common share were $0.28 for 2016 , 2015 and 2014 . First Commonwealth Financial Corporation has an unsecured $15.0 million line of credit with another financial institution. As of December 31, 2016 , there are no amounts outstanding on this line and we are in compliance with all debt covenants related to the line of credit.

Statement of Accounting Polic36

Statement of Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Business Combinations Policy [Policy Text Block]	Business Combinations Business combinations are accounted for by using the acquisition method of accounting. Under the acquisition method, identifiable assets acquired and liabilities assumed at the acquisition date are measured at their fair values as of that date, and are recognized separately from goodwill. The difference between the purchase price and the fair value of the net assets acquired is recorded as goodwill. Results of operations of the acquired entities are included in the consolidated statement of income from the date of acquisition. Acquisition costs are expensed when incurred.
General	General The following summary of accounting and reporting policies is presented to aid the reader in obtaining a better understanding of the consolidated financial statements of First Commonwealth Financial Corporation and its subsidiaries (“First Commonwealth”) contained in this report. The financial information is presented in accordance with generally accepted accounting principles and general practice for financial institutions in the United States of America. In preparing financial statements, management is required to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, these estimates and assumptions affect revenues and expenses in the financial statements and as such, actual results could differ from those estimates. Through its subsidiaries, which include a commercial bank and an insurance agency, First Commonwealth provides a full range of loan, deposit, trust, insurance and personal financial planning services primarily to individuals and small to middle market businesses in fifteen counties in central and western Pennsylvania as well as in central and northern Ohio. First Commonwealth has determined that it has one business segment. First Commonwealth is subject to regulations of certain state and federal agencies. These regulatory agencies periodically examine First Commonwealth for adherence to laws and regulations.
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements include the accounts of First Commonwealth previously defined above. All material intercompany transactions have been eliminated in consolidation. Equity investments of less than a majority but at least 20% ownership are accounted for by the equity method and classified as “Other assets.” Earnings on these investments are reflected in “Other income” on the Consolidated Statements of Income, as appropriate, in the period earned.
Securities	Securities Debt securities that First Commonwealth has the positive intent and ability to hold to maturity are classified as securities held to maturity and are reported at amortized cost adjusted for amortization of premium and accretion of discount on a level yield basis. Debt and equity securities that are bought and held principally for the purpose of selling them in the near term are to be classified as trading securities and reported at fair value, with unrealized gains and losses included in earnings. Debt and equity securities not classified as either held-to-maturity securities or trading securities are classified as securities available for sale and are reported at fair value, with unrealized gains and losses that are not related to impairment excluded from earnings and reported as a component of other comprehensive income, which is included in shareholders’ equity, net of deferred taxes. First Commonwealth has securities classified as held to maturity and available for sale and does not engage in trading activities. First Commonwealth utilizes the specific identification method to determine the net gain or loss on debt securities and the average cost method to determine the net gain or loss on the equity securities. First Commonwealth conducts a comprehensive review of the investment portfolio on a quarterly basis to determine whether other-than-temporary impairment has occurred. Issuer-specific securities whose market values have fallen below their book values are initially selected for more in-depth analysis based on the percentage decline in value and duration of the decline. Issuer-specific securities include obligations of U.S. Government agencies and sponsored enterprises, single issue trust preferred securities, corporate debentures and obligations of states and political subdivisions. Further analysis of these securities includes a review of research reports, analysts’ recommendations, credit rating changes, news stories, annual reports, impact of interest rate changes and any other relevant information pertaining to the affected security. Pooled trust preferred collateralized debt obligations are measured by evaluating all relevant credit and structural aspects, determining appropriate performance assumptions and performing a discounted cash flow analysis. This evaluation includes detailed credit, performance and structural evaluations for each piece of collateral. Other factors in the pooled trust preferred collateralized debt obligations valuation include terms of the structure, the cash flow waterfall (for both interest and principal), the over collateralization and interest coverage tests and events of default/liquidation. Based on this review, a determination is made on a case by case basis as to a potential impairment. Declines in the fair value of individual securities below their cost that are not expected to be recovered will result in write-downs of the individual securities to their fair value. The related write-downs are included in earnings as impairment losses.
Finance, Loan and Lease Receivables, Held-for-sale, Policy [Policy Text Block]	Mortgage Loans Held for Sale Certain residential mortgage loans are originated for sale in the secondary mortgage loan market with the majority sold with servicing rights released. These loans are classified as loans held for sale and are carried at the lower of cost or estimated market value on an aggregate basis. Market value is determined on the basis of rates obtained in the respective secondary market for the type of loan held for sale. Loans are generally sold at a premium or discount from the carrying amount of the loan. Such premium or discount is recognized at the date of sale. Gain or loss on the sale of loans is recorded in non-interest income at the time consideration is received and all other criteria for sales treatment have been met.
Loans	Loans Loans are carried at the principal amount outstanding. Interest is accrued as earned. Loans held for sale are carried at the lower of cost or fair value determined on an individual basis. First Commonwealth considers a loan to be past due and still accruing interest when payment of interest or principal is contractually past due but the loan is both well secured and in the process of collection. For installment, mortgage, term and other loans with amortizing payments that are scheduled monthly, 90 days past due is reached when four monthly payments are due and unpaid. For demand, time and other multi-payment obligations with payments scheduled other than monthly, delinquency status is calculated using number of days instead of number of payments. Revolving credit loans, including personal credit lines and home equity lines, are considered to be 90 days past due when the borrower has not made the minimum payment for four monthly cycles. A loan is placed in nonaccrual status when, based on current information and events, it is probable that First Commonwealth will be unable to fully collect principal or interest due according to the contractual terms of the loan. A loan is also placed in nonaccrual status when, based on regulatory definitions, the loan is maintained on a “cash basis” due to the weakened financial condition of the borrower. When a determination is made to place a loan in nonaccrual status, all accrued and unpaid interest is reversed. Nonaccrual loans are restored to accrual status when, based on a sustained period of repayment by the borrower in accordance with the contractual terms of the loan, First Commonwealth expects repayment of the remaining contractual principal and interest or when the loan otherwise becomes well-secured and in the process of collection. First Commonwealth considers a loan to be a troubled debt restructured loan when the loan terms have been renegotiated to provide a reduction or deferral of principal or interest as a result of the financial difficulties experienced by the borrower, who could not obtain comparable terms from alternate financing sources. A loan is considered to be impaired when, based on current information and events, it is probable that First Commonwealth will be unable to collect principal or interest that is due in accordance with contractual terms of the loan. Impaired loans include nonaccrual loans and troubled debt restructured loans. Loan impairment is measured based on the present value of expected cash flows discounted at the loan’s effective interest rate or, as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. For loans other than those that First Commonwealth expects repayment through liquidation of the collateral, when the remaining recorded investment in the impaired loan is less than or equal to the present value of the expected cash flows, income is applied as a reduction to loan principal rather than interest income. Loans deemed uncollectible are charged off through the allowance for credit losses. Factors considered in assessing ultimate collectibility include past due status, financial condition of the borrower, collateral values and debt covenants including secondary sources of repayment by guarantors. Payments received on previously charged off loans are recorded as recoveries in the allowance for credit losses. Acquired loans are recorded at estimated fair value on the date of acquisition with no carryover of the related allowance for credit losses. The fair value of acquired loans is determined by estimating the principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The estimated fair value considers factors such as loan term, internal risk rating, delinquency status, prepayment rates, estimated value of the underlying collateral and the current interest rate environment.
Loan Fees	Loan Fees Loan origination and commitment fees, net of associated direct costs, are deferred and the net amount is amortized as an adjustment to the related loan yield on the interest method, generally over the contractual life of the related loans or commitments.
Other Real Estate Owned	Other Real Estate Owned Real estate, other than bank premises, is recorded at fair value less estimated selling costs at the time of acquisition. After that time, other real estate is carried at the lower of cost or fair value less estimated costs to sell. Fair value is determined based on an independent appraisal. Expenses related to holding the property and rental income earned on the property are generally reflected in earnings in the current period. Depreciation is not recorded on the other real estate owned properties.
Allowance for Credit Losses	Allowance for Credit Losses First Commonwealth maintains an allowance for credit losses at a level deemed sufficient to absorb losses that are inherent in the loan portfolio. First Commonwealth’s management determines and reviews with the Board of Directors the adequacy of the allowance on a quarterly basis to ensure that the provision for credit losses has been charged against earnings in an amount necessary to maintain the allowance at a level that is appropriate based on management’s assessment of probable estimated losses. First Commonwealth’s methodology for assessing the appropriateness of the allowance for credit losses consists of several key elements. These elements include an assessment of individual problem loans, delinquency and loss experience trends and other relevant factors, all of which may be susceptible to significant changes. The major loan classifications used in the allowance for credit losses calculation include pass, other assets especially mentioned (“OAEM”), substandard and doubtful. Additional information related to these credit quality categories is provided in Note 10, "Loans and Allowance for Credit Losses." First Commonwealth consistently applies the following comprehensive methodology and procedure for determining the allowance for credit losses. All impaired credits in excess of $100 thousand are individually reviewed quarterly. A specific reserve is established for impaired loans that is equal to the total amount of probable unconfirmed losses for the impaired loans that are reviewed. Based on this reserve as a percentage of reviewed loan balances, a reserve is also established for the impaired loan balances that are not individually reviewed. The allowance calculation uses historical charge-off trends to estimate probable unconfirmed losses for each loan category. A multiplier known as the emergence factor is applied to the historical loss rates for non-criticized loans. The emergence factor is calculated by loan category and represents the average time period from when a loss is incurred until the bank experiences a charge-off against the loan. Before applying the adjusted historical loss experience percentages, loan balances are reduced by the portion of the loan balances which are subject to guarantee by a government agency. An additional component of the allowance is determined by management based on a qualitative analysis of certain factors related to portfolio risks and economic conditions. Factors considered by management include employment trends, macroeconomic trends, commercial real estate trends, lending practices, ability and experience of the credit staff, the overall lending environment and external factors such as the regulatory environment and competition. Portfolio risks include unusual changes or recent trends in specific portfolios such as unexpected changes in the trends or levels of delinquency. No matter how detailed an analysis of potential credit losses is performed, these estimates are inherently imprecise. Management must make estimates using assumptions and information that is often subjective and changes rapidly. Loans acquired with evidence of credit deterioration were evaluated and not considered to be significant. The premium or discount estimated through the loan fair value calculation is recognized into interest income on a level yield or straight-line basis over the remaining contractual life of the loans. Additional credit deterioration on acquired loans, in excess of the original credit discount embedded in the fair value determination on the date of acquisition, will be recognized in the allowance for credit losses through the provision for loan losses.
Allowance for Off-Balance Sheet Credit Exposures	Allowance for Off-Balance Sheet Credit Exposures First Commonwealth maintains an allowance for off-balance sheet credit exposure at a level deemed sufficient to absorb losses that are inherent to off-balance sheet credit risk. Management determines the adequacy of the allowance on a quarterly basis, charging the provision against earnings in an amount necessary to maintain the allowance at a level that is appropriate based on management’s assessment of probable estimated losses. The Company’s methodology for assessing the appropriateness of the allowance for off-balance sheet credit exposure consists of analysis of historical usage trends as well as loss history and probability of default rates related to the off-balance sheet category. The calculation begins with historical usage trends related to lines of credit as well as letters of credit and then utilizes those figures to determine the probable usage of available lines. These values are then adjusted by a determined probability of default as well as a loss given default. This amount is adjusted quarterly and reported as part of other operating expenses on the Consolidated Statements of Income.
Bank Owned Life Insurance	Bank Owned Life Insurance First Commonwealth and the banks that First Commonwealth has acquired have purchased insurance on the lives of certain groups of employees. The policies accumulate asset values to meet future liabilities, including the payment of employee benefits such as health care. Increases in the cash surrender value are recorded as non-interest income in the Consolidated Statements of Income. Under some of these policies, the beneficiaries receive a portion of the death benefit.
Premises and Equipment	Premises and Equipment Premises and equipment are carried at cost less accumulated depreciation on First Commonwealth’s Consolidated Statements of Financial Condition. Depreciation is computed on the straight-line and accelerated methods over the estimated useful life of the asset. A straight-line depreciation method was used for substantially all furniture and equipment. The straight-line depreciation method was used for buildings and improvements. Charges for maintenance and repairs are expensed as incurred. Leasehold improvements are expensed over the term of the lease or the estimated useful life of the improvement, whichever is shorter. Software costs are amortized on a straight-line basis over a period not to exceed seven years
Goodwill	Goodwill Intangible assets resulting from acquisitions under the purchase method of accounting consist of goodwill and other intangible assets (see “Other Intangible Assets” section below). Goodwill is not amortized and is subject to at least annual assessments for impairment by applying a fair value based test. First Commonwealth reviews goodwill annually and again at any quarter-end if a material event occurs during the quarter that may affect goodwill. If goodwill testing is required, an assessment of qualitative factors can be completed before performing the two step goodwill impairment test. If an assessment of qualitative factors determines it is more likely than not that the fair value of a reporting unit exceeds its carrying amount, then the two step goodwill impairment test is not required. Goodwill is evaluated for potential impairment by determining if our fair value has fallen below carrying value.
Other Intangible Assets	Other Intangible Assets Other intangible assets consist of core deposits and customer lists obtained through acquisitions. Core deposit intangibles are amortized over their estimated lives using the present value of the benefit of the core deposits and straight-line methods of amortization. Customer list intangibles are amortized over the expected lives using expected cash flows based on retention of the customer base. These intangibles are evaluated for impairment on an annual basis and when events or changes in circumstances indicate that the carrying amount may not be recoverable.
Accounting for the Impairment of Long-Lived Assets	Accounting for the Impairment of Long-Lived Assets First Commonwealth reviews long-lived assets, such as premises and equipment and intangibles, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. These changes in circumstances may include a significant decrease in the market value of an asset or the extent or manner in which an asset is used. If there is an indication that the carrying amount of an asset may not be recoverable, future undiscounted cash flows expected to result from the use of the asset are estimated. If the sum of the expected cash flows is less than the carrying value of the asset, a loss is recognized for the difference between the carrying value and fair value of the asset. Long-lived assets classified as held for sale are measured at the lower of their carrying amount or fair value less cost to sell. Depreciation or amortization is discontinued on long-lived assets classified as held for sale.
Income Taxes	Income Taxes First Commonwealth records taxes in accordance with the asset and liability method of FASB ASC Topic 740, “Income Taxes,” whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities and their respective tax bases given the provisions of the enacted tax laws. Deferred tax assets are reduced, if necessary, by the amount of such benefits that are more likely than not expected to be realized based upon available evidence. In accordance with FASB ASC Topic 740, interest or penalties incurred for taxes will be recorded as a component of noninterest expense.
Comprehensive Income Disclosures	Comprehensive Income Disclosures “Other Comprehensive Income” (comprehensive income, excluding net income) includes the after-tax effect of changes in unrealized holding gains and losses on available-for-sale securities, changes in the funded status of defined benefit postretirement plans and changes in the fair value of the effective portion of cash flow hedges. Comprehensive income is reported in the accompanying Consolidated Statements of Comprehensive Income, net of tax.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks, federal funds sold and interest-bearing bank deposits. Generally, federal funds are sold for one-day periods.
Employee Stock Ownership Plan
Derivatives and Hedging Activities	Derivatives and Hedging Activities First Commonwealth accounts for derivative instruments and hedging activities in accordance with FASB ASC Topic 815, “Derivatives and Hedging.” All derivatives are evaluated at inception as to whether or not they are hedging or non-hedging activities, and appropriate documentation is maintained to support the final determination. First Commonwealth recognizes all derivatives as either assets or liabilities on the Consolidated Statements of Financial Condition and measures those instruments at fair value. For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in OCI. When the cash flows associated with the hedged item are realized, the gain or loss included in OCI is recognized in the Consolidated Statement of Income. When First Commonwealth purchases a portion of a commercial loan that has an existing interest rate swap, it enters a Risk Participation Agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to First Commonwealth as a result of the risk participation agreement is offset by credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties. Management periodically reviews contracts from various functional areas of First Commonwealth to identify potential derivatives embedded within selected contracts. As of December 31, 2016 , First Commonwealth has interest derivative positions that are not designated as hedging instruments. See Note 7, “Derivatives,” for a description of these instruments.
Earnings Per Common Share	Earnings Per Common Share Basic earnings per share excludes dilution and is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity. For all periods presented, the dilutive effect on average shares outstanding is the result of compensatory stock options outstanding and unvested restricted stock grants.
Fair Value Measurements	Fair Value Measurements In accordance with FASB ASC Topic 820, “Fair Value Measurements and Disclosures,” First Commonwealth groups financial assets and financial liabilities measured at fair value into three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: • Level 1—Valuations for assets and liabilities traded in active exchange markets, such as the New York Stock Exchange. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities. • Level 2—Valuations for assets and liabilities traded in less active dealer or broker markets. Valuations are obtained for identical or comparable assets or liabilities from alternative pricing sources with reasonable levels of price transparency. Level 2 securities include U.S. Government securities issued by Agencies and Sponsored Enterprises, Obligations of States and Political Subdivisions, certain corporate securities, FHLB stock, loans held for sale, interest rate derivatives that include interest rate swaps, risk participation agreements and foreign currency contracts, certain other real estate owned and certain impaired loans. • Level 3—Valuations for assets and liabilities that are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and not based on market exchange, dealer or broker traded transactions. If the inputs used to provide the evaluation are unobservable and/or there is very little, if any, market activity for the security or similar securities, the securities would be considered Level 3 securities. Level 3 valuations incorporate certain assumptions and projections in determining the fair value assigned to such assets or liabilities. The assets included in Level 3 are pooled trust preferred collateralized debt obligations, nonmarketable equity investments, certain other real estate owned and certain impaired loans. In general, fair values of financial instruments are based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon pricing models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and our creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. See Note 18 “Fair Values of Assets and Liabilities” for additional information.
New Accounting Pronouncements, Policy	New Accounting Pronouncements In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers (Topic 606) ” . In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers (Topic 606)", with an original effective date for annual reporting periods beginning after December 15, 2016. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2015-14 deferred the effective date of ASU 2014-09 to annual periods and interim periods within those annual periods beginning after December 15, 2017. We are currently evaluating the potential impact of ASU 2015-14 on our financial statements. In January 2016, the FASB issued ASU 2016-1, “Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments, (vi) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and (viii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. ASU 2016-1 will be effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, and is not expected to have a significant impact on our financial statements In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)," requiring the recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. Lessor accounting under the new guidance remains largely unchanged as it is substantially equivalent to existing guidance for sales-type leases, direct financing leases, and operating leases. Leveraged leases have been eliminated, although lessors can continue to account for existing leveraged leases using the current accounting guidance. All entities will classify leases to determine how to recognize lease-related revenue and expense. Quantitative and qualitative disclosures will be required by lessees and lessors to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. All entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. We are currently evaluating the potential impact of ASU 2016-02 on our financial statements. In March 2016, FASB issued ASU No. 2016-05, "Derivatives and Hedging (Topic 815)," which clarifies that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument under Topic 815 does not, in and of itself, require de-designation of that hedging relationship provided that all other hedge accounting criteria continue to be met. This ASU is effective for public entities beginning after December 15, 2016, and interim periods within those fiscal years. The adoption of this ASU is not expected to have a material impact on First Commonwealth’s financial condition or results of operations. In March 2016, FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718) - Improvements to Employee Share-Based Payment Accounting.” This update requires all income tax effects of awards to be recognized in the income statement when the awards vest or are settled. It also allows an employer to repurchase more of an employee’s shares than it can today for tax withholding purposes without triggering liability accounting and to make a policy election for forfeitures as they occur. The guidance is effective for public business entities for fiscal years beginning after December 15, 2016, and interim periods within those years. The adoption of this ASU is not expected to have a material impact on First Commonwealth’s financial condition or results of operations. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments,” which amends the guidance for recognizing credit losses from an “incurred loss” methodology that delays recognition of credit losses until it is probable a loss has been incurred to an expected credit loss methodology. The guidance requires the use of the modified retrospective transition method by means of a cumulative-effect adjustment to equity as of the beginning of the period in which the guidance is adopted. The standard is effective for the Company as of January 1, 2020. Management is currently evaluating the impact of the amended guidance on First Commonwealth’s financial condition or results of operations. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230),” which provides guidance on eight specific cash flow issues: 1. debt prepayment or extinguishment costs; 2. settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates; 3. contingent consideration payments made after a business combination; 4. proceeds from the settlement of insurance claims; 5. proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; 6. distributions received from equity method investees; 7. beneficial interests in securitizations transactions; and 8. separately identifiable cash flows and application of the predominance principle. This ASU provides additional guidance for these eight issues, reducing current and potential diversity in practice. This standard is effective for the Company as of January 1, 2018. Management is currently evaluating the impact of the amended guidance on First Commonwealth’s financial condition or results of operations.

Supplemental Comprehensive In37

Supplemental Comprehensive Income Disclosures (Tables)	12 Months Ended
	Dec. 31, 2016
Supplemental Comprehensive Income Disclosures [Abstract]
Schedule of Amounts Recognized in Accumulated Other Comprehensive Income	The following table identifies the related tax effects allocated to each component of other comprehensive income in the Consolidated Statements of Comprehensive Income as of December 31 . Reclassification adjustments related to securities available for sale are included in the “ Net securities gains (losses) ” line in the Consolidated Statements of Income and reclassification adjustments related to losses on derivatives are included in the "Other operating expenses" line in the Consolidated Statements of Income. 2016 2015 2014 Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount (dollars in thousands) Unrealized gains (losses) on securities: Unrealized holding (losses) gains on securities arising during the period $ (6,304 ) $ 2,206 $ (4,098 ) $ 2,798 $ (978 ) $ 1,820 $ 25,153 $ (8,803 ) $ 16,350 Reclassification adjustment for (gains) losses on securities included in net income (617 ) 216 (401 ) 153 (54 ) 99 (550 ) 193 (357 ) Total unrealized (losses) gains on securities (6,921 ) 2,422 (4,499 ) 2,951 (1,032 ) 1,919 24,603 (8,610 ) 15,993 Unrealized gains (losses) on derivatives: Unrealized holding (losses) gains on derivatives arising during the period (479 ) 168 (311 ) 450 (158 ) 292 472 (165 ) 307 Reclassification adjustment for gains on derivatives included in net income (70 ) 24 (46 ) (49 ) 17 (32 ) (10 ) 3 (7 ) Total unrealized (losses) gains on derivatives (549 ) 192 (357 ) 401 (141 ) 260 462 (162 ) 300 Unrealized gains (losses) for postretirement obligations: Transition obligation — — — — — — — — — Net gain (loss) 331 (116 ) 215 (102 ) 36 (66 ) (313 ) 109 (204 ) Total unrealized gains (losses) for postretirement obligations 331 (116 ) 215 (102 ) 36 (66 ) (313 ) 109 (204 ) Total other comprehensive (loss) income $ (7,139 ) $ 2,498 $ (4,641 ) $ 3,250 $ (1,137 ) $ 2,113 $ 24,752 $ (8,663 ) $ 16,089 The following table sets forth the amounts recognized in accumulated other comprehensive income that have not yet been recognized as components of net periodic benefit costs as of December 31: 2016 2015 2014 (dollars in thousands) Amounts recognized in accumulated other comprehensive income, net of tax: Net (gain) loss $ (225 ) $ (10 ) $ (76 ) Transition obligation — — — Total $ (225 ) $ (10 ) $ (76 )
Related Tax Effects Allocated to Each Component of Other Comprehensive Income	The following table details the change in components of OCI for the year-ended December 31: 2016 Securities Available for Sale Derivatives Post-Retirement Obligation Accumulated Other Comprehensive Income (dollars in thousands) Balance at January 1 $ (2,956 ) $ 560 $ 10 $ (2,386 ) Other comprehensive loss before reclassification adjustment (4,098 ) (311 ) (4,409 ) Amounts reclassified from accumulated other comprehensive income (loss) (401 ) (46 ) (447 ) Net gain 215 215 Net other comprehensive loss during the period (4,499 ) (357 ) 215 (4,641 ) Balance at December 31 $ (7,455 ) $ 203 $ 225 $ (7,027 ) 2015 Securities Available for Sale Derivatives Post-Retirement Obligation Accumulated Other Comprehensive Income (dollars in thousands) Balance at January 1 $ (4,875 ) $ 300 $ 76 $ (4,499 ) Other comprehensive income before reclassification adjustment 1,820 292 2,112 Amounts reclassified from accumulated other comprehensive income (loss) 99 (32 ) 67 Net gain (66 ) (66 ) Net other comprehensive income during the period 1,919 260 (66 ) 2,113 Balance at December 31 $ (2,956 ) $ 560 $ 10 $ (2,386 ) 2014 Securities Available for Sale Derivatives Post-Retirement Obligation Accumulated Other Comprehensive Income (dollars in thousands) Balance at January 1 $ (20,868 ) $ — $ 280 $ (20,588 ) Other comprehensive income before reclassification adjustment 16,350 307 16,657 Amounts reclassified from accumulated other comprehensive income (loss) (357 ) (7 ) (364 ) Net gain (204 ) (204 ) Net other comprehensive income during the period 15,993 300 (204 ) 16,089 Balance at December 31 $ (4,875 ) $ 300 $ 76 $ (4,499 )

Supplemental Cash Flow Disclo38

Supplemental Cash Flow Disclosures (Tables)	12 Months Ended
	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Non-cash Investing and Financing Activities	The following table presents information related to cash paid during the year for interest and income taxes as well as detail on non-cash investing and financing activities for the years ended December 31 : 2016 2015 2014 (dollars in thousands) Cash paid during the period for: Interest $ 19,208 $ 15,818 $ 18,943 Income taxes 19,950 8,331 10,700 Non-cash investing and financing activities: Loans transferred to other real estate owned and repossessed assets 4,824 8,257 5,061 Fair value of loans transferred from held to maturity to available for sale 18,758 3,196 3,035 Gross (decrease) increase in market value adjustment to securities available for sale (6,919 ) 2,949 24,601 Gross (decrease) increase in market value adjustment to securities derivatives (549 ) 401 472 Investments redeemed, not settled 3,769 — — Investments committed to purchase, not settled — 694 — Net (liabilities) assets acquired through acquisition (501,516 ) 463 — Proceeds from death benefit on bank-owned life insurance not received 437 — — Contribution of premises — — 682

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Composition of Weighted-Average Common Shares (Denominator) Used in Basic and Diluted Earnings Per Share	The following table summarizes the composition of the weighted-average common shares (denominator) used in the basic and diluted earnings per share computation for the years ending December 31 : 2016 2015 2014 Weighted average common shares issued 105,563,455 105,563,455 105,563,455 Average treasury shares (16,605,461 ) (16,045,900 ) (12,294,217 ) Average unearned nonvested shares (106,421 ) (160,788 ) (154,584 ) Weighted average common shares and common stock equivalents used to calculate basic earnings per share 88,851,573 89,356,767 93,114,654 Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share — — — Weighted average common shares and common stock equivalents used to calculate diluted earnings per share 88,851,573 89,356,767 93,114,654
Common Stock Equivalents Not Included in Computation of Diluted Earnings Per Share	The following table shows the number of shares and the price per share related to common stock equivalents that were not included in the computation of diluted earnings per share for the years ended December 31 , because to do so would have been anti-dilutive. 12/31/2016 12/31/2015 12/31/2014 Price Range Price Range Price Range Shares From To Shares From To Shares From To Stock Options — $ — $ — — $ — $ — 15,000 $ 14.55 $ 14.55 Restricted Stock 67,920 8.38 13.96 92,002 6.82 9.84 106,977 5.26 9.26

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Credit Value Adjustment Recorded Related to Notional Amount of Derivatives Outstanding	The following table depicts the credit value adjustment recorded related to the notional amount of derivatives outstanding as well as the notional amount of risk participation agreements participated to other banks at December 31 : 2016 2015 (dollars in thousands) Derivatives not Designated as Hedging Instruments Credit value adjustment $ (317 ) $ (542 ) Notional Amount: Interest rate derivatives 345,102 276,860 Interest rate caps 14,762 22,793 Risk participation agreements 174,213 126,612 Sold credit protection on risk participation agreements (40,281 ) (20,383 ) Derivatives Designated as Hedging Instruments Fair value adjustment (443 ) 922 Notional Amount - Interest rate derivatives 200,000 200,000
Schedule of Change in Fair Value of Derivative Assets and Liabilities	The table below presents the amount representing the change in the fair value of derivative assets and derivative liabilities attributable to credit risk included in “Other income” on the Consolidated Statements of Income for the years ended December 31 : 2016 2015 2014 (dollars in thousands) Non-hedging interest rate derivatives: Increase (decrease) in other income $ 219 $ (274 ) $ (345 ) Hedging interest rate derivatives: Increase in interest income 1,627 2,049 330 Increase in other income 70 64 10

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Held-to-maturity Securities	Below is an analysis of the amortized cost and fair values of debt securities held to maturity at December 31:. 2016 2015 Amortized Gross Gross Estimated Amortized Gross Gross Estimated (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 4,297 $ — $ (4 ) $ 4,293 $ 4,775 $ — $ (7 ) $ 4,768 Mortgage-Backed Securities – Commercial 34,444 — (561 ) 33,883 16,843 — (247 ) 16,596 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 280,430 5 (2,527 ) 277,908 315,609 30 (1,824 ) 313,815 Mortgage-Backed Securities – Commercial 14,675 — (142 ) 14,533 15,187 — (178 ) 15,009 Obligations of States and Political Subdivisions 38,667 55 (721 ) 38,001 31,910 301 (58 ) 32,153 Total Securities Held to Maturity $ 372,513 $ 60 $ (3,955 ) $ 368,618 $ 384,324 $ 331 $ (2,314 ) $ 382,341
Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale	The amortized cost and estimated fair value of debt securities available for sale at December 31, 2016 , by contractual maturity, are shown below: Amortized Estimated (dollars in thousands) Due within 1 year $ 3,300 $ 3,292 Due after 1 but within 5 years 17,397 17,343 Due after 5 but within 10 years 27,075 27,229 Due after 10 years 41,895 35,607 89,667 83,471 Mortgage-Backed Securities (a) 698,745 693,471 Total Debt Securities $ 788,412 $ 776,942 (a) Mortgage Backed Securities include an amortized cost of $15.1 million and a fair value of $16.6 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $683.6 million and a fair value of $676.9 million Below is an analysis of the amortized cost and fair values of securities available for sale at December 31 : 2016 2015 Amortized Gross Gross Estimated Amortized Gross Gross Estimated (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 15,143 $ 1,481 $ (7 ) $ 16,617 $ 20,034 $ 2,071 $ (13 ) $ 22,092 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 683,601 4,557 (11,305 ) 676,853 778,476 7,983 (8,882 ) 777,577 Mortgage-Backed Securities – Commercial 1 — — 1 28 — — 28 Other Government-Sponsored Enterprises 16,700 — (69 ) 16,631 19,201 2 (85 ) 19,118 Obligations of States and Political Subdivisions 27,075 195 (41 ) 27,229 27,066 532 — 27,598 Corporate Securities 5,903 416 — 6,319 1,897 422 — 2,319 Pooled Trust Preferred Collateralized Debt Obligations 39,989 427 (7,124 ) 33,292 42,239 916 (7,497 ) 35,658 Total Debt Securities 788,412 7,076 (18,546 ) 776,942 888,941 11,926 (16,477 ) 884,390 Equities 1,670 — — 1,670 2,170 — — 2,170 Total Securities Available for Sale $ 790,082 $ 7,076 $ (18,546 ) $ 778,612 $ 891,111 $ 11,926 $ (16,477 ) $ 886,560
Proceeds from Sale, Gross Gains (Losses) Realized on Sales, Maturities and Other-Than-Temporary Impairment Charges Related to Securities Available for Sale	(a) Mortgage Backed Securities include an amortized cost of $15.1 million and a fair value of $16.6 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $683.6 million and a fair value of $676.9 million
Investments Classified by Contractual Maturity Date	The amortized cost and estimated fair value of debt securities held to maturity at December 31, 2016 , by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Amortized Estimated (dollars in thousands) Due within 1 year $ — $ — Due after 1 but within 5 years 2,636 2,615 Due after 5 but within 10 years 31,893 31,384 Due after 10 years 4,138 4,002 38,667 38,001 Mortgage-Backed Securities (a) 333,846 330,617 Total Debt Securities $ 372,513 $ 368,618 (a) Mortgage Backed Securities include an amortized cost of $38.7 million and a fair value of $38.2 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $295.1 million and a fair value of $292.4 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac.

Impairment of Investment Secu42

Impairment of Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2016
Impairment of Investment Securities Disclosure [Abstract]
Schedule of Unrealized Losses and Estimated Fair Values	The following table presents the gross unrealized losses and estimated fair values at December 31, 2016 for both available for sale and held to maturity securities by investment category and time frame for which the securities have been in a continuous unrealized loss position: Less Than 12 Months 12 Months or More Total Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 4,898 $ (11 ) $ — $ — $ 4,898 $ (11 ) Mortgage-Backed Securities – Commercial 33,883 (561 ) — — 33,883 (561 ) Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 670,708 (11,630 ) 56,200 (2,202 ) 726,908 (13,832 ) Mortgage-Backed Securities – Commercial 14,534 (142 ) — — 14,534 (142 ) Other Government-Sponsored Enterprises 16,632 (69 ) — — 16,632 (69 ) Obligations of States and Political Subdivisions 33,277 (762 ) — — 33,277 (762 ) Pooled Trust Preferred Collateralized Debt Obligations — — 28,952 (7,124 ) 28,952 (7,124 ) Total Securities $ 773,932 $ (13,175 ) $ 85,152 $ (9,326 ) $ 859,084 $ (22,501 ) At December 31, 2016 , pooled trust preferred collateralized debt obligations accounted for 32% of unrealized losses due to changes in interest rates and the illiquid market for this type of investment. Fixed income securities issued by U.S. Government-sponsored enterprises comprised 62% of total unrealized losses due to changes in market interest rates. Government agencies and obligations of state and political subdivisions each account for 3% of total unrealized losses as a result of changes in market interest rates. At December 31, 2016 , there were 122 debt securities in an unrealized loss position. There were no equity securities in an unrealized loss position at December 31, 2016 . The following table presents the gross unrealized losses and estimated fair value at December 31, 2015 for both available for sale and held to maturity securities by investment category and time frame for which the securities had been in a continuous unrealized loss position: Less Than 12 Months 12 Months or More Total Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities – Residential $ 6,798 $ (20 ) $ — $ — $ 6,798 $ (20 ) Mortgage-Backed Securities – Commercial 16,596 (247 ) — — 16,596 (247 ) Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities – Residential 436,011 (3,293 ) 263,119 (7,413 ) 699,130 (10,706 ) Mortgage-Backed Securities – Commercial 15,009 (178 ) — — 15,009 (178 ) Other Government-Sponsored Enterprises 12,316 (85 ) — — 12,316 (85 ) Obligations of States and Political Subdivisions 7,208 (58 ) — — 7,208 (58 ) Pooled Trust Preferred Collateralized Debt Obligations — — 29,957 (7,497 ) 29,957 (7,497 ) Total Securities $ 493,938 $ (3,881 ) $ 293,076 $ (14,910 ) $ 787,014 $ (18,791 )
Pooled Trust Preferred Collateralized Debt Obligations	The following table provides additional information related to our pooled trust preferred collateralized debt obligations as of December 31, 2016 : Deal Class Book Estimated Fair Unrealized Moody’s/ Number Deferrals Excess (dollars in thousands) Pre TSL IV Mezzanine $ 1,830 $ 1,360 $ (470 ) B1/BB 6 18.05 % 59.78 % Pre TSL VIII Mezzanine 1,963 2,053 90 C/C 28 44.37 0.00 Pre TSL IX Mezzanine 2,412 1,952 (460 ) B1/C 37 27.83 12.79 Pre TSL X Mezzanine 1,738 1,986 248 Caa1/C 42 31.58 2.17 Pre TSL XII Mezzanine 5,890 4,817 (1,073 ) B3/C 64 24.54 0.00 Pre TSL XIII Mezzanine 12,949 10,900 (2,049 ) Ba3/C 54 11.21 55.77 Pre TSL XIV Mezzanine 12,995 9,923 (3,072 ) B1/CC 52 12.78 31.90 MMCap I Mezzanine 212 301 89 Ca/C 8 58.11 80.31 Total $ 39,989 $ 33,292 $ (6,697 )
Cumulative Roll Forward of Credit Losses Recognized in Earnings for Debt Securities Held and Not Intended to be Sold	The table below provides a cumulative roll forward of credit losses recognized in earnings for debt securities held and not intended to be sold for the years ended December 31: 2016 2015 2014 (dollars in thousands) Balance, beginning (a) $ 24,851 $ 26,246 $ 27,543 Credit losses on debt securities for which other-than-temporary impairment was not previously recognized — — — Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized — — — Increases in cash flows expected to be collected, recognized over the remaining life of the security (b) (1,124 ) (1,177 ) (1,297 ) Reduction for debt securities called during the period (6,671 ) (218 ) — Balance, ending $ 17,056 $ 24,851 $ 26,246 (a) The beginning balance represents credit related losses included in other-than-temporary impairment charges recognized on debt securities in prior periods. (b) Represents the increase in cash flows recognized either as principal payments or interest income during the period.

Loans and Allowance for Credi43

Loans and Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Abstract]
Outstanding Balances of Loan	The following table provides outstanding balances related to each of our loan types as of December 31 : 2016 2015 Originated Loans Acquired Loans Total Loans Total Loans (dollars in thousands) Commercial, financial, agricultural and other $ 1,131,148 $ 8,399 $ 1,139,547 $ 1,150,906 Real estate construction 217,840 1,781 219,621 220,736 Residential real estate 1,165,851 63,341 1,229,192 1,224,465 Commercial real estate 1,717,043 25,167 1,742,210 1,479,000 Loans to individuals 546,589 2,188 548,777 608,643 Total loans $ 4,778,471 $ 100,876 $ 4,879,347 $ 4,683,750
Credit Risk Profile by Creditworthiness	The following tables represent our credit risk profile by creditworthiness category for the years ended December 31 : 2016 Commercial, financial, agricultural and other Real estate construction Residential real estate Commercial real estate Loans to individuals Total (dollars in thousands) Originated loans Pass $ 1,038,844 $ 217,565 $ 1,152,511 $ 1,691,220 $ 546,316 $ 4,646,456 Non-Pass OAEM 27,387 275 5,923 7,596 — 41,181 Substandard 64,917 — 7,417 18,227 273 90,834 Doubtful — — — — — — Total Non-Pass 92,304 275 13,340 25,823 273 132,015 Total $ 1,131,148 $ 217,840 $ 1,165,851 $ 1,717,043 $ 546,589 $ 4,778,471 Acquired Loans Pass $ 7,591 $ 1,781 $ 62,919 $ 24,043 $ 2,185 $ 98,519 Non-Pass OAEM 486 — — — — 486 Substandard 322 — 422 1,124 3 1,871 Doubtful — — — — — — Total Non-Pass 808 — 422 1,124 3 2,357 Total $ 8,399 $ 1,781 $ 63,341 $ 25,167 $ 2,188 $ 100,876 2015 Commercial, financial, agricultural and other Real estate construction Residential real estate Commercial real estate Loans to individuals Total (dollars in thousands) Pass $ 1,074,858 $ 220,267 $ 1,209,606 $ 1,436,714 $ 608,342 $ 4,549,787 Non-Pass OAEM 11,825 442 5,244 30,012 — 47,523 Substandard 64,223 27 9,615 12,274 301 86,440 Doubtful — — — — — — Total Non-Pass 76,048 469 14,859 42,286 301 133,963 Total $ 1,150,906 $ 220,736 $ 1,224,465 $ 1,479,000 $ 608,643 $ 4,683,750
Age Analysis of Past Due Loans by Segment	The following tables delineate the aging analysis of the recorded investments in past due loans as of December 31 . Also included in these tables are loans that are 90 days or more past due and still accruing because they are well-secured and in the process of collection. 2016 30 - 59 60 - 89 90 days Nonaccrual Total past Current Total (dollars in thousands) Originated Loans Commercial, financial, agricultural and other $ 2,380 $ 171 $ 75 $ 17,928 $ 20,554 $ 1,110,594 $ 1,131,148 Real estate construction 183 — — — 183 217,657 217,840 Residential real estate 4,133 1,089 995 5,792 12,009 1,153,842 1,165,851 Commercial real estate 265 327 57 3,443 4,092 1,712,951 1,717,043 Loans to individuals 1,640 776 970 273 3,659 542,930 546,589 Total $ 8,601 $ 2,363 $ 2,097 $ 27,436 $ 40,497 $ 4,737,974 $ 4,778,471 Acquired Loans Commercial, financial, agricultural and other $ 486 $ — $ — $ — $ 486 $ 7,913 $ 8,399 Real estate construction — — — — — 1,781 1,781 Residential real estate 148 39 34 422 643 62,698 63,341 Commercial real estate — — — 162 162 25,005 25,167 Loans to individuals 1 7 — 3 11 2,177 2,188 Total $ 635 $ 46 $ 34 $ 587 $ 1,302 $ 99,574 $ 100,876 2015 30 - 59 60 - 89 90 days Nonaccrual Total past Current Total (dollars in thousands) Commercial, financial, agricultural and other $ 364 $ 49 $ 129 $ 23,653 $ 24,195 $ 1,126,711 $ 1,150,906 Real estate construction 280 — — 28 308 220,428 220,736 Residential real estate 4,175 1,055 1,315 6,500 13,045 1,211,420 1,224,465 Commercial real estate 781 — 65 6,223 7,069 1,471,931 1,479,000 Loans to individuals 2,998 774 946 301 5,019 603,624 608,643 Total $ 8,598 $ 1,878 $ 2,455 $ 36,705 $ 49,636 $ 4,634,114 $ 4,683,750
Recorded Investment and Unpaid Principal Balance for Impaired Loans with Associated Allowance	The following tables include the recorded investment and unpaid principal balance for impaired loans with the associated allowance amount, if applicable, as of December 31, 2016 and 2015 . Also presented are the average recorded investment in impaired loans and the related amount of interest recognized while the loan was considered impaired for the years ended December 31, 2016 , 2015 and 2014 . Average balances are calculated based on month-end balances of the loans for the period reported and are included in the table below based on its period end allowance position. 2016 Recorded Unpaid Related Average Interest (dollars in thousands) Originated Loans: With no related allowance recorded: Commercial, financial, agricultural and other $ 9,549 $ 15,369 $ 23,146 $ 576 Real estate construction — — 4 44 Residential real estate 10,873 13,004 10,957 312 Commercial real estate 5,765 6,905 6,718 170 Loans to individuals 382 507 409 15 Subtotal 26,569 35,785 41,234 1,117 With an allowance recorded: Commercial, financial, agricultural and other 13,423 19,226 $ 2,530 13,885 99 Real estate construction — — — — — Residential real estate 424 475 164 241 4 Commercial real estate 810 810 434 555 25 Loans to individuals — — — — — Subtotal 14,657 20,511 3,128 14,681 128 Total $ 41,226 $ 56,296 $ 3,128 $ 55,915 $ 1,245 Acquired Loans: With no related allowance recorded: Commercial, financial, agricultural and other $ — $ — $ — $ — Real estate construction — — — — Residential real estate 406 480 406 — Commercial real estate 162 162 162 — Loans to individuals 3 3 3 — Subtotal 571 645 571 — With an allowance recorded: Commercial, financial, agricultural and other — — $ — — — Real estate construction — — — — — Residential real estate 16 16 16 16 — Commercial real estate — — — — — Loans to individuals — — — — — Subtotal 16 16 16 16 — Total $ 587 $ 661 $ 16 $ 587 $ — 2015 Recorded Unpaid Related Average Interest With no related allowance recorded: Commercial, financial, agricultural and other $ 11,344 $ 15,673 $ 17,692 $ 216 Real estate construction 28 117 95 — Residential real estate 9,952 11,819 10,635 172 Commercial real estate 7,562 9,449 7,890 90 Loans to individuals 421 507 338 4 Subtotal 29,307 37,565 36,650 482 With an allowance recorded: Commercial, financial, agricultural and other 20,132 22,590 $ 6,952 7,731 129 Real estate construction — — — — — Residential real estate 461 672 51 403 — Commercial real estate 944 1,008 42 674 4 Loans to individuals — — — — — Subtotal 21,537 24,270 7,045 8,808 133 Total $ 50,844 $ 61,835 $ 7,045 $ 45,458 $ 615 2014 Average Interest (dollars in thousands) With no related allowance recorded: Commercial, financial, agricultural and other $ 11,536 $ 133 Real estate construction 1,190 19 Residential real estate 11,592 210 Commercial real estate 8,830 98 Loans to individuals 308 4 Subtotal 33,456 464 With an allowance recorded: Commercial, financial, agricultural and other 15,797 143 Real estate construction — — Residential real estate 357 14 Commercial real estate 184 4 Loans to individuals — — Subtotal 16,338 161 Total $ 49,794 $ 625
Troubled Debt Restructured Loans and Commitments	The following table provides information related to restructured loans that were considered to be in default during the year ending December 31 : 2016 2015 2014 Number of Recorded Number of Recorded Number of Recorded (dollars in thousands) Residential real estate 4 $ 313 3 $ 97 2 $ 7 Commercial real estate — — — — 1 6 Total 4 $ 313 3 $ 97 3 $ 13 The following table provides detail as to the total troubled debt restructured loans and total commitments outstanding on troubled debt restructured loans as of December 31 : 2016 2015 2014 (dollars in thousands) Troubled debt restructured loans Accrual status $ 13,790 $ 14,139 $ 12,584 Nonaccrual status 11,569 12,360 16,952 Total $ 25,359 $ 26,499 $ 29,536 Commitments Unused lines of credit 358 3,252 4,120
Troubled Debt Restructurings is 90 Days or More Past Due	he following tables provide detail, including specific reserve and reasons for modification, related to loans identified as troubled debt restructurings during the years ending December 31 : 2016 Type of Modification Number Extend Modify Modify Total Post- Specific (dollars in thousands) Commercial, financial, agricultural and other 5 $ 23 $ 6,318 $ 3,854 $ 10,195 $ 6,210 $ 317 Residential real estate 39 107 214 2,619 2,940 2,698 124 Commercial real estate 8 1,368 — 25 1,393 1,271 59 Loans to individuals 13 23 82 25 130 96 — Total 65 $ 1,521 $ 6,614 $ 6,523 $ 14,658 $ 10,275 $ 500 2015 Type of Modification Number Extend Modify Modify Total Post- Specific (dollars in thousands) Commercial, financial, agricultural and other 12 $ 1,751 $ 3,195 $ 4,527 $ 9,473 $ 8,823 $ 1,330 Residential real estate 32 — 296 1,414 1,710 1,575 2 Commercial real estate 1 — — 464 464 389 — Loans to individuals 16 3 167 35 205 169 — Total 61 $ 1,754 $ 3,658 $ 6,440 $ 11,852 $ 10,956 $ 1,332 2014 Type of Modification Number Extend Modify Modify Total Post- Specific (dollars in thousands) Commercial, financial, agricultural and other 9 $ 5,487 $ — $ 14,529 $ 20,016 $ 13,785 $ 4,665 Residential real estate 52 — 629 1,797 2,426 2,062 — Commercial real estate 1 — — 8 8 6 — Loans to individuals 15 — 103 47 150 114 — Total 77 $ 5,487 $ 732 $ 16,381 $ 22,600 $ 15,967 $ 4,665
Allowance for Credit Losses	The following tables provide detail related to the allowance for credit losses for the years ended December 31 . 2016 Commercial, Real estate Residential Commercial Loans to Total (dollars in thousands) Allowance for credit losses: Beginning Balance on Originated Loans $ 31,035 $ 887 $ 2,606 $ 11,924 $ 4,360 $ 50,812 Charge-offs (19,603 ) — (1,189 ) (570 ) (4,943 ) (26,305 ) Recoveries 4,164 562 481 1,522 469 7,198 Provision (credit) 20,378 (872 ) 594 (6,257 ) 4,618 18,461 Ending Balance on Originated Loans 35,974 577 2,492 6,619 4,504 50,166 Ending Balance on Acquired Loans (1) — — 19 — — 19 Total Ending Balance $ 35,974 $ 577 $ 2,511 $ 6,619 $ 4,504 $ 50,185 Ending balance: individually evaluated for impairment $ 2,530 $ — $ 180 $ 434 $ — $ 3,144 Ending balance: collectively evaluated for impairment 33,444 577 2,331 6,185 4,504 47,041 Loans: Ending balance 1,139,547 219,621 1,229,192 1,742,210 548,777 4,879,347 Ending balance: individually evaluated for impairment 22,325 — 5,875 5,468 — 33,668 Ending balance: collectively evaluated for impairment 1,117,222 219,621 1,223,317 1,736,742 548,777 4,845,679 (1) Amount reflects provision expense and ending allowance balance for loans acquired in 2016 as part of the purchase of FirstMerit branches. 2015 Commercial, Real estate Residential Commercial Loans to Total (dollars in thousands) Allowance for credit losses: Beginning Balance $ 29,627 $ 2,063 $ 3,664 $ 11,881 $ 4,816 $ 52,051 Charge-offs (11,429 ) (8 ) (1,539 ) (1,538 ) (4,354 ) (18,868 ) Recoveries 1,097 84 587 229 684 2,681 Provision (credit) 11,740 (1,252 ) (106 ) 1,352 3,214 14,948 Ending Balance $ 31,035 $ 887 $ 2,606 $ 11,924 $ 4,360 $ 50,812 Ending balance: individually evaluated for impairment $ 6,952 $ — $ 51 $ 42 $ — $ 7,045 Ending balance: collectively evaluated for impairment 24,083 887 2,555 11,882 4,360 43,767 Loans: Ending balance 1,150,906 220,736 1,224,465 1,479,000 608,643 4,683,750 Ending balance: individually evaluated for impairment 30,767 — 6,099 7,143 — 44,009 Ending balance: collectively evaluated for impairment 1,120,139 220,736 1,218,366 1,471,857 608,643 4,639,741 2014 Commercial, Real estate Residential Commercial Loans to Total (dollars in thousands) Allowance for credit losses: Beginning Balance $ 22,663 $ 6,600 $ 7,727 $ 11,778 $ 5,457 $ 54,225 Charge-offs (8,911 ) (296 ) (3,153 ) (1,148 ) (3,964 ) (17,472 ) Recoveries 734 1,340 650 612 766 4,102 Provision (credit) 15,141 (5,581 ) (1,560 ) 639 2,557 11,196 Ending Balance $ 29,627 $ 2,063 $ 3,664 $ 11,881 $ 4,816 $ 52,051 Ending balance: individually evaluated for impairment $ 9,304 $ — $ 56 $ 101 $ — $ 9,461 Ending balance: collectively evaluated for impairment 20,323 2,063 3,608 11,780 4,816 42,590 Loans: Ending balance 1,052,109 120,785 1,226,344 1,405,256 652,814 4,457,308 Ending balance: individually evaluated for impairment 33,332 193 7,127 7,790 — 48,442 Ending balance: collectively evaluated for impairment 1,018,777 120,592 1,219,217 1,397,466 652,814 4,408,866

Commitments and Letters of Cr44

Commitments and Letters of Credit (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Notional Amount of Commitments and Letter of Credit Instruments	The following table identifies the notional amount of those instruments at December 31 : 2016 2015 (dollars in thousands) Financial instruments whose contract amounts represent credit risk: Commitments to extend credit $ 1,733,820 $ 1,643,187 Financial standby letters of credit 18,108 17,843 Performance standby letters of credit 26,630 26,497 Commercial letters of credit 1,301 1,672

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Schedule of Premises and Equipment	Premises and equipment are described as follows: Estimated Useful Life 2016 2015 (dollars in thousands) Land Indefinite $ 13,679 $ 12,185 Buildings and improvements 10-50 years 80,364 77,086 Leasehold improvements 5-40 years 15,871 14,518 Furniture and equipment 3-7 years 61,324 59,463 Software 3-7 years 36,077 34,472 Subtotal 207,315 197,724 Less accumulated depreciation and amortization 139,781 134,270 Total premises and equipment $ 67,534 $ 63,454
Schedule of Future Minimum Rentals	First Commonwealth leases various premises and assorted equipment under non-cancellable agreements. Total future minimal rental commitments at December 31, 2016 , were as follows: Premises Equipment (dollars in thousands) 2017 $ 3,844 $ 10 2018 3,559 — 2019 3,137 — 2020 2,556 — 2021 2,265 — Thereafter 9,693 — Total $ 25,054 $ 10

Goodwill and Other Amortizing46

Goodwill and Other Amortizing Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill Disclosure [Abstract]
Summarized Other Intangible Assets	The following table summarizes other intangible assets: Gross Intangible Assets Accumulated Amortization Net Intangible Assets (dollars in thousands) December 31, 2016 Customer deposit intangibles $ 30,471 $ (18,998 ) $ 11,473 Customer list intangible $ 984 $ (444 ) $ 540 Total other intangible assets $ 31,455 $ (19,442 ) $ 12,013 December 31, 2015 Customer deposit intangibles $ 19,142 $ (18,619 ) $ 523 Customer list intangible $ 984 $ (276 ) $ 708 Total other intangible assets $ 20,126 $ (18,895 ) $ 1,231
Estimated Amortization Expense of Core Deposit Intangibles	The following presents the estimated amortization expense of core deposit intangibles and the customer intangible list: Core Deposit Intangibles Customer List Intangible Total (dollars in thousands) 2017 $ 2,133 $ 129 $ 2,262 2018 1,923 99 2,022 2019 1,709 77 1,786 2020 1,443 59 1,502 2021 1,234 45 1,279 Thereafter 3,031 131 3,162 Total $ 11,473 $ 540 $ 12,013

Interest-Bearing Deposits (Tabl

Interest-Bearing Deposits (Tables)	12 Months Ended
	Dec. 31, 2016
Deposits [Abstract]
Components of Interest-Bearing Deposits	Components of interest-bearing deposits at December 31 were as follows: 2016 2015 (dollars in thousands) Interest-bearing demand deposits $ 114,043 $ 86,365 Savings deposits 2,972,747 2,390,607 Time deposits 591,832 602,233 Total interest-bearing deposits $ 3,678,622 $ 3,079,205
Scheduled Maturities of Time Deposits	Included in time deposits at December 31, 2016 , were certificates of deposit with the following scheduled maturities (dollars in thousands): 2017 $ 319,298 2018 133,754 2019 66,121 2020 33,859 2021 and thereafter 38,800 Total $ 591,832

Short-term Borrowings (Tables)

Short-term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2016
Short-term Debt [Abstract]
Summary of Short-Term Borrowings	Short-term borrowings at December 31 were as follows: 2016 2015 2014 Ending Average Average Ending Average Average Ending Average Average (dollars in thousands) Federal funds purchased $ — $ 6,887 0.60 % $ 4,000 $ 14,832 0.36 % $ 9,000 $ 11,691 0.36 % Borrowings from FHLB 748,000 1,265,932 0.61 1,400,000 1,117,522 0.42 945,000 644,651 0.31 Securities sold under agreements to repurchase 119,943 114,918 0.23 106,825 120,177 0.23 151,876 159,051 0.24 Total $ 867,943 $ 1,387,737 0.58 $ 1,510,825 $ 1,252,531 0.40 $ 1,105,876 $ 815,393 0.30 Maximum total at any month-end $ 1,530,678 $ 1,510,825 $ 1,105,876 Weighted average rate at year-end 0.63 % 0.53 % 0.30 %
Interest Expense on Short-Term Borrowings	Interest expense on short-term borrowings for the years ended December 31 is detailed below: 2016 2015 2014 (dollars in thousands) Federal funds purchased $ 41 $ 54 $ 42 Borrowings from FHLB 7,765 4,684 2,019 Securities sold under agreements to repurchase 270 280 388 Total interest on short-term borrowings $ 8,076 $ 5,018 $ 2,449

Subordinated Debentures (Tables

Subordinated Debentures (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Subordinated Debentures [Abstract]
Subordinated Debentures Outstanding	Subordinated Debentures outstanding at December 31 are as follows: 2016 2015 Due Amount Rate Amount Rate (dollars in thousands) Owed to: First Commonwealth Capital Trust II 2034 $ 30,929 LIBOR + 2.85 $ 30,929 LIBOR + 2.85 First Commonwealth Capital Trust III 2034 41,238 LIBOR + 2.85 41,238 LIBOR + 2.85 Total $ 72,167 $ 72,167

Other Long-term Debt (Tables)

Other Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Summary of Other Long-Term Debt	Other long-term debt at December 31 follows: 2016 2015 Amount Weighted Amount Weighted (dollars in thousands) Borrowings from FHLB due: 2016 $ 563 3.82 % 2017 $ 586 3.83 % 585 3.83 2018 609 3.83 607 3.83 2019 633 3.84 631 3.83 2020 658 3.84 659 3.84 2021 684 3.84 Thereafter 5,579 3.81 6,269 3.81 Total $ 8,749 $ 9,314

Fair Values of Assets and Lia51

Fair Values of Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Quantitative Inputs and Assumptions Used in Level 3 Fair Value Measurements	In accordance with ASU 2011-4, the following table provides information related to quantitative inputs and assumptions used in Level 3 fair value measurements. Fair Value Valuation Technique Unobservable Inputs Range / (weighted Pooled Trust Preferred Securities $ 33,292 Discounted Cash Flow Probability of default 0.00% - 100% (10.67%) Prepayment rates 0.00% - 72.66% (4.15%) Discount rates 5.25% - 12.00% (a) Equities 1,670 Par Value N/A N/A Impaired Loans 2,281 (b) Gas Reserve study Discount rate 10.00% Gas per MCF $1.63 - $3.38 (c) Oil per BBL/d $40.97 - $56.16 (c) 9,303 (b) Discounted Cash Flow Discount Rate 1.90% - 4.68% Limited Partnership Investments 930 Par Value N/A N/A (a) incorporates spread over the risk free rate related primarily to credit quality and illiquidity of securities. (b) the remainder of impaired loans valued using Level 3 inputs are not included in this disclosure as the values of those loans are based on bankruptcy agreement documentation. (c) unobservable inputs are defined as follows: MCF—million cubic feet; BBL/d—barrels per day
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The tables below present the balances of assets and liabilities measured at fair value on a recurring basis at December 31: 2016 Level 1 Level 2 Level 3 Total (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities—Residential $ — $ 16,617 $ — $ 16,617 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities—Residential — 676,853 — 676,853 Mortgage-Backed Securities—Commercial — 1 — 1 Other Government-Sponsored Enterprises — 16,631 — 16,631 Obligations of States and Political Subdivisions — 27,229 — 27,229 Corporate Securities — 6,319 — 6,319 Pooled Trust Preferred Collateralized Debt Obligations — — 33,292 33,292 Total Debt Securities — 743,650 33,292 776,942 Equities — — 1,670 1,670 Total Securities Available for Sale — 743,650 34,962 778,612 Other Investments — 36,498 — 36,498 Loans Held for Sale — 7,052 — 7,052 Other Assets (a) — 6,089 930 7,019 Total Assets $ — $ 793,289 $ 35,892 $ 829,181 Other Liabilities (a) $ — $ 5,972 $ — $ 5,972 Total Liabilities $ — $ 5,972 $ — $ 5,972 (a) Hedging and non-hedging interest rate derivatives and limited partnership investments 2015 Level 1 Level 2 Level 3 Total (dollars in thousands) Obligations of U.S. Government Agencies: Mortgage-Backed Securities—Residential $ — $ 22,092 $ — $ 22,092 Obligations of U.S. Government-Sponsored Enterprises: Mortgage-Backed Securities—Residential — 777,577 — 777,577 Mortgage-Backed Securities—Commercial — 28 — 28 Other Government-Sponsored Enterprises — 19,118 — 19,118 Obligations of States and Political Subdivisions — 27,598 — 27,598 Corporate Securities — 2,319 — 2,319 Pooled Trust Preferred Collateralized Debt Obligations — — 35,658 35,658 Total Debt Securities — 848,732 35,658 884,390 Equities — — 2,170 2,170 Total Securities Available for Sale — 848,732 37,828 886,560 Other Investments — 62,952 — 62,952 Loans Held for Sale — 5,763 — 5,763 Other Assets (a) — 11,273 — 11,273 Total Assets $ — $ 928,720 $ 37,828 $ 966,548 Other Liabilities (a) $ — $ 10,829 $ — $ 10,829 Total Liabilities $ — $ 10,829 $ — $ 10,829 (a) Non-hedging interest rate derivatives
Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis	The changes in Level 3 assets and liabilities measured at fair value on a recurring basis are summarized as follows for the year ended December 31, 2016 : Pooled Trust Equities Other Total (dollars in thousands) Balance, beginning of year $ 35,658 $ 2,170 $ — $ 37,828 Total gains or losses Included in earnings 589 — — 589 Included in other comprehensive income 850 — — 850 Purchases, issuances, sales, and settlements Purchases — 36 394 430 Issuances — — — — Sales — — — — Settlements (3,805 ) — — (3,805 ) Transfers from Level 3 — (536 ) — (536 ) Transfers into Level 3 — — 536 536 Balance, end of year $ 33,292 $ 1,670 $ 930 $ 35,892 There are no gains or losses included in earnings for the period that are attributable to the change in realized gains (losses) relating to assets held at December 31, 2016 . During the year ended December 31, 2016 , $0.5 million in investments in limited partnerships were moved from other equity securities to other assets constituting the transfers into and out of Level 3. There were no transfers between fair value Levels 1 and 2. The changes in Level 3 assets and liabilities measured at fair value on a recurring basis are summarized as follows for the year ended December 31, 2015 : Pooled Trust Equities Other Total (dollars in thousands) Balance, beginning of year $ 28,999 $ 1,420 $ — $ 30,419 Total gains or losses Included in earnings 111 — — 111 Included in other comprehensive income 7,608 — — 7,608 Purchases, issuances, sales, and settlements Purchases — 750 — 750 Issuances — — — — Sales — — — — Settlements (1,060 ) — — (1,060 ) Transfers from Level 3 — — — — Transfers into Level 3 — — — — Balance, end of year $ 35,658 $ 2,170 $ — $ 37,828
Schedule of Assets Measured on Nonrecurring Basis	The tables below present the balances of assets measured at fair value on a nonrecurring basis at December 31 and total gains and losses realized on these assets during the year ended December 31: 2016 Level 1 Level 2 Level 3 Total Total (dollars in thousands) Impaired loans $ — $ 18,679 $ 19,990 $ 38,669 $ (9,032 ) Other real estate owned — 7,566 — 7,566 (703 ) Total Assets $ — $ 26,245 $ 19,990 $ 46,235 $ (9,735 ) 2015 Level 1 Level 2 Level 3 Total Total (dollars in thousands) Impaired loans $ — $ 30,979 $ 12,820 $ 43,799 $ (9,098 ) Other real estate owned — 10,039 8 10,047 (1,693 ) Total Assets $ — $ 41,018 $ 12,828 $ 53,846 $ (10,791 )
Carrying Amounts and Fair Values of Financial Instruments	The following table presents carrying amounts and estimated fair values of First Commonwealth’s financial instruments at December 31: 2016 Fair Value Measurements Using: Carrying Total Level 1 Level 2 Level 3 (dollars in thousands) Financial assets Cash and due from banks $ 91,033 $ 91,033 $ 91,033 $ — $ — Interest-bearing deposits 24,644 24,644 24,644 — — Securities available for sale 778,612 778,612 — 743,650 34,962 Securities held to maturity 372,513 368,618 — 368,618 — Other investments 36,498 36,498 — 36,498 — Loans held for sale 7,052 7,052 — 7,052 — Loans 4,879,347 4,878,254 — 18,679 4,859,575 Financial liabilities Deposits 4,947,408 4,949,714 — 4,949,714 — Short-term borrowings 867,943 867,667 — 867,667 — Long-term debt 8,749 9,169 — 9,169 — Subordinated debt 72,167 65,656 — — 65,656 2015 Fair Value Measurements Using: Carrying Total Level 1 Level 2 Level 3 (dollars in thousands) Financial assets Cash and due from banks $ 66,644 $ 66,644 $ 66,644 $ — $ — Interest-bearing deposits 2,808 2,808 2,808 — — Securities available for sale 886,560 886,560 — 848,732 37,828 Securities held to maturity 384,324 382,341 — 382,341 — Other investments 62,952 62,952 — 62,952 — Loans held for sale 5,763 5,763 — 5,763 — Loans 4,683,750 4,690,852 — 30,979 4,659,873 Financial liabilities Deposits 4,195,894 4,198,817 — 4,198,817 — Short-term borrowings 1,510,825 1,510,718 — 1,510,718 — Long-term debt 9,314 9,834 — 9,834 — Subordinated debt 72,167 62,794 — — 62,794

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Provision (Benefit)	The income tax provision for the years ended December 31 is as follows: 2016 2015 2014 (dollars in thousands) Current tax provision Federal $ 19,879 $ 8,610 $ 12,661 State 154 68 157 Total current tax provision 20,033 8,678 12,818 Deferred tax provision (benefit): Federal 5,846 12,158 4,862 State (240 ) — — Total deferred tax provision 5,606 12,158 4,862 Total tax provision $ 25,639 $ 20,836 $ 17,680
Schedule of Effective Income Tax Rate Reconciliation	The statutory to effective tax rate reconciliation for the years ended December 31 is as follows: 2016 2015 2014 Amount % of Amount % of Amount % of (dollars in thousands) Tax at statutory rate $ 29,830 35 % $ 24,843 35 % $ 21,747 35 % Increase (decrease) resulting from: Income from bank owned life insurance (1,883 ) (2 ) (1,894 ) (3 ) (1,926 ) (3 ) Tax-exempt interest income, net (2,434 ) (3 ) (2,232 ) (3 ) (2,133 ) (4 ) Tax credits — — (61 ) — (134 ) — Other 126 — 180 — 126 — Total tax provision $ 25,639 30 % $ 20,836 29 % $ 17,680 28 %
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences between the financial statement carrying amounts and the tax bases of assets and liabilities that represent significant portions of the deferred tax assets and liabilities at December 31 are presented below: 2016 2015 (dollars in thousands) Deferred tax assets: Allowance for credit losses $ 17,616 $ 17,784 Postretirement benefits other than pensions 611 641 Alternative minimum tax credit carryforward — 5,065 Litigation reserve 106 — Unrealized loss on securities available for sale 3,905 1,291 Writedown of other real estate owned 1,266 1,087 Deferred compensation 1,966 2,113 Accrued interest on nonaccrual loans 1,701 1,452 Other-than-temporary impairment of securities 88 89 Depreciation of assets — 879 Accrued incentives 2,627 1,629 Unfunded loan commitment allowance 1,452 1,557 Accrued severance 102 808 Basis difference in assets acquired 296 417 Loan origination fees and costs 290 141 Deferred rent 1,285 1,258 Other 1,084 1,105 Total deferred tax assets 34,395 37,316 Deferred tax liabilities: Income from unconsolidated subsidiary (623 ) (619 ) Depreciation of assets (28 ) — Other (429 ) (337 ) Total deferred tax liabilities (1,080 ) (956 ) Net deferred tax asset $ 33,315 $ 36,360

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Schedule of Components of Net Periodic Benefit Cost	Net periodic benefit cost of these plans for the years ended December 31, was as follows: 2016 2015 2014 (dollars in thousands) Service cost $ — $ — $ — Interest cost on projected benefit obligation 67 62 62 Amortization of transition obligation — — — Gain amortization (7 ) (4 ) (29 ) Net periodic benefit cost $ 60 $ 58 $ 33
Schedule of Changes in Benefit Obligations and Plan Assets	The following table sets forth the change in the benefit obligation and plan assets as of December 31: 2016 2015 (dollars in thousands) Change in Benefit Obligation Benefit obligation at beginning of year $ 1,815 $ 1,822 Service cost — — Interest cost 67 62 Amendments — — Actuarial loss (gain) (337 ) 98 Net benefits paid (151 ) (167 ) Benefit obligation at end of year 1,394 1,815 Change in Plan Assets Fair value of plan assets at beginning of year — — Actual return on plan assets — — Employer contributions 151 167 Net benefits paid (151 ) (167 ) Fair value of plan assets at end of year — — Funded Status at End of Year 1,394 1,815 Unrecognized transition obligation — — Unrecognized net gain 345 15 Amounts recognized in retained earnings $ 1,739 $ 1,830
Schedule of Amounts Recognized as Other Liabilities	As of December 31, the funded status of the plan is: 2016 2015 (dollars in thousands) Amounts Recognized in the Statement of Financial Condition as Other liabilities $ 1,394 $ 1,815
Schedule of Amounts Recognized in Accumulated Other Comprehensive Income	The following table identifies the related tax effects allocated to each component of other comprehensive income in the Consolidated Statements of Comprehensive Income as of December 31 . Reclassification adjustments related to securities available for sale are included in the “ Net securities gains (losses) ” line in the Consolidated Statements of Income and reclassification adjustments related to losses on derivatives are included in the "Other operating expenses" line in the Consolidated Statements of Income. 2016 2015 2014 Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount (dollars in thousands) Unrealized gains (losses) on securities: Unrealized holding (losses) gains on securities arising during the period $ (6,304 ) $ 2,206 $ (4,098 ) $ 2,798 $ (978 ) $ 1,820 $ 25,153 $ (8,803 ) $ 16,350 Reclassification adjustment for (gains) losses on securities included in net income (617 ) 216 (401 ) 153 (54 ) 99 (550 ) 193 (357 ) Total unrealized (losses) gains on securities (6,921 ) 2,422 (4,499 ) 2,951 (1,032 ) 1,919 24,603 (8,610 ) 15,993 Unrealized gains (losses) on derivatives: Unrealized holding (losses) gains on derivatives arising during the period (479 ) 168 (311 ) 450 (158 ) 292 472 (165 ) 307 Reclassification adjustment for gains on derivatives included in net income (70 ) 24 (46 ) (49 ) 17 (32 ) (10 ) 3 (7 ) Total unrealized (losses) gains on derivatives (549 ) 192 (357 ) 401 (141 ) 260 462 (162 ) 300 Unrealized gains (losses) for postretirement obligations: Transition obligation — — — — — — — — — Net gain (loss) 331 (116 ) 215 (102 ) 36 (66 ) (313 ) 109 (204 ) Total unrealized gains (losses) for postretirement obligations 331 (116 ) 215 (102 ) 36 (66 ) (313 ) 109 (204 ) Total other comprehensive (loss) income $ (7,139 ) $ 2,498 $ (4,641 ) $ 3,250 $ (1,137 ) $ 2,113 $ 24,752 $ (8,663 ) $ 16,089 The following table sets forth the amounts recognized in accumulated other comprehensive income that have not yet been recognized as components of net periodic benefit costs as of December 31: 2016 2015 2014 (dollars in thousands) Amounts recognized in accumulated other comprehensive income, net of tax: Net (gain) loss $ (225 ) $ (10 ) $ (76 ) Transition obligation — — — Total $ (225 ) $ (10 ) $ (76 )
Schedule of Weighted-Average Assumptions Used to Determine Benefit Obligation	Weighted-average assumptions used to determine the benefit obligation as of December 31 are as follows: 2016 2015 2014 Weighted-average Assumptions Discount rate 3.74 % 3.88 % 3.61 % Health care cost trend: Initial 6.00 % 6.25 % 6.50 % Health care cost trend: Ultimate 4.75 % 4.75 % 4.75 % Year ultimate reached 2022 2022 2022
Schedule of Weighted-Average Assumptions Used to Determine Net Periodic Cost	Weighted-average assumptions used to determine the benefit obligation as of December 31 are as follows: 2016 2015 2014 Weighted-average Assumptions Discount rate 3.74 % 3.88 % 3.61 % Health care cost trend: Initial 6.00 % 6.25 % 6.50 % Health care cost trend: Ultimate 4.75 % 4.75 % 4.75 % Year ultimate reached 2022 2022 2022 Weighted-average assumptions used to determine the net benefit costs as of December 31 are as follows: 2016 2015 2014 Weighted Average Assumptions for Net Periodic Cost Discount rate 3.88 % 3.61 % 4.01 % Health care cost trend: Initial 6.25 % 6.50 % 6.75 % Health care cost trend: Ultimate 4.75 % 4.75 % 4.75 % Year ultimate reached 2022 2022 2022 Corridor 10.00 % 10.00 % 10.00 % Recognition period for gains and losses 11.0 11.0 10.0
Schedule of Impact of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	The health care cost trend rate assumption can have a significant impact on the amounts reported for this plan. A one-percentage-point change in assumed health care cost trend rates would have the following effects: One-Percentage- One-Percentage- (dollars in thousands) Effect on postretirement benefit obligation $ 44 $ (40 ) Effect on total of service and interest cost components 3 (3 )
Schedule of Projected Benefit Payments	As of December 31, 2016 , the projected benefit payments for the next ten years are as follows: Projected Benefit (dollars in thousands) 2017 $ 174 2018 162 2019 137 2020 130 2021 123 2022 - 2026 500
Schedule of Amounts Recognized in Accumulated Other Comprehensive Income	The estimated costs that will be amortized from accumulated other comprehensive income into net periodic cost for 2017 are as follows (dollars in thousands): Postretirement (dollars in thousands) Net gain $ 21 Transition obligation — Total $ 21

Incentive Compensation Plan (Ta

Incentive Compensation Plan (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]	The following provides detail on the restricted stock awards which were issued and outstanding in 2016 , 2015 and 2014 in order to retain and attract key employees. The grant date fair value of the restricted stock awards is equal to the price of First Commonwealth’s common stock on grant date. Grant Date Shares issued Grant Price Vesting Date Number of Equal Vesting Periods December 19, 2016 15,000 $ 13.96 December 19, 2019 3 September 30, 2016 10,000 10.09 September 30, 2019 1 September 19, 2016 33,000 10.02 September 19, 2019 3 June 7, 2016 10,000 9.34 June 7, 2019 1 March 1, 2016 10,000 8.84 March 1, 2019 1 March 1, 2016 5,000 8.84 March 1, 2019 1 March 1, 2016 20,000 8.84 March 1, 2019 1 February 18, 2016 18,348 8.43 December 31, 2016 1 June 26, 2015 1,000 9.84 June 26, 2018 1 February 20, 2015 10,000 8.45 February 20, 2018 1 February 20, 2015 34,200 8.45 December 31, 2015 1 February 5, 2015 50,000 8.55 February 5, 2018 1 January 29, 2015 20,170 7.93 December 31, 2015 1 January 15, 2015 20,000 8.38 January 15, 2017 1 November 17, 2014 3,500 9.26 November 17, 2017 1 April 8, 2014 27,500 8.89 April 8, 2017 3 March 24, 2014 46,000 9.18 March 24, 2017 1 March 4, 2014 5,000 8.75 March 4, 2017 1 January 1, 2014 12,626 8.82 December 31, 2014 1 August 16, 2013 3,000 7.57 August 16, 2016 1 May 31, 2013 45,000 7.21 May 31, 2016 3 March 1, 2013 10,000 7.35 March 1, 2016 1 February 24, 2012 34,000 5.96 December 31, 2014 1 February 24, 2012 90,000 5.96 February 24, 2015 1 January 1, 2012 100,000 5.26 January 1, 2016 4 November 21, 2011 10,000 4.41 November 21, 2014 1 April 1, 2011 25,000 6.82 April 1, 2016 1
Unvested Service-Based Restricted Stock Awards	A summary of the status of First Commonwealth’s unvested service-based restricted stock awards as of December 31 and changes for the years ended on those dates is presented below: 2016 2015 2014 Shares Weighted Shares Weighted Shares Weighted Outstanding, beginning of the year 231,834 $ 8.01 265,000 $ 7.08 271,000 $ 6.07 Granted 121,348 9.88 135,370 8.41 94,626 9.03 Vested (105,514 ) 7.04 (168,536 ) 6.87 (98,487 ) 6.18 Forfeited — — — — (2,139 ) 5.96 Outstanding, end of the year 247,668 9.34 231,834 8.01 265,000 7.08
Schedule of Restricted Stock Units Granted Based on Performance [Table Text Block]	The following provides detail on restricted stock awards estimated to be granted on a performance award basis during 2016 , 2015 and 2014 . These plans were previously approved by the Board of Directors. Grant Date Target Share Award Performance Period (years) Award if threshold met Award if targets are met Award if superior met Award if threshold not achieved Vesting After Performance Period (years) Final vesting January 17, 2011 54,166 3 40 % 100 % 200 % — % 1 January 17, 2014 February 24, 2012 68,000 3 40 % 100 % 200 % — % 1 December 31, 2015 January 28, 2013 128,611 3 40 % 100 % 200 % — % 1 December 31, 2016 January 27, 2014 125,000 3 40 % 100 % 200 % — % 0 December 31, 2016 January 26, 2015 125,000 3 40 % 100 % 200 % — % 0 December 31, 2017 December 30, 2015 60,000 5 0 December 31, 2020 February 18, 2016 160,650 3 40 % 100 % 200 % — % 0 December 31, 2018
Unvested Target Award	The following table summarizes the estimated unvested target share awards for the Plans as of December 31: 2016 2015 2014 Outstanding, beginning of the year 320,705 284,000 250,777 Granted 176,936 185,000 126,389 Issued (18,348 ) (34,200 ) (12,626 ) Forfeited (52,697 ) (114,095 ) (80,540 ) Outstanding, end of the year 426,596 320,705 284,000
Outstanding Stock Options

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Loans to Related Parties	The following is an analysis of loans to related parties (dollars in thousands): December 31, 2015 $ 1,139 Advances 800 Repayments (775 ) December 31, 2016 $ 1,164

Regulatory Restrictions and C56

Regulatory Restrictions and Capital Adequacy (Tables)	12 Months Ended
	Dec. 31, 2016
Regulatory Capital Requirements [Abstract]
Schedule of Capital Amount and Ratio Considered to be Capitalized	To be considered well-capitalized, the Company must maintain minimum Total risk-based capital, Tier I risk-based capital, Tier I leverage ratio and Common equity tier I risk-based capital as set forth in the table below: Actual Minimum Capital Required - Basel III Phase-In Schedule Minimum Capital Required - Basel III Fully Phased-In Required to be Considered Well Capital Ratio Capital Ratio Capital Ratio Capital Ratio (dollars in thousands) As of December 31, 2016 Total Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 687,554 12.28 % $ 483,034 8.63 % $ 588,042 10.50 % $ 560,040 10.00 % First Commonwealth Bank 617,076 11.06 481,248 8.63 585,867 10.50 557,969 10.00 Tier I Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 633,262 11.31 % $ 371,026 6.63 % $ 476,034 8.50 % $ 448,032 8.00 % First Commonwealth Bank 562,784 10.09 369,654 6.63 474,273 8.50 446,375 8.00 Tier I Capital to Average Assets First Commonwealth Financial Corporation $ 633,262 9.83 % $ 257,776 4.00 % $ 257,776 4.00 % $ 322,220 5.00 % First Commonwealth Bank 562,784 8.79 256,214 4.00 256,214 4.00 320,268 5.00 Common Equity Tier I to Risk Weighted Assets First Commonwealth Financial Corporation $ 563,262 10.06 % $ 287,020 5.13 % $ 392,028 7.00 % $ 364,026 6.50 % First Commonwealth Bank 562,784 10.09 285,959 5.13 390,578 7.00 362,680 6.50 Actual Minimum Capital Required - Basel III Phase-In Schedule Minimum Capital Required - Basel III Fully Phased-In Required to be Considered Well Capital Ratio Capital Ratio Capital Ratio Capital Ratio (dollars in thousands) As of December 31, 2015 Total Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 682,199 12.25 % $ 445,650 8.00 % $ 584,915 10.50 % $ 557,062 10.00 % First Commonwealth Bank 656,244 11.78 445,642 8.00 584,905 10.50 557,052 10.00 Tier I Capital to Risk Weighted Assets First Commonwealth Financial Corporation $ 626,939 11.25 % $ 334,237 6.00 % $ 473,503 8.50 % $ 445,650 8.00 % First Commonwealth Bank 600,984 10.79 334,231 6.00 473,494 8.50 445,642 8.00 Tier I Capital to Average Assets First Commonwealth Financial Corporation $ 626,939 9.85 % $ 254,631 4.00 % $ 254,631 4.00 % $ 318,289 5.00 % First Commonwealth Bank 600,984 9.46 254,095 4.00 254,095 4.00 317,618 5.00 Common Equity Tier I to Risk Weighted Assets First Commonwealth Financial Corporation $ 556,939 10.00 % $ 250,678 4.50 % $ 389,944 7.00 % $ 362,091 6.50 % First Commonwealth Bank 535,814 9.62 250,673 4.50 389,937 7.00 362,084 6.50

Acquisition (Tables)

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Summary of Net Assets Acquired and Consideration Transferred	The table below summarizes the net assets acquired (at fair value) and consideration transferred in connection with the First Community acquisition (dollars in thousands): Consideration Paid Cash Paid to shareholders $ 14,750 Total consideration paid $ 14,750 Fair Value of Assets Acquired Cash and cash equivalents 11,217 Investment Securities 25,980 FHLB Stock 832 Loans 61,173 Premises and other equipment 1,801 Core deposit intangible 172 Other real estate 816 Other assets 1,115 Total assets acquired 103,106 Fair Value of Liabilities Assumed Deposits 90,311 Other Liabilities 1,115 Total liabilities assumed 91,426 Total Fair Value of Identifiable Net Assets 11,680 Goodwill $ 3,070

Condensed Financial Informati58

Condensed Financial Information of First Commonwealth Financial Corporation (parent company only) (Tables)	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Statements of Financial Condition	Statements of Financial Condition December 31, 2016 2015 (dollars in thousands) Assets Cash $ 30,387 $ 10,003 Loans 19 22 Investment in subsidiaries 770,214 719,073 Investment in unconsolidated subsidiary trusts 2,185 2,182 Investment in jointly-owned company 9,042 8,978 Premises and equipment, net 3,793 3,780 Receivable from subsidiaries 33 441 Dividends receivable from subsidiaries 4,662 714 Other assets 2,453 47,631 Total assets $ 822,788 $ 792,824 Liabilities and Shareholders’ Equity Accrued expenses and other liabilities $ 692 $ 1,111 Subordinated debentures payable 72,167 72,167 Shareholders’ equity 749,929 719,546 Total liabilities and shareholders’ equity $ 822,788 $ 792,824
Statements of Operations	Statements of Income For the years ended December 31, 2016 2015 2014 (dollars in thousands) Interest and dividends $ 1 $ 1 $ 1 Dividends from subsidiaries 55,510 49,917 49,207 Interest expense (2,635 ) (2,357 ) (2,335 ) Other income 83 232 1,251 Operating expense (4,700 ) (4,989 ) (6,766 ) Income (loss) before taxes and equity in undistributed (loss) earnings of subsidiaries 48,259 42,804 41,358 Applicable income tax benefits 2,515 2,528 2,968 Income before equity in undistributed (loss) earnings of subsidiaries 50,774 45,332 44,326 Equity in undistributed earnings (loss) of subsidiaries 8,816 4,811 127 Net income $ 59,590 $ 50,143 $ 44,453
Statements of Cash Flow	For the years ended December 31, Statements of Cash Flow 2016 2015 2014 (dollars in thousands) Operating Activities Net income $ 59,590 $ 50,143 $ 44,453 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 355 493 2,150 Net gain (loss) on sales of assets — 240 — Decrease (increase) in prepaid income taxes 7,380 (6,993 ) (487 ) Undistributed equity in subsidiaries (8,816 ) (4,811 ) (127 ) Other net 7,759 10,753 13,077 Net cash provided by operating activities 66,268 49,825 59,066 Investing Activities Net change in loans 3 2 3 Purchases of premises and equipment — 54 (47 ) Proceeds from sale of other assets (332 ) — 13 Proceeds from dissolution of subsidiary 27,017 — — Investment in subsidiaries (47,017 ) — — Net cash (used in) provided by investing activities (20,329 ) 56 (31 ) Financing Activities Discount on dividend reinvestment plan purchases — — (65 ) Dividends paid (24,907 ) (25,089 ) (26,174 ) Proceeds from reissuance of treasury stock 216 192 192 Purchase of treasury stock (864 ) (25,383 ) (30,956 ) Net cash used in financing activities (25,555 ) (50,280 ) (57,003 ) Net increase (decrease) in cash 20,384 (399 ) 2,032 Cash at beginning of year 10,003 10,402 8,370 Cash at end of year $ 30,387 $ 10,003 $ 10,402

Statement of Accounting Polic59

Statement of Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)countySegment	Dec. 31, 2015USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of counties in which entity provides services | county	15
Business segments | Segment	1
Equity investments	20.00%
Loans past due days	90 days
Excess impaired credits	$ 100,000
Other liabilities	$ 3,300,000
Software purchases and developed are capitalized and amortized on straight-line basis	7 years
Guaranteed Minimum Death Benefit [Member]
Summary Of Significant Accounting Policies [Line Items]
Other liabilities		$ 3,700,000

Supplemental Comprehensive In60

Supplemental Comprehensive Income Disclosures - Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Comprehensive Income Disclosures [Abstract]
Unrealized holding (losses) gains on securities arising during the period, Pretax Amount	$ (6,304)	$ 2,798	$ 25,153
Less: reclassification adjustment for (gains) losses on securities included in net income, Pretax Amount	(617)	153	(550)
Total Unrealized (Losses) Gains on Securities, before Tax	(6,921)	2,951	24,603
Unrealized holding gains on derivatives arising during the period, Pretax Amount	(479)	450	472
Reclassification adjustment for gains on derivatives included in net income, Pretax Amount	70	49	10
Total unrealized gains on derivatives, Pretax Amount	(549)	401	462
Unrealized holding gains on derivatives arising during the period, Tax (Expense) Benefit	168	(158)	(165)
Reclassification adjustment for gains on derivatives included in net income, Tax (Expense) Benefit	24	17	3
Total unrealized gains on derivatives, Tax (Expense) Benefit	192	(141)	(162)
Unrealized holding gains on derivatives arising during the period, Net of Tax Amount	(311)	292	307
Reclassification adjustment for gains on derivatives included in net income, Tax (Expense) Benefit	(46)	(32)	(7)
Total unrealized gains on derivatives, Tax (Expense) Benefit	(357)	260	300
Transition obligation	0	0	0
Net (loss) gain, Pretax Amount	331	(102)	(313)
Total Unrealized Gains (Losses) for Postretirement Obligations, Before Tax	331	(102)	(313)
Total other comprehensive (loss) income, Pretax Amount	(7,139)	3,250	24,752
Unrealized holding (losses) gains on securities arising during the period, Tax (Expense) Benefit	2,206	(978)	(8,803)
Less: reclassification adjustment for (gains) losses on securities included in net income, Tax (Expense) Benefit	216	(54)	193
Total Unrealized (Losses) Gains on Securities, Tax (Expense) Benefit	2,422	(1,032)	(8,610)
Transition obligation, Tax (Expense) Benefit	0	0	0
Net (loss) gain, Tax (Expense) Benefit	(116)	36	109
Total Unrealized Gains (Losses) for Postretirement Obligations, Tax (Expense) Benefit	(116)	36	109
Total other comprehensive (loss) income, Tax (Expense) Benefit	2,498	(1,137)	(8,663)
Unrealized holding (losses) gains on securities arising during the period, Net of Tax Amount	(4,098)	1,820	16,350
Less: reclassification adjustment for (gains) losses on securities included in net income, Net of Tax Amount	(401)	99	(357)
Total Unrealized (Losses) Gains on Securities, Net of Tax	(4,499)	1,919	15,993
Transition obligation, Net of Tax Amount	0	0	0
Net gain	215	(66)	(204)
Total Unrealized Gains (Losses) for Postretirement Obligations, Net of Tax	215	(66)	(204)
Total other comprehensive (loss) Income	$ (4,641)	$ 2,113	$ 16,089

Supplemental Comprehensive In61

Supplemental Comprehensive Income Disclosures Supplemental Comprehensive Income Disclosures (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income [Line Items]
Balance at beginning of period	$ (2,386)	$ (4,499)	$ (20,588)
Other comprehensive loss before reclassification adjustment	(4,409)	2,112	16,657
Amounts reclassified from accumulated other comprehensive income (loss)	(447)	67	(364)
Net gain	215	(66)	(204)
Net other comprehensive loss during the period	(4,641)	2,113	16,089
Balance at end of period	(7,027)	(2,386)	(4,499)
Securities Available for Sale
Accumulated Other Comprehensive Income [Line Items]
Balance at beginning of period	(2,956)	(4,875)	(20,868)
Other comprehensive loss before reclassification adjustment	(4,098)	1,820	16,350
Amounts reclassified from accumulated other comprehensive income (loss)	(401)	99	(357)
Net other comprehensive loss during the period	(4,499)	1,919	15,993
Balance at end of period	(7,455)	(2,956)	(4,875)
Derivatives
Accumulated Other Comprehensive Income [Line Items]
Balance at beginning of period	560	300	0
Other comprehensive loss before reclassification adjustment	(311)	292	307
Amounts reclassified from accumulated other comprehensive income (loss)	(46)	(32)	(7)
Net other comprehensive loss during the period	(357)	260	300
Balance at end of period	203	560	300
Post-Retirement Obligation
Accumulated Other Comprehensive Income [Line Items]
Balance at beginning of period	10	76	280
Net gain	215	(66)	(204)
Net other comprehensive loss during the period	215	(66)	(204)
Balance at end of period	$ 225	$ 10	$ 76

Supplemental Cash Flow Disclo62

Supplemental Cash Flow Disclosures - Non-cash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash paid during the year for:
Interest	$ 19,208	$ 15,818	$ 18,943
Income taxes	19,950	8,331	10,700
Non-cash investing and financing activities:
Loans transferred to other real estate owned and repossessed assets	4,824	8,257	5,061
Fair value of loans transferred from held to maturity to available for sale	18,758	3,196	3,035
Gross (decrease) increase in market value adjustment to securities available for sale	(6,919)	2,949	24,601
Gross (decrease) increase in market value adjustment to securities derivatives	(549)	401	472
Investments committed to purchase, not settled	0	694	0
Net (liabilities) assets acquired through acquisition	$ (501,516)	$ 463	$ 0
Other Significant Noncash Transaction, Consideration Received	437	0	0
Other Significant Noncash Transaction, Value of Consideration Received	$ 3,769	$ 0	$ 0
Contribution of premises	$ 0	$ 0	$ 682

Earnings per Share - Compositio

Earnings per Share - Composition of Weighted-Average Common Shares (Denominator) Used in Basic and Diluted Earnings Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Weighted average common shares issued	105,563,455	105,563,455	105,563,455
Average treasury shares	(16,605,461)	(16,045,900)	(12,294,217)
Average unearned nonvested shares	(106,421)	(160,788)	(154,584)
Weighted average common shares and common stock equivalents used to calculate basic earnings per share	88,851,573	89,356,767	93,114,654
Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share	0	0	0
Weighted average common shares and common stock equivalents used to calculate diluted earnings per share	88,851,573	89,356,767	93,114,654

Earnings per Share - Common Sto

Earnings per Share - Common Stock Equivalents Not Included in Computation of Diluted Earnings Per Share (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock, par value (in dollars per share)	$ 1	$ 1
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	0	0	15,000
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	67,920	92,002	106,977
Minimum [Member] | Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock, par value (in dollars per share)	$ 0	$ 0	$ 14.55
Minimum [Member] | Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock, par value (in dollars per share)	8.38	6.82	5.26
Maximum [Member] | Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock, par value (in dollars per share)	0	0	14.55
Maximum [Member] | Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock, par value (in dollars per share)	$ 13.96	$ 9.84	$ 9.26

Cash and Due from Banks - Addit

Cash and Due from Banks - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Cash and Due from Banks [Abstract]
Cash or balances held with the Federal Reserve Bank	$ 5.1	$ 4.6

Derivatives - Additional Inform

Derivatives - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)Derivative	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Derivative [Line Items]
Number of participation agreements for interest rate swaps, participant | Derivative	26
Number of participation agreements for interest rate swaps, lead bank | Derivative	8
Derivative, Gain (Loss) on Derivative, Net	$ 219	$ (274)	$ (345)
Interest Income [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1,627	2,049	$ 330
Interest rate swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Number of interest rate swap contracts | Derivative	4
Derivative, notional amount	$ 200,000
Collateral Already Posted, Aggregate Fair Value	200,000
Interest rate swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, notional amount	200,000	$ 200,000
Three Year [Member] | Interest rate swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, notional amount	$ 85,000
Derivative, Term of Contract	3 years
Four Year [Member] | Interest rate swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, notional amount	$ 115,000
Derivative, Term of Contract	4 years

Derivatives - Credit Value Adju

Derivatives - Credit Value Adjustment Recorded Related to Notional Amount of Derivatives Outstanding (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Credit value adjustment	$ (317)	$ (542)
Not Designated as Hedging Instrument [Member] | Interest rate swap [Member]
Derivative [Line Items]
Derivative, notional amount	345,102	276,860
Not Designated as Hedging Instrument [Member] | Interest Rate Cap [Member]
Derivative [Line Items]
Derivative, notional amount	14,762	22,793
Not Designated as Hedging Instrument [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative, notional amount	174,213	126,612
Not Designated as Hedging Instrument [Member] | Credit Default Swap, Selling Protection [Member]
Derivative [Line Items]
Derivative, Sold Protection Notional Amount	(40,281)	(20,383)
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair value adjustment	(443)	922
Designated as Hedging Instrument [Member] | Interest rate swap [Member]
Derivative [Line Items]
Derivative, notional amount	$ 200,000	$ 200,000

Derivatives - Schedule of Chang

Derivatives - Schedule of Change in Fair Value of Derivative Assets and Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 219	$ (274)	$ (345)
Other Income [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	219	(274)	(345)
Other Income [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	70	64	10
Interest Income [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1,627	$ 2,049	$ 330

Investment Securities - Analysi

Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Investment Securities [Line Items]
Amortized Cost	$ 790,082	$ 891,111
Gross Unrealized Gains	7,076	11,926
Gross Unrealized Losses	(18,546)	(16,477)
Estimated Fair Value of Available for Sale	778,612	886,560
US States and Political Subdivisions Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	27,075	27,066
Gross Unrealized Gains	195	532
Gross Unrealized Losses	(41)	0
Estimated Fair Value of Available for Sale	27,229	27,598
Corporate Securities [Member]
Investment Securities [Line Items]
Amortized Cost	5,903	1,897
Gross Unrealized Gains	416	422
Gross Unrealized Losses	0	0
Estimated Fair Value of Available for Sale	6,319	2,319
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Investment Securities [Line Items]
Amortized Cost	39,989	42,239
Gross Unrealized Gains	427	916
Gross Unrealized Losses	(7,124)	(7,497)
Estimated Fair Value of Available for Sale	33,292	35,658
Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	788,412	888,941
Gross Unrealized Gains	7,076	11,926
Gross Unrealized Losses	(18,546)	(16,477)
Estimated Fair Value of Available for Sale	776,942	884,390
Mortgage - Backed Securities - Residential [Member] | US Government Agencies Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	15,143	20,034
Gross Unrealized Gains	1,481	2,071
Gross Unrealized Losses	(7)	(13)
Estimated Fair Value of Available for Sale	16,617	22,092
Mortgage - Backed Securities - Residential [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Amortized Cost	683,601	778,476
Gross Unrealized Gains	4,557	7,983
Gross Unrealized Losses	(11,305)	(8,882)
Estimated Fair Value of Available for Sale	676,853	777,577
Mortgage - Backed Securities - Commercial [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Amortized Cost	1	28
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value of Available for Sale	1	28
Other Government - Sponsored Enterprises [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Amortized Cost	16,700	19,201
Gross Unrealized Gains	0	2
Gross Unrealized Losses	(69)	(85)
Estimated Fair Value of Available for Sale	16,631	19,118
Equity Securities [Member]
Investment Securities [Line Items]
Amortized Cost	1,670	2,170
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value of Available for Sale	$ 1,670	$ 2,170

Investment Securities - Additio

Investment Securities - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Maturity of contract	less than one year
Approximate year of maturity	30 years
Gross Unrealized Gains (Losses)	$ 18,546	$ 16,477
Securities available for sale	778,612	886,560
Amortized Cost	790,082	891,111
Gain (loss) on sales of securities	617	(153)	$ 550
Available-for-sale securities pledged as collateral	445,800	416,100
Held-to-maturity securities pledged as collateral	119,200	$ 45,700
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Sale of available securities	75,000
Gain (loss) on sales of securities	$ (300)

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities Available for Sale (Detail) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Investment Securities [Line Items]
Due within 1 year, Amortized Cost		$ 3,300
Due after 1 but within 5 years, Amortized Cost		17,397
Due after 5 but within 10 years, Amortized Cost		27,075
Due after 10 years, Amortized Cost		41,895
Debt securities gross, Amortized Cost		89,667
Amortized Cost		790,082	$ 891,111
Total debt securities, Amortized Cost		788,412
Due within 1 year, Estimated Fair Value		3,292
Due after 1 but within 5 years, Estimated Fair Value		17,343
Due after 5 but within 10 years, Estimated Fair Value		27,229
Due after 10 years, Estimated Fair Value		35,607
Debt securities gross, Estimated Fair Value		83,471
Estimated Fair Value of Available for Sale		778,612	$ 886,560
Total debt securities, Estimated Fair Value		776,942
Mortgage-Backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	[1]	698,745
Estimated Fair Value of Available for Sale	[1]	$ 693,471
[1]	Mortgage Backed Securities include an amortized cost of $15.1 million and a fair value of $16.6 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $683.6 million and a fair value of $676.9 million

Investment Securities - Amort72

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities Available for Sale, Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investment Securities [Line Items]
Amortized Cost	$ 790,082	$ 891,111
Estimated Fair Value of Available for Sale	778,612	$ 886,560
US Government Agencies Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	15,100
Estimated Fair Value of Available for Sale	16,600
Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Amortized Cost	683,600
Estimated Fair Value of Available for Sale	$ 676,900

Investment Securities - Proceed

Investment Securities - Proceeds from Sale, Gross Gains (Losses) Realized on Sales, Maturities and Other-Than-Temporary Impairment Charges Related to Securities Available for Sale (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Proceeds from sale	$ 55,744	$ 88,054	$ 132,868
Sales Transactions:
Gross gains	305	0	291
Gross losses	(277)	(284)	(243)
Total gain (losses) from sales transactions	28	(284)	48
Maturities, calls and impairment:
Gross gains	589	131	502
Gross losses	0	0	0
Other-than-temporary impairment	0	0	0
Total gain (losses) maturities and impairment	589	131	502
Net gains (losses) and impairment	$ 617	$ (153)	$ 550

Investment Securities - Amort74

Investment Securities - Amortized Cost and Fair Values of Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 372,513	$ 384,324
Gross Unrealized Gains	60	331
Gross Unrealized Losses	(3,955)	(2,314)
Estimated Fair Value	368,618	382,341
Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	38,667	31,910
Gross Unrealized Gains	55	301
Gross Unrealized Losses	(721)	(58)
Estimated Fair Value	38,001	32,153
Mortgage - Backed Securities - Residential [Member] | US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	4,297	4,775
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(7)
Estimated Fair Value	4,293	4,768
Mortgage - Backed Securities - Residential [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	280,430	315,609
Gross Unrealized Gains	5	30
Gross Unrealized Losses	(2,527)	(1,824)
Estimated Fair Value	277,908	313,815
Mortgage - Backed Securities - Commercial [Member] | US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	34,444	16,843
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(561)	(247)
Estimated Fair Value	33,883	16,596
Mortgage - Backed Securities - Commercial [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,675	15,187
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(142)	(178)
Estimated Fair Value	$ 14,533	$ 15,009

Investment Securities - Schedul

Investment Securities - Schedule of Debt Securities Expected Maturity (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
Due within 1 year		$ 0
Due after 1 but within 5 years		2,636
Due after 5 but within 10 years		31,893
Due after 10 years		4,138
Amortized Cost		38,667
Held-to-maturity Securities		372,513	$ 384,324
Estimated Fair Value
Due within 1 year		0
Due after 1 but within 5 years		2,615
Due after 5 but within 10 years		31,384
Due after 10 years		4,002
Estimated Fair Value		38,001
Securities held to maturity, fair value		368,618	$ 382,341
Mortgage-Backed Securities [Member]
Amortized Cost
Held-to-maturity Securities	[1]	333,846
Estimated Fair Value
Securities held to maturity, fair value	[1]	330,617
Mortgage-Backed Securities [Member] | US Government Agencies Debt Securities [Member]
Amortized Cost
Held-to-maturity Securities		38,700
Estimated Fair Value
Securities held to maturity, fair value		38,200
Mortgage-Backed Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Amortized Cost
Held-to-maturity Securities		295,100
Estimated Fair Value
Securities held to maturity, fair value		$ 292,400
[1]	Mortgage Backed Securities include an amortized cost of $38.7 million and a fair value of $38.2 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $295.1 million and a fair value of $292.4 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac.

Impairment of Investment Secu76

Impairment of Investment Securities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)SecurityBank	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Corporate/Mortgage-Backed Securities, Amortized cost	$ 790,082,000	$ 891,111,000
Estimated Fair Value of Available for Sale	$ 778,612,000	886,560,000
Number of banks and other financial institutions comprising the security | Bank	259
Number Of Pooled Securities with No Senior Class | Security	2
Number of Securities with No Excess Subordination | Security	2
Number of Securities with Excess Subordination | Security	6
Collateral issued by financial institutions	$ 15,000,000,000
Coupon interest rate	7.00%
Prepayment rate	5.00%
Estimate of future cash flows prepayment percentage in year three	40.00%
Estimate of future cash flows prepayment percentage thereafter	2.00%
Fair Value Input Coupon Rates	10.00%
Probability of default	100.00%
Projected recovery rate	0.00%
Probability percentage assigned to default bank subject to market indicators	10.00%
Probability percentage assigned to default bank	100.00%
Other than-temporary impairment charge	$ 6,671,000	218,000	$ 0
Other investments	$ 36,498,000	62,952,000
Minimum [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Subordinated tranches range	7.00%
Total principal amount of the respective securities	5.00%
Excess subordination as a percentage of current performing collateral	2.00%
Collateral issued by financial institutions	$ 15,000,000,000
Probabilities for performing collateral range	0.33%
Excess percent value of future cash flows over current book value	19.00%
Over Fifteen Million [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Prepayment rate	100.00%
Maximum [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Subordinated tranches range	35.00%
Excess subordination as a percentage of current performing collateral	80.00%
Collateral issued by financial institutions	$ 2,000,000,000
Probabilities for performing collateral range	75.00%
Excess percent value of future cash flows over current book value	119.00%
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total unrealized losses	32.00%
Corporate/Mortgage-Backed Securities, Amortized cost	$ 39,989,000	42,239,000
Estimated Fair Value of Available for Sale	33,292,000	35,658,000
Other than-temporary impairment charge	$ 0	0	$ 0
Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total unrealized losses	62.00%
Corporate Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Corporate/Mortgage-Backed Securities, Amortized cost	$ 5,903,000	1,897,000
Estimated Fair Value of Available for Sale	$ 6,319,000	2,319,000
Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Number of securities in an unrealized loss positions | Security	122
Estimated Fair Value of Available for Sale	$ 776,942,000	884,390,000
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Number of securities in an unrealized loss positions | Security	0
Corporate/Mortgage-Backed Securities, Amortized cost	$ 1,670,000	2,170,000
Estimated Fair Value of Available for Sale	1,670,000	2,170,000
Corporate Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Estimated Fair Value of Available for Sale	$ 6,319,000	$ 2,319,000
Trust Preferred Collateralized Debt Obligations [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Percentage of Current Performing Collateral	0.00%
Mezzanine [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Corporate/Mortgage-Backed Securities, Amortized cost	$ 39,989,000
Estimated Fair Value of Available for Sale	33,292,000
Mezzanine [Member] | Pre TSL VII [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Corporate/Mortgage-Backed Securities, Amortized cost	3,100,000
Net securities gains (losses)	$ 600,000

Impairment of Investment Secu77

Impairment of Investment Securities - Schedule of Unrealized Losses and Estimated Fair Values (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	$ 773,932	$ 493,938
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(13,175)	(3,881)
Estimated Fair Value, 12 Months or More	85,152	293,076
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	(9,326)	(14,910)
Total Estimated Fair Value	859,084	787,014
Total Gross Unrealized Losses	(22,501)	(18,791)
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	0	0
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	0	0
Estimated Fair Value, 12 Months or More	28,952	29,957
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	(7,124)	(7,497)
Total Estimated Fair Value	28,952	29,957
Total Gross Unrealized Losses	(7,124)	(7,497)
Obligations of U.S. Government [Member] | Mortgage - Backed Securities - Residential [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	4,898	6,798
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(11)	(20)
Estimated Fair Value, 12 Months or More	0	0
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	0	0
Total Estimated Fair Value	4,898	6,798
Total Gross Unrealized Losses	(11)	(20)
Obligations of U.S. Government [Member] | Mortgage - Backed Securities - Commercial [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	33,883
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(561)
Estimated Fair Value, 12 Months or More	0
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	0
Total Estimated Fair Value	33,883
Total Gross Unrealized Losses	(561)
Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage - Backed Securities - Residential [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	670,708	436,011
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(11,630)	(3,293)
Estimated Fair Value, 12 Months or More	56,200	263,119
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	(2,202)	(7,413)
Total Estimated Fair Value	726,908	699,130
Total Gross Unrealized Losses	(13,832)	(10,706)
Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage - Backed Securities - Commercial [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	14,534
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(142)
Estimated Fair Value, 12 Months or More	0
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	0
Total Estimated Fair Value	14,534
Total Gross Unrealized Losses	(142)
Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	16,632	12,316
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(69)	(85)
Estimated Fair Value, 12 Months or More	0	0
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	0	0
Total Estimated Fair Value	16,632	12,316
Total Gross Unrealized Losses	(69)	(85)
US States and Political Subdivisions Debt Securities [Member] | Other Government - Sponsored Enterprises [Member]
Schedule Of Unrealized Losses On Securities [Line Items]
Estimated Fair Value, Less Than 12 Months	33,277	7,208
Available For Sale Securities Continuous Unrealized Income Loss Position Less Than Twelve Months Aggregate Gain Losses	(762)	(58)
Estimated Fair Value, 12 Months or More	0	0
SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	0	0
Total Estimated Fair Value	33,277	7,208
Total Gross Unrealized Losses	$ (762)	$ (58)

Impairment of Investment Secu78

Impairment of Investment Securities - Pooled Trust Preferred Collateralized Debt Obligations (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)Bank	Dec. 31, 2015USD ($)
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 790,082	$ 891,111
Estimated Fair Value of Available for Sale	778,612	$ 886,560
Mezzanine [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	39,989
Estimated Fair Value of Available for Sale	33,292
Unrealized Gain (Loss)	(6,697)
Mezzanine [Member] | Pre TSL IV [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	1,830
Estimated Fair Value of Available for Sale	1,360
Unrealized Gain (Loss)	$ (470)
Debt Instrument, Credit Rating	B1/BB
Number of Banks | Bank	6
Deferrals and Defaults as a % of Current Collateral	18.05%
Excess Subordination as a % of Current Performing Collateral	59.78%
Mezzanine [Member] | Pre TSL VII [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 3,100
Mezzanine [Member] | Pre TSL VIII [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	1,963
Estimated Fair Value of Available for Sale	2,053
Unrealized Gain (Loss)	$ 90
Debt Instrument, Credit Rating	C/C
Number of Banks | Bank	28
Deferrals and Defaults as a % of Current Collateral	44.37%
Excess Subordination as a % of Current Performing Collateral	0.00%
Mezzanine [Member] | Pre TSL IX [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 2,412
Estimated Fair Value of Available for Sale	1,952
Unrealized Gain (Loss)	$ (460)
Debt Instrument, Credit Rating	B1/C
Number of Banks | Bank	37
Deferrals and Defaults as a % of Current Collateral	27.83%
Excess Subordination as a % of Current Performing Collateral	12.79%
Mezzanine [Member] | Pre TSL X [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 1,738
Estimated Fair Value of Available for Sale	1,986
Unrealized Gain (Loss)	$ 248
Debt Instrument, Credit Rating	Caa1/C
Number of Banks | Bank	42
Deferrals and Defaults as a % of Current Collateral	31.58%
Excess Subordination as a % of Current Performing Collateral	2.17%
Mezzanine [Member] | Pre TSL XII [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 5,890
Estimated Fair Value of Available for Sale	4,817
Unrealized Gain (Loss)	$ (1,073)
Debt Instrument, Credit Rating	B3/C
Number of Banks | Bank	64
Deferrals and Defaults as a % of Current Collateral	24.54%
Excess Subordination as a % of Current Performing Collateral	0.00%
Mezzanine [Member] | Pre TSL XIII [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 12,949
Estimated Fair Value of Available for Sale	10,900
Unrealized Gain (Loss)	$ (2,049)
Debt Instrument, Credit Rating	Ba3/C
Number of Banks | Bank	54
Deferrals and Defaults as a % of Current Collateral	11.21%
Excess Subordination as a % of Current Performing Collateral	55.77%
Mezzanine [Member] | Pre TSL XIV [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 12,995
Estimated Fair Value of Available for Sale	9,923
Unrealized Gain (Loss)	$ (3,072)
Debt Instrument, Credit Rating	B1/CC
Number of Banks | Bank	52
Deferrals and Defaults as a % of Current Collateral	12.78%
Excess Subordination as a % of Current Performing Collateral	31.90%
Mezzanine [Member] | MMCap I [Member]
Impairment Of Investment Securities [Line Items]
Amortized Cost	$ 212
Estimated Fair Value of Available for Sale	301
Unrealized Gain (Loss)	$ 89
Debt Instrument, Credit Rating	Ca/C
Number of Banks | Bank	8
Deferrals and Defaults as a % of Current Collateral	58.11%
Excess Subordination as a % of Current Performing Collateral	80.31%

Impairment of Investment Secu79

Impairment of Investment Securities - Cumulative Roll Forward of Credit Losses Recognized in Earnings for Debt Securities Held and Not Intended to be Sold (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning	[1]	$ 24,851	$ 26,246		$ 27,543
Credit losses on debt securities for which other-than-temporary impairment was not previously recognized		0	0		0
Additional credit losses on debt securities for which other-than- temporary impairment was previously recognized		0	0		0
Increases in cash flows expected to be collected, recognized over the remaining life of the security	[2]	(1,124)	(1,177)		(1,297)
Reduction for debt securities called during the period		(6,671)	(218)		0
Balance, ending		$ 17,056	$ 24,851	[1]	$ 26,246	[1]
[1]	The beginning balance represents credit related losses included in other-than-temporary impairment charges recognized on debt securities in prior periods.
[2]	Represents the increase in cash flows recognized either as principal payments or interest income during the period.

Loans and Allowance for Credi80

Loans and Allowance for Credit Losses - Outstanding Balances of Loan (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 4,879,347	$ 4,683,750	$ 4,457,308
Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,139,547	1,150,906
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	219,621	220,736
Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,229,192	1,224,465
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,742,210	1,479,000
Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	548,777	$ 608,643
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,778,471
Originated Loans [Member] | Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,131,148
Originated Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	217,840
Originated Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,165,851
Originated Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,717,043
Originated Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	546,589
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	100,876
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,399
Acquired Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,781
Acquired Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	63,341
Acquired Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	25,167
Acquired Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 2,188

Loans and Allowance for Credi81

Loans and Allowance for Credit Losses - Credit Risk Profile by Creditworthiness (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		$ 4,683,750
Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		4,549,787
OAEM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		47,523
Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		86,440
Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		133,963
Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,150,906
Commercial, financial, agricultural and other [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,074,858
Commercial, financial, agricultural and other [Member] | OAEM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		11,825
Commercial, financial, agricultural and other [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		64,223
Commercial, financial, agricultural and other [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Commercial, financial, agricultural and other [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		76,048
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		220,736
Real Estate Construction [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		220,267
Real Estate Construction [Member] | OAEM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		442
Real Estate Construction [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		27
Real Estate Construction [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Real Estate Construction [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		469
Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,224,465
Residential real estate [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,209,606
Residential real estate [Member] | OAEM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		5,244
Residential real estate [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		9,615
Residential real estate [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Residential real estate [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		14,859
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,479,000
Commercial real estate [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,436,714
Commercial real estate [Member] | OAEM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		30,012
Commercial real estate [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		12,274
Commercial real estate [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Commercial real estate [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		42,286
Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		608,643
Loans To Individuals [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		608,342
Loans To Individuals [Member] | OAEM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Loans To Individuals [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		301
Loans To Individuals [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		0
Loans To Individuals [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		$ 301
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 4,778,471
Originated Loans [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	4,646,456
Originated Loans [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	41,181
Originated Loans [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	90,834
Originated Loans [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	132,015
Originated Loans [Member] | Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,131,148
Originated Loans [Member] | Commercial, financial, agricultural and other [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,038,844
Originated Loans [Member] | Commercial, financial, agricultural and other [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	27,387
Originated Loans [Member] | Commercial, financial, agricultural and other [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	64,917
Originated Loans [Member] | Commercial, financial, agricultural and other [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Commercial, financial, agricultural and other [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	92,304
Originated Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	217,840
Originated Loans [Member] | Real Estate Construction [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	217,565
Originated Loans [Member] | Real Estate Construction [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	275
Originated Loans [Member] | Real Estate Construction [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Real Estate Construction [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Real Estate Construction [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	275
Originated Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,165,851
Originated Loans [Member] | Residential real estate [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,152,511
Originated Loans [Member] | Residential real estate [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	5,923
Originated Loans [Member] | Residential real estate [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	7,417
Originated Loans [Member] | Residential real estate [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Residential real estate [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	13,340
Originated Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,717,043
Originated Loans [Member] | Commercial real estate [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,691,220
Originated Loans [Member] | Commercial real estate [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	7,596
Originated Loans [Member] | Commercial real estate [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	18,227
Originated Loans [Member] | Commercial real estate [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Commercial real estate [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	25,823
Originated Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	546,589
Originated Loans [Member] | Loans To Individuals [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	546,316
Originated Loans [Member] | Loans To Individuals [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Loans To Individuals [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	273
Originated Loans [Member] | Loans To Individuals [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Originated Loans [Member] | Loans To Individuals [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	273
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	100,876
Acquired Loans [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	98,519
Acquired Loans [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	486
Acquired Loans [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,871
Acquired Loans [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	2,357
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	8,399
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	7,591
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	486
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	322
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	808
Acquired Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,781
Acquired Loans [Member] | Real Estate Construction [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,781
Acquired Loans [Member] | Real Estate Construction [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Real Estate Construction [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Real Estate Construction [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Real Estate Construction [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	63,341
Acquired Loans [Member] | Residential real estate [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	62,919
Acquired Loans [Member] | Residential real estate [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Residential real estate [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	422
Acquired Loans [Member] | Residential real estate [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Residential real estate [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	422
Acquired Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	25,167
Acquired Loans [Member] | Commercial real estate [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	24,043
Acquired Loans [Member] | Commercial real estate [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Commercial real estate [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,124
Acquired Loans [Member] | Commercial real estate [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Commercial real estate [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,124
Acquired Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	2,188
Acquired Loans [Member] | Loans To Individuals [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	2,185
Acquired Loans [Member] | Loans To Individuals [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Loans To Individuals [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	3
Acquired Loans [Member] | Loans To Individuals [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	0
Acquired Loans [Member] | Loans To Individuals [Member] | Total Non-Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 3

Loans and Allowance for Credi82

Loans and Allowance for Credit Losses - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2016USD ($)Contractloan	Dec. 31, 2015USD ($)Contract	Dec. 31, 2014USD ($)Contract	Dec. 31, 2013USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses		$ 18,480,000	$ 14,948,000	$ 11,196,000
Charge-offs			18,868,000	$ 17,472,000
Recorded Investment			$ 50,844,000
Number of loans modified | Contract		65	61	77
Total amount of loan modified	$ 10,275,000	$ 10,275,000	$ 10,956,000	$ 15,967,000
Gain (loss) on sale of impaired loans			444,000
Off balance sheet reserve to nonperforming loans			13,000
Loans held for sale	7,052,000	7,052,000	5,763,000
Total gains or losses included in earnings		589,000	111,000
Loans with modification to rate and payment due to amortization		$ 6,600,000	3,700,000	$ 600,000
Minimum days required for conversion of trouble debt to be in default		90 days
Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded commitments related to nonperforming loans	1,800,000	$ 1,800,000	141,000
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non Accrual Status Of Loans After Number Of Days Past Due		150 days
Gear Manufacturer [Member] | Nonaccrual Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Chargeoffs of loans	500,000
Nonaccrual	3,100,000	$ 3,100,000
Local Energy Company [Member] | Nonaccrual Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Chargeoffs of loans	1,300,000
Reserve for Off-balance Sheet Activities [Member] | Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Off balance sheet reserve to nonperforming loans	0	0
Steel and Aluminum Servicing Company [Member] | Commercial and Industrial Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Chargeoffs of loans		4,200,000
Nonaccrual	7,600,000	$ 7,600,000
Local Energy Company [Member] | Commercial and Industrial Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans modified | loan		2
Total amount of loan modified			$ 2,300,000		$ 1,000,000
Nonaccrual	$ 3,300,000	$ 3,300,000

Loans and Allowance for Credi83

Loans and Allowance for Credit Losses - Age Analysis of Past Due Loans by Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual		$ 49,636
Current		4,634,114
Loans	$ 4,879,347	4,683,750	$ 4,457,308
Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual		24,195
Current		1,126,711
Loans	1,139,547	1,150,906
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual		308
Current		220,428
Loans	219,621	220,736
Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual		13,045
Current		1,211,420
Loans	1,229,192	1,224,465
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual		7,069
Current		1,471,931
Loans	1,742,210	1,479,000
Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual		5,019
Current		603,624
Loans	548,777	608,643
Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,139,547	1,150,906	1,052,109
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	219,621	220,736	120,785
Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,229,192	1,224,465	1,226,344
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,742,210	1,479,000	1,405,256
Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	548,777	608,643	$ 652,814
Financing Receivables, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		8,598
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		364
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		280
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		4,175
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		781
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		2,998
Financing Receivables, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		1,878
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		49
Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		0
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		1,055
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		774
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		2,455
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		129
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		1,315
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		65
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		946
Nonaccrual Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		36,705
Nonaccrual Commercial Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		23,653
Nonaccrual Commercial Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		28
Nonaccrual Commercial Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		6,500
Nonaccrual Commercial Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		6,223
Nonaccrual Commercial Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due		$ 301
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	40,497
Current	4,737,974
Loans	4,778,471
Originated Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	20,554
Current	1,110,594
Loans	1,131,148
Originated Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	183
Current	217,657
Loans	217,840
Originated Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	12,009
Current	1,153,842
Loans	1,165,851
Originated Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	4,092
Current	1,712,951
Loans	1,717,043
Originated Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	3,659
Current	542,930
Loans	546,589
Originated Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,131,148
Originated Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	217,840
Originated Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,165,851
Originated Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,717,043
Originated Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	546,589
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	8,601
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,380
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	183
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	4,133
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	265
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,640
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,363
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	171
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,089
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	327
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	776
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,097
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	75
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	995
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	57
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	970
Originated Loans [Member] | Nonaccrual Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	27,436
Originated Loans [Member] | Nonaccrual Commercial Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	17,928
Originated Loans [Member] | Nonaccrual Commercial Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Originated Loans [Member] | Nonaccrual Commercial Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	5,792
Originated Loans [Member] | Nonaccrual Commercial Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	3,443
Originated Loans [Member] | Nonaccrual Commercial Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	273
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	1,302
Current	99,574
Loans	100,876
Acquired Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	486
Current	7,913
Loans	8,399
Acquired Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	0
Current	1,781
Loans	1,781
Acquired Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	643
Current	62,698
Loans	63,341
Acquired Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	162
Current	25,005
Loans	25,167
Acquired Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due and nonaccrual	11
Current	2,177
Loans	2,188
Acquired Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,399
Acquired Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,781
Acquired Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	63,341
Acquired Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	25,167
Acquired Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,188
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	635
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	486
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	148
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	1
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	46
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	39
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	7
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	34
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	34
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Nonaccrual Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	587
Acquired Loans [Member] | Nonaccrual Commercial Loans [Member] | Commercial Financial Agricultural And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Nonaccrual Commercial Loans [Member] | Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	0
Acquired Loans [Member] | Nonaccrual Commercial Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	422
Acquired Loans [Member] | Nonaccrual Commercial Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	162
Acquired Loans [Member] | Nonaccrual Commercial Loans [Member] | Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 3

Loans and Allowance for Credi84

Loans and Allowance for Credit Losses - Recorded Investment and Unpaid Principal Balance for Impaired Loans with Associated Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Recorded Investment		$ 50,844
Unpaid Principal Balance		61,835
Related Allowance		7,045
Average Recorded Investment		45,458	$ 49,794
Interest Income Recognized		615	625
Commercial, financial, agricultural and other with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		11,344
Unpaid Principal Balance		15,673
Average Recorded Investment		17,692	11,536
Interest Income Recognized		216	133
Real estate construction with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		28
Unpaid Principal Balance		117
Average Recorded Investment		95	1,190
Interest Income Recognized		0	19
Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		9,952
Unpaid Principal Balance		11,819
Average Recorded Investment		10,635	11,592
Interest Income Recognized		172	210
Commercial real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		7,562
Unpaid Principal Balance		9,449
Average Recorded Investment		7,890	8,830
Interest Income Recognized		90	98
Loans to individuals with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		421
Unpaid Principal Balance		507
Average Recorded Investment		338	308
Interest Income Recognized		4	4
Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		29,307
Unpaid Principal Balance		37,565
Average Recorded Investment		36,650	33,456
Interest Income Recognized		482	464
Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		20,132
Unpaid Principal Balance		22,590
Related Allowance		6,952
Average Recorded Investment		7,731	15,797
Interest Income Recognized		129	143
Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		0
Unpaid Principal Balance		0
Related Allowance		0
Average Recorded Investment		0	0
Interest Income Recognized		0	0
Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		461
Unpaid Principal Balance		672
Related Allowance		51
Average Recorded Investment		403	357
Interest Income Recognized		0	14
Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		944
Unpaid Principal Balance		1,008
Related Allowance		42
Average Recorded Investment		674	184
Interest Income Recognized		4	4
Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		0
Unpaid Principal Balance		0
Related Allowance		0
Average Recorded Investment		0	0
Interest Income Recognized		0	0
Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment		21,537
Unpaid Principal Balance		24,270
Related Allowance		7,045
Average Recorded Investment		8,808	16,338
Interest Income Recognized		$ 133	$ 161
Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 41,226
Unpaid Principal Balance	56,296
Related Allowance	3,128
Average Recorded Investment	55,915
Interest Income Recognized	1,245
Originated Loans [Member] | Commercial, financial, agricultural and other with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	9,549
Unpaid Principal Balance	15,369
Average Recorded Investment	23,146
Interest Income Recognized	576
Originated Loans [Member] | Real estate construction with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	4
Interest Income Recognized	44
Originated Loans [Member] | Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	10,873
Unpaid Principal Balance	13,004
Average Recorded Investment	10,957
Interest Income Recognized	312
Originated Loans [Member] | Commercial real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,765
Unpaid Principal Balance	6,905
Average Recorded Investment	6,718
Interest Income Recognized	170
Originated Loans [Member] | Loans to individuals with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	382
Unpaid Principal Balance	507
Average Recorded Investment	409
Interest Income Recognized	15
Originated Loans [Member] | Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	26,569
Unpaid Principal Balance	35,785
Average Recorded Investment	41,234
Interest Income Recognized	1,117
Originated Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	13,423
Unpaid Principal Balance	19,226
Related Allowance	2,530
Average Recorded Investment	13,885
Interest Income Recognized	99
Originated Loans [Member] | Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Originated Loans [Member] | Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	424
Unpaid Principal Balance	475
Related Allowance	164
Average Recorded Investment	241
Interest Income Recognized	4
Originated Loans [Member] | Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	810
Unpaid Principal Balance	810
Related Allowance	434
Average Recorded Investment	555
Interest Income Recognized	25
Originated Loans [Member] | Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Originated Loans [Member] | Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	14,657
Unpaid Principal Balance	20,511
Related Allowance	3,128
Average Recorded Investment	14,681
Interest Income Recognized	128
Acquired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	587
Unpaid Principal Balance	661
Related Allowance	16
Average Recorded Investment	587
Interest Income Recognized	0
Acquired Loans [Member] | Commercial, financial, agricultural and other with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	0
Interest Income Recognized	0
Acquired Loans [Member] | Real estate construction with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Average Recorded Investment	0
Interest Income Recognized	0
Acquired Loans [Member] | Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	406
Unpaid Principal Balance	480
Average Recorded Investment	406
Interest Income Recognized	0
Acquired Loans [Member] | Commercial real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	162
Unpaid Principal Balance	162
Average Recorded Investment	162
Interest Income Recognized	0
Acquired Loans [Member] | Loans to individuals with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	3
Unpaid Principal Balance	3
Average Recorded Investment	3
Interest Income Recognized	0
Acquired Loans [Member] | Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	571
Unpaid Principal Balance	645
Average Recorded Investment	571
Interest Income Recognized	0
Acquired Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Acquired Loans [Member] | Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Acquired Loans [Member] | Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	16
Unpaid Principal Balance	16
Related Allowance	16
Average Recorded Investment	16
Interest Income Recognized	0
Acquired Loans [Member] | Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Acquired Loans [Member] | Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Average Recorded Investment	0
Interest Income Recognized	0
Acquired Loans [Member] | Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	16
Unpaid Principal Balance	16
Related Allowance	16
Average Recorded Investment	16
Interest Income Recognized	$ 0

Loans and Allowance for Credi85

Loans and Allowance for Credit Losses - Troubled Debt Restructured Loans and Commitments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans and Leases Receivable Disclosure [Abstract]
Accrual status	$ 13,790	$ 14,139	$ 12,584
Nonaccrual status	11,569	12,360	16,952
Total	25,359	26,499	29,536
Unused lines of credit	$ 358	$ 3,252	$ 4,120

Loans and Allowance for Credi86

Loans and Allowance for Credit Losses - Troubled Debt Restructurings Identified During Period (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)Contract	Dec. 31, 2015USD ($)Contract	Dec. 31, 2014USD ($)Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	65	61	77
Extend Maturity	$ 1,521	$ 1,754	$ 5,487
Modify Rate	6,614	3,658	732
Modify Payments	6,523	6,440	16,381
Total Pre-Modification Outstanding Recorded Investment	14,658	11,852	22,600
Post-Modification Outstanding Recorded Investment	10,275	10,956	15,967
Specific Reserve	$ 500	$ 1,332	$ 4,665
Commercial Financial Agricultural And Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	5	12	9
Extend Maturity	$ 23	$ 1,751	$ 5,487
Modify Rate	6,318	3,195	0
Modify Payments	3,854	4,527	14,529
Total Pre-Modification Outstanding Recorded Investment	10,195	9,473	20,016
Post-Modification Outstanding Recorded Investment	6,210	8,823	13,785
Specific Reserve	$ 317	$ 1,330	$ 4,665
Residential real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	39	32	52
Extend Maturity	$ 107	$ 0	$ 0
Modify Rate	214	296	629
Modify Payments	2,619	1,414	1,797
Total Pre-Modification Outstanding Recorded Investment	2,940	1,710	2,426
Post-Modification Outstanding Recorded Investment	2,698	1,575	2,062
Specific Reserve	$ 124	$ 2	$ 0
Commercial real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	8	1	1
Extend Maturity	$ 1,368	$ 0	$ 0
Modify Rate	0	0	0
Modify Payments	25	464	8
Total Pre-Modification Outstanding Recorded Investment	1,393	464	8
Post-Modification Outstanding Recorded Investment	1,271	389	6
Specific Reserve	$ 59	$ 0	$ 0
Loans To Individuals [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	13	16	15
Extend Maturity	$ 23	$ 3	$ 0
Modify Rate	82	167	103
Modify Payments	25	35	47
Total Pre-Modification Outstanding Recorded Investment	130	205	150
Post-Modification Outstanding Recorded Investment	96	169	114
Specific Reserve	$ 0	$ 0	$ 0

Loans and Allowance for Credi87

Loans and Allowance for Credit Losses - Restructured Loans that are Considered to be in Default (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)loan	Dec. 31, 2015USD ($)loan	Dec. 31, 2014USD ($)loan
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loan	4	3	3
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 313	$ 97	$ 13
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loan	4	3	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 313	$ 97	$ 7
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loan	0	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0	$ 6

Loans and Allowance for Credi88

Loans and Allowance for Credit Losses - Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 50,812	$ 52,051	$ 54,225
Charge-offs		(18,868)	(17,472)
Recoveries		2,681	4,102
Provision for credit losses	18,480	14,948	11,196
Ending Balance	50,185	50,812	52,051
Ending balance: individually evaluated for impaired	3,144	7,045	9,461
Ending balance: collectively evaluated for impaired	47,041	43,767	42,590
Ending balance	4,879,347	4,683,750	4,457,308
Ending balance: individually evaluated for impaired	33,668	44,009	48,442
Ending balance: collectively evaluated for impaired	4,845,679	4,639,741	4,408,866
Commercial, financial, agricultural and other [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	31,035	29,627	22,663
Charge-offs		(11,429)	(8,911)
Recoveries		1,097	734
Provision for credit losses		11,740	15,141
Ending Balance	35,974	31,035	29,627
Ending balance: individually evaluated for impaired	2,530	6,952	9,304
Ending balance: collectively evaluated for impaired	33,444	24,083	20,323
Ending balance	1,139,547	1,150,906	1,052,109
Ending balance: individually evaluated for impaired	22,325	30,767	33,332
Ending balance: collectively evaluated for impaired	1,117,222	1,120,139	1,018,777
Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	887	2,063	6,600
Charge-offs		(8)	(296)
Recoveries		84	1,340
Provision for credit losses		(1,252)	(5,581)
Ending Balance	577	887	2,063
Ending balance: individually evaluated for impaired	0	0	0
Ending balance: collectively evaluated for impaired	577	887	2,063
Ending balance	219,621	220,736	120,785
Ending balance: individually evaluated for impaired	0	0	193
Ending balance: collectively evaluated for impaired	219,621	220,736	120,592
Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,606	3,664	7,727
Charge-offs		(1,539)	(3,153)
Recoveries		587	650
Provision for credit losses		(106)	(1,560)
Ending Balance	2,511	2,606	3,664
Ending balance: individually evaluated for impaired	180	51	56
Ending balance: collectively evaluated for impaired	2,331	2,555	3,608
Ending balance	1,229,192	1,224,465	1,226,344
Ending balance: individually evaluated for impaired	5,875	6,099	7,127
Ending balance: collectively evaluated for impaired	1,223,317	1,218,366	1,219,217
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	11,924	11,881	11,778
Charge-offs		(1,538)	(1,148)
Recoveries		229	612
Provision for credit losses		1,352	639
Ending Balance	6,619	11,924	11,881
Ending balance: individually evaluated for impaired	434	42	101
Ending balance: collectively evaluated for impaired	6,185	11,882	11,780
Ending balance	1,742,210	1,479,000	1,405,256
Ending balance: individually evaluated for impaired	5,468	7,143	7,790
Ending balance: collectively evaluated for impaired	1,736,742	1,471,857	1,397,466
Loans To Individuals [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	4,360	4,816	5,457
Charge-offs		(4,354)	(3,964)
Recoveries		684	766
Provision for credit losses		3,214	2,557
Ending Balance	4,504	4,360	4,816
Ending balance: individually evaluated for impaired	0	0	0
Ending balance: collectively evaluated for impaired	4,504	4,360	4,816
Ending balance	548,777	608,643	652,814
Ending balance: individually evaluated for impaired	0	0	0
Ending balance: collectively evaluated for impaired	548,777	608,643	$ 652,814
Originated Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	50,812
Charge-offs	(26,305)
Recoveries	7,198
Provision for credit losses	18,461
Ending Balance	50,166	50,812
Ending balance	4,778,471
Originated Loans [Member] | Commercial, financial, agricultural and other [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	31,035
Charge-offs	(19,603)
Recoveries	4,164
Provision for credit losses	20,378
Ending Balance	35,974	31,035
Ending balance	1,131,148
Originated Loans [Member] | Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	887
Charge-offs	0
Recoveries	562
Provision for credit losses	(872)
Ending Balance	577	887
Ending balance	217,840
Originated Loans [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,606
Charge-offs	(1,189)
Recoveries	481
Provision for credit losses	594
Ending Balance	2,492	2,606
Ending balance	1,165,851
Originated Loans [Member] | Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	11,924
Charge-offs	(570)
Recoveries	1,522
Provision for credit losses	(6,257)
Ending Balance	6,619	11,924
Ending balance	1,717,043
Originated Loans [Member] | Loans To Individuals [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	4,360
Charge-offs	(4,943)
Recoveries	469
Provision for credit losses	4,618
Ending Balance	4,504	$ 4,360
Ending balance	546,589
Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Ending Balance	19
Ending balance	100,876
Acquired Loans [Member] | Commercial, financial, agricultural and other [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Ending Balance	0
Ending balance	8,399
Acquired Loans [Member] | Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Ending Balance	0
Ending balance	1,781
Acquired Loans [Member] | Residential real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Ending Balance	19
Ending balance	63,341
Acquired Loans [Member] | Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Ending Balance	0
Ending balance	25,167
Acquired Loans [Member] | Loans To Individuals [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Ending Balance	0
Ending balance	$ 2,188

Commitments and Letters of Cr89

Commitments and Letters of Credit - Notional Amount of Commitments and Letter of Credit Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Commitments to extend credit
Loss Contingencies [Line Items]
Financial instrument of credit risk	$ 1,733,820	$ 1,643,187
Financial standby letters of credit
Loss Contingencies [Line Items]
Financial instrument of credit risk	18,108	17,843
Performance standby letters of credit
Loss Contingencies [Line Items]
Financial instrument of credit risk	26,630	26,497
Commercial letters of credit
Loss Contingencies [Line Items]
Financial instrument of credit risk	$ 1,301	$ 1,672

Commitments and Letters of Cr90

Commitments and Letters of Credit - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Notional amount of financial standby letters of credit	$ 400,000
Notional amount of performance standby letters of credit	3,000,000
Notional amount of commercial letters of credit	201,000
Financial instrument of credit risk	165,000	$ 200,000
Unused commitments and letters of credit [Member]
Loss Contingencies [Line Items]
Commitment liability	$ 4,100,000	$ 4,400,000

Premises and Equipment - Schedu

Premises and Equipment - Schedule of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 207,315	$ 197,724
Less accumulated depreciation and amortization	139,781	134,270
Total premises and equipment	67,534	63,454
Land [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	13,679	12,185
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 80,364	77,086
Buildings and improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Buildings and improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	50 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 15,871	14,518
Leasehold improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Leasehold improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	40 years
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 61,324	59,463
Furniture and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Furniture and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years
Software [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 36,077	$ 34,472
Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Amount paid under sale-leaseback arrangement	$ 202
Gain on sale of branch	$ 297
Sale-leaseback transaction	15 year
Total lease expense	$ 3,700	$ 2,900	$ 2,900
Premises and Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation included in noninterest expense	$ 7,500	$ 7,200	$ 13,200

Premises and Equipment - Sche93

Premises and Equipment - Schedule of Future Minimum Rentals (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Premises [Member]
Operating Leased Assets [Line Items]
2,016	$ 3,844
2,017	3,559
2,018	3,137
2,019	2,556
2,020	2,265
Thereafter	9,693
Total	25,054
Equipment [Member]
Operating Leased Assets [Line Items]
2,016	10
2,017	0
2,018	0
2,019	0
2,020	0
Thereafter	0
Total	$ 10

Goodwill and Other Amortizing94

Goodwill and Other Amortizing Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 02, 2016
Goodwill And Other Intangibles [Line Items]
Goodwill	$ 186,483,000	$ 164,500,000
Impairment charges on goodwill	0	0	$ 0
Total amortization	19,442,000	18,895,000
Amortization of other intangible assets	547,000	605,000	$ 631,000
FirstMerit Bank, NA, Branch Acquisition [Member]
Goodwill And Other Intangibles [Line Items]
Goodwill				$ 22,047,000
Goodwill, Acquired During Period	$ 22,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ 11,330,000
Customer deposit intangibles
Goodwill And Other Intangibles [Line Items]
Core deposits remaining amortization period	9 years 11 months
Core deposits weighted average amortization period	10 years
Customer list intangible
Goodwill And Other Intangibles [Line Items]
Core deposits weighted average amortization period	12 years 10 months
Total amortization	$ 444,000	$ 276,000

Goodwill and Other Amortizing95

Goodwill and Other Amortizing Intangible Assets - Summarized Other Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 31,455	$ 20,126
Accumulated Amortization	(19,442)	(18,895)
Net Intangible Assets	12,013	1,231
Customer Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	30,471	19,142
Accumulated Amortization	(18,998)	(18,619)
Net Intangible Assets	11,473	523
Customer list intangible
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	984	984
Accumulated Amortization	(444)	(276)
Net Intangible Assets	$ 540	$ 708

Goodwill and Other Amortizing96

Goodwill and Other Amortizing Intangible Assets - Estimated Amortization Expense of Core Deposit Intangibles (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Other Intangibles [Line Items]
2,016	$ 2,262
2,017	2,022
2,018	1,786
2,019	1,502
2,020	1,279
Thereafter	3,162
Net Intangible Assets	12,013	$ 1,231
Customer list intangible
Goodwill And Other Intangibles [Line Items]
2,016	129
2,017	99
2,018	77
2,019	59
2,020	45
Thereafter	131
Net Intangible Assets	540	$ 708
Customer deposit intangibles
Goodwill And Other Intangibles [Line Items]
2,016	2,133
2,017	1,923
2,018	1,709
2,019	1,443
2,020	1,234
Thereafter	3,031
Net Intangible Assets	$ 11,473

Interest-Bearing Deposits - Com

Interest-Bearing Deposits - Components of Interest-Bearing Deposits (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deposits [Abstract]
Interest-bearing demand deposits	$ 114,043	$ 86,365
Savings deposits	2,972,747	2,390,607
Time deposits	591,832	602,233
Total interest-bearing deposits	$ 3,678,622	$ 3,079,205

Interest-Bearing Deposits - Add

Interest-Bearing Deposits - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deposits [Abstract]
Interest-bearing demand deposit, money market	$ 779.2	$ 580.8
Certificates of deposit in denominations of $100 thousand or more	145.4	157.7
Interest expense related to certificates of deposit $100 thousand or greater	$ 1.2	$ 1.8	$ 3.7

Interest-Bearing Deposits - Sch

Interest-Bearing Deposits - Scheduled Maturities of Time Deposits (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deposits [Abstract]
2,017	$ 319,298
2,018	133,754
2,019	66,121
2,020	33,859
2021 and thereafter	38,800
Total	$ 591,832	$ 602,233

Short-term Borrowings - Summary

Short-term Borrowings - Summary of Short-Term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Ending Balance	$ 867,943	$ 1,510,825	$ 1,105,876
Average Balance	$ 1,387,737	$ 1,252,531	$ 815,393
Average Rate	0.58%	0.40%	0.30%
Federal funds purchased
Short-term Debt [Line Items]
Ending Balance	$ 0	$ 4,000	$ 9,000
Average Balance	$ 6,887	$ 14,832	$ 11,691
Average Rate	0.60%	0.36%	0.36%
Borrowings from FHLB
Short-term Debt [Line Items]
Ending Balance	$ 748,000	$ 1,400,000	$ 945,000
Average Balance	$ 1,265,932	$ 1,117,522	$ 644,651
Average Rate	0.61%	0.42%	0.31%
Securities sold under agreements to repurchase
Short-term Debt [Line Items]
Ending Balance	$ 119,943	$ 106,825	$ 151,876
Average Balance	$ 114,918	$ 120,177	$ 159,051
Average Rate	0.23%	0.23%	0.24%
Maximum [Member]
Short-term Debt [Line Items]
Ending Balance	$ 1,530,678	$ 1,510,825	$ 1,105,876
Weighted Average [Member]
Short-term Debt [Line Items]
Average Rate	0.63%	0.53%	0.30%

Short-term Borrowings - Interes

Short-term Borrowings - Interest Expense on Short-Term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	$ 8,076	$ 5,018	$ 2,449
Federal funds purchased
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	41	54	42
Borrowings from FHLB
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	7,765	4,684	2,019
Securities sold under agreements to repurchase
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	$ 270	$ 280	$ 388

Subordinated Debentures - Subor

Subordinated Debentures - Subordinated Debentures Outstanding (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Subordinated Borrowing [Line Items]
Subordinated Debentures outstanding, Amount	$ 72,167	$ 72,167
First Commonwealth Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated Debentures outstanding, Due	Jan. 1, 2034
Subordinated Debentures outstanding, Amount	$ 30,929	30,929
First Commonwealth Capital Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated Debentures outstanding, Due	Jan. 1, 2034
Subordinated Debentures outstanding, Amount	$ 41,238	$ 41,238

Subordinated Debentures - Addit

Subordinated Debentures - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)trust	Dec. 31, 2015
Subordinated Borrowing [Line Items]
Number of trusts | trust	2
First Commonwealth Capital Trust III [Member]
Subordinated Borrowing [Line Items]
Redemption price as percentage of principal amount	100.00%
Deferred finance costs	$ 630
First Commonwealth Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Redemption price as percentage of principal amount	100.00%
Deferred finance costs	$ 471
LIBOR [Member] | Subordinated Debt [Member] | First Commonwealth Capital Trust III [Member]
Subordinated Borrowing [Line Items]
Variable interest rate	2.85%	2.85%
LIBOR [Member] | Subordinated Debt [Member] | First Commonwealth Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Variable interest rate	2.85%	2.85%

Other Long-term Debt (Detail)

Other Long-term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amount
Long-term debt	$ 8,749	$ 9,314
Borrowings from FHLB [Member]
Amount
2,015		563
2,016	586	585
2,017	609	607
2,018	633	631
2,019	658	659
2,020	684
Thereafter		$ 6,269
Thereafter	$ 5,579
2015, Weighted Average Contractual Rate		3.82%
2016, Weighted Average Contractual Rate	3.83%	3.83%
2017, Weighted Average Contractual Rate	3.83%	3.83%
2018, Weighted Average Contractual Rate	3.84%	3.83%
2019, Weighted Average Contractual Rate	3.84%	3.84%
2020, Weighted Average Contractual Rate	3.84%
Thereafter, Weighted Average Contractual Rate		3.81%
Thereafter, Weighted Average Contractual Rate	3.81%

Fair Values of Assets and Li105

Fair Values of Assets and Liabilities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Random sample percentage of securities for each quarter	100.00%
Credit loss recognized	$ 0	$ 0	$ 0
Total gains or losses included in earnings	(589,000)	(111,000)
Interest rate swaps transferred into Level 3 from Level 2	536,000	0
Corporate securities transferred from Level 3 to Level 2	(536,000)	0
Impaired loans considered to be credit risk of non-collection	100,000
Updated appraisal requirement floor	250,000
Other real estate owned	6,805,000	9,398,000
Financial instrument of credit risk	165,000	200,000
Provision for credit losses	18,480,000	14,948,000	$ 11,196,000
Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total gains or losses included in earnings	0	0
Interest rate swaps transferred into Level 3 from Level 2	536,000	0
Corporate securities transferred from Level 3 to Level 2	$ 0	$ 0

Fair Values of Assets and Li106

Fair Values of Assets and Liabilities - Quantitative Inputs and Assumptions Used in Level 3 Fair Value Measurements (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 829,181,000	$ 966,548,000
Other Assets, Fair Value Disclosure	7,019,000	11,273,000
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	35,892,000	37,828,000
Other Assets, Fair Value Disclosure	930,000	0
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 33,292,000
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Probability Of Default [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Probability of default
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Prepayment Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Prepayment rates
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Discount Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Discount rates
Other Assets [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Valuation Techniques	Discounted Cash Flow
Other Assets [Member] | Par Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Valuation Techniques	Par Value
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 1,670,000
Equity Securities [Member] | Par Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Valuation Techniques	Par Value
Impaired Loans [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 9,303,000
Fair Value Measurements, Valuation Techniques	Discounted Cash Flow
Impaired Loans [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 2,281,000
Fair Value Measurements, Valuation Techniques	Gas Reserve study
Impaired Loans [Member] | Discount Rates [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Discount Rate
Impaired Loans [Member] | Discount Rates [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Discount rate
Impaired Loans [Member] | Gas Per Million Cubic Feet [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Gas per MCF
Impaired Loans [Member] | Oil Per Barrels Per Day [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Measurements, Significant Assumptions	Oil per BBL/d
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 46,235,000	53,846,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 19,990,000	$ 12,828,000
Maximum [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	4.68%
Maximum [Member] | Probability Of Default [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	10000.00%
Maximum [Member] | Prepayment Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	7266.00%
Maximum [Member] | Gas Per Million Cubic Feet [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Weighted Average Inputs Price	$ 3.38
Maximum [Member] | Oil Per Barrels Per Day [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Weighted Average Inputs Price	$ 56.16
Maximum [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member] | Discount Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	1200.00%
Weighted Average [Member] | Probability Of Default [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	1067.00%
Weighted Average [Member] | Prepayment Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	415.00%
Weighted Average [Member] | Impaired Loans [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	10.00%
Minimum [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	1.90%
Minimum [Member] | Probability Of Default [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	0.00%
Minimum [Member] | Prepayment Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	0.00%
Minimum [Member] | Gas Per Million Cubic Feet [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Weighted Average Inputs Price	$ 1.63
Minimum [Member] | Oil Per Barrels Per Day [Member] | Reserve [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Weighted Average Inputs Price	$ 40.97
Minimum [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member] | Discount Rates [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	525.00%

Fair Values of Assets and Li107

Fair Values of Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	$ 778,612	$ 886,560
Other investments	36,498	62,952
Loans Held for Sale	7,052	5,763
Other Assets	7,019	11,273
Total Assets	829,181	966,548
Other Liabilities	5,972	10,829
Total Liabilities	5,972	10,829
US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	16,617	22,092
Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	676,853	777,577
Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	1	28
Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	16,631	19,118
Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	27,229	27,598
Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	6,319	2,319
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	33,292	35,658
Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	776,942	884,390
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	1,670	2,170
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Other investments	0	0
Loans Held for Sale	0	0
Other Assets	0	0
Total Assets	0	0
Other Liabilities	0	0
Total Liabilities	0	0
Level 1 [Member] | US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 1 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	743,650	848,732
Other investments	36,498	62,952
Loans Held for Sale	7,052	5,763
Other Assets	6,089	11,273
Total Assets	793,289	928,720
Other Liabilities	5,972	10,829
Total Liabilities	5,972	10,829
Level 2 [Member] | US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	16,617	22,092
Level 2 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	676,853	777,577
Level 2 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	1	28
Level 2 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	16,631	19,118
Level 2 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	27,229	27,598
Level 2 [Member] | Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	6,319	2,319
Level 2 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	743,650	848,732
Level 2 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	34,962	37,828
Other investments	0	0
Loans Held for Sale	0	0
Other Assets	930	0
Total Assets	35,892	37,828
Other Liabilities	0	0
Total Liabilities	0	0
Level 3 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Assets	1,670
Level 3 [Member] | US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member] | Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	0	0
Level 3 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale	$ 33,292	35,658
Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale		35,658
Level 3 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value of Available for Sale		$ 2,170

Fair Values of Assets and Li108

Fair Values of Assets and Liabilities - Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	$ (778,612)	$ (886,560)
Assets, Fair Value Disclosure	829,181	966,548
Balance, beginning of period	37,828	30,419
Total gains or losses included in earnings	589	111
Total gains or losses included in other comprehensive income	850	7,608
Purchases	430	750
Issuances	0	0
Sales	0	0
Settlements	(3,805)	(1,060)
Transfers from Level 3	536	0
Transfers into Level 3	536	0
Balance, end of period	35,892	37,828
Federal Home Loan Bank Stock	36,498	62,952
Loans Held-for-sale, Fair Value Disclosure	7,052	5,763
Other Assets, Fair Value Disclosure	7,019	11,273
Other Liabilities, Fair Value Disclosure	5,972	10,829
Financial and Nonfinancial Liabilities, Fair Value Disclosure	5,972	10,829
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	35,658	28,999
Total gains or losses included in earnings	589	111
Total gains or losses included in other comprehensive income	850	7,608
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(3,805)	(1,060)
Transfers from Level 3	0	0
Transfers into Level 3	0	0
Balance, end of period	33,292	35,658
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	2,170	1,420
Total gains or losses included in earnings	0	0
Total gains or losses included in other comprehensive income	0	0
Purchases	36	750
Issuances	0	0
Sales	0	0
Settlements	0	0
Transfers from Level 3	536	0
Transfers into Level 3	0	0
Balance, end of period	1,670	2,170
Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	0	0
Total gains or losses included in earnings	0	0
Total gains or losses included in other comprehensive income	0	0
Purchases	394	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Transfers from Level 3	0	0
Transfers into Level 3	536	0
Balance, end of period	930	0
Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(6,319)	(2,319)
Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(776,942)	(884,390)
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(33,292)	(35,658)
US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(16,617)	(22,092)
Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(676,853)	(777,577)
Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(1)	(28)
Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(16,631)	(19,118)
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(27,229)	(27,598)
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(1,670)	(2,170)
Level 1 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Assets, Fair Value Disclosure	0	0
Federal Home Loan Bank Stock	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Other Assets, Fair Value Disclosure	0	0
Other Liabilities, Fair Value Disclosure	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Level 1 [Member] | Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 1 [Member] | Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(743,650)	(848,732)
Assets, Fair Value Disclosure	793,289	928,720
Federal Home Loan Bank Stock	36,498	62,952
Loans Held-for-sale, Fair Value Disclosure	7,052	5,763
Other Assets, Fair Value Disclosure	6,089	11,273
Other Liabilities, Fair Value Disclosure	5,972	10,829
Financial and Nonfinancial Liabilities, Fair Value Disclosure	5,972	10,829
Level 2 [Member] | Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(6,319)	(2,319)
Level 2 [Member] | Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(743,650)	(848,732)
Level 2 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Level 2 [Member] | US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(16,617)	(22,092)
Level 2 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(676,853)	(777,577)
Level 2 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(1)	(28)
Level 2 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(16,631)	(19,118)
Level 2 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(27,229)	(27,598)
Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(34,962)	(37,828)
Assets, Fair Value Disclosure	35,892	37,828
Federal Home Loan Bank Stock	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Other Assets, Fair Value Disclosure	930	0
Other Liabilities, Fair Value Disclosure	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets, Fair Value Disclosure	33,292
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets, Fair Value Disclosure	1,670
Fair Value, Inputs, Level 3 [Member] | Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value		(35,658)
Fair Value, Inputs, Level 3 [Member] | Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	(33,292)	(35,658)
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Residential [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Mortgage-Backed Securities-Commercial [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Obligations of U.S. Government-Sponsored Enterprises [Member] | Other Government - Sponsored Enterprises [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value	$ 0	0
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale, at fair value		$ (2,170)

Fair Values of Assets and Li109

Fair Values of Assets and Liabilities - Schedule of Assets Measured on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 829,181	$ 966,548
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	38,669	43,799
Other real estate owned	7,566	10,047
Total Assets	46,235	53,846
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	0	0
Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate owned	0	0
Total Assets	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	793,289	928,720
Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	18,679	30,979
Other real estate owned	7,566	10,039
Total Assets	26,245	41,018
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	35,892	37,828
Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	19,990	12,820
Other real estate owned	0	8
Total Assets	19,990	12,828
Total Gains (Losses) [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Of Assets On Nonrecurring Basis Net Losses On Impaired Loans	(9,032)	(9,098)
Fair Value Measurement Of Assets On Nonrecurring Basis Net Losses On Other Real Estate Owned	(703)	(1,693)
Fair Value Measurement Of Assets On Nonrecurring Basis Net Loss	$ (9,735)	$ (10,791)

Fair Values of Assets and Li110

Fair Values of Assets and Liabilities - Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	$ 91,033,000	$ 66,644,000
Interest-bearing deposits	24,644,000	2,808,000
Securities available for sale	778,612,000	886,560,000
Held-to-maturity Securities	372,513,000	384,324,000
Other investments	36,498,000	62,952,000
Loans held for sale	7,052,000	5,763,000
Loans	4,879,347,000	4,683,750,000	$ 4,457,308,000
Deposits	4,947,408,000	4,195,894,000
Short-term borrowings	867,943,000	1,510,825,000	$ 1,105,876,000
Long-term debt	8,749,000	9,314,000
Subordinated debt	72,167,000	72,167,000
Level 1 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Securities available for sale	0	0
Other investments	0	0
Level 2 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Securities available for sale	743,650,000	848,732,000
Other investments	36,498,000	62,952,000
Level 3 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Securities available for sale	34,962,000	37,828,000
Other investments	0	0
Carrying Amount [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	91,033,000	66,644,000
Interest-bearing deposits	24,644,000	2,808,000
Securities available for sale	778,612,000	886,560,000
Held-to-maturity Securities	372,513,000	384,324,000
Other investments	36,498,000	62,952,000
Loans held for sale	7,052,000	5,763,000
Loans	4,879,347,000	4,683,750,000
Deposits	4,947,408,000	4,195,894,000
Short-term borrowings	867,943,000	1,510,825,000
Long-term debt	8,749,000	9,314,000
Subordinated debt	72,167,000	72,167,000
Estimated Fair Value [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	91,033,000	66,644,000
Interest-bearing deposits	24,644,000	2,808,000
Securities available for sale	778,612,000	886,560,000
Held-to-maturity Securities	368,618,000	382,341,000
Other investments	36,498,000	62,952,000
Loans held for sale	7,052,000	5,763,000
Loans	4,878,254,000	4,690,852,000
Deposits	4,949,714,000	4,198,817,000
Short-term borrowings	867,667,000	1,510,718,000
Long-term debt	9,169,000	9,834,000
Subordinated debt	65,656,000	62,794,000
Estimated Fair Value [Member] | Level 1 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	91,033,000	66,644,000
Interest-bearing deposits	24,644,000	2,808,000
Securities available for sale	0	0
Held-to-maturity Securities	0	0
Other investments	0	0
Loans held for sale	0	0
Loans	0	0
Deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Subordinated debt	0	0
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Securities available for sale	743,650,000	848,732,000
Held-to-maturity Securities	368,618,000	382,341,000
Other investments	36,498,000	62,952,000
Loans held for sale	7,052,000	5,763,000
Loans	18,679,000	30,979,000
Deposits	4,949,714,000	4,198,817,000
Short-term borrowings	867,667,000	1,510,718,000
Long-term debt	9,169,000	9,834,000
Subordinated debt	0	0
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Securities available for sale	34,962,000	37,828,000
Held-to-maturity Securities	0	0
Other investments	0	0
Loans held for sale	0	0
Loans	4,859,575,000	4,659,873,000
Deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Subordinated debt	$ 65,656,000	$ 62,794,000

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal	$ 19,879	$ 8,610	$ 12,661
State	154	68	157
Total current tax provision	20,033	8,678	12,818
Deferred State and Local Income Tax Expense (Benefit)	5,846	12,158	4,862
Deferred State and Local Income Tax Expense (Benefit)	(240)	0	0
Deferred Income Tax Expense (Benefit)	5,606	12,158	4,862
Total tax provision (benefit), Amount	$ 25,639	$ 20,836	$ 17,680

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax at statutory rate, Amount	$ 29,830	$ 24,843	$ 21,747
Income Tax Reconciliation, Bank Owned Life Insurance Income	(1,883)	(1,894)	(1,926)
Tax-exempt interest income, net, Amount	(2,434)	(2,232)	(2,133)
Tax credits, Amount	0	(61)	(134)
Other, Amount	126	180	126
Total tax provision (benefit), Amount	$ 25,639	$ 20,836	$ 17,680
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Tax at statutory rate, Pretax Income	35.00%	35.00%	35.00%
Income from bank owned life insurance, Pretax Income	(2.00%)	(3.00%)	(3.00%)
Tax-exempt interest income, net, Pretax Income	(3.00%)	(3.00%)	(4.00%)
Tax credits, Pretax Income	(0.00%)	(0.00%)	(0.00%)
Other, Pretax Income	0.00%	0.00%	0.00%
Total tax provision (benefit), Pretax Income	30.00%	29.00%	28.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 0
Federal statutory rate	35.00%	35.00%	35.00%
Annual effective income tax rate, percentage	30.00%	29.00%	28.00%
Net deferred tax asset	$ 33,315,000	$ 36,360,000
Alternative minimum tax credit carryforward	$ 0	$ 5,065,000

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets, Gross [Abstract]
Allowance for credit losses	$ 17,616	$ 17,784
Postretirement benefits other than pensions	611	641
Alternative minimum tax credit carryforward	0	5,065
Litigation reserve	106	0
Unrealized loss on securities available for sale	3,905	1,291
Writedown of other real estate owned	1,266	1,087
Deferred compensation	1,966	2,113
Accrued interest on nonaccrual loans	1,701	1,452
Other-than-temporary impairment of securities	88	89
Depreciation of assets	0	879
Accrued incentives	2,627	1,629
Unfunded loan commitment allowance	1,452	1,557
Accrued severance	102	808
Basis difference in assets acquired	296	417
Loan origination fees and costs	290	141
Deferred rent	1,285	1,258
Other	1,084	1,105
Total deferred tax assets	34,395	37,316
Deferred tax liabilities:
Income from unconsolidated subsidiary	(623)	(619)
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(28)	0
Other	(429)	(337)
Total deferred tax liabilities	(1,080)	(956)
Net deferred tax asset	$ 33,315	$ 36,360

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employer contribution	6.00%
Employee contribution	80.00%
Plan expense	$ 2,500,000	$ 2,700,000	$ 2,600,000
Retirement Plan expense	0	$ 0
Minimum [Member]
Total annual compensation for a calendar year for non-qualified deferred compensation plan	$ 110,000
Eligibility of participants	1.00%
Maximum [Member]
Eligibility of participants	25.00%

Retirement Plans - Schedule of

Retirement Plans - Schedule of Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 0	$ 0	$ 0
Interest cost on projected benefit obligation	67	62	62
Amortization of transition obligation	0	0	0
Gain amortization	(7)	(4)	(29)
Net periodic benefit cost	$ 60	$ 58	$ 33

Retirement Plans - Schedule 117

Retirement Plans - Schedule of Changes in Benefit Obligations and Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	$ 0	$ 0	$ 0
Interest cost	67	62	62
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Funded Status at End of Year	1,394	1,815
Unrecognized transition obligation	0	0
Unrecognized net gain	345	15
Amounts recognized in retained earnings	1,739	1,830
Change in Benefit Obligation [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	1,815	1,822
Service cost	0	0
Interest cost	67	62
Amendments	0	0
Actuarial gain	(337)	98
Net benefits paid	(151)	(167)
Benefit obligation at end of year	1,394	1,815	1,822
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net benefits paid	(151)	(167)
Change In Plan Assets [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Net benefits paid	(151)	(167)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	151	167
Net benefits paid	(151)	(167)
Fair value of plan assets at end of year	$ 0	$ 0	$ 0

Retirement Plans - Schedule 118

Retirement Plans - Schedule of Amounts Recognized as Other Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Amounts Recognized in the Statement of Financial Condition as Other liabilities	$ 1,394	$ 1,815

Retirement Plans - Schedule 119

Retirement Plans - Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (gain) loss	$ (225)	$ (10)	$ (76)
Transition obligation	0	0	0
Total	(225)	$ (10)	$ (76)
Postretirement Benefit Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (gain) loss	21
Transition obligation	0
Total	$ 21

Retirement Plans - Schedule 120

Retirement Plans - Schedule of Weighted-Average Assumptions Used to Determine Benefit Obligation (Detail) - Benefit Obligation [Member]	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Periodic Benefit Cost Assumptions [Line Items]
Discount rate	3.74%	3.88%	3.61%
Health care cost trend: Initial	6.00%	6.25%	6.50%
Health care cost trend: Ultimate	4.75%	4.75%	4.75%
Year ultimate reached	2,022	2,022	2,022

Retirement Plans - Schedule 121

Retirement Plans - Schedule of Weighted-Average Assumptions Used to Determine Net Periodic Cost (Detail) - Plans Net Periodic Cost [Member]	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Periodic Benefit Cost Assumptions [Line Items]
Discount rate	3.88%	3.61%	4.01%
Health care cost trend: Initial	6.25%	6.50%	6.75%
Health care cost trend: Ultimate	4.75%	4.75%	4.75%
Year ultimate reached	2,022	2,022	2,022
Corridor	10.00%	10.00%	10.00%
Recognition period for gains and losses	11 years	11 years	10 years

Retirement Plans - Schedule 122

Retirement Plans - Schedule of Impact of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Compensation and Retirement Disclosure [Abstract]
Effect on total of service and interest cost components, One-Percentage-Point Increase	$ 44
Effect on postretirement benefit obligation, One-Percentage-Point Increase	3
Effect on total of service and interest cost components, One-Percentage-Point Decrease	(40)
Effect on postretirement benefit obligation, One-Percentage-Point Decrease	$ (3)

Retirement Plans - Schedule 123

Retirement Plans - Schedule of Projected Benefit Payments (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	$ 174
2,017	162
2,018	137
2,019	130
2,020	123
2021 - 2025	$ 500

Incentive Compensation Plan - A

Incentive Compensation Plan - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Dec. 19, 2016	Sep. 30, 2016	Sep. 19, 2016	Jun. 07, 2016	Mar. 01, 2016	Mar. 01, 2016	Mar. 01, 2016	Feb. 18, 2016	Dec. 30, 2015	Jun. 26, 2015	Feb. 20, 2015	Feb. 20, 2015	Feb. 05, 2015	Jan. 29, 2015	Jan. 26, 2015	Jan. 15, 2015	Nov. 18, 2014	Apr. 08, 2014	Mar. 25, 2014	Mar. 05, 2014	Jan. 27, 2014	Jan. 01, 2014	Aug. 16, 2013	May 31, 2013	Mar. 01, 2013	Jan. 28, 2013	Jan. 02, 2012	Apr. 01, 2011	Feb. 24, 2012	Nov. 21, 2011	Jan. 17, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Price (in dollars per share)																																$ 9.88	$ 8.41	$ 9.03
Maximum number of shares that are available to be awarded																																5,000,000
Vesting period of restricted stock								0 years	0 years						0 years						0 years					1 year			1 year		1 year
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant																																3,673,796
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Price (in dollars per share)																																$ 14.18
Allocated Share-based Compensation Expense																																$ 3.2
Compensation expense																																	$ 1.4	$ 1
Unrecognized compensation cost related to unvested restricted stock																																$ 3.8
Executive [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	15,000	10,000	33,000	10,000	10,000	5,000	20,000	18,348		1,000	34,200	10,000				20,000	3,500	27,500	46,000	5,000		12,626	3,000	45,000	10,000		100,000	25,000		10,000
Grant Price (in dollars per share)	$ 13.96	$ 10.09	$ 10.02	$ 9.34	$ 8.84	$ 8.84	$ 8.84	$ 8.43		$ 9.84	$ 8.45	$ 8.45				$ 8.38	$ 9.26	$ 8.89	$ 9.18	$ 8.75		$ 8.82	$ 7.57	$ 7.21	$ 7.35		$ 5.26	$ 6.82		$ 4.41
Vesting Date	Dec. 19, 2019	Sep. 30, 2019	Sep. 19, 2019	Jun. 7, 2019	Mar. 1, 2019	Mar. 1, 2019	Mar. 1, 2019	Dec. 31, 2016		Jun. 26, 2018	Dec. 31, 2015	Feb. 20, 2018				Jan. 15, 2017	Nov. 17, 2017	Apr. 8, 2017	Mar. 24, 2017	Mar. 4, 2017		Dec. 31, 2014	Aug. 16, 2016	May 31, 2016	Mar. 1, 2016		Jan. 1, 2016	Apr. 1, 2016		Nov. 21, 2014
Number of Equal Vesting Periods	3	1	3	1	1	1	1	1		1	1	1				1	1	3	1	1		1	1	3	1		4	1		1
Executive [Member] | Restricted Stock [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)													50,000																34,000
Grant Price (in dollars per share)													$ 8.55																$ 5.96
Vesting Date													Feb. 5, 2018																Dec. 31, 2014
Number of Equal Vesting Periods													1																1
Executive [Member] | Restricted Stock [Member] | Annual Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)														20,170															90,000
Grant Price (in dollars per share)														$ 7.93															$ 5.96
Vesting Date														Dec. 31, 2015															Feb. 24, 2015
Number of Equal Vesting Periods														1															1

Incentive Compensation Plan - U

Incentive Compensation Plan - Unvested Service-Based Restricted Stock Awards (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of the year, Shares	231,834	265,000	271,000
Granted, Shares	121,348	135,370	94,626
Vested, Shares	(105,514)	(168,536)	(98,487)
Forfeited, Shares	0	0	(2,139)
Outstanding, end of the year, Shares	247,668	231,834	265,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding, beginning of the year, Weighted Average Grant Date Fair Value	$ 8.01	$ 7.08	$ 6.07
Grant Price (in dollars per share)	9.88	8.41	9.03
Vested, Weighted Average Grant Date Fair Value	7.04	6.87	6.18
Forfeited, Weighted Average Grant Date Fair Value	0	0	5.96
Outstanding, end of the year, Weighted Average Grant Date Fair Value	$ 9.34	$ 8.01	$ 7.08

Incentive Compensation Plan Inc

Incentive Compensation Plan Incentive Compensation Plan - Restricted Stock Awards Estimated to be Granted on a Performance Award (Details) - shares	Feb. 18, 2016	Dec. 30, 2015	Jan. 26, 2015	Jan. 27, 2014	Jan. 28, 2013	Feb. 24, 2012	Jan. 17, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Award Participants Earn	40.00%		40.00%	40.00%	40.00%	40.00%	40.00%
Performance Shares Awards As Percentage Of Target	100.00%		100.00%	100.00%	100.00%	100.00%	100.00%
Percentage Of Target Award Opportunities Maximum In Certain Cases	200.00%		200.00%	200.00%	200.00%	200.00%	200.00%
Vesting period of restricted stock	0 years	0 years	0 years	0 years	1 year	1 year	1 year
Performance Based Stock Awards Vesting Period	3 years	5 years	3 years	3 years	3 years	3 years	3 years
Restricted Stock [Member] | Executive [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued to executive	160,650,000	60,000,000	125,000,000	125,000,000	128,611,000	68,000,000	54,166,000

Incentive Compensation Plan 127

Incentive Compensation Plan - Unvested Target Award (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of the year, Shares	231,834	265,000	271,000
Granted, Shares	121,348	135,370	94,626
Vested, Shares	(105,514)	(168,536)	(98,487)
Forfeited, Shares	0	0	(2,139)
Outstanding, end of the year, Shares	247,668	231,834	265,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of the year, Shares	320,705	284,000	250,777
Granted, Shares	176,936	185,000	126,389
Vested, Shares	(18,348)	(34,200)	(12,626)
Forfeited, Shares	(52,697)	(114,095)	(80,540)
Outstanding, end of the year, Shares	426,596	320,705	284,000

Contingent Liabilities - Additi

Contingent Liabilities - Additional Information (Detail)	Aug. 27, 2015plaintiff	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | plaintiff	8
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses		$ 0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses		$ 7,000,000

Related Party Transactions - Lo

Related Party Transactions - Loans to Related Parties (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Loans and Leases Receivable, Related Parties [Roll Forward]
Beginning balance	$ 1,139
Advances	800
Repayments	(775)
Ending balance	$ 1,164

Regulatory Restrictions and 130

Regulatory Restrictions and Capital Adequacy - Schedule of Capital Amount and Ratio Considered to be Capitalized (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
First Commonwealth Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Common Equity to Risk Weighted Assets	$ 563,262	$ 556,939
Tier 1 Common Equity to Risk Weighted Assets	10.06%	10.00%
Tier 1 Common Equity Required to be Well Capitalized	$ 364,026	$ 362,091
Tier 1 Common Equity Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
First Commonwealth Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Common Equity to Risk Weighted Assets	$ 562,784	$ 535,814
Tier 1 Common Equity to Risk Weighted Assets	10.09%	9.62%
Tier 1 Common Equity Required to be Well Capitalized	$ 362,680	$ 362,084
Tier 1 Common Equity Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Actual | First Commonwealth Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk Weighted Assets	$ 687,554	$ 682,199
Tier I Capital to Risk Weighted Assets	633,262	626,939
Tier I Capital to Average Assets	$ 633,262	$ 626,939
Total Capital to Risk Weighted Assets, Ratio	12.28%	12.25%
Tier I Capital to Risk Weighted Assets, Ratio	11.31%	11.25%
Tier I Capital to Average Assets, Ratio	9.83%	9.85%
Actual | First Commonwealth Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk Weighted Assets	$ 617,076	$ 656,244
Tier I Capital to Risk Weighted Assets	562,784	600,984
Tier I Capital to Average Assets	$ 562,784	$ 600,984
Total Capital to Risk Weighted Assets, Ratio	11.06%	11.78%
Tier I Capital to Risk Weighted Assets, Ratio	10.09%	10.79%
Tier I Capital to Average Assets, Ratio	8.79%	9.46%
Minimum Capital Required - Basel III Phase-In Schedule | First Commonwealth Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	$ 483,034	$ 445,650
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	371,026	334,237
Tier I Capital to Average Assets, Regulatory Minimum Capital Amount	257,776	254,631
Tier 1 Common Equity Required for Capital Adequacy	$ 287,020	$ 250,678
Total Capital to Risk Weighted Assets, Regulatory Minimum Ratio	8.625%	8.00%
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Ratio	6.625%	6.00%
Tier I Capital to Average Assets, Regulatory Minimum Ratio	4.00%	4.00%
Tier 1 Common Equity Required for Capital Adequacy to Risk Weighted Assets	5.125%	4.50%
Minimum Capital Required - Basel III Phase-In Schedule | First Commonwealth Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	$ 481,248	$ 445,642
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	369,654	334,231
Tier I Capital to Average Assets, Regulatory Minimum Capital Amount	256,214	254,095
Tier 1 Common Equity Required for Capital Adequacy	$ 285,959	$ 250,673
Total Capital to Risk Weighted Assets, Regulatory Minimum Ratio	8.625%	8.00%
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Ratio	6.625%	6.00%
Tier I Capital to Average Assets, Regulatory Minimum Ratio	4.00%	4.00%
Tier 1 Common Equity Required for Capital Adequacy to Risk Weighted Assets	5.125%	4.50%
Minimum Capital Required - Basel III Fully Phased-In | First Commonwealth Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	$ 588,042	$ 584,915
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	476,034	473,503
Tier I Capital to Average Assets, Regulatory Minimum Capital Amount	257,776	254,631
Tier 1 Common Equity Required for Capital Adequacy	$ 392,028	$ 389,944
Total Capital to Risk Weighted Assets, Regulatory Minimum Ratio	10.50%	10.50%
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Ratio	8.50%	8.50%
Tier I Capital to Average Assets, Regulatory Minimum Ratio	4.00%	4.00%
Tier 1 Common Equity Required for Capital Adequacy to Risk Weighted Assets	7.00%	7.00%
Minimum Capital Required - Basel III Fully Phased-In | First Commonwealth Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	$ 585,867	$ 584,905
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Capital Amount	474,273	473,494
Tier I Capital to Average Assets, Regulatory Minimum Capital Amount	256,214	254,095
Tier 1 Common Equity Required for Capital Adequacy	$ 390,578	$ 389,937
Total Capital to Risk Weighted Assets, Regulatory Minimum Ratio	10.50%	10.50%
Tier I Capital to Risk Weighted Assets, Regulatory Minimum Ratio	8.50%	8.50%
Tier I Capital to Average Assets, Regulatory Minimum Ratio	4.00%	4.00%
Tier 1 Common Equity Required for Capital Adequacy to Risk Weighted Assets	7.00%	7.00%
Required to be Considered Well Capitalized | First Commonwealth Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Risk Based Capital Required to be Well Capitalized	$ 448,032	$ 445,650
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 322,220	$ 318,289
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Total Capital to Risk Weighted Assets, Well Capitalized Regulatory Guidelines	$ 560,040	$ 557,062
Total Capital to Risk Weighted Assets, Well Capitalized Regulatory Guidelines	10.00%	10.00%
Required to be Considered Well Capitalized | First Commonwealth Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Risk Based Capital Required to be Well Capitalized	$ 446,375	$ 445,642
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 320,268	$ 317,618
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Total Capital to Risk Weighted Assets, Well Capitalized Regulatory Guidelines	$ 557,969	$ 557,052
Total Capital to Risk Weighted Assets, Well Capitalized Regulatory Guidelines	10.00%	10.00%

Capital - Additional Informatio

Capital - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended	48 Months Ended
	Dec. 31, 2016program$ / sharesshares	Jun. 30, 2016$ / sharesshares	Dec. 02, 2016USD ($)branch	Oct. 03, 2016USD ($)branch	Feb. 17, 2016shares	Jan. 27, 2015shares	Jan. 28, 2014shares	Jan. 29, 2013shares	Jun. 19, 2012USD ($)
Announcement of common stock repurchase program									$ 50,000
Number of shares authorized to be repurchased | shares					25,000,000	25,000,000	25,000,000	25,000,000
Number of repurchase programs | program	4
Stock repurchased (in shares) | shares	45,612	16,665,735
Average price per share | $ / shares	$ 8.46	$ 7.55
FirstMerit Bank, NA, Branch Acquisition [Member]
Business Combination, Acquired Receivables, Gross Contractual Amount			$ 105,627
Number of Stores | branch			13
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets			$ 121,197
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits			$ 619,729
DCB Financial Corp [Member]
Business Combination, Acquired Receivables, Gross Contractual Amount				$ 388,000
Number of Stores | branch				9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets				$ 550,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits				$ 477,000

Acquisition - Narrative (Detail

Acquisition - Narrative (Details) $ in Thousands	Dec. 02, 2016USD ($)branch	Oct. 01, 2015USD ($)branch	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Oct. 03, 2016USD ($)branch
Business Acquisition [Line Items]
Costs related to the acquisition			$ 3,173	$ 922	$ 0
Goodwill			$ 186,483	$ 164,500
FirstMerit Bank, NA, Branch Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 121,197
Business Combination, Acquired Receivables, Gross Contractual Amount	105,627
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	619,729
Total consideration paid	$ (476,555)
Number of Stores | branch	13
Goodwill	$ 22,047
Business Combination, Acquired Receivables, Fair Value Adjustment	$ 3,530
DCB Financial Corp [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets						$ 550,000
Business Combination, Acquired Receivables, Gross Contractual Amount						388,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits						$ 477,000
Number of Stores | branch						9
First Community Bank
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		$ 103,106
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits		90,311
Total consideration paid		14,750
Gross loans receivable acquired		62,500
Credit market adjustment of gross loans acquired		1,300
Costs related to the acquisition		$ 900
Number of Stores | branch		4
Goodwill		$ 3,070

Acquisition - Summary (Details)

Acquisition - Summary (Details) - USD ($) $ in Thousands	Dec. 02, 2016	Oct. 01, 2015	Dec. 31, 2016	Dec. 31, 2015
Fair Value of Liabilities Assumed
Goodwill			$ 186,483	$ 164,500
First Community Bank
Consideration Paid
Cash Paid to shareholders		$ 14,750
Total consideration paid		14,750
Fair Value of Assets Acquired
Cash and cash equivalents		11,217
Investment Securities		25,980
FHLB Stock		832
Loans		61,173
Premises and other equipment		1,801
Core deposit intangible		172
Other real estate		816
Other assets		1,115
Total assets acquired		103,106
Fair Value of Liabilities Assumed
Deposits		90,311
Other Liabilities		1,115
Total liabilities assumed		91,426
Total Fair Value of Identifiable Net Assets		11,680
Goodwill		$ 3,070
FirstMerit Bank, NA, Branch Acquisition [Member]
Consideration Paid
Cash Paid to shareholders	$ (476,555)
Total consideration paid	(476,555)
Fair Value of Assets Acquired
Cash and cash equivalents	2,914
Loans	102,097
Premises and other equipment	4,562
Core deposit intangible	11,330
Other assets	294
Total assets acquired	121,197
Fair Value of Liabilities Assumed
Deposits	619,729
Other Liabilities	70
Total liabilities assumed	619,799
Total Fair Value of Identifiable Net Assets	(498,602)
Goodwill	$ 22,047

Condensed Financial Informat134

Condensed Financial Information of First Commonwealth Financial Corporation (Parent Company Only) - Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Loans	$ 4,829,162	$ 4,632,938
Premises and equipment, net	67,534	63,454
Other assets	84,648	103,717
Total assets	6,684,018	6,566,890
Liabilities and Shareholders' Equity
Subordinated debentures payable	72,167	72,167
Shareholders' equity	749,929	719,546	$ 716,145	$ 711,697
Total liabilities and shareholders’ equity	6,684,018	6,566,890
Parent [Member]
Assets
Cash	30,387	10,003
Loans	19	22
Investment in subsidiaries	770,214	719,073
Investment in unconsolidated subsidiary trusts	2,185	2,182
Investment in Jointly-Owned Company	9,042	8,978
Premises and equipment, net	3,793	3,780
Recievable from subsidiaries	33	441
Dividends receivable from subsidiaries	4,662	714
Other assets	2,453	47,631
Total assets	822,788	792,824
Liabilities and Shareholders' Equity
Accrued expenses and other liabilities	692	1,111
Subordinated debentures payable	72,167	72,167
Shareholders' equity	749,929	719,546
Total liabilities and shareholders’ equity	$ 822,788	$ 792,824

Condensed Financial Informat135

Condensed Financial Information of First Commonwealth Financial Corporation (Parent Company Only) - Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Interest and dividends	$ 217,614	$ 204,071	$ 202,181
Interest expense	(18,579)	(15,595)	(18,501)
Other income	6,372	7,041	7,279
Applicable income tax (provision) benefits	(25,639)	(20,836)	(17,680)
Net Income	59,590	50,143	44,453
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest and dividends	1	1	1
Dividends from subsidiaries	55,510	49,917	49,207
Interest expense	(2,635)	(2,357)	(2,335)
Other income	83	232	1,251
Operating expense	(4,700)	(4,989)	(6,766)
Income (loss) before taxes and equity in undistributed earnings of subsidiaries	48,259	42,804	41,358
Applicable income tax (provision) benefits	2,515	2,528	2,968
Income (loss) before equity in undistributed earnings of subsidiaries	50,774	45,332	44,326
Equity in undistributed (loss) earnings of subsidiaries	8,816	4,811	127
Net Income	$ 59,590	$ 50,143	$ 44,453

Condensed Financial Informat136

Condensed Financial Information of First Commonwealth Financial Corporation (parent company only) - Statements of Cash Flow (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net Income	$ 59,590	$ 50,143	$ 44,453
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,116	7,640	13,721
Other net	3,111	(7,929)	8,253
Net cash provided by operating activities	89,273	72,751	82,137
Investing Activities
Net cash provided by (used in) investing activities	(493,774)	142,433	164,055
Financing Activities
Discount on dividend reinvestment plan purchases	0	0	(65)
Dividends paid	(24,907)	(25,089)	(26,174)
Proceeds from reissuance of treasury stock	216	192	192
Purchase of treasury stock	(864)	(25,383)	(30,956)
Net cash (used in) provided by financing activities	(536,822)	64,596	79,017
Net increase (decrease) in cash and cash equivalents	46,225	(5,086)	(2,901)
Cash and cash equivalents at January 1	69,452	74,538	77,439
Cash and cash equivalents at December 31	115,677	69,452	74,538
Parent [Member]
Operating Activities
Net Income	59,590	50,143	44,453
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	355	493	2,150
Net gain (loss) on sales of assets	0	240	0
Decrease (increase) in prepaid income taxes	7,380	(6,993)	(487)
Undistributed equity in subsidiaries	(8,816)	(4,811)	(127)
Other net	7,759	10,753	13,077
Net cash provided by operating activities	66,268	49,825	59,066
Investing Activities
Net change in loans	(3)	2	3
Payments to Acquire Property and Equipment	0	(54)	47
Proceeds from sale of other assets	(332)	0	(13)
Proceeds from Divestiture of Businesses	27,017	0	0
Payments to Acquire Additional Interest in Subsidiaries	(47,017)	0	0
Net cash provided by (used in) investing activities	(20,329)	(56)	31
Financing Activities
Discount on dividend reinvestment plan purchases	0	0	(65)
Dividends paid	(24,907)	(25,089)	(26,174)
Proceeds from reissuance of treasury stock	216	192	192
Purchase of treasury stock	(864)	(25,383)	(30,956)
Net cash (used in) provided by financing activities	(25,555)	(50,280)	(57,003)
Net increase (decrease) in cash and cash equivalents	20,384	(399)	2,032
Cash and cash equivalents at January 1	10,003	10,402	8,370
Cash and cash equivalents at December 31	$ 30,387	$ 10,003	$ 10,402

Condensed Financial Informat137

Condensed Financial Information of First Commonwealth Financial Corporation (Parent Company Only) - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Cash Dividends Declared per Common Share (in dollars per share)	$ 0.28	$ 0.28	$ 0.28
Line of credit	$ 15,000,000
Borrowings		$ 0	$ 0