TrustCo Bank Corp NY (TRST) 10-K 1 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 28, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	TRUSTCO BANK CORP N Y
Entity Central Index Key	357,301
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 719
Entity Common Stock, Shares Outstanding		96,354,600
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividend income:
Interest and fees on loans	$ 148,133	$ 143,679	$ 141,887
Interest and dividends on securities available for sale:
U. S. government sponsored enterprises	2,281	1,489	1,418
State and political subdivisions	39	52	87
Mortgage-backed securities and collateralized mortgage obligations-residential	7,447	7,963	9,132
Corporate bonds	606	246	1
Small Business Administration-guaranteed participation securities	1,547	1,801	2,004
Mortgage-backed securities and collateralized mortgage obligations-commercial	109	133	149
Other	16	16	16
Total interest and dividends on securities available for sale	12,045	11,700	12,807
Interest on held to maturity securities:
Mortgage-backed securities and collateralized mortgage obligations-residential	1,149	1,454	1,844
Corporate bonds	410	617	615
Total interest on held to maturity securities	1,559	2,071	2,459
Federal Reserve Bank and Federal Home Loan Bank stock	544	502	467
Interest on federal funds sold and other short-term investments	6,679	3,407	1,725
Total interest and dividend income	168,960	161,359	159,345
Interest expense:
Interest on deposits	13,190	14,213	14,983
Interest on short-term borrowings	1,402	1,091	1,214
Total interest expense	14,592	15,304	16,197
Net interest income	154,368	146,055	143,148
Provision for loan losses	2,000	2,950	3,700
Net interest income after provision for loan losses	152,368	143,105	139,448
Noninterest income:
Trustco Financial Services income	6,584	5,886	5,971
Fees for services to customers	10,798	10,857	10,689
Net gain on securities transactions	0	668	251
Other	991	1,601	961
Total noninterest income	18,373	19,012	17,872
Noninterest expense:
Salaries and employee benefits	40,665	36,508	32,521
Net occupancy expense	16,543	16,078	15,799
Equipment expense	6,118	6,320	6,871
Professional services	6,895	8,200	7,878
Outsourced services	6,410	6,216	5,860
Advertising expense	2,578	2,515	2,593
FDIC and other insurance expense	4,179	5,967	6,339
Other real estate expense, net	1,171	2,558	2,001
Other	9,435	9,465	10,698
Total noninterest expense	93,994	93,827	90,560
Income before income taxes	76,747	68,290	66,760
Income taxes	33,602	25,689	24,522
Net income	$ 43,145	$ 42,601	$ 42,238
Earnings per share:
Basic (in dollars per share)	$ 0.449	$ 0.446	$ 0.444
Diluted (in dollars per share)	$ 0.448	$ 0.445	$ 0.444

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 43,145	$ 42,601	$ 42,238
Net unrealized holding gain (loss) on securities available for sale	2,524	(3,096)	(1,079)
Reclassification adjustments for net gain recognized in income	0	(688)	(251)
Tax effect	(792)	1,514	531
Net unrealized gain (loss) on securities available for sale, net of tax	1,732	(2,270)	(799)
Change in overfunded position in pension and postretirement plans arising during the year	3,824	1,333	711
Tax effect	(812)	(533)	(281)
Change in overfunded position in pension and postretirement plans arising during the year, net of tax	3,012	800	430
Amortization of net actuarial (gain) loss	(289)	(90)	70
Amortization of prior service cost	90	90	90
Tax effect	(100)	0	(63)
Amortization of net actuarial (gain) loss and prior service (credit) cost on pension and postretirement plans, net of tax	(299)	0	97
Other comprehensive income (loss), net of tax	4,445	(1,470)	(272)
Comprehensive income	$ 47,590	$ 41,131	$ 41,966

Consolidated Statements of Cond

Consolidated Statements of Condition - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and due from banks	$ 44,125	$ 48,719
Federal funds sold and other short term investments	568,615	658,555
Total cash and cash equivalents	612,740	707,274
Securities available for sale	571,965	620,360
Held to maturity securities ($28,701 and $47,526 fair value at December 31, 2017 and 2016, respectively)	27,551	45,490
Federal Reserve Bank and Federal Home Loan Bank stock	8,779	9,579
Loans, net of deferred net costs	3,636,407	3,430,586
Less: Allowance for loan losses	44,170	43,890
Net loans	3,592,237	3,386,696
Bank premises and equipment, net	35,157	35,466
Other assets	59,579	63,941
Total assets	4,908,008	4,868,806
Deposits:
Demand	398,399	377,755
Savings accounts	1,260,447	1,271,449
Interest-bearing checking	891,052	815,534
Money market deposit accounts	556,462	571,962
Time accounts	1,066,966	1,159,463
Total deposits	4,173,326	4,196,163
Short-term borrowings	242,991	209,406
Accrued expenses and other liabilities	33,383	30,551
Total liabilities	4,449,700	4,436,120
Commitments and contingent liabilities
SHAREHOLDERS' EQUITY:
Capital stock: $1 par value; 150,000,000 shares authorized, 99,998,482 and 99,214,382 shares issued at December 31, 2017 and 2016, respectively	99,998	99,214
Surplus	175,651	171,425
Undivided profits	219,436	201,517
Accumulated other comprehensive loss, net of tax	(1,806)	(6,251)
Treasury stock: 3,709,171 and 3,434,205 shares, at cost, at December 31, 2017 and 2016, respectively	(34,971)	(33,219)
Total shareholders' equity	458,308	432,686
Total liabilities and shareholders' equity	$ 4,908,008	$ 4,868,806

Consolidated Statements of Con5

Consolidated Statements of Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Held to maturity securities, fair value	$ 28,701	$ 47,526
SHAREHOLDERS' EQUITY:
Capital stock, par value (in dollars per share)	$ 1	$ 1
Capital stock, shares authorized (in shares)	150,000,000	150,000,000
Capital stock, shares issued (in shares)	99,998,482	99,214,382
Treasury stock, at cost (in shares)	3,709,171	3,434,205

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Capital Stock [Member]	Surplus [Member]	Undivided Profits [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2014	$ 98,945	$ 172,353	$ 166,745	$ (4,509)	$ (40,090)	$ 393,444
Net Income	0	0	42,238	0	0	42,238
Change in other comprehensive income (loss), net of tax	0	0	0	(272)	0	(272)
Stock option exercises	28	119	0	0	0	147
Cash dividend declared	0	0	(24,974)	0	0	(24,974)
Purchase of treasury stock	0	0	0	0	(147)	(147)
Sale of treasury stock	0	(1,233)	0	0	3,903	2,670
Stock based compensation expense	0	204	0	0	0	204
Balance at Dec. 31, 2015	98,973	171,443	184,009	(4,781)	(36,334)	413,310
Net Income	0	0	42,601	0	0	42,601
Change in other comprehensive income (loss), net of tax	0	0	0	(1,470)	0	(1,470)
Stock option exercises	241	1,127	0	0	0	1,368
Cash dividend declared	0	0	(25,093)	0	0	(25,093)
Purchase of treasury stock	0	0	0	0	(701)	(701)
Sale of treasury stock	0	(1,369)	0	0	3,816	2,447
Stock based compensation expense	0	224	0	0	0	224
Balance at Dec. 31, 2016	99,214	171,425	201,517	(6,251)	(33,219)	432,686
Net Income	0	0	43,145	0	0	43,145
Change in other comprehensive income (loss), net of tax	0	0	0	4,445	0	4,445
Stock option exercises	784	4,452	0	0	0	5,236
Cash dividend declared	0	0	(25,226)	0	0	(25,226)
Purchase of treasury stock	0	0	0	0	(4,608)	(4,608)
Sale of treasury stock	0	(376)	0	0	2,856	2,480
Stock based compensation expense	0	150	0	0	0	150
Balance at Dec. 31, 2017	$ 99,998	$ 175,651	$ 219,436	$ (1,806)	$ (34,971)	$ 458,308

Consolidated Statements of Cha7

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Changes in Shareholders' Equity [[Abstract]
Cash dividend declared (in dollars per share)	$ 0.2625	$ 0.2625	$ 0.2625
Purchase of treasury stock (in shares)	574,256	22,364	38,390
Sale of treasury stock (in shares)	299,290	398,431	414,881

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 43,145	$ 42,601	$ 42,238
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,816	4,038	4,554
Net gain on sale of other real estate owned	(924)	(298)	(373)
Writedown of other real estate owned	1,071	1,242	1,143
Provision for loan losses	2,000	2,950	3,700
Deferred tax (benefit) expense	(183)	3,261	3,011
Net amortization of securities	4,326	4,986	5,486
Stock based compensation expense	150	224	204
Net loss (gain) on sale of bank premises and equipment	43	(480)	0
Net gain on securities transactions	0	(668)	(251)
Decrease (increase) in taxes receivable	6,124	(921)	3,510
(Increase) decrease in interest receivable	(371)	(808)	538
Increase (decrease) in interest payable	11	25	(47)
Decrease in other assets	(310)	(1,677)	(4,168)
Increase in accrued expenses and other liabilities	2,792	419	463
Total adjustments	18,545	12,293	17,770
Net cash provided by operating activities	61,690	54,894	60,008
Cash flows from investing activities:
Proceeds from sales and calls of securities available for sale	124,624	245,929	254,955
Purchases of securities available for sale	(83,031)	(275,303)	(189,823)
Proceeds from maturities of securities available for sale	5,000	1,949	4,025
Proceeds from calls and maturities of held to maturity securities	17,939	10,975	14,481
Purchases of Federal Reserve Bank and Federal Home Loan Bank stock	(143)	(99)	(252)
Proceeds from redemptions of Federal Reserve Bank and Federal Home Loan Bank stock	943	0	0
Net increase in loans	(212,028)	(146,629)	(148,532)
Proceeds from dispositions of other real estate owned	5,362	6,768	7,511
Proceeds from dispositions of bank premises and equipment	63	674	112
Purchases of bank premises and equipment	(3,613)	(2,055)	(3,744)
Net cash used in investing activities	(144,884)	(157,791)	(61,267)
Cash flows from financing activities:
Net (decrease) increase in deposits	(22,837)	95,785	68,137
Net increase in short-term borrowings	33,585	18,180	2,110
Proceeds from exercise of stock options	5,237	1,368	147
Proceeds from sales of treasury stock	2,480	2,447	2,670
Purchases of treasury stock	(4,608)	(701)	(147)
Dividends paid	(25,197)	(25,064)	(24,950)
Net cash (used in) provided by financing activities	(11,340)	92,015	47,967
Net (decrease) increase in cash and cash equivalents	(94,534)	(10,882)	46,708
Cash and cash equivalents at beginning of period	707,274	718,156	671,448
Cash and cash equivalents at end of period	612,740	707,274	718,156
Cash paid during the year for:
Interest paid	14,581	15,279	16,244
Income taxes paid	26,127	23,494	21,005
Non cash investing and financing activities:
Transfer of loans to real estate owned	4,487	5,525	8,295
Transfer of other real estate owned to fixed assets	0	0	0
Increase in dividends payable	29	29	24
Change in unrealized gain (loss) on securities available for sale - gross of deferred taxes	2,524	(3,784)	(1,330)
Change in deferred tax effect on unrealized (loss) gain on securities available for sale, net of reclassification adjustment	(792)	1,514	531
Amortization of net actuarial loss and prior service credit on pension and post retirement plans, gross of deferred taxes	(199)	0	160
Change in deferred tax effect of amortization of net actuarial loss and prior service credit on pension and post retirement plans	(100)	0	(63)
Change in overfunded portion of pension and post retirement benefit plans (ASC 715) - gross of deferred taxes	3,824	1,333	711
Deferred tax effect of change in overfunded portion of pension and post retirement benefit plans (ASC 715)	$ (812)	$ (533)	$ (281)

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2017
Basis of Presentation [Abstract]
Basis of Presentation	(1) Basis of Presentation The accounting and financial reporting policies of TrustCo Bank Corp NY (the Company or TrustCo), ORE Subsidiary Corp., Trustco Bank (referred to as Trustco Bank or the Bank), and its wholly owned subsidiaries, Trustco Realty Corporation, Trustco Insurance Agency, Inc., ORE Property, Inc. and its subsidiaries ORE Property One, Inc. and ORE Property Two, Inc. conform to general practices within the banking industry and are in conformity with U.S. generally accepted accounting principles. A description of the more significant policies follows. Consolidation The consolidated financial statements of the Company include the accounts of the subsidiaries after elimination of all significant intercompany accounts and transactions. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Securities Available for Sale and Held to Maturity Securities available for sale are carried at fair value with any unrealized appreciation or depreciation of value, net of tax, included as an element of accumulated other comprehensive income or loss in shareholders’ equity. Management maintains an available for sale portfolio in order to provide maximum flexibility in balance sheet management. The designation of available for sale is made at the time of purchase based upon management’s intent to hold the securities for an indefinite period of time. These securities, however, are available for sale in response to changes in market interest rates, related changes in liquidity needs, or changes in the availability of and yield on alternative investments. Unrealized losses on securities that reflect a decline in value which is other-than-temporary, if any, are charged to earnings and/or accumulated other comprehensive income (loss). Debt securities that management has the positive intent and ability to hold until maturity are classified as held to maturity and are carried at their remaining unpaid principal balance, net of unamortized premiums or unaccreted discounts. The cost of debt securities is adjusted for amortization of premium and accretion of discount using the interest method. Premiums and discounts on securities are amortized on the interest method over the estimated remaining term of the underlying security without anticipating prepayments, except for mortgage backed securities where prepayments are anticipated. Gains and losses on the sale of securities available for sale are recorded at trade date and determined using the specific identification method. Other-Than-Temporary-Impairment (“OTTI”) A decline in the fair value of any available for sale or held to maturity security below cost that is deemed to be other than temporary is charged to earnings and/or accumulated other comprehensive income (loss), resulting in the establishment of a new cost basis of the security. Management evaluates these types of securities for OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. Additional discussion of OTTI is included in Note 3 of the consolidated financial statements. Federal Reserve Bank (FRB) and Federal Home Loan Bank (FHLB) stock The Bank is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Dividends are reported as income. The Bank is also a member of its regional Federal Reserve Bank. FRB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Any dividends received are reported as income. Loans Loans are carried at the principal amount outstanding net of unearned income and unamortized loan fees and costs, which are recognized as adjustments to interest income over the applicable loan term. Interest income on loans is accrued based on the principal amount outstanding. Nonperforming loans include non-accrual loans and loans which are three payments or more past due and still accruing interest. Generally, loans are placed in non-accrual status either due to the delinquent status of principal and/or interest payments, or a judgment by management that, although payments of principal and/or interest are current, such action is prudent based upon specific facts and circumstances surrounding the borrower. Typically, a loan is moved to non-accrual status after 90 days of non-payment in accordance with the Company’s policy. Past due status is based on the contractual terms of the loan. All interest accrued but not received for loans placed on non-accrual status is reversed against interest income. Future payments received on nonperforming loans are recorded as interest income or principal reductions based upon management’s ultimate expectation for collection. Loans may be removed from non-accrual status when they become current as to principal and interest and have demonstrated a sustained ability to make loan payments in accordance with the contractual terms of the loan. Loans may also be removed from non-accrual status when, in the opinion of management, the loan is expected to be fully collectable as to principal and interest. When, in the opinion of management, the collection of principal appears unlikely, the loan balance is evaluated in light of its sources of repayment, and a charge-off is recorded when appropriate. Loan origination fees, net of certain direct origination costs, are deferred and recognized using the level yield method without anticipating prepayments. Allowance for Loan Losses The allowance for loan losses is maintained at a level considered adequate by management to provide for probable incurred loan losses. The allowance is increased by provisions charged against income, while loan losses are charged against the allowance when management deems a loan balance to be uncollectible. Subsequent recoveries, if any, are credited to the allowance. The Company performs an analysis of the adequacy of the allowance on at least a quarterly basis. Management estimates the allowance balance required using past loan loss experience, the nature and volume of the portfolio, information about specific borrower situations, current economic conditions, past due and charge-off trends and other factors. In addition, various regulatory agencies, as an integral part of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to change the allowance based on their judgments of information available to them at the time of their examination. Allocations of the allowance may be made for specific loans, but the entire allowance is available for any loan that, in management’s judgment, should be charged off. The allowance methodology consists of specific and general components. The specific component relates to loans that are individually classified as impaired. A loan is impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Additionally, loans for which the terms have been modified resulting in a concession, and for which the borrower is experiencing financial difficulties, are considered troubled debt restructurings (TDR’s) and classified as impaired. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. TDR’s are measured at the present value of estimated future cash flows using the loan’s effective rate at inception. If a TDR is considered to be a collateral dependent loan, the loan is reported at the fair value of the collateral with any charge-off recognized at that time. For TDR’s that subsequently default, the Company determines the amount of additional charge-off, if any, in accordance with the accounting policy for the allowance for loan losses with respect to impaired loans described previously. Commercial and commercial real estate loans in non-accrual status are defined as impaired loans and are individually evaluated for impairment. In addition, any restructured loans that meet the definition of a TDR are defined as impaired. If a loan is impaired, a charge-off is taken so that the loan is reported at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral, if repayment is expected solely from the collateral. Residential real estate loans and consumer loans are collectively evaluated for impairment. The general component of the allowance covers non-impaired loans and is based on historical loss experience adjusted for current factors. The historical loss experience is determined by geography for each portfolio segment and is based on the actual net loss history experienced by the Company over the most recent four years. This actual loss experience is supplemented with other qualitative factors based on the risks present in each geography and portfolio segment. These factors include consideration of the following: changes in national, regional and local economic trends and conditions; effects of any changes in interest rates; changes in the volume and severity of net charge-offs, delinquencies, and nonperforming loans; changes in the experience, ability, and depth of lending management and other relevant staff; changes in the quality of the Company’s loan review system; effects of any changes in credit concentrations; effects of any changes in underwriting standards, lending policies, procedures, and practices; and changes in the nature, volume and terms of loans. Changes in the volume and severity of net charge-offs, delinquencies, and nonperforming loans includes consideration of levels and trends of loan delinquencies and net charge-offs by portfolio segment. The Company’s allowance methodology also includes additional allocation percentages for residential and installment loans in non-accrual status and residential and installment loans three payments past due and still accruing interest, and residential loans with loan-to-value ratios in excess of 90% at the time of origination. Additional allocation percentages are applied to commercial loans classified as special mention and substandard by the Company’s loan review grading process that are not considered as impaired to recognize the added risk associated with these loans. The reserve percentages are determined based upon a review of recent charge-offs and take into consideration the type of loan, the fixed or variable nature of the loan, and the type and geography of the underlying collateral, if any, specifically for loans that are in these categories. The following portfolio segments have been identified: commercial loans, residential real estate loans, and installment loans: Commercial: Commercial real estate loans and other commercial loans are made based primarily on the identified cash flow of the borrower and secondarily on the underlying collateral provided by the borrower. Commercial real estate collateral is generally located within the Bank’s geographic territories; while collateral for non-real estate secured commercial loans is typically accounts receivable, inventory, and/or equipment. Repayment is primarily dependent upon the borrower’s ability to service the debt based upon cash flows generated from the underlying business. Additional support involves liquidation of the pledged collateral and enforcement of a personal guarantee, if a guarantee is obtained. Residential real estate: Residential real estate loans, including first mortgages, home equity loans and home equity lines of credit, are collateralized by first or second liens on one-to-four family residences generally located within the Bank’s market areas. Proof of ownership title, clear mortgage title, and hazard insurance coverage are normally required. Installment: The Company’s installment loans are primarily made up of installment loans, personal lines of credit, as well as secured and unsecured credit cards. The installment loans represent a relatively small portion of the loan portfolio and are primarily used for personal expenses and are secured by automobiles, equipment and other forms of collateral, while personal lines of credit are unsecured as are most credit card loans. Bank Premises and Equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed on either the straight-line or accelerated methods over the remaining useful lives of the assets; generally 20 to 40 years for buildings, 3 to 7 years for furniture and equipment, and the shorter of the estimated life of the asset or the lease term for leasehold improvements. Other Real Estate Owned Assets that are acquired through or instead of foreclosure are initially recorded at fair value less costs to sell. These assets are subsequently accounted for at the lower of cost or fair value less costs to sell. Subsequent write downs and gains and losses on sale are included in noninterest expense. Operating costs after acquisition are also included in noninterest expense. At December 31, 2017 and 2016, there were $3.2 million and $4.3 million, respectively, of other real estate owned included in the category of Other Assets in the accompanying Consolidated Statements of Condition. Income Taxes Deferred taxes are recorded for the future tax consequences of events that have been recognized in the financial statements or tax returns based upon enacted tax laws and rates. Deferred tax assets are recognized subject to management’s judgment that realization is more likely than not. The amount recognized is the largest amount of tax benefit that has a greater than 50% likelihood of being realized on examination. For tax positions not meeting the “more likely than not” test, no benefit is recorded. Dividend Restrictions The Company’s ability to pay dividends to its shareholders is dependent upon the ability of the Bank to pay dividends to the Company. The payment of dividends by the Bank to the Company is subject to continued compliance with minimum regulatory capital requirements and the filing of notices or applications with the Bank’s and the Company’s regulators. The Bank’s primary regulator may disapprove a dividend if: the Bank would be undercapitalized following the distribution; the proposed capital distribution raises safety and soundness concerns; or the capital distribution would violate a prohibition contained in any statue, regulation or agreement between the Bank and a regulator or a condition imposed in a previously approved application or notice. Currently the Bank meets the regulatory definition of a well-capitalized institution. During 2018, the Bank could declare dividends of approximately $68.2 million plus any 2018 net profits retained to the date of the dividend declaration. Benefit Plans The Company has a defined benefit pension plan covering substantially all of its employees. The benefits are based on years of service and the employee’s compensation. This plan was frozen as of December 31, 2006. The Company has a postretirement benefit plan that permits retirees under age 65 to participate in the Company’s medical plan by which retirees pay all of their premiums. Under certain employment contracts with selected executive officers, the Company is obligated to provide postretirement benefits to these individuals once they attain certain vesting requirements. The Company recognized in the Consolidated Statement of Condition the funded status of the pension plan and postretirement benefit plan with an offset, net of tax, recorded in accumulated other comprehensive loss. Stock-Based Compensation Plans The Company has stock-based compensation plans for employees and directors. Compensation cost is recognized for stock options and restricted stock awards issued to employees and directors based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options while, for restricted stock awards, the fair value of the Company’s common stock at the date of grant is used. Compensation cost for stock options and restricted stock awards to be settled in stock are recognized over the required service period generally defined as the vesting period. The expense is recognized over the shorter of each award’s vesting period or the retirement date for any awards that vest immediately upon eligible retirement. Awards to be settled in cash based on the fair value of the Company’s stock at vesting are treated as liability based awards. Compensation costs for liability based awards are re-measured at each reporting date and recognized over the vesting period. For awards with performance based conditions, compensation cost is recognized over the performance period based on the Company’s expectation of the likelihood of meeting the specific performance criteria. Earnings Per Share Basic earnings per common share is net income divided by the weighted average number of common shares outstanding during the period. All outstanding unvested share-based payment awards that contain rights to non-forfeitable dividends are considered participating securities for this calculation. Diluted earnings per common share includes the dilutive effect of additional potential common shares issuable under stock options. At December 31, 2017, 2016, and 2015, the Company did not have any unvested awards that would be considered participating securities. Reclassification of Prior Year Statements It is the Company’s policy to reclassify prior year consolidated financial statements to conform to the current year presentation. Segment Reporting The Company’s operations are exclusively in the financial services industry and include the provision of traditional banking services. Management evaluates the performance of the Company based on only one business segment, that of community banking. The Company operates primarily in the geographical region of Upstate New York with branches also in Florida and the mid-Hudson valley region of New York. In the opinion of management, the Company does not have any other reportable segments as defined by “Accounting Standards Codification” (ASC) Topic 280, “Disclosure about Segments of an Enterprise and Related Information”. Cash and Cash Equivalents The Company classifies cash on hand, cash due from banks, Federal Funds sold, and other short-term investments as cash and cash equivalents for disclosure purposes. Trust Assets Assets under management with the Trustco Financial Services Department are not included in the Company’s consolidated financial statements because Trustco Financial Services holds these assets in a fiduciary capacity. Comprehensive Income (Loss) Comprehensive income (loss) represents the sum of net income and items of other comprehensive income or loss, which are reported directly in shareholders’ equity, net of tax, such as the change in net unrealized gain or loss on securities available for sale and changes in the funded position of the pension and postretirement benefit plans. Accumulated other comprehensive income or loss, which is a component of shareholders’ equity, represents the net unrealized gain or loss on securities available for sale, net of tax and the funded position in the Company’s pension plan and postretirement benefit plans, net of tax. Fair Value of Financial Instruments Fair values of financial instruments are estimated using relevant market information and other assumptions, as more fully disclosed in Note 13. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments, and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect these estimates.

Balances at Other Banks

Balances at Other Banks	12 Months Ended
	Dec. 31, 2017
Balances at Other Banks [Abstract]
Balances at Other Banks	(2) Balances at Other Banks The Company is required to maintain certain reserves of vault cash and/or deposits with the Federal Reserve Bank. The amount of this reserve requirement, included in cash and due from banks and federal funds sold and other short-term investments, was approximately $ 34.5 million and $32.3 million at December 31, 2017 and 2016, respectively.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2017
Investment Securities [Abstract]
Investment Securities	(3) Investment Securities (a) Securities available for sale The amortized cost and fair value of the securities available for sale are as follows: (dollars in thousands) December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government sponsored enterprises $ 139,890 27 2,066 137,851 State and political subdivisions 515 10 - 525 Mortgage backed securities and collateralized mortgage obligations - residential 320,614 84 4,715 315,983 Corporate bonds 40,270 - 108 40,162 Small Business Administration-guaranteed participation securities 68,921 - 1,862 67,059 Mortgage backed securities and collateralized mortgage obligations - commercial 9,810 - 110 9,700 Other 650 - - 650 Total debt securities 580,670 121 8,861 571,930 Equities 35 35 Total securities available for sale $ 580,705 121 8,861 571,965 (dollars in thousands) December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government sponsored enterprises $ 119,887 - 2,621 117,266 State and political subdivisions 873 13 - 886 Mortgage backed securities and collateralized mortgage obligations - residential 378,068 123 5,883 372,308 Corporate bonds 40,956 - 251 40,705 Small Business Administration- guaranteed participation securities 81,026 - 2,527 78,499 Mortgage backed securities and collateralized mortgage obligations - commercial 10,130 - 119 10,011 Other 650 - - 650 Total securities 631,590 136 11,401 620,325 Equities 35 35 Total securities available for sale $ 631,625 136 11,401 620,360 The following table distributes the amortized cost and fair value of debt securities included in the available for sale portfolio as of December 31, 2017, based on the securities’ final maturity. Actual maturities may differ because of securities prepayments and the right of certain issuers to call or prepay their obligations without penalty. Securities not due at a single maturity are shown separately: (dollars in thousands) Amortized Cost Fair Value Due in one year or less $ 45,783 45,739 Due in one year through five years 135,483 133,390 Due after five years through ten years 59 59 Due after ten years - - Mortgage backed securities and collateralized mortgage obligations - residential 320,614 315,983 Small Business Administration- guaranteed participation securities 68,921 67,059 Mortgage backed securities and collateralized mortgage obligations - commercial 9,810 9,700 $ 580,670 571,930 Gross unrealized losses on securities available for sale and the related fair values aggregated by the length of time that individual securities have been in an unrealized loss position, were as follows: (dollars in thousands) December 31, 2017 Less than 12 months 12 months or more Total Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss U.S. government sponsored enterprises $ 29,734 266 98,090 1,800 127,824 2,066 Mortgage backed securities and collateralized mortgage obligations - residential 48,080 371 266,394 4,344 314,474 4,715 Corporate bonds - - 40,162 108 40,162 108 Small Business Administration- guaranteed participation securities - - 67,059 1,862 67,059 1,862 Mortgage backed securities and collateralized mortgage obligations - commercial - 9,700 110 9,700 110 Total $ 77,814 637 481,405 8,224 559,219 8,861 (dollars in thousands) December 31, 2016 Less than 12 months 12 months or more Total Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss U.S. government sponsored enterprises $ 102,266 2,621 - - 102,266 2,621 Mortgage backed securities and collateralized mortgage obligations - residential 359,622 5,766 4,713 117 364,335 5,883 Small Business Administration- guaranteed participation securities 40,705 251 - - 40,705 251 Mortgage backed securities and collateralized mortgage obligations - commercial 64,560 1,960 13,940 567 78,500 2,527 10,011 119 - - 10,011 119 Total $ 577,164 10,717 18,653 684 595,817 11,401 The proceeds from sales and calls of securities available for sale, gross realized gains and gross realized losses from sales and calls during 2017, 2016 and 2015 are as follows: (dollars in thousands) Year ended December 31, 2017 2016 2015 Proceeds from sales $ - 44,829 22,945 Proceeds from calls 124,624 201,100 232,010 Gross realized gains - 668 251 Gross realized losses - - - Tax expense recognized on net gains on sales of securities available for sale were approximately $267 thousand, and $100 thousand for the years ended December 31, 2016, and 2015, respectively. The amount of securities that have been pledged to secure short-term borrowings and for other purposes amounted to $326.5 million and $264.8 million at December 31, 2017 and 2016, respectively. (b) Held to maturity securities The amortized cost and fair value of the held to maturity securities are as follows: (dollars in thousands) December 31, 2017 Amortized Cost Gross Unrecognized Gains Gross Unrecognized Losses Fair Value Mortgage backed securities and collateralized mortgage obligations - residential $ 27,551 1,150 - 28,701 Corporate bonds - - - - Total held to maturity $ 27,551 1,150 - 28,701 (dollars in thousands) December 31, 2016 Amortized Cost Gross Unrecognized Gains Gross Unrecognized Losses Fair Value Mortgage backed securities and collateralized mortgage obligations - residential $ 35,500 1,736 - 37,236 Corporate bonds 9,990 300 - 10,290 Total held to maturity $ 45,490 2,036 - 47,526 The following table distributes the debt securities included in the held to maturity portfolio as of December 31, 2017, based on the securities’ final maturity. Actual maturities may differ because of securities prepayments and the right of certain issuers to call or prepay their obligations without penalty. Securities not due at a single maturity date are shown separately. (dollars in thousands) Amortized Cost Fair Value Mortgage backed securities and collateralized mortgage obligations - residential $ 27,551 28,701 $ 27,551 28,701 There were no held to maturity securities with gross unrecognized losses as of December 31, 2017 and 2016. There were no sales or transfers of held to maturity securities during 2017 and 2016. (c) Concentrations The Company has the following balances of securities held in the available for sale and held to maturity portfolios as of December 31, 2017 that represent greater than 10% of shareholders’ equity: (dollars in thousands) Amortized Cost Fair Value Federal Home Loan Mortgage Corporation $ 112,564 111,183 Federal National Mortgage Association 260,882 257,386 Government National Mortgage Association 68,921 67,059 Small Business Administration 50,000 49,414 (d) Other-Than-Temporary-Impairment Management evaluates securities for other-than-temporary impairment (“OTTI”) at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. The investment securities portfolio is evaluated for OTTI by segregating the portfolio by type and applying the appropriate OTTI model. Investment securities classified as available for sale or held-to-maturity are generally evaluated for OTTI under ASC 320 “Investments – Debt and Equity Securities.” In determining OTTI under the FASB ASC 320 model, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the Company has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether any other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time. When OTTI occurs, the amount of the OTTI recognized in earnings depends on whether management intends to sell the security or it is more likely than not it will be required to sell the security before recovery of its amortized cost basis. If management intends to sell or it is more likely than not it will be required to sell the security before recovery of its amortized cost basis, the OTTI shall be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If management does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis, the OTTI on debt securities shall be separated into the amount representing the credit loss and the amount related to all other factors. The amount of the total OTTI related to the credit loss is determined based on the present value of cash flows expected to be collected and is recognized in earnings. The amount of the total OTTI related to other factors is recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the OTTI recognized in earnings becomes the new amortized cost basis of the investment. As of December 31, 2017, the Company’s security portfolio included certain securities which were in an unrealized loss position, and are discussed below. U.S. government sponsored enterprises In the case of unrealized losses on U.S. government sponsored enterprises, because the decline in fair value is attributable to changes in interest rates, and not credit quality, and because the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery, the Company does not consider these securities to be other-than-temporarily impaired at December 31, 2017. Mortgage backed securities and collateralized mortgage obligations - residential At December 31, 2017, all mortgage backed securities and collateralized mortgage obligations held by the Company were issued by U.S. government sponsored entities and agencies, primarily Ginnie Mae, Fannie Mae and Freddie Mac, institutions which the government has affirmed its commitment to support. Because the decline in fair value is attributable to changes in interest rates, and not credit quality, and because the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery, the Company does not consider these securities to be other-than-temporarily impaired at December 31, 2017. Corporate Bonds At December 31, 2017, corporate bonds held by the Company are investment grade quality. Because the decline in fair value is attributable to changes in interest rates, and not credit quality, and because the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery, the Company does not consider these securities to be other-than-temporarily impaired at December 31, 2017. Small Business Administration (SBA) - guaranteed participation securities At December 31, 2017, all of the SBA securities held by the Company were issued and guaranteed by U.S. Small Business Administration. Because the decline in fair value is attributable to changes in interest rates, and not credit quality, and because the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery, the Company does not consider these securities to be other-than-temporarily impaired at December 31, 2017. Mortgage backed securities and collateralized mortgage obligations - commercial As of December 31, 2017, all of the mortgage backed securities and collateralized mortgage obligations held by the Company were issued by U.S. government sponsored entities and agencies, are current as to the payment of interest and principal and the Company expects to collect the full amount of the principal and interest payments. Because the decline in fair value is attributable to changes in interest rates, and not credit quality, and because the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery, the Company does not consider these securities to be other-than-temporarily impaired at December 31, 2017. As a result of the above analysis, for the year ended December 31, 2017, the Company did not recognize any other-than-temporary impairment losses for credit or any other reason.

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2017
Loans and Allowance for Loan Losses [Abstract]
Loans and Allowance for Loan Losses	(4) Loans and Allowance for Loan Losses The following tables present the recorded investment in loans by loan class: December 31, 2017 (dollars in thousands) New York and other states* Florida Total Commercial: Commercial real estate $ 149,368 12,524 161,892 Other 23,606 709 24,315 Real estate mortgage - 1 to 4 family: First mortgages 2,286,148 765,929 3,052,077 Home equity loans 66,455 13,989 80,444 Home equity lines of credit 263,275 45,641 308,916 Installment 7,141 1,622 8,763 Total loans, net $ 2,795,993 840,414 3,636,407 Less: Allowance for loan losses 44,170 Net loans $ 3,592,237 December 31, 2016 (dollars in thousands) New York and other states* Florida Total Commercial: Commercial real estate $ 151,366 12,243 163,609 Other 27,539 46 27,585 Real estate mortgage - 1 to 4 family: First mortgages 2,158,904 665,183 2,824,087 Home equity loans 60,892 10,754 71,646 Home equity lines of credit 286,586 48,255 334,841 Installment 7,048 1,770 8,818 Total loans, net $ 2,692,335 738,251 3,430,586 Less: Allowance for loan losses 43,890 Net loans $ 3,386,696 * Includes New York, New Jersey, Vermont, and Massachusetts. At December 31, 2017 and 2016, the Company had approximately $30.9 million and $24.8 million of real estate construction loans, respectively. Of the $30.9 million in real estate construction loans at December 31, 2017, approximately $21.1 million were secured by first mortgages to residential borrowers with the remaining $9.8 million were to commercial borrowers for residential construction projects. Of the $24.8 million in real estate construction loans at December 31, 2016, approximately $16.3 million are secured by first mortgages to residential borrowers while approximately $8.5 million were to commercial borrowers for residential construction projects. The vast majority of construction loans are in the Company’s New York market. At December 31, 2017 and 2016, loans to executive officers, directors, and to associates of such persons aggregated $6.9 million and $7.6 million, respectively. During 2017, approximately $3.6 million of new loans were made and repayments of loans totaled approximately $4.3 million. The composition of related parties changed during the year resulting in a reduction of approximately $100 thousand to outstanding loans to related parties at December 31, 2017. All loans are current according to their terms. TrustCo lends in the geographic territory of its branch locations in New York, Florida, Massachusetts, New Jersey and Vermont. Although the loan portfolio is diversified, a portion of its debtors’ ability to repay depends significantly on the economic conditions prevailing in the respective geographic territory. The following tables present the recorded investment in non-accrual loans by loan class: December 31, 2017 (dollars in thousands) New York and other states Florida Total Loans in non-accrual status: Commercial: Commercial real estate $ 1,443 - 1,443 Other 100 - 100 Real estate mortgage - 1 to 4 family: First mortgages 16,654 2,259 18,913 Home equity loans 93 - 93 Home equity lines of credit 3,603 130 3,733 Installment 57 - 57 Total non-accrual loans 21,950 2,389 24,339 Restructured real estate mortgages - 1 to 4 family 38 - 38 Total nonperforming loans $ 21,988 2,389 24,377 December 31, 2016 (dollars in thousands) New York and other states Florida Total Loans in non-accrual status: Commercial: Commercial real estate $ 1,843 - 1,843 Other - - - Real estate mortgage - 1 to 4 family: First mortgages 17,727 1,659 19,386 Home equity loans 95 - 95 Home equity lines of credit 3,376 270 3,646 Installment 48 - 48 Total non-accrual loans 23,089 1,929 25,018 Restructured real estate mortgages - 1 to 4 family 42 - 42 Total nonperforming loans $ 23,131 1,929 25,060 The Company transfers loans to other real estate owned, at fair value less cost to sell, in the period the Company obtains physical possession of the property (through legal title or through a deed in lieu). As of December 31, 2017 and December 31, 2016, other real estate owned included $2.7 million and $3.5 million, respectively, of residential foreclosed properties. In addition, non-accrual residential mortgage loans that are in the process of foreclosure had a recorded investment of $12.6 million and $12.5 million as of December 31, 2017 and December 31, 2016, respectively. The following tables present the aging of the recorded investment in past due loans by loan class and by region as of December 31, 2017 and 2016: New York and other states: December 31, 2017 (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90+ Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 183 174 1,332 1,689 147,679 149,368 Other - - 100 100 23,506 23,606 Real estate mortgage - 1 to 4 family: First mortgages 5,669 1,300 9,014 15,983 2,270,165 2,286,148 Home equity loans 6 - 45 51 66,404 66,455 Home equity lines of credit 489 18 2,139 2,646 260,629 263,275 Installment 46 17 25 88 7,053 7,141 Total $ 6,393 1,509 12,655 20,557 2,775,436 2,795,993 Florida: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90+ Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ - - - - 12,524 12,524 Other - - - - 709 709 Real estate mortgage - 1 to 4 family: First mortgages 277 - 1,404 1,681 764,248 765,929 Home equity loans - - - - 13,989 13,989 Home equity lines of credit - - - - 45,641 45,641 Installment 3 5 26 34 1,588 1,622 Total $ 280 5 1,430 1,715 838,699 840,414 Total: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 183 174 1,332 1,689 160,203 161,892 Other - - 100 100 24,215 24,315 Real estate mortgage - 1 to 4 family: First mortgages 5,946 1,300 10,418 17,664 3,034,413 3,052,077 Home equity loans 6 - 45 51 80,393 80,444 Home equity lines of credit 489 18 2,139 2,646 306,270 308,916 Installment 49 22 51 122 8,641 8,763 Total $ 6,673 1,514 14,085 22,272 3,614,135 3,636,407 New York and other states: December 31, 2016 (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 50 43 1,706 1,799 149,567 151,366 Other - - - - 27,539 27,539 Real estate mortgage - 1 to 4 family: First mortgages 6,379 2,924 9,643 18,946 2,139,958 2,158,904 Home equity loans 50 3 74 127 60,765 60,892 Home equity lines of credit 685 111 1,839 2,635 283,951 286,586 Installment 34 32 15 81 6,967 7,048 Total $ 7,198 3,113 13,277 23,588 2,668,747 2,692,335 Florida: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ - - - - 12,243 12,243 Other - - - - 46 46 Real estate mortgage - 1 to 4 family: First mortgages 1,942 69 1,255 3,266 661,917 665,183 Home equity loans 19 - - 19 10,735 10,754 Home equity lines of credit - - 156 156 48,099 48,255 Installment 30 6 - 36 1,734 1,770 Total $ 1,991 75 1,411 3,477 734,774 738,251 Total: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 50 43 1,706 1,799 161,810 163,609 Other - - - - 27,585 27,585 Real estate mortgage - 1 to 4 family: First mortgages 8,321 2,993 10,898 22,212 2,801,875 2,824,087 Home equity loans 69 3 74 146 71,500 71,646 Home equity lines of credit 685 111 1,995 2,791 332,050 334,841 Installment 64 38 15 117 8,701 8,818 Total $ 9,189 3,188 14,688 27,065 3,403,521 3,430,586 At December 31, 2017 and 2016, there were no loans that are 90 days past due and still accruing interest. As a result, non-accrual loans includes all loans 90 days past due and greater as well as certain loans less than 90 days past due that were placed in non-accruing status for reasons other than delinquent status. There are no commitments to extend further credit on nonaccrual or restructured loans. Activity in the allowance for loan losses by portfolio segment is summarized as follows: (dollars in thousands) For the year ended December 31, 2017 Commercial Real Estate Mortgage- 1 to 4 Family Installment Total Balance at beginning of period $ 4,929 38,231 730 43,890 Loans charged off: New York and other states* 72 2,053 200 2,325 Florida - 167 19 186 Total loan chargeoffs 72 2,220 219 2,511 Recoveries of loans previously charged off: New York and other states* 96 596 26 718 Florida - 73 - 73 Total recoveries 96 669 26 791 Net loans charged off (24 ) 1,551 193 1,720 Provision for loan losses (629 ) 2,397 232 2,000 Balance at end of period $ 4,324 39,077 769 44,170 (dollars in thousands) For the year ended December 31, 2016 Commercial Real Estate Mortgage- 1 to 4 Family Installment Total Balance at beginning of period $ 4,491 39,753 518 44,762 Loans charged off: New York and other states* 795 3,447 303 4,545 Florida - 126 39 165 Total loan chargeoffs 795 3,573 342 4,710 Recoveries of loans previously charged off: New York and other states* 207 613 64 884 Florida - 4 - 4 Total recoveries 207 617 64 888 Net loans charged off 588 2,956 278 3,822 Provision for loan losses 1,026 1,434 490 2,950 Balance at end of period $ 4,929 38,231 730 43,890 (dollars in thousands) For the year ended December 31, 2015 Commercial Real Estate Mortgage- 1 to 4 Family Installment Total Balance at beginning of period $ 4,071 42,088 168 46,327 Loans charged off: New York and other states* 779 4,631 168 5,578 Florida - 320 17 337 Total loan chargeoffs 779 4,951 185 5,915 Recoveries of loans previously charged off: New York and other states* 20 572 46 638 Florida 7 5 - 12 Total recoveries 27 577 46 650 Net loans charged off 752 4,374 139 5,265 Provision for loan losses 1,172 2,039 489 3,700 Balance at end of period $ 4,491 39,753 518 44,762 The following tables present the balance in the allowance for loan losses and the recorded investment in loans by portfolio segment and based on impairment method as of December 31, 2017 and 2016: December 31, 2017 (dollars in thousands) Commercial Loans 1-to-4 Family Residential Real Estate Installment Loans Total Allowance for loan losses: Ending allowance balance attributable to loans: Individually evaluated for impairment $ - - - - Collectively evaluated for impairment 4,324 39,077 769 44,170 Total ending allowance balance $ 4,324 39,077 769 44,170 Loans: Individually evaluated for impairment $ 2,248 22,032 - 24,280 Collectively evaluated for impairment 183,959 3,419,405 8,763 3,612,127 Total ending loans balance $ 186,207 3,441,437 8,763 3,636,407 December 31, 2016 (dollars in thousands) Commercial Loans 1-to-4 Family Residential Real Estate Installment Loans Total Allowance for loan losses: Ending allowance balance attributable to loans: Individually evaluated for impairment $ - - - - Collectively evaluated for impairment 4,929 38,231 730 43,890 Total ending allowance balance $ 4,929 38,231 730 43,890 Loans: Individually evaluated for impairment $ 2,418 21,607 - 24,025 Collectively evaluated for impairment 188,776 3,208,967 8,818 3,406,561 Total ending loans balance $ 191,194 3,230,574 8,818 3,430,586 The Company has identified nonaccrual commercial and commercial real estate loans, as well as all loans restructured under a troubled debt restructuring (TDR), as impaired loans. A loan is considered impaired when it is probable that the borrower will be unable to repay the loan according to the original contractual terms of the loan agreement or the loan is restructured in a TDR. A loan for which the terms have been modified, and for which the borrower is experiencing financial difficulties, is considered a TDR and is classified as impaired. TDR’s at December 31, 2017 and 2016 are measured at the present value of estimated future cash flows using the loan’s effective rate at inception or the fair value of the underlying collateral if the loan is considered collateral dependent. The following tables present impaired loans by loan class as of December 31, 2017 and 2016: New York and other states: December 31, 2017 (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,148 3,120 - 2,711 Other 100 100 - 87 Real estate mortgage - 1 to 4 family: First mortgages 15,850 16,540 - 16,508 Home equity loans 270 291 - 263 Home equity lines of credit 2,606 2,847 - 2,193 Total $ 20,974 22,898 - 21,762 Florida: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ - - - - Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 2,707 2,813 - 2,335 Home equity loans 89 89 - 92 Home equity lines of credit 510 510 - 561 Total $ 3,306 3,412 - 2,988 Total: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,148 3,120 - 2,711 Other 100 100 - 87 Real estate mortgage - 1 to 4 family: First mortgages 18,557 19,353 - 18,843 Home equity loans 359 380 - 355 Home equity lines of credit 3,116 3,357 - 2,754 Total $ 24,280 26,310 - 24,750 New York and other states: December 31, 2016 (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,418 3,470 - 2,214 Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 16,675 17,439 - 15,665 Home equity loans 269 305 - 251 Home equity lines of credit 1,999 2,160 - 1,806 Total $ 21,361 23,374 - 19,936 Florida: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ - - - - Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 2,009 2,100 - 1,800 Home equity loans 94 94 - 81 Home equity lines of credit 561 633 - 591 Total $ 2,664 2,827 - 2,472 Total: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,418 3,470 - 2,214 Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 18,684 19,539 - 17,465 Home equity loans 363 399 - 332 Home equity lines of credit 2,560 2,793 - 2,397 Total $ 24,025 26,201 - 22,408 The Company has not committed to lend additional amounts to customers with outstanding loans that are classified as impaired. Interest income recognized on impaired loans was not material in 2017, 2016, and 2015. Included in impaired loans as of December 31, 2017 and 2016 are approximately $11.8 million and $11.5 million, respectively, of loans in accruing status that were identified as TDR’s. Management evaluates impairment on impaired loans on a quarterly basis. If, during this evaluation, impairment of the loan is identified, a charge-off is taken at that time if necessary. As a result, as of December 31, 2017 and 2016, based upon management’s evaluation and due to the sufficiency of charge-offs taken, none of the allowance for loan losses has been allocated to a specific impaired loan(s). The following table presents modified loans by class that were determined to be TDR’s that occurred during the years ended December 31, 2017, 2016 and 2015: The following table presents modified loans by class that were determined to be TDR's that occurred: Year ended 12/31/2017 Year ended 12/31/2016 Year ended 12/31/2015 New York and other states*: Pre- Modification Post- Modification Pre- Modification Post-Modification Pre- Modification Post- Modification (dollars in thousands) Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Commercial: Commercial real estate 4 $ 426 426 2 $ 401 401 - $ - - Real estate mortgage - 1 to 4 family: First mortgages 44 5,653 5,653 30 2,871 2,871 35 4,797 4,797 Home equity loans 3 56 56 1 44 44 1 137 137 Home equity lines of credit 18 868 868 10 402 402 7 506 506 Total 69 $ 7,003 7,003 43 $ 3,718 3,718 43 $ 5,440 5,440 Florida: Pre- Modification Post-Modification Pre- Modification Post- Modification Pre- Modification Post- Modification (dollars in thousands) Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Real estate mortgage - 1 to 4 family: First mortgages 10 1,076 1,076 4 504 504 6 780 780 Home equity loans - - - 1 45 45 - - - Home equity lines of credit 2 95 95 1 6 6 4 107 107 Total 12 $ 1,171 1,171 6 $ 555 555 10 $ 887 887 The addition of these TDR’s did not have a significant impact on the allowance for loan losses. The following table presents loans by class modified as TDR’s that occurred during the years ended December 31, 2017, 2016 and 2015 for which there was a payment default within 12 months of modification: Year ended 12/31/2017 Year ended 12/31/2016 Year ended 12/31/2015 New York and other states*: Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment (dollars in thousands) Real estate mortgage - 1 to 4 family: First mortgages 1 72 3 291 2 148 Home equity lines of credit 1 3 1 141 2 24 Total 2 $ 75 4 $ 432 4 $ 172 Florida: Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment (dollars in thousands) Real estate mortgage - 1 to 4 family: First mortgages - $ - - $ - - $ - Home equity lines of credit - - - - - - Total - $ - - $ - - $ - In situations where the Bank considers a loan modification, management determines whether the borrower is experiencing financial difficulty by performing an evaluation of the probability that the borrower will be in payment default on any of its debt in the foreseeable future without the modification. This evaluation is performed under the Company’s underwriting policy. Generally, the modification of the terms of loans was the result of the borrower filing for bankruptcy protection. Chapter 13 bankruptcies generally include the deferral of all past due amounts for a period of generally 60 months in accordance with the bankruptcy court order. In the case of Chapter 7 bankruptcies, even though there is no modification of terms, the borrowers’ debt to the Company was discharged and they may not reaffirm the debt. A loan is considered to be in payment default once it is 90 days contractually past due under the modified terms. In situations involving a borrower filing for Chapter 13 bankruptcy protection, however, a loan is considered to be in payment default once it is 30 days contractually past due, consistent with the treatment by the bankruptcy court. The TDR’s that subsequently defaulted described above did not have a material impact on the allowance for loan losses as the underlying collateral was evaluated at the time these loans were identified as TDR’s, and a charge-off was taken at that time, if necessary. Collateral values on these loans are reviewed for collateral sufficiency on a quarterly basis. The Company categorizes non-homogenous loans such as commercial and commercial real estate loans into risk categories based on relevant information about the ability of borrowers to service their debt, such as: current financial information, historical payment experience, credit documentation, public information, and current economic trends, among other factors. On at least an annual basis, in accordance with the Company’s Loan Policy, the Company analyzes non-homogeneous loans, individually by grading the loans based on credit risk. The loan grades assigned to all loan types are tested by the Company’s loan review department in accordance with the Company’s loan review policy. The Company uses the following definitions for classified loans: Special Mention Substandard Doubtful: Loans not meeting the criteria above that are analyzed individually as part of the above-described process are considered to be pass rated loans. As of December 31, 2017 and 2016, and based on the most recent analysis performed, the risk category of loans by class of loans is as follows: December 31, 2017 New York and other states: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 140,806 8,562 149,368 Other 21,936 1,670 23,606 $ 162,742 10,232 172,974 Florida: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 12,406 118 12,524 Other 709 - 709 $ 13,115 118 13,233 Total: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 153,212 8,680 161,892 Other 22,645 1,670 24,315 $ 175,857 10,350 186,207 December 31, 2016 New York and other states: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 136,676 14,690 151,366 Other 25,442 2,097 27,539 $ 162,118 16,787 178,905 Florida: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 12,243 - 12,243 Other 46 - 46 $ 12,289 - 12,289 Total: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 148,919 14,690 163,609 Other 25,488 2,097 27,585 $ 174,407 16,787 191,194 Included in classified loans in the above tables are impaired loans of $1.5 million and $1.8 million at December 31, 2017 and 2016, respectively. For homogeneous loan pools, such as residential mortgages, home equity lines of credit, and installment loans, the Company uses payment status to identify the credit risk in these loan portfolios. Payment status is reviewed on a daily basis by the Bank’s collection area and on a monthly basis with respect to determining the adequacy of the allowance for loan losses. The payment status of these homogeneous pools at December 31, 2017 and 2016 is included in the aging of the recorded investment of past due loans table. In addition, the total nonperforming portion of these homogeneous loan pools at December 31, 2017 and 2016 is presented in the recorded investment in non-accrual loans table.

Bank Premises and Equipment

Bank Premises and Equipment	12 Months Ended
	Dec. 31, 2017
Bank Premises and Equipment [Abstract]
Bank Premises and Equipment	(5) Bank Premises and Equipment A summary of premises and equipment at December 31, 2017 and 2016 follows: (dollars in thousands) 2017 2016 Land $ 2,308 $ 2,308 Buildings 34,599 33,617 Furniture, fixtures and equipment 50,832 49,503 Leasehold improvements 30,275 29,695 Total bank premises and equipment 118,014 115,123 Accumulated depreciation and amortization (82,857 ) (79,657 ) Total $ 35,157 $ 35,466 Depreciation and amortization expense was approximately $3.8 million, $4.0 million, and $4.6 million for the years 2017, 2016, and 2015, respectively. Occupancy expense of the Bank’s premises included rental expense of $7.8 million in 2017, $7.6 million in 2016, and $7.5 million in 2015.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Deposits	(6) Deposits Interest expense on deposits was as follows: (dollars in thousands) For the year ended December 31, 2017 2016 2015 Interest bearing checking accounts $ 478 $ 473 448 Savings accounts 1,729 2,148 2,468 Time deposits and money market accounts 10,983 11,592 12,067 Total $ 13,190 $ 14,213 14,983 At December 31, 2017, the maturity of total time deposits is as follows: (dollars in thousands) Under 1 year $ 652,270 1 to 2 years 392,618 2 to 3 years 15,849 3 to 4 years 1,585 4 to 5 years 4,474 Over 5 years 170 $ 1,066,966 Included in total time deposits as of December 31, 2017 and 2016 is $ 136.8 million and $144.2 million in time deposits with balances in excess of $250,000.

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2017
Short-Term Borrowings [Abstract]
Short-Term Borrowings	(7) Short-Term Borrowings Short-term borrowings of the Company were cash management accounts as follows: (dollars in thousands) 2017 2016 2015 Amount outstanding at December 31, $ 242,991 209,406 191,226 Maximum amount outstanding at any month end 252,996 209,406 194,738 Average amount outstanding 228,086 185,672 184,725 Weighted average interest rate: For the year 0.61 % 0.59 % 0.66 As of year end 0.62 0.59 0.60 Cash management accounts represent retail accounts with customers for which the Bank has pledged certain assets as collateral. Trustco Bank also has an available line of credit with the Federal Home Loan Bank of New York which approximates the balance of securities and/or loans pledged against such borrowings. The line of credit requires securities and/or loans to be pledged as collateral for the amount borrowed. As of December 31, 2017 and 2016, the Company had no outstanding borrowings with the Federal Home Loan Bank of New York. Trustco Bank is approved to borrow on a short-term basis from the Federal Reserve Bank of New York. The Bank can pledge certain securities to the Federal Reserve Bank to support this arrangement. As of December 31, 2017 and 2016, the Bank had no outstanding borrowings and loans with the Federal Reserve Bank of New York.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Income Taxes	(8) Income Taxes A summary of income tax expense included in the Consolidated Statements of Income follows: (dollars in thousands) For the year ended December 31, 2017 2016 2015 Current tax expense: Federal $ 26,510 $ 20,904 19,864 State 2,221 1,524 1,647 Total current tax expense 28,731 22,428 21,511 Enactment of Federal Tax Reform 5,054 - - Deferred tax (benefit) expense (183 ) 3,261 3,011 Total income tax expense $ 33,602 $ 25,689 24,522 The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities at December 31, 2017 and 2016, are as follows: December 31, (dollars in thousands) 2017 2016 Deductible temporary differences Deductible temporary differences Benefits and deferred remuneration $ (4,087 ) $ (5,474 ) Difference in reporting the allowance for loan losses, net 12,002 18,117 Other income or expense not yet reported for tax purposes (327 ) 129 Depreciable assets (325 ) (638 ) Net deferred tax asset at end of year 7,263 12,134 Net deferred tax asset at beginning of year 12,134 15,395 Enactment of Federal Tax Reform 5,054 - Deferred tax expense $ (183 ) $ 3,261 Deferred tax assets are recognized subject to management’s judgment that realization is more likely than not. Based primarily on the sufficiency of historical and expected future taxable income, management believes it is more likely than not that the remaining deferred tax asset of $7.3 million and $12.1 million at December 31, 2017 and 2016, respectively, will be realized. In addition to the deferred tax items described in the preceding table, the Company has deferred tax assets of $2.3 million and $4.4 million at December 31, 2017 and 2016, respectively, relating to the net unrealized losses on securities available for sale and deferred tax (liabilities) assets of ($1.2) million and ($339) thousand at December 31, 2017 and 2016, respectively, as a result of changes in the unrecognized overfunded position in the Company’s pension and postretirement benefit plans recorded, net of tax, as an adjustment to accumulated other comprehensive loss. The effective tax rates differ from the statutory federal income tax rate. The reasons for these differences are as follows: For the years ended 2017 2016 2015 Statutory federal income tax rate 35.0 % 35.0 % 35.0 Increase/(decrease) in taxes resulting from: Tax exempt income (0.1 ) (0.1 ) (0.1 ) State income tax (including alternative minimum tax), net of federal tax benefit 1.6 1.8 1.8 Enactment of Tax Reform 6.6 Other items 0.7 0.9 - Effective income tax rate 43.8 % 37.6 36.7 On a periodic basis, the Company evaluates its income tax positions based on tax laws and regulations and financial reporting considerations, and records adjustments as appropriate. This evaluation takes into consideration the status of taxing authorities’ current examinations of the Company’s tax returns, recent positions taken by the taxing authorities on similar transactions, if any, and the overall tax environment in relation to uncertain tax positions. The Company does not anticipate a material charge to the amount of unrecognized tax benefits in the next twelve months. The Company recognizes interest and/or penalties related to income tax matters in noninterest expense. For the years 2017, 2016, and 2015, these amounts were not material. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction as well as in various states. In the normal course of business, the Company is subject to U.S. federal, state, and local income tax examinations by tax authorities. The Company's federal and state income tax returns for the years 2014 through 2017 remain open to examination. On December 22, 2017 H.R.1, commonly known as the Tax Cuts and Jobs Act (the “Act”), was signed into law. The Act includes many provisions that will affect our income tax expense, including reducing our federal tax rate from 35% to 21%, effective January 1, 2018. As a result of this rate reduction, we are required to re-measure, through income tax expense in the period of enactment, our deferred tax assets and liabilities using the enacted rate at which we expect them to be recovered or settled. The re-measurement of our net deferred tax asset resulted in additional 2017 income tax expense of $5.1 million. Also on December 22, 2017, the U.S. Securities and Exchange Commission (“SEC”) released Staff Accounting Bulletin No. 118 (“SAB 118”) to address any uncertainty or diversity of views in practice in accounting for the income tax effect of the Act in situations where a registrant does not have the necessary information available, prepared, or analyzed in reasonable detail to complete this accounting in the reporting period that includes the enactment date. SAB 118 allows for a measurement period, not to extend beyond one year of the Act’s enactment date, to complete the necessary accounting. The Company recorded provisional amounts of deferred income taxes using reasonable estimates in two areas where the information necessary to determine the final deferred tax asset or liability was either not available, not prepared, or, not sufficiently analyzed as of the report filing date: 1) The Company’s deferred tax liability for temporary differences between the tax and financial reporting bases of fixed assets is awaiting completion and implementation of software updates to process the calculations associated with the Act’s provisions allowing for 100% bonus depreciation on fixed assets placed in service after September 27, 2017. 2) Our deferred tax asset for temporary difference associated with accrued compensation is awaiting final determinations of amounts that will be paid on or before March 15, 2018 and deducted on the 2017 income tax returns. In a third area, The Company made no adjustments to deferred tax assets representing future deductions for accrued compensation that may be subject to new limitations under Internal Revenue Code Section 162(m) which, generally, limits, the annual deduction for certain compensation paid to certain employees to $1 million. As of the report filing date, there is uncertainty regarding how the newly-enacted rules in this area apply to existing contracts. Consequently, The Company is seeking further clarification of these matters before completing the analysis. The Company will complete and record the income tax effects of these provisional items during the period necessary information becomes available. This measurement period will not extend beyond December 22, 2018.

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2017
Benefit Plans [Abstract]
Benefit Plans	(9) Benefit Plans (a) Retirement Plan The Company maintains a trusteed non-contributory pension plan covering employees that have completed one year of employment and 1,000 hours of service. The benefits are based on the sum of (a) a benefit equal to a prior service benefit plus the average of the employees’ highest five consecutive years’ compensation in the ten years preceding retirement multiplied by a percentage of service after a specified date plus (b) a benefit based upon career average compensation. The amounts contributed to the plan are determined annually on the basis of (a) the maximum amount that can be deducted for federal income tax purposes or (b) the amount certified by a consulting actuary as necessary to avoid an accumulated funding deficiency as defined by the Employee Retirement Income Security Act of 1974. Contributions are intended to provide for benefits attributed to service to date. Assets of the plan are administered by Trustco Bank’s Financial Services Department. This plan was frozen as of December 31, 2006. The following tables set forth the plan’s funded status and amounts recognized in the Company’s consolidated statements of condition at December 31, 2017 and 2016: Change in Projected Benefit Obligation: December 31, (dollars in thousands) 2017 2016 Projected benefit obligation at beginning of year $ 30,730 30,889 Service cost 42 61 Interest cost 1,303 1,371 Benefit payments and expected expenses (2,050 ) (1,782 ) Net actuarial loss 1,194 191 Projected benefit obligation at end of year $ 31,219 30,730 Change in Plan Assets and Reconciliation of Funded Status: December 31, (dollars in thousands) 2017 2016 Fair Value of plan assets at beginning of year $ 43,100 41,677 Actual gain on plan assets 6,169 3,187 Benefit payments and actual expenses (2,042 ) (1,764 ) Fair value of plan assets at end of year 47,227 43,100 Funded status at end of year $ 16,008 12,370 Amounts recognized in accumulated other comprehensive loss consist of the following as of: December 31, 2017 2016 Net actuarial loss $ 2,972 5,279 The accumulated benefit obligation was $31.2 million and $30.7 million at December 31, 2017 and 2016, respectively. Components of Net Periodic Pension Income and Other Amounts Recognized in Other Comprehensive (Loss) Income: Components of Net Periodic Pension (Credit) Expense and Other Amounts Recognized in Other Comprehensive Income: (dollars in thousands) For the years ended December 31, 2017 2016 2015 Service cost $ 42 61 60 Interest cost 1,303 1,371 1,329 Expected return on plan assets (2,742 ) (2,648 ) (2,735 ) Amortization of net loss 67 184 210 Net periodic pension credit (1,330 ) (1,032 ) (1,136 ) Amortization of net loss (67 ) (184 ) (210 ) Net actuarial (gain) loss included in other comprehensive (loss) income (2,240 ) (367 ) (109 ) Total recognized in other comprehensive loss (2,307 ) (551 ) (319 ) Total recognized in net periodic benefit (credit) cost and other comprehensive (loss) income $ (3,637 ) (1,583 ) (1,455 ) The estimated net loss for the plan that will be amortized from accumulated other comprehensive loss into net periodic benefit income over the next fiscal year is $67 thousand. Estimated Future Benefit Payments The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: (dollars in thousands) Year Pension Benefits 2018 $ 1,773 2019 1,802 2020 1,839 2021 1,894 2022 1,875 2023 - 2027 9,327 The assumptions used to determine benefit obligations at December 31 are as follows: 2017 2016 2015 Discount rate 3.93 % 4.41 4.55 The assumptions used to determine net periodic pension expense (benefit) for the years ended December 31 are as follows: 2017 2016 2015 Discount rate 4.41 % 4.55 4.03 Expected long-term rate of return on assets 6.50 6.50 6.50 The annual rate assumption used for purposes of computing the service and interest costs components is determined based upon factors including the yields on high quality corporate bonds and other appropriate yield curves along with analysis prepared by the Company’s actuaries. (b) Supplemental Retirement Plan The Company also has a supplementary pension plan under which additional retirement benefits are accrued for eligible executive officers. This plan supplements the defined benefit retirement plan for eligible employees that exceed the Internal Revenue Service limit on the amount of pension payments that are allowed from a retirement plan. The supplemental plan provides eligible employees with total benefit payments as calculated by the retirement plan without regard to this limitation. Benefits under this plan are calculated using the same actuarial assumptions and interest rates as used for the retirement plan calculations. The accumulated benefits under this supplementary pension plan was approximately $5.6 million as of December 31, 2017 and 2016. Effective as of December 31, 2008, this plan has been frozen and no additional benefits will accrue. Instead, the amount of the Company’s annual contribution to the plan plus interest is paid directly to each eligible employee. The expense recorded for this plan was $1.1 million, $1.0 million, and $1.0 million, in 2017, 2016, and 2015, respectively. Rabbi trusts have been established for this plan. These trust accounts are administered by the Trustco Financial Services Department and invest primarily in bonds issued by government-sponsored enterprises and money market instruments. These assets are recorded at their fair value and are included in short-term investments in the Consolidated Statements of Condition. As of December 31, 2017 and 2016, the trusts had assets totaling $5.6 million. (c) Postretirement Benefits The Company permits retirees under age 65 to participate in the Company’s medical plan by making certain payments. In addition, the plan provides a death benefit to certain eligible employees and retirees. In 2003, the Company amended the medical plan to reflect changes to the retiree medical insurance coverage portion. The Company’s subsidy of the retiree medical insurance premiums was eliminated at that time. The Company continues to provide postretirement medical benefits for a limited number of executives in accordance with their employment contracts. The following tables show the plan’s funded status and amounts recognized in the Company’s Consolidated Statements of Condition at December 31, 2017 and 2016: Change in Accumulated Benefit Obligation: December 31, (dollars in thousands) 2017 2016 Accumulated benefit obligation at beginning of year $ 5,120 5,434 Service cost 103 116 Interest cost 218 221 Benefits paid (93 ) (70 ) Net actuarial loss (gain) 265 (581 ) Accumulated benefit obligation at end of year $ 5,613 5,120 Change in Plan Assets and Reconciliation of Funded Status: December 31, (dollars in thousands) 2017 2016 Fair value of plan assets at beginning of year $ 20,338 19,238 Actual gain on plan assets 2,611 1,104 Company contributions 66 66 Benefits paid (93 ) (70 ) Fair value of plan assets at end of year 22,922 20,338 Funded status at end of year $ 17,309 15,218 December 31, Amounts recognized in accumulated other comprehensive loss consist of the following as of: 2017 2016 Net actuarial gain $ (5,810 ) (4,581 ) Prior service credit (1,636 ) (1,547 ) Total $ (7,446 ) (6,128 ) The accumulated benefit obligation was $5.6 million and $5.1 million at December 31, 2017 and 2016, respectively. Components of Net Periodic Benefit Income and Other Amounts Recognized in Other Comprehensive (Loss) Income: For the years ended (dollars in thousands) 2017 2016 2015 Service cost $ 103 $ 116 165 Interest cost 218 221 268 Expected return on plan assets (761 ) (720 ) (722 ) Amortization of net actuarial gain (356 ) (274 ) (140 ) Amortization of prior service cost 90 90 90 Net periodic benefit credit (706 ) (567 ) (339 ) Net (gain) loss (1,584 ) (966 ) (602 ) Amortization of prior service cost (90 ) (90 ) (90 ) Amortization of net gain 356 274 140 Total amount recognized in other comprehensive (loss) income (1,318 ) (782 ) (552 ) Total amount recognized in net periodic benefit cost and other comprehensive (loss) income $ (2,024 ) $ (1,349 ) (891 ) The estimated amount of net gain that will be amortized from accumulated other comprehensive loss into net periodic benefit income over the next fiscal year is approximately $355 thousand while the estimated amount of prior service cost that will be amortized from accumulated other comprehensive loss into net periodic benefit income over the next fiscal year is approximately $90 thousand. Expected Future Benefit Payments The following benefit payments are expected to be paid: (dollars in thousands) Year Postretirement Benefits 2018 98 2019 112 2020 117 2021 146 2022 158 2023 - 2027 1,040 The discount rate assumption used to determine benefit obligations at December 31 is as follows: 2017 2016 2015 Discount rate 3.93 % 4.41 % 4.55 The assumptions used to determine net periodic pension expense (benefit) for the years ended December 31 are as follows: 2016 2015 2014 Discount rate 4.41 % 4.55 % 4.03 Expected long-term rate of return on assets, net of tax 3.75 3.75 3.75 The annual rate assumption used for purposes of computing the service and interest costs components is determined based upon factors including the yields on high quality corporate bonds and other appropriate yield curves along with analysis prepared by the Company’s actuaries. For measurement purposes, a graded annual rate of increase in the per capita cost of covered benefits (i.e., health care cost trend rate) was assumed for 2017 and thereafter. A one percentage point increase in the assumed health care cost in each year would have an approximate $1.2 million impact on the accumulated postretirement benefit obligation as of December 31, 2017, while a 1% decrease would have an approximate ($907) thousand impact. The impact on the interest and service components of net periodic postretirement benefit credit for the year ended December 31, 2017 would be $68 thousand for a one percentage point increase and ($53) thousand for a one percentage point decrease. (d) Components of Accumulated Other Comprehensive Loss Related to Retirement and Postretirement Benefit Plans The following table details the change in the components of other comprehensive (loss) income related to the retirement plan and the postretirement benefit plan, at December 31, 2017 and 2016, respectively: (dollars in thousands) December 31, 2017 Retirement Plan Post- Retirement Benefit Plan Total Change in overfunded position of pension and postretirement benefits $ (2,240 ) (1,584 ) (3,824 ) Amortization of net actuarial (loss) gain (67 ) 356 289 Amortization of prior service cost - (90 ) (90 ) Total $ (2,307 ) (1,318 ) (3,625 ) December 31, 2016 Retirement Plan Post- Retirement Benefit Plan Total Change in overfunded position of pension and postretirement benefits $ (367 ) (966 ) (1,333 ) Amortization of net actuarial gain (loss) (184 ) 274 90 Amortization of prior service credit - (90 ) (90 ) Total $ (551 ) (782 ) (1,333 ) (e) Major Categories of Pension and Postretirement Benefit Plan Assets: The asset allocations of the Company’s pension and postretirement benefit plans at December 31, were as follows: Pension Benefit Postretirement Benefit 2017 2016 2017 2016 Debt Securities 29 % 31 34 33 Equity Securities 69 64 64 62 Other 2 5 2 6 Total 100 % 100 100 100 The expected long-term rate-of-return on plan assets, noted in sections (a) and (b) above, reflects long-term earnings expectations on existing plan assets. In estimating that rate, appropriate consideration was given to historical returns earned by plan assets and the rates of return expected to be available for reinvestment. Rates of return were adjusted to reflect current capital market assumptions and changes in investment allocations. The Company’s investment policies and strategies for the pension benefit and postretirement benefit plans prescribe a target allocation of 50% to 70% equity securities, 25% to 40% debt securities, and 0% to 10% for other securities for the asset categories. The Company’s investment goals are to maximize returns subject to specific risk management policies. Its risk management policies permit direct investments in equity and debt securities and mutual funds while prohibiting direct investment in derivative financial instruments. The Company addresses diversification by the use of mutual fund investments whose underlying investments are in domestic and international debt and equity securities. These mutual funds are readily marketable and can be sold to fund benefit payment obligations as they become payable. Fair Value of Plan Assets: Fair value is the exchange price that would be received for an asset in the principal or most advantageous market for the asset in an orderly transaction between market participants on the measurement date. The Company used the following methods and significant assumptions to estimate the fair value of each type of financial instrument: Equity mutual funds, Fixed Income mutual funds and Debt Securities The fair value of the plan assets at December 31, 2017and 2016, by asset category, is as follows: Retirement Plan Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 1,034 1,034 - - Equity mutual funds 32,509 32,509 - - U.S. government sponsored enterprises 6,920 - 6,920 - Corporate bonds 6,163 - 6,163 - Fixed income mutual funds 601 601 - - Total Plan Assets $ 47,227 34,144 13,083 - Postretirement Benefits Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 409 406 - - Equity mutual funds 14,703 14,703 - - U.S. government sponsored enterprises 3,512 - 3,512 - Corporate bonds 3,610 - 3,610 - State and political subdivisions 688 - 688 - Total Plan Assets $ 22,922 15,112 7,810 - Retirement Plan Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 2,027 2,027 - - Equity mutual funds 27,706 27,706 - - U.S. government sponsored enterprises 4,233 - 4,233 - Corporate bonds 8,535 - 8,535 - Fixed income mutual funds 599 599 - - Total Plan Assets $ 43,100 30,332 12,768 - Postretirement Benefits Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 1,172 1,172 - - Equity mutual funds 12,540 12,540 - - U.S. government sponsored enterprises 2,049 - 2,049 - Corporate bonds 3,127 - 3,127 - State and political subdivisions 1,450 - 1,450 - Total Plan Assets $ 20,338 13,712 6,626 - At December 31, 2017 and 2016, the majority of the equity mutual funds included in the plan assets of the retirement plan and postretirement benefit plan consist of large-cap index funds, while the remainder of the equity mutual funds consists of mid-cap, small-cap and international funds. There were no transfers between Level 1 and Level 2 in 2017 and 2016. The Company made no contributions to its pension and postretirement benefit plans in 2017 or 2016. The Company does not expect to make any contributions to its pension and postretirement benefit plans in 2018. (f) Incentive and Bonus Plans During 2006, the Company amended its profit sharing plan to include a 401(k) feature. Under the 401(k) feature, the Company matches 100% of the aggregate salary contribution up to the first 3% of compensation and 50% of the aggregate contribution of the next 3%. No profit sharing contributions were made in 2017, 2016 or 2015 but were replaced with Company contributions to the 401(k) feature of the plan. Expenses related to the plan aggregated $1.0 million for 2017, $986 thousand in 2016 and $944 thousand in 2015. The Company also has an officers and executive incentive plan. The expense of these plans generally are based on the Company’s performance and estimated distributions to participants are accrued during the year and generally paid in the following year. The expense recorded for this plan was $1.9 million, $1.7 million and $715 thousand in 2017, 2016 and 2015, respectively. The Company has also awarded 1.5 million performance bonus units to the executive officers and directors. These units become vested and exercisable only under a change of control as defined in the plan. The units were awarded based upon the stock price at the time of grant and, if exercised under a change of control, allow the holder to receive the increase in value offered in the exchange over the stock price at the date of grant for each unit, if any. As of December 31, 2017, the weighted average strike price of each unit was $8.81. (g) Stock-Based Compensation Plans-Equity Awards Equity awards are types of stock-based compensation that are to be settled in shares. As such, the amount of compensation expense to be paid at the time of settlement is included in surplus in the Consolidated Statement of Condition. Under the Amended and Restated TrustCo Bank Corp NY 2010 Equity Incentive Plan (Equity Incentive Plan), the Company may grant stock options and restricted stock to its eligible employees for up to approximately 2.3 million shares of common stock, and may make certain other equity based, cash-settled awards (description in section (h) below) for up to the equivalent of approximately 1.4 million shares of common stock. Under the Amended and Restated TrustCo Bank Corp NY 2010 Directors Equity Incentive Plan (Directors Plan), the Company may grant stock options and restricted stock to its directors for up to approximately 250 thousand shares of common stock, and may make certain other equity based, cash-settled awards (description in section (h) below) for up to the equivalent of approximately 250 thousand shares of common stock. Under each of these plans, the exercise price of each option equals the fair value of the Company’s stock on the date of grant, and an option’s maximum term is ten years. Options vest over five years from the date the options are granted for the employees plans and they are immediately vested under the directors’ plans. A summary of the status of TrustCo’s stock option awards as of December 31, 2017 and changes during the year then ended, are as follows: Outstanding Options Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life Balance, January 1, 2017 2,084,041 $ 7.57 New options awarded - 2017 - - Expired options - 2017 (553,000 ) - Options forfeited-2017 (4,000 ) - Exercised options - 2017 (784,100 ) 6.68 Balance, December 31, 2017 742,941 $ 6.78 5.8 years Exercisable Options Balance, December 31, 2017 531,641 $ 6.77 5.2 years At December 31, 2017, the intrinsic value of outstanding stock options and vested stock options was approximately $1.6 million and $1.2 million, respectively. The Company expects all unvested options to vest according to plan provisions. During 2017, 2016 and 2015, options for 784 thousand, 241 thousand and 28 thousand shares of stock were exercised, respectively. The intrinsic value and related tax benefits of stock options exercised in these years was not material. It is the Company’s policy to generally issue stock for stock option exercises from previously unissued shares of common stock or treasury shares. Unrecognized stock-based compensation expense related to non-vested stock options totaled $184 thousand at December 31, 2017. At such date, the weighted-average period over which this unrecognized expense was expected to be recognized was 2.17 years. Income tax benefits recognized in the accompanying Consolidated Statements of Income related to stock-based compensation was approximately $788 thousand. Valuation of Stock-Based Compensation: The fair value of the Company’s employee and director stock options granted is estimated on the measurement date, which, for the Company, is the date of grant. The Company did not grant new stock option awards in 2017. During 2017, 2016 and 2015, the Company recognized $150 thousand, $224 thousand and $204 thousand in stock-based compensation expense related to the equity awards, respectively. (h) Stock-Based Compensation Plans-Liability Awards Liability awards are types of stock-based compensation that can be settled in cash (not shares). As such, the amount of compensation expense to be paid at the time of settlement is included in accrued expenses and other liabilities in the Consolidated Statement of Condition. The Company granted both service-based and performance based liability awards in 2017, 2016 and 2015. The activity for service-based awards during 2017 was as follows: Restricted share units Outstanding Units Balance, December 31, 2016 215,050 New awards granted 70,650 Forfeited awards (9,200 ) Awards settled (63,400 ) Balance, December 31, 2017 213,100 Service-Based Awards: officers During 2017, 2016 and 2015, the Company issued restricted share units to certain eligible officers, executives and its board of directors. The restricted share units do not hold voting powers, are not eligible for common stock dividends. The awards vest in whole units in equal installments from the first through the third year following the award date, beginning November 21, 2018. The 2016 and 2015 awards become 100% vested after three years based upon a cliff-vesting schedule. Upon issuance, the fair value of these awards is the fair value of the Company’s common stock on the grant date. Thereafter, the amount of compensation expense recognized is based on the fair value of the Company’s stock. During 2017, 2016 and 2015, the Company recognized $633 thousand, $610 thousand and $324 thousand, respectively, in stock-based compensation expense related to these awards. Unrecognized stock-based compensation expense related to the outstanding restricted share units totaled $1.2 million at December 31, 2017. During 2017, awards granted in 2014 became fully vested and settled. Awards granted after 2014 were unvested at December 31, 2017. The weighted average period over which the unrecognized expense is expected to be recognized was approximately 26 months as of December 31, 2017. The liability related to service-based liability awards totaled $749 thousand and $687 thousand at December 31, 2017 and 2016, respectively. The activity for performance-based awards during 2017 was as follows: Performance share units Outstanding Units Balance, December 31, 2016 357,000 New awards granted 94,600 Awards settled (81,500 ) Balance, December 31, 2017 370,100 Performance Based Awards: During 2017, 2016 and 2015, the Company issued performance share units to certain eligible officers and executives. These units do not hold voting powers, are not eligible for common stock dividends, and become 100% vested after three years based upon a cliff-vesting schedule. Upon issuance, fair value of these units was the fair value of the Company’s common stock on the grant date. Thereafter, the amount of compensation expense recognized is based upon the Company’s achievement of certain performance criteria in accordance with Plan provisions as well as the fair value of the Company’s stock. For units granted in 2014, those have been fully vested and unpaid. For units granted subsequent to 2014, all of the units are unvested as of December 31, 2017 and the company expects to meet the required performance criteria of the awards. During 2017, 2016 and 2015, the Company recognized approximately $1.2 million, $23 thousand and ($48) thousand, respectively, in stock based compensation expense (benefit) related to these units. Unrecognized stock-based compensation expense related to the outstanding performance share units totaled $1.9 million at December 31, 2017. At December 31, 2017, the units awarded in 2014 were fully vested and unpaid. The weighted average period over which the unrecognized expense is expected to be recognized was approximately 24 months as of December 31, 2017. The liability related to performance based liability awards totaled $1.5 million and $323 thousand at December 31, 2017 and 2016, respectively. (i) Stock and Liability Based Compensation Expense Total compensation expense totaled $1.9 million, $857 thousand and $480 thousand in 2017, 2016 and 2015, respectively, related to awards under the Company’s equity-based compensation plans. Of the $1.9 million of stock based compensation expense recognized in 2017, $1.8 million related to liability awards as they may be settled in cash instead of shares, while the remaining $151 thousand related to equity awards Of the $857 thousand of stock based compensation expense recognized in 2016, $633 thousand related to liability awards as they may be settled in cash instead of shares, while the remaining $224 thousand related to equity awards. Of the $480 thousand of stock based compensation expense recognized in 2015, $276 thousand related to liability awards as they may be settled in cash instead of shares, while the remaining $204 thousand related to equity awards. Stock-based compensation expense is recognized ratably over the vesting period for all awards. Income tax benefits recognized in the accompanying Consolidated Statements of Income related to stock-based compensation in 2016 and 2015 was approximately $343 thousand and $192 thousand, respectively.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2017
Commitments and Contingent Liabilities [Abstract]
Commitments and Contingent Liabilities	(10) (a) Leases The Bank leases certain banking premises. These leases are accounted for as operating leases with minimum rental commitments in the amounts presented below. The majority of these leases contain options to renew. (dollars in thousands) 2018 $ 7,267 2019 7,178 2020 6,916 2021 6,720 2022 5,913 2023 and after 31,803 $ 65,797 (b) Litigation Existing litigation arising in the normal course of business is not expected to result in any material loss to the Company. (c) Outsourced Services The Company contracted with third-party service providers to perform certain banking functions. The outsourced services include data and item processing for the Bank and trust operations. The service expense can vary based upon the volume and nature of transactions processed. Outsourced service expense was $6.4 million for 2017, $6.2 million for 2016 and $5.9 million in 2015. The Company is contractually obligated to pay these third-party service providers approximately $6 to $7 million per year through 2025.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	(11) Earnings Per Share The Company computes earnings per share in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 260, Earnings Per Share Determining Whether Instruments Granted in Share-Based Payment Transactions Are Participating Securities, A reconciliation of the component parts of earnings per share for 2017, 2016 and 2015 follows: (dollars in thousands, except per share data) 2017 2016 2015 For the years ended December 31: Net income $ 43,145 42,601 42,238 Less: Net income allocated to participating securities - - - Net income allocated to common shareholders $ 43,145 42,601 42,238 Weighted average common shares outstanding including participating securities 96,111 95,548 95,103 Less: Participating securities - - - Weighted average common shares 96,111 95,548 95,103 Effect of Dilutive Securities: Stock Options 111 100 110 Weighted average common shares including potential dilutive shares 96,222 95,648 95,213 Basic EPS $ 0.449 0.446 0.444 Diluted EPS $ 0.448 0.445 0.444 For the year ended December 31, 2017, there were no antidilutive stock options excluded from diluted earnings per share. For the year ended December 31, 2016 and 2015, the weighted average number of antidilutive stock options excluded from diluted earnings per share were approximately 1.4 million. The stock options are antidilutive because the strike price is greater than the average fair value of the Company’s common stock for the periods presented.

Off-Balance Sheet Financial Ins

Off-Balance Sheet Financial Instruments	12 Months Ended
	Dec. 31, 2017
Off Balance Sheet Financial Instruments [Abstract]
Off-Balance Sheet Financial Instruments	(12) Loan 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 a fee. Commitments sometimes expire without being drawn upon. Therefore, the total commitment amounts do not necessarily represent future cash requirements. These arrangements have credit risk essentially the same as that involved in extending loans to customers and are subject to the Bank’s normal credit policies, including obtaining collateral. The Bank’s maximum exposure to credit loss for loan commitments, including unused lines of credit, at December 31, 2017 and 2016, was $414.3 million and $462.5 million, respectively. Approximately 80% of these commitments were for variable rate products at the end of 2017 and 2016. The Company does not issue any guarantees that require liability-recognition or disclosure, other than its standby letters of credit. The Company has issued conditional commitments in the form of standby letters of credit to guarantee payment on behalf of a customer and guarantee the performance of a customer to a third party. Standby letters of credit generally arise in connection with lending relationships. The credit risk involved in issuing these instruments is essentially the same as that involved in extending loans to customers. Contingent obligations under standby letters of credit totaled approximately $3.8 million and $4.6 million at December 31, 2017 and 2016, respectively, and represent the maximum potential future payments the Company could be required to make. Typically, these instruments have terms of 12 months or less and expire unused; therefore, the total amounts do not necessarily represent future cash requirements. Each customer is evaluated individually for creditworthiness under the same underwriting standards used for commitments to extend credit and on-balance sheet instruments. Company policies governing loan collateral apply to standby letters of credit at the time of credit extension. Loan-to-value ratios are generally consistent with loan-to-value requirements for other commercial loans secured by similar types of collateral. The fair value of the Company’s standby letters of credit at December 31, 2017 and 2016 was insignificant. No losses are anticipated as a result of loan commitments or standby letters of credit.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2017
Fair Value of Financial Instruments [Abstract]
Fair Value of Financial Instruments	(13) Fair value measurements (ASC 820) defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair values: Level 1 – Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity can access as of the measurement date. Level 2 – Significant other observable inputs other than Level 1 prices such as quoted prices or similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3 – Significant unobservable inputs that reflect a company’s own assumptions about the value that market participants would use in pricing an asset or liability. The Company used the following methods and significant assumptions to estimate the fair value of assets and liabilities: Securities Available for Sale Other Real Estate Owned Impaired Loans Indications of value for both collateral-dependent impaired loans and other real estate owned are obtained from third party providers or the Company’s internal Appraisal Department. All indications of value are reviewed for reasonableness by a member of the Appraisal Department for the assumptions and approaches utilized in the appraisal as well as the overall resulting fair value via comparison with independent data sources such as recent market data or industry-wide statistics. Assets and liabilities measured at fair value under ASC 820 on a recurring basis are summarized below: Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Securities available for sale: U.S. government sponsored enterprises $ 137,851 - $ 137,851 - State and political subdivisions 525 - 525 - Mortgage backed securities and collateralized mortgage obligations - residential 315,983 - 315,983 - Corporate bonds 40,162 - 40,162 - Small Business Administration- guaranteed participation securities 67,059 - 67,059 - Mortgage backed securities and collateralized mortgage obligations - commercial 9,700 - 9,700 - Other 685 35 650 - Total securities available for sale $ 571,965 $ 35 $ 571,930 $ - Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Securities available for sale: U.S. government sponsored enterprises $ 117,266 $ - $ 117,266 $ - State and political subdivisions 886 - 886 - Mortgage backed securities and collateralized mortgage obligations - residential 372,308 - 372,308 - Corporate bonds 40,705 40,705 Small Business Administration- guaranteed participation securities 78,499 - 78,499 - Mortgage backed securities and collateralized mortgage obligations - commercial 10,011 - 10,011 - Other 685 35 650 - Total securities available for sale $ 620,360 $ 35 $ 620,325 $ - There were no transfers between Level 1 and Level 2 in 2017 and 2016. Assets measured at fair value on a non-recurring basis are summarized below: Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Valuation technique Unobservable inputs Range (Weighted Average) (dollars in thousands) Other real estate owned $ 3,246 $ - $ - $ 3,246 Sales comparison approach Adjustments for differences between comparable sales 1% - 14% (7 %) Impaired loans: Commercial real estate - - - Sales comparison approach Adjustments for differences between comparable sales Real estate mortgage - 1 to 4 family 844 - - 844 Sales comparison approach Adjustments for differences between comparable sales 5% - 14% (10 %) Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Valuation technique Unobservable inputs Range (Weighted Average) (dollars in thousands) Other real estate owned $ 4,268 $ - $ - $ 4,268 Sales comparison approach Adjustments for differences between comparable sales 1% - 14% (7 %) Impaired loans: Commercial real estate 1,250 - - 1,250 Sales comparison approach Adjustments for differences between comparable sales 7% - 35% (23 %) Real estate mortgage - 1 to 4 family 458 - - 458 Sales comparison approach Adjustments for differences between comparable sales 5% - 14% (10 %) Other real estate owned, which is carried at fair value less costs to sell, was approximately $3.2 million at December 31, 2017, and consisted of $541 thousand of commercial real estate and $2.7 million of residential real estate properties. A valuation charge of $1.1 million is included in earnings for the year ended December 31, 2017. Of the total impaired loans of $24.1 million at December 31, 2017, $844 thousand are collateral dependent and are carried at fair value measured on a non-recurring basis. Due to the sufficiency of charge-offs taken on these loans and the adequacy of the underlying collateral, there were no specific valuation allowances for these loans at December 31, 2017. Gross charge-offs related to residential impaired loans included in the table above amounted to $151 thousand. Other real estate owned, which is carried at fair value less costs to sell, was approximately $4.3 million at December 31, 2016, and consisted of $756 thousand of commercial real estate and $3.5 million of residential real estate properties. A valuation charge of $1.2 million is included in earnings for the year ended December 31, 2016. Of the total impaired loans of $24.0 million at December 31, 2016, $1.7 million are collateral dependent and are carried at fair value measured on a non-recurring basis. Due to the sufficiency of charge-offs taken on these loans and the adequacy of the underlying collateral, there were no specific valuation allowances for these loans at December 31, 2016. Gross charge-offs related to commercial impaired loans included in the table above were $482 thousand for the year ended December 31, 2016, while gross charge-offs related to residential impaired loans included in the table above amounted to $226 thousand. In accordance with ASC 825, the carrying amounts and estimated fair values of financial instruments at December 31, 2017 and 2016 are as follows: (dollars in thousands) Carrying Fair Value Measurements at December 31, 2017 Using: Value Level 1 Level 2 Level 3 Total Financial assets: Cash and cash equivalents $ 612,740 612,740 - - 612,740 Securities available for sale 571,965 35 571,930 - 571,965 Held to maturity securities 27,551 - 28,701 - 28,701 Federal Reserve Bank and Federal Home Loan Bank stock 8,779 N/A N/A N/A N/A Net loans 3,592,237 - - 3,598,213 3,598,213 Accrued interest receivable 11,441 243 2,440 8,758 11,441 Financial liabilities: Demand deposits 398,399 398,399 - - 398,399 Interest bearing deposits 3,774,927 2,707,961 1,076,213 - 3,784,174 Short-term borrowings 242,991 - 242,991 - 242,991 Accrued interest payable 537 77 460 - 537 (dollars in thousands) Carrying Fair Value Measurements at December 31, 2016 Using: Value Level 1 Level 2 Level 3 Total Financial assets: Cash and cash equivalents $ 707,274 707,274 - - 707,274 Securities available for sale 620,360 35 620,325 - 620,360 Held to maturity securities 45,490 - 47,526 - 47,526 Federal Reserve Bank and Federal Home Loan Bank stock 9,579 N/A N/A N/A N/A Net loans 3,386,696 - - 3,370,976 3,370,976 Accrued interest receivable 11,070 145 2,654 8,271 11,070 Financial liabilities: Demand deposits 377,755 377,755 - - 377,755 Interest bearing deposits 3,818,408 2,658,945 1,156,025 - 3,814,970 Short-term borrowings 209,406 - 209,406 - 209,406 Accrued interest payable 526 82 444 - 526 The specific estimation methods and assumptions used can have a substantial impact on the resulting fair values of financial instruments. Following is a brief summary of the significant methods and assumptions used in estimating fair values: Cash and Cash Equivalents The carrying values of these financial instruments approximate fair values and are classified as level 1. Federal Reserve Bank and Federal Home Loan Bank stock It is not practical to determine the fair value of Federal Reserve Bank and Federal Home Loan Bank stock due to their restrictive nature. Securities Held to Maturity Similar to securities available for sale described previously, the fair value of securities held to maturity are determined utilizing an independent pricing service for identical assets or significantly similar securities. The pricing service uses a variety of techniques to arrive at fair value including market maker bids, quotes and pricing models. Inputs to the pricing models include recent trades, benchmark interest rates, spreads and actual and projected cash flows. This results in a level 2 classification of the inputs for determining fair value. Interest and dividend income is recorded on the accrual method and included in the income statement in the respective investment class under total interest income. The Company does not have any securities that would be designated as level 3. Loans The fair values of all loans are estimated using discounted cash flow analyses with discount rates equal to the interest rates currently being offered for loans with similar terms to borrowers of similar credit quality resulting in a level 3 classification. Impaired loans are valued at the lower of cost or fair value as described previously. The methods utilized to estimate the fair value of loans do not necessarily represent an exit price. Deposit Liabilities The fair values disclosed for noninterest bearing demand deposits, interest bearing checking accounts, savings accounts, and money market accounts are, by definition, equal to the amount payable on demand at the balance sheet date resulting in a level 1 classification. The carrying value of all variable rate certificates of deposit approximates fair value resulting in a level 2 classification. The fair value of fixed rate certificates of deposit is estimated using discounted cash flow analyses with discount rates equal to the interest rates currently being offered on certificates of similar size and remaining maturity resulting in a level 2 classification. Accrued Interest Receivable/Payable The carrying amounts of accrued interest approximate fair value resulting in a level 1, level 2 or level 3 classification consistent with the asset or liability that they are associated with. Short-Term Borrowings and Other Financial Instruments The fair value of all short-term borrowings, and other financial instruments approximates the carrying value resulting in a level 2 classification. Financial Instruments with Off-Balance Sheet Risk The Company is a party to financial instruments with off-balance sheet risk. Such financial instruments consist of commitments to extend financing and standby letters of credit. If the commitments are exercised by the prospective borrowers, these financial instruments will become interest earning assets of the Company. If the commitments expire, the Company retains any fees paid by the prospective borrower. The fair value of commitments is estimated based upon fees currently charged to enter into similar agreements, taking into consideration the remaining terms of the agreements and the present creditworthiness of the borrower. For fixed rate commitments, the fair value estimation takes into consideration an interest rate risk factor. The fair value of these off-balance sheet items approximates the recorded amounts of the related fees, which are considered to be immaterial. The Company does not engage in activities involving interest rate swaps, forward placement contracts, or any other instruments commonly referred to as derivatives.

Regulatory Capital Requirements

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Regulatory Capital Requirements	(14) Regulatory Capital Requirements Banks and bank holding companies are subject to regulatory capital requirements administered by federal banking agencies. Capital adequacy regulations and, additionally for banks, the prompt corrective action regulations, involve quantitative measures of assets, liabilities, and certain off-balance-sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgments by regulators. Failure to meet capital requirements can result in regulatory action. The final rules implementing Basel Committee on Banking Supervision’s capital guidelines for U.S. banks (Basel III rules) became effective for the Company on January 1, 2015 with full compliance with all of the requirements being phased in over a multi-year schedule, and fully phased in by January 1, 2019. The capital rules include a capital conservation buffer that is designed to absorb losses during periods of economic stress and to require increased capital levels before capital distributions and certain other payments can be made. Failure to meet the full amount of the buffer will result in restrictions on the Company’s ability to make capital distributions, including dividend payments and stock repurchases, and to pay discretionary bonuses to executive officers. Implementation of the buffer began in January 2016 at the 0.625% level, and the buffer increases 0.625% each year thereafter until it reaches 2.5% on January 1, 2019. Management believes, as of December 31, 2017, the Company and Bank meet all capital adequacy requirements to which they are subject. Prompt corrective action regulations provide five classifications: well capitalized, adequately capitalized, undercapitalized, significantly undercapitalized, and critically undercapitalized, although these terms are not used to represent overall financial condition. If a bank is adequately capitalized, regulatory approval is required to accept brokered deposits. If a bank is undercapitalized, capital distributions are limited, as is asset growth and expansion, and capital restoration plans are required. The federal banking agencies are required to take certain supervisory actions (and may take additional discretionary actions) with respect to an undercapitalized institution or its holding company. Such actions could have a direct material effect on an institution’s or its holding company’s financial statements. As of December 31, 2017 and December 31, 2016, the most recent regulatory notifications categorized the Bank as well capitalized under the regulatory framework for prompt corrective action. There are no conditions or events since that notification that management believes have changed the Bank’s category. The following is a summary of actual capital amounts and ratios as of December 31, 2017 and 2016, for Trustco Bank: (dollars in thousands) As of December 31, 2017 Well Adequately Amount Ratio Capitalized(1) Capitalized(1)(2) Tier 1 leverage ratio $ 444,931 9.152 % 5.000 % 4.000 % Common equity Tier 1 capital 444,931 17.460 6.500 5.750 Tier 1 risk-based capital 444,931 17.460 8.000 7.250 Total risk-based capital 476,942 18.720 10.000 9.250 (dollars in thousands) As of December 31, 2016 Well Adequately Amount Ratio Capitalized(1) Capitalized(1) Tier 1 leverage ratio $ 424,802 8.829 % 5.000 % 4.000 % Common equity Tier 1 capital 424,802 17.238 6.500 5.125 Tier 1 risk-based capital 424,802 17.238 8.000 6.625 Total risk-based capital 455,772 18.492 10.000 8.625 (1) Federal regulatory minimum requirements to be considered to be Well Capitalized and Adequately Capitalized (2) The December 31, 2016 common equity tier 1, tier 1 risk-based, and total risk-based capital ratios include a transition capital conservation buffer of 1.25 percent The following is a summary of actual capital amounts and ratios as of December 31, 2017 and 2016 for TrustCo on a consolidated basis. (dollars in thousands) As of December 31, 2017 Minimum for Amount Ratio Capital Adequacy plus Capital Conservation Buffer(1)(2) Tier 1 leverage ratio $ 459,561 9.449 % 4.000 % Common equity Tier 1 capital 459,561 18.020 5.750 Tier 1 risk-based capital 459,561 18.020 7.250 Total risk-based capital 491,590 19.280 9.250 (dollars in thousands) As of December 31, 2016 Minimum for Amount Ratio Capital Adequacy plus Capital Conservation Buffer(1)(2) Tier 1 leverage ratio $ 438,426 9.110 % 4.000 % Common equity Tier 1 capital 438,426 17.782 5.125 Tier 1 risk-based capital 438,426 17.782 6.625 Total risk-based capital 469,411 19.038 8.625 (1) Federal regulatory minimum requirements to be considered to be Well Capitalized and Adequately Capitalized (2) The December 31, 2017 and 2016 common equity tier 1, tier 1 risk-based, and total risk-based capital ratios include a transition capital conservation buffer of 1.25 percent, and 0.625 percent respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Loss [Abstract]
Accumulated Other Comprehensive Loss	(15) Accumulated Other Comprehensive Loss The following is a summary of the accumulated other comprehensive loss balances, net of tax: The following represents the reclassifications out of accumulated other comprehensive loss for the years ended December 31, 2017,2016 and 2015: For the year ended 12/31/17 (dollars in thousands) Balance at 12/31/2016 Other comprehensive income (loss) - before reclassifications Amount reclassified from accumulated other comprehensive loss Other comprehensive income (loss) - year ended 12/31/2017 Balance at 12/31/2017 Net unrealized holding loss on securities available for sale, net of tax $ (6,762 ) 1,732 1,732 (5,030 ) Net change in overfunded position in pension and postretirement plans arising during the year, net of tax 42 3,012 - 3,012 3,054 Net change in net actuarial loss and prior service cost on pension and postretirement benefit plans, net of tax 469 - (299 ) (299 ) 170 Accumulated other comprehensive loss, net of tax (6,251 ) 4,744 (299 ) 4,445 (1,806 ) For the year ended 12/31/16 (dollars in thousands) Balance at 12/31/2014 Other comprehensive (loss) income - before reclassifications Amount reclassified from accumulated other comprehensive loss Other comprehensive (loss) income - year ended 12/31/2016 Balance at 12/31/2016 Net unrealized holding gain (loss) on securities available for sale, net of tax $ (4,492 ) (1,869 ) (401 ) (2,270 ) (6,762 ) Net change in overfunded position in pension and postretirement plans arising during the year, net of tax (758 ) 800 - 800 42 Net change in net actuarial loss and prior service credit on pension and postretirement benefit plans, net of tax 469 - - - 469 Accumulated other comprehensive loss, net of tax (4,781 ) (1,069 ) (401 ) (1,470 ) (6,251 ) For the year ended 12/31/15 (dollars in thousands) Balance at 12/31/2014 Other comprehensive (loss) income - before reclassifications Amount reclassified from accumulated other comprehensive loss Other comprehensive (loss) Income- year ended 12/31/2015 Balance at 12/31/2015 Net unrealized holding gain (loss) on securities available for sale, net of tax $ (3,693 ) (648 ) (151 ) (799 ) (4,492 ) Net change in overfunded position in pension and postretirement plans arising during the year, net of tax (1,188 ) 430 - 430 (758 ) Net change in net actuarial loss and prior service credit on pension and postretirement benefit plans, net of tax 372 - 97 97 469 Accumulated other comprehensive loss, net of tax $ (4,509 ) (218 ) (54 ) (272 ) (4,781 ) (dollars in thousands) Years Ended Affected Line Item 2017 2016 2015 in Financial Statements Unrealized gains on securities available for sale Realized gain on securities transactions $ - 668 251 Net gain on securities transactions Income tax expense - (267 ) (100 ) Income taxes Net of tax - 401 151 Amortization of pension and postretirement benefit items Amortization of net actuarial gain (loss) 289 90 (70 ) Salaries and employee benefits Amortization of prior service cost (90 ) (90 ) (90 ) Salaries and employee benefits Income tax benefit 100 - 63 Income taxes Net of tax 299 - (97 ) Total reclassifications, net of tax $ 299 401 54

Agreement with the Office of th

Agreement with the Office of the Comptroller of the Currency	12 Months Ended
	Dec. 31, 2017
Agreement with the Office of the Comptroller of the Currency [Abstract]
Agreement with the Office of the Comptroller of the Currency	(16) Agreement with the Office of the Comptroller of the Currency On July 21, 2015 Trustco Bank (the “Bank”), the wholly owned subsidiary of TrustCo Bank Corp NY, entered into a formal agreement (the “Agreement”) with the Comptroller of the Currency of the United States (the “OCC”). The Agreement relates to the findings of the OCC following an examination of the Bank. The Agreement requires the Bank to take various actions, within prescribed time frames, with respect to certain areas of the Bank. These include, among others, (i) establishment of a committee of at least three Directors to monitor and coordinate the Bank’s response to the Agreement; (ii) adoption of compliance plans to respond to the Agreement with the assistance of an independent qualified consultant; (iii) evaluation and implementation of improvements in corporate governance with the assistance of an independent qualified consultant; (iv) evaluation and implementation of improvements in internal audit; (v) development of a strategic plan; (vi) development of a revised capital plan consistent with the strategic plan; (vii) development, and implementation of improvements to the Bank’s loan review system; and (viii) such other necessary steps to address the issues and questions noted by the OCC in the Agreement. As noted above, the OCC has terminated the formal agreement with the Bank effective February 7, 2018. As a result of the termination of the agreement, the Bank will not be required to obtain prior OCC approval of proposed dividend payments to the Company, although the Bank will be required to provide prior notice of intended dividends to the Federal Reserve Board and the OCC.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
Recent Accounting Pronouncements [Abstract]
Recent Accounting Pronouncements	(17) Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606)” which implements a common revenue standard that clarifies the principles for recognizing revenue. 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. To achieve that core principle, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies a performance obligation. In July 2015, FASB deferred the effective date of the ASU by one year which means ASU 2014-09 will be effective for the Company on January 1, 2018. In addition, the FASB issued targeted updates to clarify specific implementation issues of ASU 2014-09. These updates include ASU No. 2016-08 - Principal versus Agent Considerations (Reporting Revenue Gross versus Net), ASU No. 2016-10 - Identifying Performance Obligations and Licensing and ASU No. 2016-12 - Narrow-Scope Improvements and Practical Expedients. The company has completed the evaluation of the ASU and discovered that a majority of the revenue contracts are not applicable and those that were determined applicable are not material to the financial statements. The company has completed the evaluation of the ASU and determined that a majority of the revenue line items are not applicable for the ASU. Wealth Management products and services were evaluated and determined within scope of the ASU requiring the Company to treat services within wealth management contracts as a single performance obligation. The effects of this requirement would not lead to significantly different recognition and measurement outcomes when compared to current accounting practices. Service charges on deposit accounts and gains on sales of Other Real Estate Owned were evaluated and determined within scope of the ASU, however, would not lead to significantly different recognition and measurement outcomes when compared to current accounting practices. For those revenue items that were determined within scope, the Company has determined the ASU will not have a significant impact to revenue recognition policies and will not have a material impact on the financial statements upon adoption. In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities” which amended existing guidance to improve accounting standards for financial instruments including clarification and simplification of accounting and disclosure requirements and the requirement for public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. These amendments are effective for public business entities for annual periods and interim periods within those annual periods beginning after December 15, 2017. The ASU is not expected to significantly impact the Company’s consolidated financial statements and the Company will be making enhanced disclosures for fair value of financial instruments (primarily loans) to comply with the exit price notion as required under the ASU beginning March 31, 2018. In February 2016, the FASB issued ASU No. 2016-02, “Leases” which amended existing guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. These amendments are effective for public business entities for annual periods and interim periods within those annual periods beginning after December 15, 2018. The Company is evaluating the impact of ASU No. 2016-02 on its consolidated financial statements. In June 2016, the FASB released ASU 2016-13, “Financial Instruments – Credit Losses” which amended existing guidance to replace current generally accepted accounting principles used to measure a reporting entity’s credit losses. The main objective of this update is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. To achieve this objective, the amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. These amendments are effective for public business entities for annual periods and interim periods within those annual periods beginning after December 15, 2019. The ASU represents a significant departure from current GAAP and the Company is evaluating the impact of the ASU on its consolidated financial statements, which includes developing a roadmap for implementation of the new standard. In February 2018, the FASB issued ASU 2018-02, “Income statement – Reporting Comprehensive Income (Topic 220) Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” which will allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. These amendments are effective for all entities for fiscal years beginning after December 15, 2018. For Interim periods within those fiscal years, early adoption of the amendment is permitted including public business entities for reporting periods for which financial statements have not yet been issued. The Company intends to early adopt the ASU in the first quarter of 2018 and will reclassify the stranded tax effect in accumulated other comprehensive income to retained earnings in the period ended March 31, 2018.

Parent Company Only

Parent Company Only	12 Months Ended
	Dec. 31, 2017
Parent Company Only [Abstract]
Parent Company Only	(18) Parent Company Only The following statements pertain to TrustCo Bank Corp NY (Parent Company): Statements of Comprehensive Income (dollars in thousands) Years Ended December 31, Income: 2017 2016 2015 Dividends and interest from subsidiaries $ 24,510 24,498 24,501 Net gain on securities transactions - - - Miscellaneous income - - - Total income 24,510 24,498 24,501 Expense: Operating supplies 26 21 33 Professional services 122 461 577 Miscellaneous expense 2,573 1,258 664 Total expense 2,721 1,740 1,274 Income before income taxes and subsidiaries' undistributed earnings 21,789 22,758 23,227 Income tax benefit (1,171 ) (578 ) (405 ) Income before subsidiaries' undistributed earnings 22,960 23,336 23,632 Equity in undistributed earnings of subsidiaries 20,185 19,265 18,606 Net income $ 43,145 42,601 42,238 Change in other comprehensive income (loss) 4,445 (1,470 ) (272 ) Comprehensive income $ 47,590 41,131 41,966 Statements of Condition (dollars in thousands) December 31, Assets: 2017 2016 Cash in subsidiary bank $ 21,773 19,886 Investments in subsidiaries 443,692 419,075 Securities available for sale 35 35 Other assets 771 824 Total assets 466,271 439,820 Liabilities and shareholders' equity: Accrued expenses and other liabilities 7,964 7,134 Total liabilities 7,964 7,134 Shareholders' equity 458,307 432,686 Total liabilities and shareholders' equity $ 466,271 439,820 Statements of Cash Flows (dollars in thousands) Years Ended December 31, 2017 2016 2015 Increase/(decrease) in cash and cash equivalents: Cash flows from operating activities: Net income $ 43,145 42,601 42,238 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed earnings of subsidiaries (20,185 ) (19,265 ) (18,606 ) Stock based compensation expense 150 224 204 Net change in other assets and accrued expenses 853 (196 ) (140 ) Total adjustments (19,182 ) (19,237 ) (18,542 ) Net cash provided by operating activities 23,963 23,364 23,696 Cash flows from financing activities: Proceeds from exercise of stock options 5,236 1,368 147 Dividends paid (25,184 ) (25,055 ) (24,937 ) Payments to acquire treasury stock (4,608 ) (701 ) (147 ) Proceeds from sales of treasury stock 2,480 2,447 2,670 Net cash used in financing activities (22,076 ) (21,941 ) (22,267 ) Net increase in cash and cash equivalents 1,887 1,423 1,429 Cash and cash equivalents at beginning of year 19,886 18,463 17,034 Cash and cash equivalents at end of year $ 21,773 19,886 18,463

Basis of Presentation (Policies

Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2017
Basis of Presentation [Abstract]
Consolidation	Consolidation The consolidated financial statements of the Company include the accounts of the subsidiaries after elimination of all significant intercompany accounts and transactions.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Securities Available for Sale and Held to Maturity	Securities Available for Sale and Held to Maturity Securities available for sale are carried at fair value with any unrealized appreciation or depreciation of value, net of tax, included as an element of accumulated other comprehensive income or loss in shareholders’ equity. Management maintains an available for sale portfolio in order to provide maximum flexibility in balance sheet management. The designation of available for sale is made at the time of purchase based upon management’s intent to hold the securities for an indefinite period of time. These securities, however, are available for sale in response to changes in market interest rates, related changes in liquidity needs, or changes in the availability of and yield on alternative investments. Unrealized losses on securities that reflect a decline in value which is other-than-temporary, if any, are charged to earnings and/or accumulated other comprehensive income (loss). Debt securities that management has the positive intent and ability to hold until maturity are classified as held to maturity and are carried at their remaining unpaid principal balance, net of unamortized premiums or unaccreted discounts. The cost of debt securities is adjusted for amortization of premium and accretion of discount using the interest method. Premiums and discounts on securities are amortized on the interest method over the estimated remaining term of the underlying security without anticipating prepayments, except for mortgage backed securities where prepayments are anticipated. Gains and losses on the sale of securities available for sale are recorded at trade date and determined using the specific identification method.
Other Than Temporary Impairment ("OTTI")	Other-Than-Temporary-Impairment (“OTTI”) A decline in the fair value of any available for sale or held to maturity security below cost that is deemed to be other than temporary is charged to earnings and/or accumulated other comprehensive income (loss), resulting in the establishment of a new cost basis of the security. Management evaluates these types of securities for OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. Additional discussion of OTTI is included in Note 3 of the consolidated financial statements.
Federal Reserve Bank (FRB) and Federal Home Loan Bank (FHLB) stock	Federal Reserve Bank (FRB) and Federal Home Loan Bank (FHLB) stock The Bank is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Dividends are reported as income. The Bank is also a member of its regional Federal Reserve Bank. FRB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Any dividends received are reported as income.
Loans	Loans Loans are carried at the principal amount outstanding net of unearned income and unamortized loan fees and costs, which are recognized as adjustments to interest income over the applicable loan term. Interest income on loans is accrued based on the principal amount outstanding. Nonperforming loans include non-accrual loans and loans which are three payments or more past due and still accruing interest. Generally, loans are placed in non-accrual status either due to the delinquent status of principal and/or interest payments, or a judgment by management that, although payments of principal and/or interest are current, such action is prudent based upon specific facts and circumstances surrounding the borrower. Typically, a loan is moved to non-accrual status after 90 days of non-payment in accordance with the Company’s policy. Past due status is based on the contractual terms of the loan. All interest accrued but not received for loans placed on non-accrual status is reversed against interest income. Future payments received on nonperforming loans are recorded as interest income or principal reductions based upon management’s ultimate expectation for collection. Loans may be removed from non-accrual status when they become current as to principal and interest and have demonstrated a sustained ability to make loan payments in accordance with the contractual terms of the loan. Loans may also be removed from non-accrual status when, in the opinion of management, the loan is expected to be fully collectable as to principal and interest. When, in the opinion of management, the collection of principal appears unlikely, the loan balance is evaluated in light of its sources of repayment, and a charge-off is recorded when appropriate. Loan origination fees, net of certain direct origination costs, are deferred and recognized using the level yield method without anticipating prepayments.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses is maintained at a level considered adequate by management to provide for probable incurred loan losses. The allowance is increased by provisions charged against income, while loan losses are charged against the allowance when management deems a loan balance to be uncollectible. Subsequent recoveries, if any, are credited to the allowance. The Company performs an analysis of the adequacy of the allowance on at least a quarterly basis. Management estimates the allowance balance required using past loan loss experience, the nature and volume of the portfolio, information about specific borrower situations, current economic conditions, past due and charge-off trends and other factors. In addition, various regulatory agencies, as an integral part of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to change the allowance based on their judgments of information available to them at the time of their examination. Allocations of the allowance may be made for specific loans, but the entire allowance is available for any loan that, in management’s judgment, should be charged off. The allowance methodology consists of specific and general components. The specific component relates to loans that are individually classified as impaired. A loan is impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Additionally, loans for which the terms have been modified resulting in a concession, and for which the borrower is experiencing financial difficulties, are considered troubled debt restructurings (TDR’s) and classified as impaired. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. TDR’s are measured at the present value of estimated future cash flows using the loan’s effective rate at inception. If a TDR is considered to be a collateral dependent loan, the loan is reported at the fair value of the collateral with any charge-off recognized at that time. For TDR’s that subsequently default, the Company determines the amount of additional charge-off, if any, in accordance with the accounting policy for the allowance for loan losses with respect to impaired loans described previously. Commercial and commercial real estate loans in non-accrual status are defined as impaired loans and are individually evaluated for impairment. In addition, any restructured loans that meet the definition of a TDR are defined as impaired. If a loan is impaired, a charge-off is taken so that the loan is reported at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral, if repayment is expected solely from the collateral. Residential real estate loans and consumer loans are collectively evaluated for impairment. The general component of the allowance covers non-impaired loans and is based on historical loss experience adjusted for current factors. The historical loss experience is determined by geography for each portfolio segment and is based on the actual net loss history experienced by the Company over the most recent four years. This actual loss experience is supplemented with other qualitative factors based on the risks present in each geography and portfolio segment. These factors include consideration of the following: changes in national, regional and local economic trends and conditions; effects of any changes in interest rates; changes in the volume and severity of net charge-offs, delinquencies, and nonperforming loans; changes in the experience, ability, and depth of lending management and other relevant staff; changes in the quality of the Company’s loan review system; effects of any changes in credit concentrations; effects of any changes in underwriting standards, lending policies, procedures, and practices; and changes in the nature, volume and terms of loans. Changes in the volume and severity of net charge-offs, delinquencies, and nonperforming loans includes consideration of levels and trends of loan delinquencies and net charge-offs by portfolio segment. The Company’s allowance methodology also includes additional allocation percentages for residential and installment loans in non-accrual status and residential and installment loans three payments past due and still accruing interest, and residential loans with loan-to-value ratios in excess of 90% at the time of origination. Additional allocation percentages are applied to commercial loans classified as special mention and substandard by the Company’s loan review grading process that are not considered as impaired to recognize the added risk associated with these loans. The reserve percentages are determined based upon a review of recent charge-offs and take into consideration the type of loan, the fixed or variable nature of the loan, and the type and geography of the underlying collateral, if any, specifically for loans that are in these categories. The following portfolio segments have been identified: commercial loans, residential real estate loans, and installment loans: Commercial: Commercial real estate loans and other commercial loans are made based primarily on the identified cash flow of the borrower and secondarily on the underlying collateral provided by the borrower. Commercial real estate collateral is generally located within the Bank’s geographic territories; while collateral for non-real estate secured commercial loans is typically accounts receivable, inventory, and/or equipment. Repayment is primarily dependent upon the borrower’s ability to service the debt based upon cash flows generated from the underlying business. Additional support involves liquidation of the pledged collateral and enforcement of a personal guarantee, if a guarantee is obtained. Residential real estate: Residential real estate loans, including first mortgages, home equity loans and home equity lines of credit, are collateralized by first or second liens on one-to-four family residences generally located within the Bank’s market areas. Proof of ownership title, clear mortgage title, and hazard insurance coverage are normally required. Installment: The Company’s installment loans are primarily made up of installment loans, personal lines of credit, as well as secured and unsecured credit cards. The installment loans represent a relatively small portion of the loan portfolio and are primarily used for personal expenses and are secured by automobiles, equipment and other forms of collateral, while personal lines of credit are unsecured as are most credit card loans.
Bank Premises and Equipment	Bank Premises and Equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed on either the straight-line or accelerated methods over the remaining useful lives of the assets; generally 20 to 40 years for buildings, 3 to 7 years for furniture and equipment, and the shorter of the estimated life of the asset or the lease term for leasehold improvements.
Other Real Estate Owned	Other Real Estate Owned Assets that are acquired through or instead of foreclosure are initially recorded at fair value less costs to sell. These assets are subsequently accounted for at the lower of cost or fair value less costs to sell. Subsequent write downs and gains and losses on sale are included in noninterest expense. Operating costs after acquisition are also included in noninterest expense. At December 31, 2017 and 2016, there were $3.2 million and $4.3 million, respectively, of other real estate owned included in the category of Other Assets in the accompanying Consolidated Statements of Condition.
Income Taxes	Income Taxes Deferred taxes are recorded for the future tax consequences of events that have been recognized in the financial statements or tax returns based upon enacted tax laws and rates. Deferred tax assets are recognized subject to management’s judgment that realization is more likely than not. The amount recognized is the largest amount of tax benefit that has a greater than 50% likelihood of being realized on examination. For tax positions not meeting the “more likely than not” test, no benefit is recorded.
Dividend Restrictions	Dividend Restrictions The Company’s ability to pay dividends to its shareholders is dependent upon the ability of the Bank to pay dividends to the Company. The payment of dividends by the Bank to the Company is subject to continued compliance with minimum regulatory capital requirements and the filing of notices or applications with the Bank’s and the Company’s regulators. The Bank’s primary regulator may disapprove a dividend if: the Bank would be undercapitalized following the distribution; the proposed capital distribution raises safety and soundness concerns; or the capital distribution would violate a prohibition contained in any statue, regulation or agreement between the Bank and a regulator or a condition imposed in a previously approved application or notice. Currently the Bank meets the regulatory definition of a well-capitalized institution. During 2018, the Bank could declare dividends of approximately $68.2 million plus any 2018 net profits retained to the date of the dividend declaration.
Benefit Plans	Benefit Plans The Company has a defined benefit pension plan covering substantially all of its employees. The benefits are based on years of service and the employee’s compensation. This plan was frozen as of December 31, 2006. The Company has a postretirement benefit plan that permits retirees under age 65 to participate in the Company’s medical plan by which retirees pay all of their premiums. Under certain employment contracts with selected executive officers, the Company is obligated to provide postretirement benefits to these individuals once they attain certain vesting requirements. The Company recognized in the Consolidated Statement of Condition the funded status of the pension plan and postretirement benefit plan with an offset, net of tax, recorded in accumulated other comprehensive loss.
Stock-Based Compensation Plans	Stock-Based Compensation Plans The Company has stock-based compensation plans for employees and directors. Compensation cost is recognized for stock options and restricted stock awards issued to employees and directors based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options while, for restricted stock awards, the fair value of the Company’s common stock at the date of grant is used. Compensation cost for stock options and restricted stock awards to be settled in stock are recognized over the required service period generally defined as the vesting period. The expense is recognized over the shorter of each award’s vesting period or the retirement date for any awards that vest immediately upon eligible retirement. Awards to be settled in cash based on the fair value of the Company’s stock at vesting are treated as liability based awards. Compensation costs for liability based awards are re-measured at each reporting date and recognized over the vesting period. For awards with performance based conditions, compensation cost is recognized over the performance period based on the Company’s expectation of the likelihood of meeting the specific performance criteria.
Earnings Per Share	Earnings Per Share Basic earnings per common share is net income divided by the weighted average number of common shares outstanding during the period. All outstanding unvested share-based payment awards that contain rights to non-forfeitable dividends are considered participating securities for this calculation. Diluted earnings per common share includes the dilutive effect of additional potential common shares issuable under stock options. At December 31, 2017, 2016, and 2015, the Company did not have any unvested awards that would be considered participating securities.
Reclassification of Prior Year Statements	Reclassification of Prior Year Statements It is the Company’s policy to reclassify prior year consolidated financial statements to conform to the current year presentation.
Segment Reporting	Segment Reporting The Company’s operations are exclusively in the financial services industry and include the provision of traditional banking services. Management evaluates the performance of the Company based on only one business segment, that of community banking. The Company operates primarily in the geographical region of Upstate New York with branches also in Florida and the mid-Hudson valley region of New York. In the opinion of management, the Company does not have any other reportable segments as defined by “Accounting Standards Codification” (ASC) Topic 280, “Disclosure about Segments of an Enterprise and Related Information”.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company classifies cash on hand, cash due from banks, Federal Funds sold, and other short-term investments as cash and cash equivalents for disclosure purposes.
Trust Assets	Trust Assets Assets under management with the Trustco Financial Services Department are not included in the Company’s consolidated financial statements because Trustco Financial Services holds these assets in a fiduciary capacity.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) represents the sum of net income and items of other comprehensive income or loss, which are reported directly in shareholders’ equity, net of tax, such as the change in net unrealized gain or loss on securities available for sale and changes in the funded position of the pension and postretirement benefit plans. Accumulated other comprehensive income or loss, which is a component of shareholders’ equity, represents the net unrealized gain or loss on securities available for sale, net of tax and the funded position in the Company’s pension plan and postretirement benefit plans, net of tax.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair values of financial instruments are estimated using relevant market information and other assumptions, as more fully disclosed in Note 13. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments, and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect these estimates.

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investment Securities [Abstract]
Amortized cost and fair value of the securities available for sale	The amortized cost and fair value of the securities available for sale are as follows: (dollars in thousands) December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government sponsored enterprises $ 139,890 27 2,066 137,851 State and political subdivisions 515 10 - 525 Mortgage backed securities and collateralized mortgage obligations - residential 320,614 84 4,715 315,983 Corporate bonds 40,270 - 108 40,162 Small Business Administration-guaranteed participation securities 68,921 - 1,862 67,059 Mortgage backed securities and collateralized mortgage obligations - commercial 9,810 - 110 9,700 Other 650 - - 650 Total debt securities 580,670 121 8,861 571,930 Equities 35 35 Total securities available for sale $ 580,705 121 8,861 571,965 (dollars in thousands) December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government sponsored enterprises $ 119,887 - 2,621 117,266 State and political subdivisions 873 13 - 886 Mortgage backed securities and collateralized mortgage obligations - residential 378,068 123 5,883 372,308 Corporate bonds 40,956 - 251 40,705 Small Business Administration- guaranteed participation securities 81,026 - 2,527 78,499 Mortgage backed securities and collateralized mortgage obligations - commercial 10,130 - 119 10,011 Other 650 - - 650 Total securities 631,590 136 11,401 620,325 Equities 35 35 Total securities available for sale $ 631,625 136 11,401 620,360
Investment [Line Items]
Proceeds from sales and calls of securities available for sale, gross realized gains and gross realized losses	The proceeds from sales and calls of securities available for sale, gross realized gains and gross realized losses from sales and calls during 2017, 2016 and 2015 are as follows: (dollars in thousands) Year ended December 31, 2017 2016 2015 Proceeds from sales $ - 44,829 22,945 Proceeds from calls 124,624 201,100 232,010 Gross realized gains - 668 251 Gross realized losses - - -
Amortized cost and fair value of the held to maturity securities	The amortized cost and fair value of the held to maturity securities are as follows: (dollars in thousands) December 31, 2017 Amortized Cost Gross Unrecognized Gains Gross Unrecognized Losses Fair Value Mortgage backed securities and collateralized mortgage obligations - residential $ 27,551 1,150 - 28,701 Corporate bonds - - - - Total held to maturity $ 27,551 1,150 - 28,701 (dollars in thousands) December 31, 2016 Amortized Cost Gross Unrecognized Gains Gross Unrecognized Losses Fair Value Mortgage backed securities and collateralized mortgage obligations - residential $ 35,500 1,736 - 37,236 Corporate bonds 9,990 300 - 10,290 Total held to maturity $ 45,490 2,036 - 47,526
Securities held in available for sale and held to maturity greater than 10% of shareholders equity	The Company has the following balances of securities held in the available for sale and held to maturity portfolios as of December 31, 2017 that represent greater than 10% of shareholders’ equity: (dollars in thousands) Amortized Cost Fair Value Federal Home Loan Mortgage Corporation $ 112,564 111,183 Federal National Mortgage Association 260,882 257,386 Government National Mortgage Association 68,921 67,059 Small Business Administration 50,000 49,414
Securities Available for Sale [Member]
Investment [Line Items]
Debt securities based on the securities contractual maturity	The following table distributes the amortized cost and fair value of debt securities included in the available for sale portfolio as of December 31, 2017, based on the securities’ final maturity. Actual maturities may differ because of securities prepayments and the right of certain issuers to call or prepay their obligations without penalty. Securities not due at a single maturity are shown separately: (dollars in thousands) Amortized Cost Fair Value Due in one year or less $ 45,783 45,739 Due in one year through five years 135,483 133,390 Due after five years through ten years 59 59 Due after ten years - - Mortgage backed securities and collateralized mortgage obligations - residential 320,614 315,983 Small Business Administration- guaranteed participation securities 68,921 67,059 Mortgage backed securities and collateralized mortgage obligations - commercial 9,810 9,700 $ 580,670 571,930
Gross unrealized losses on investment securities and the related fair values aggregated by the length of time that individual securities have been in an unrealized loss position	Gross unrealized losses on securities available for sale and the related fair values aggregated by the length of time that individual securities have been in an unrealized loss position, were as follows: (dollars in thousands) December 31, 2017 Less than 12 months 12 months or more Total Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss U.S. government sponsored enterprises $ 29,734 266 98,090 1,800 127,824 2,066 Mortgage backed securities and collateralized mortgage obligations - residential 48,080 371 266,394 4,344 314,474 4,715 Corporate bonds - - 40,162 108 40,162 108 Small Business Administration- guaranteed participation securities - - 67,059 1,862 67,059 1,862 Mortgage backed securities and collateralized mortgage obligations - commercial - 9,700 110 9,700 110 Total $ 77,814 637 481,405 8,224 559,219 8,861 (dollars in thousands) December 31, 2016 Less than 12 months 12 months or more Total Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss Fair Value Gross Unreal. Loss U.S. government sponsored enterprises $ 102,266 2,621 - - 102,266 2,621 Mortgage backed securities and collateralized mortgage obligations - residential 359,622 5,766 4,713 117 364,335 5,883 Small Business Administration- guaranteed participation securities 40,705 251 - - 40,705 251 Mortgage backed securities and collateralized mortgage obligations - commercial 64,560 1,960 13,940 567 78,500 2,527 10,011 119 - - 10,011 119 Total $ 577,164 10,717 18,653 684 595,817 11,401
Held to Maturity Securities [Member]
Investment [Line Items]
Debt securities based on the securities contractual maturity	The following table distributes the debt securities included in the held to maturity portfolio as of December 31, 2017, based on the securities’ final maturity. Actual maturities may differ because of securities prepayments and the right of certain issuers to call or prepay their obligations without penalty. Securities not due at a single maturity date are shown separately. (dollars in thousands) Amortized Cost Fair Value Mortgage backed securities and collateralized mortgage obligations - residential $ 27,551 28,701 $ 27,551 28,701

Loans and Allowance for Loan 29

Loans and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Loans and Allowance for Loan Losses [Abstract]
Recorded investment in loans by loan class	The following tables present the recorded investment in loans by loan class: December 31, 2017 (dollars in thousands) New York and other states* Florida Total Commercial: Commercial real estate $ 149,368 12,524 161,892 Other 23,606 709 24,315 Real estate mortgage - 1 to 4 family: First mortgages 2,286,148 765,929 3,052,077 Home equity loans 66,455 13,989 80,444 Home equity lines of credit 263,275 45,641 308,916 Installment 7,141 1,622 8,763 Total loans, net $ 2,795,993 840,414 3,636,407 Less: Allowance for loan losses 44,170 Net loans $ 3,592,237 December 31, 2016 (dollars in thousands) New York and other states* Florida Total Commercial: Commercial real estate $ 151,366 12,243 163,609 Other 27,539 46 27,585 Real estate mortgage - 1 to 4 family: First mortgages 2,158,904 665,183 2,824,087 Home equity loans 60,892 10,754 71,646 Home equity lines of credit 286,586 48,255 334,841 Installment 7,048 1,770 8,818 Total loans, net $ 2,692,335 738,251 3,430,586 Less: Allowance for loan losses 43,890 Net loans $ 3,386,696 * Includes New York, New Jersey, Vermont, and Massachusetts.
Recorded investment in non-accrual loans by loan class	The following tables present the recorded investment in non-accrual loans by loan class: December 31, 2017 (dollars in thousands) New York and other states Florida Total Loans in non-accrual status: Commercial: Commercial real estate $ 1,443 - 1,443 Other 100 - 100 Real estate mortgage - 1 to 4 family: First mortgages 16,654 2,259 18,913 Home equity loans 93 - 93 Home equity lines of credit 3,603 130 3,733 Installment 57 - 57 Total non-accrual loans 21,950 2,389 24,339 Restructured real estate mortgages - 1 to 4 family 38 - 38 Total nonperforming loans $ 21,988 2,389 24,377 December 31, 2016 (dollars in thousands) New York and other states Florida Total Loans in non-accrual status: Commercial: Commercial real estate $ 1,843 - 1,843 Other - - - Real estate mortgage - 1 to 4 family: First mortgages 17,727 1,659 19,386 Home equity loans 95 - 95 Home equity lines of credit 3,376 270 3,646 Installment 48 - 48 Total non-accrual loans 23,089 1,929 25,018 Restructured real estate mortgages - 1 to 4 family 42 - 42 Total nonperforming loans $ 23,131 1,929 25,060
Aging of the recorded investment in past due loans by loan class and by region	The following tables present the aging of the recorded investment in past due loans by loan class and by region as of December 31, 2017 and 2016: New York and other states: December 31, 2017 (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90+ Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 183 174 1,332 1,689 147,679 149,368 Other - - 100 100 23,506 23,606 Real estate mortgage - 1 to 4 family: First mortgages 5,669 1,300 9,014 15,983 2,270,165 2,286,148 Home equity loans 6 - 45 51 66,404 66,455 Home equity lines of credit 489 18 2,139 2,646 260,629 263,275 Installment 46 17 25 88 7,053 7,141 Total $ 6,393 1,509 12,655 20,557 2,775,436 2,795,993 Florida: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90+ Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ - - - - 12,524 12,524 Other - - - - 709 709 Real estate mortgage - 1 to 4 family: First mortgages 277 - 1,404 1,681 764,248 765,929 Home equity loans - - - - 13,989 13,989 Home equity lines of credit - - - - 45,641 45,641 Installment 3 5 26 34 1,588 1,622 Total $ 280 5 1,430 1,715 838,699 840,414 Total: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 183 174 1,332 1,689 160,203 161,892 Other - - 100 100 24,215 24,315 Real estate mortgage - 1 to 4 family: First mortgages 5,946 1,300 10,418 17,664 3,034,413 3,052,077 Home equity loans 6 - 45 51 80,393 80,444 Home equity lines of credit 489 18 2,139 2,646 306,270 308,916 Installment 49 22 51 122 8,641 8,763 Total $ 6,673 1,514 14,085 22,272 3,614,135 3,636,407 New York and other states: December 31, 2016 (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 50 43 1,706 1,799 149,567 151,366 Other - - - - 27,539 27,539 Real estate mortgage - 1 to 4 family: First mortgages 6,379 2,924 9,643 18,946 2,139,958 2,158,904 Home equity loans 50 3 74 127 60,765 60,892 Home equity lines of credit 685 111 1,839 2,635 283,951 286,586 Installment 34 32 15 81 6,967 7,048 Total $ 7,198 3,113 13,277 23,588 2,668,747 2,692,335 Florida: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ - - - - 12,243 12,243 Other - - - - 46 46 Real estate mortgage - 1 to 4 family: First mortgages 1,942 69 1,255 3,266 661,917 665,183 Home equity loans 19 - - 19 10,735 10,754 Home equity lines of credit - - 156 156 48,099 48,255 Installment 30 6 - 36 1,734 1,770 Total $ 1,991 75 1,411 3,477 734,774 738,251 Total: (dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due 90 + Days Past Due Total 30+ days Past Due Current Total Loans Commercial: Commercial real estate $ 50 43 1,706 1,799 161,810 163,609 Other - - - - 27,585 27,585 Real estate mortgage - 1 to 4 family: First mortgages 8,321 2,993 10,898 22,212 2,801,875 2,824,087 Home equity loans 69 3 74 146 71,500 71,646 Home equity lines of credit 685 111 1,995 2,791 332,050 334,841 Installment 64 38 15 117 8,701 8,818 Total $ 9,189 3,188 14,688 27,065 3,403,521 3,430,586
Activity in the allowance for loan losses by portfolio segment	Activity in the allowance for loan losses by portfolio segment is summarized as follows: (dollars in thousands) For the year ended December 31, 2017 Commercial Real Estate Mortgage- 1 to 4 Family Installment Total Balance at beginning of period $ 4,929 38,231 730 43,890 Loans charged off: New York and other states* 72 2,053 200 2,325 Florida - 167 19 186 Total loan chargeoffs 72 2,220 219 2,511 Recoveries of loans previously charged off: New York and other states* 96 596 26 718 Florida - 73 - 73 Total recoveries 96 669 26 791 Net loans charged off (24 ) 1,551 193 1,720 Provision for loan losses (629 ) 2,397 232 2,000 Balance at end of period $ 4,324 39,077 769 44,170 (dollars in thousands) For the year ended December 31, 2016 Commercial Real Estate Mortgage- 1 to 4 Family Installment Total Balance at beginning of period $ 4,491 39,753 518 44,762 Loans charged off: New York and other states* 795 3,447 303 4,545 Florida - 126 39 165 Total loan chargeoffs 795 3,573 342 4,710 Recoveries of loans previously charged off: New York and other states* 207 613 64 884 Florida - 4 - 4 Total recoveries 207 617 64 888 Net loans charged off 588 2,956 278 3,822 Provision for loan losses 1,026 1,434 490 2,950 Balance at end of period $ 4,929 38,231 730 43,890 (dollars in thousands) For the year ended December 31, 2015 Commercial Real Estate Mortgage- 1 to 4 Family Installment Total Balance at beginning of period $ 4,071 42,088 168 46,327 Loans charged off: New York and other states* 779 4,631 168 5,578 Florida - 320 17 337 Total loan chargeoffs 779 4,951 185 5,915 Recoveries of loans previously charged off: New York and other states* 20 572 46 638 Florida 7 5 - 12 Total recoveries 27 577 46 650 Net loans charged off 752 4,374 139 5,265 Provision for loan losses 1,172 2,039 489 3,700 Balance at end of period $ 4,491 39,753 518 44,762
Allowance for loan losses and the recorded investment in loans by portfolio segment and based on impairment method	The following tables present the balance in the allowance for loan losses and the recorded investment in loans by portfolio segment and based on impairment method as of December 31, 2017 and 2016: December 31, 2017 (dollars in thousands) Commercial Loans 1-to-4 Family Residential Real Estate Installment Loans Total Allowance for loan losses: Ending allowance balance attributable to loans: Individually evaluated for impairment $ - - - - Collectively evaluated for impairment 4,324 39,077 769 44,170 Total ending allowance balance $ 4,324 39,077 769 44,170 Loans: Individually evaluated for impairment $ 2,248 22,032 - 24,280 Collectively evaluated for impairment 183,959 3,419,405 8,763 3,612,127 Total ending loans balance $ 186,207 3,441,437 8,763 3,636,407 December 31, 2016 (dollars in thousands) Commercial Loans 1-to-4 Family Residential Real Estate Installment Loans Total Allowance for loan losses: Ending allowance balance attributable to loans: Individually evaluated for impairment $ - - - - Collectively evaluated for impairment 4,929 38,231 730 43,890 Total ending allowance balance $ 4,929 38,231 730 43,890 Loans: Individually evaluated for impairment $ 2,418 21,607 - 24,025 Collectively evaluated for impairment 188,776 3,208,967 8,818 3,406,561 Total ending loans balance $ 191,194 3,230,574 8,818 3,430,586
Impaired loans by loan class	The following tables present impaired loans by loan class as of December 31, 2017 and 2016: New York and other states: December 31, 2017 (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,148 3,120 - 2,711 Other 100 100 - 87 Real estate mortgage - 1 to 4 family: First mortgages 15,850 16,540 - 16,508 Home equity loans 270 291 - 263 Home equity lines of credit 2,606 2,847 - 2,193 Total $ 20,974 22,898 - 21,762 Florida: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ - - - - Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 2,707 2,813 - 2,335 Home equity loans 89 89 - 92 Home equity lines of credit 510 510 - 561 Total $ 3,306 3,412 - 2,988 Total: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,148 3,120 - 2,711 Other 100 100 - 87 Real estate mortgage - 1 to 4 family: First mortgages 18,557 19,353 - 18,843 Home equity loans 359 380 - 355 Home equity lines of credit 3,116 3,357 - 2,754 Total $ 24,280 26,310 - 24,750 New York and other states: December 31, 2016 (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,418 3,470 - 2,214 Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 16,675 17,439 - 15,665 Home equity loans 269 305 - 251 Home equity lines of credit 1,999 2,160 - 1,806 Total $ 21,361 23,374 - 19,936 Florida: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ - - - - Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 2,009 2,100 - 1,800 Home equity loans 94 94 - 81 Home equity lines of credit 561 633 - 591 Total $ 2,664 2,827 - 2,472 Total: (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance YTD Avg Recorded Investment Commercial: Commercial real estate $ 2,418 3,470 - 2,214 Other - - - - Real estate mortgage - 1 to 4 family: First mortgages 18,684 19,539 - 17,465 Home equity loans 363 399 - 332 Home equity lines of credit 2,560 2,793 - 2,397 Total $ 24,025 26,201 - 22,408
Modified loans by class that were determined to be TDR's	The following table presents modified loans by class that were determined to be TDR's that occurred: Year ended 12/31/2017 Year ended 12/31/2016 Year ended 12/31/2015 New York and other states*: Pre- Modification Post- Modification Pre- Modification Post-Modification Pre- Modification Post- Modification (dollars in thousands) Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Commercial: Commercial real estate 4 $ 426 426 2 $ 401 401 - $ - - Real estate mortgage - 1 to 4 family: First mortgages 44 5,653 5,653 30 2,871 2,871 35 4,797 4,797 Home equity loans 3 56 56 1 44 44 1 137 137 Home equity lines of credit 18 868 868 10 402 402 7 506 506 Total 69 $ 7,003 7,003 43 $ 3,718 3,718 43 $ 5,440 5,440 Florida: Pre- Modification Post-Modification Pre- Modification Post- Modification Pre- Modification Post- Modification (dollars in thousands) Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Number of Contracts Outstanding Recorded Investment Outstanding Recorded Investment Real estate mortgage - 1 to 4 family: First mortgages 10 1,076 1,076 4 504 504 6 780 780 Home equity loans - - - 1 45 45 - - - Home equity lines of credit 2 95 95 1 6 6 4 107 107 Total 12 $ 1,171 1,171 6 $ 555 555 10 $ 887 887
Loans by class modified as TDR's for which there was a payment default	The following table presents loans by class modified as TDR’s that occurred during the years ended December 31, 2017, 2016 and 2015 for which there was a payment default within 12 months of modification: Year ended 12/31/2017 Year ended 12/31/2016 Year ended 12/31/2015 New York and other states*: Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment (dollars in thousands) Real estate mortgage - 1 to 4 family: First mortgages 1 72 3 291 2 148 Home equity lines of credit 1 3 1 141 2 24 Total 2 $ 75 4 $ 432 4 $ 172 Florida: Number of Contracts Recorded Investment Number of Contracts Recorded Investment Number of Contracts Recorded Investment (dollars in thousands) Real estate mortgage - 1 to 4 family: First mortgages - $ - - $ - - $ - Home equity lines of credit - - - - - - Total - $ - - $ - - $ -
Risk category of loans by class of loans	As of December 31, 2017 and 2016, and based on the most recent analysis performed, the risk category of loans by class of loans is as follows: December 31, 2017 New York and other states: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 140,806 8,562 149,368 Other 21,936 1,670 23,606 $ 162,742 10,232 172,974 Florida: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 12,406 118 12,524 Other 709 - 709 $ 13,115 118 13,233 Total: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 153,212 8,680 161,892 Other 22,645 1,670 24,315 $ 175,857 10,350 186,207 December 31, 2016 New York and other states: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 136,676 14,690 151,366 Other 25,442 2,097 27,539 $ 162,118 16,787 178,905 Florida: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 12,243 - 12,243 Other 46 - 46 $ 12,289 - 12,289 Total: (dollars in thousands) Pass Classified Total Commercial: Commercial real estate $ 148,919 14,690 163,609 Other 25,488 2,097 27,585 $ 174,407 16,787 191,194

Bank Premises and Equipment (Ta

Bank Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Bank Premises and Equipment [Abstract]
Summary of premises and equipment	A summary of premises and equipment at December 31, 2017 and 2016 follows: (dollars in thousands) 2017 2016 Land $ 2,308 $ 2,308 Buildings 34,599 33,617 Furniture, fixtures and equipment 50,832 49,503 Leasehold improvements 30,275 29,695 Total bank premises and equipment 118,014 115,123 Accumulated depreciation and amortization (82,857 ) (79,657 ) Total $ 35,157 $ 35,466

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Interest expense on deposits	Interest expense on deposits was as follows: (dollars in thousands) For the year ended December 31, 2017 2016 2015 Interest bearing checking accounts $ 478 $ 473 448 Savings accounts 1,729 2,148 2,468 Time deposits and money market accounts 10,983 11,592 12,067 Total $ 13,190 $ 14,213 14,983
Maturity of total time deposits	At December 31, 2017, the maturity of total time deposits is as follows: (dollars in thousands) Under 1 year $ 652,270 1 to 2 years 392,618 2 to 3 years 15,849 3 to 4 years 1,585 4 to 5 years 4,474 Over 5 years 170 $ 1,066,966

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Short-Term Borrowings [Abstract]
Short-term borrowings	Short-term borrowings of the Company were cash management accounts as follows: (dollars in thousands) 2017 2016 2015 Amount outstanding at December 31, $ 242,991 209,406 191,226 Maximum amount outstanding at any month end 252,996 209,406 194,738 Average amount outstanding 228,086 185,672 184,725 Weighted average interest rate: For the year 0.61 % 0.59 % 0.66 As of year end 0.62 0.59 0.60

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Summary of income tax expense	A summary of income tax expense included in the Consolidated Statements of Income follows: (dollars in thousands) For the year ended December 31, 2017 2016 2015 Current tax expense: Federal $ 26,510 $ 20,904 19,864 State 2,221 1,524 1,647 Total current tax expense 28,731 22,428 21,511 Enactment of Federal Tax Reform 5,054 - - Deferred tax (benefit) expense (183 ) 3,261 3,011 Total income tax expense $ 33,602 $ 25,689 24,522
Tax effects of temporary differences	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities at December 31, 2017 and 2016, are as follows: December 31, (dollars in thousands) 2017 2016 Deductible temporary differences Deductible temporary differences Benefits and deferred remuneration $ (4,087 ) $ (5,474 ) Difference in reporting the allowance for loan losses, net 12,002 18,117 Other income or expense not yet reported for tax purposes (327 ) 129 Depreciable assets (325 ) (638 ) Net deferred tax asset at end of year 7,263 12,134 Net deferred tax asset at beginning of year 12,134 15,395 Enactment of Federal Tax Reform 5,054 - Deferred tax expense $ (183 ) $ 3,261
Effective income tax rate	The effective tax rates differ from the statutory federal income tax rate. The reasons for these differences are as follows: For the years ended 2017 2016 2015 Statutory federal income tax rate 35.0 % 35.0 % 35.0 Increase/(decrease) in taxes resulting from: Tax exempt income (0.1 ) (0.1 ) (0.1 ) State income tax (including alternative minimum tax), net of federal tax benefit 1.6 1.8 1.8 Enactment of Tax Reform 6.6 Other items 0.7 0.9 - Effective income tax rate 43.8 % 37.6 36.7

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Change in component of other comprehensive (loss) income related to retirement plan and post-retirement benefit plan	The following table details the change in the components of other comprehensive (loss) income related to the retirement plan and the postretirement benefit plan, at December 31, 2017 and 2016, respectively: (dollars in thousands) December 31, 2017 Retirement Plan Post- Retirement Benefit Plan Total Change in overfunded position of pension and postretirement benefits $ (2,240 ) (1,584 ) (3,824 ) Amortization of net actuarial (loss) gain (67 ) 356 289 Amortization of prior service cost - (90 ) (90 ) Total $ (2,307 ) (1,318 ) (3,625 ) December 31, 2016 Retirement Plan Post- Retirement Benefit Plan Total Change in overfunded position of pension and postretirement benefits $ (367 ) (966 ) (1,333 ) Amortization of net actuarial gain (loss) (184 ) 274 90 Amortization of prior service credit - (90 ) (90 ) Total $ (551 ) (782 ) (1,333 )
Asset allocation of pension and postretirement benefit plans	The asset allocations of the Company’s pension and postretirement benefit plans at December 31, were as follows: Pension Benefit Postretirement Benefit 2017 2016 2017 2016 Debt Securities 29 % 31 34 33 Equity Securities 69 64 64 62 Other 2 5 2 6 Total 100 % 100 100 100
Fair value of plan assets by type of financial instrument and level hierarchy	Retirement Plan Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 1,034 1,034 - - Equity mutual funds 32,509 32,509 - - U.S. government sponsored enterprises 6,920 - 6,920 - Corporate bonds 6,163 - 6,163 - Fixed income mutual funds 601 601 - - Total Plan Assets $ 47,227 34,144 13,083 - Postretirement Benefits Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 409 406 - - Equity mutual funds 14,703 14,703 - - U.S. government sponsored enterprises 3,512 - 3,512 - Corporate bonds 3,610 - 3,610 - State and political subdivisions 688 - 688 - Total Plan Assets $ 22,922 15,112 7,810 - Retirement Plan Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 2,027 2,027 - - Equity mutual funds 27,706 27,706 - - U.S. government sponsored enterprises 4,233 - 4,233 - Corporate bonds 8,535 - 8,535 - Fixed income mutual funds 599 599 - - Total Plan Assets $ 43,100 30,332 12,768 - Postretirement Benefits Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Plan Assets Cash and cash equivalents $ 1,172 1,172 - - Equity mutual funds 12,540 12,540 - - U.S. government sponsored enterprises 2,049 - 2,049 - Corporate bonds 3,127 - 3,127 - State and political subdivisions 1,450 - 1,450 - Total Plan Assets $ 20,338 13,712 6,626 -
Summary of the status of stock option plans	A summary of the status of TrustCo’s stock option awards as of December 31, 2017 and changes during the year then ended, are as follows: Outstanding Options Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life Balance, January 1, 2017 2,084,041 $ 7.57 New options awarded - 2017 - - Expired options - 2017 (553,000 ) - Options forfeited-2017 (4,000 ) - Exercised options - 2017 (784,100 ) 6.68 Balance, December 31, 2017 742,941 $ 6.78 5.8 years Exercisable Options Balance, December 31, 2017 531,641 $ 6.77 5.2 years
Restricted share units	Restricted share units Outstanding Units Balance, December 31, 2016 215,050 New awards granted 70,650 Forfeited awards (9,200 ) Awards settled (63,400 ) Balance, December 31, 2017 213,100
Performance share units	Performance share units Outstanding Units Balance, December 31, 2016 357,000 New awards granted 94,600 Awards settled (81,500 ) Balance, December 31, 2017 370,100
Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Change in projected/accumulated benefit obligation	The following tables set forth the plan’s funded status and amounts recognized in the Company’s consolidated statements of condition at December 31, 2017 and 2016: Change in Projected Benefit Obligation: December 31, (dollars in thousands) 2017 2016 Projected benefit obligation at beginning of year $ 30,730 30,889 Service cost 42 61 Interest cost 1,303 1,371 Benefit payments and expected expenses (2,050 ) (1,782 ) Net actuarial loss 1,194 191 Projected benefit obligation at end of year $ 31,219 30,730
Change in plan assets and reconciliation of funded status	Change in Plan Assets and Reconciliation of Funded Status: December 31, (dollars in thousands) 2017 2016 Fair Value of plan assets at beginning of year $ 43,100 41,677 Actual gain on plan assets 6,169 3,187 Benefit payments and actual expenses (2,042 ) (1,764 ) Fair value of plan assets at end of year 47,227 43,100 Funded status at end of year $ 16,008 12,370
Amounts recognized in accumulated other comprehensive income	Amounts recognized in accumulated other comprehensive loss consist of the following as of: December 31, 2017 2016 Net actuarial loss $ 2,972 5,279
Components of net periodic pension income and other amounts recognized in other comprehensive (loss) income	Components of Net Periodic Pension (Credit) Expense and Other Amounts Recognized in Other Comprehensive Income: (dollars in thousands) For the years ended December 31, 2017 2016 2015 Service cost $ 42 61 60 Interest cost 1,303 1,371 1,329 Expected return on plan assets (2,742 ) (2,648 ) (2,735 ) Amortization of net loss 67 184 210 Net periodic pension credit (1,330 ) (1,032 ) (1,136 ) Amortization of net loss (67 ) (184 ) (210 ) Net actuarial (gain) loss included in other comprehensive (loss) income (2,240 ) (367 ) (109 ) Total recognized in other comprehensive loss (2,307 ) (551 ) (319 ) Total recognized in net periodic benefit (credit) cost and other comprehensive (loss) income $ (3,637 ) (1,583 ) (1,455 )
Estimated future benefit payments	Estimated Future Benefit Payments The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: (dollars in thousands) Year Pension Benefits 2018 $ 1,773 2019 1,802 2020 1,839 2021 1,894 2022 1,875 2023 - 2027 9,327
Assumptions used to determine benefit obligation and net periodic expense	The assumptions used to determine benefit obligations at December 31 are as follows: 2017 2016 2015 Discount rate 3.93 % 4.41 4.55 The assumptions used to determine net periodic pension expense (benefit) for the years ended December 31 are as follows: 2017 2016 2015 Discount rate 4.41 % 4.55 4.03 Expected long-term rate of return on assets 6.50 6.50 6.50
Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Change in projected/accumulated benefit obligation	Change in Accumulated Benefit Obligation: December 31, (dollars in thousands) 2017 2016 Accumulated benefit obligation at beginning of year $ 5,120 5,434 Service cost 103 116 Interest cost 218 221 Benefits paid (93 ) (70 ) Net actuarial loss (gain) 265 (581 ) Accumulated benefit obligation at end of year $ 5,613 5,120
Change in plan assets and reconciliation of funded status	Change in Plan Assets and Reconciliation of Funded Status: December 31, (dollars in thousands) 2017 2016 Fair value of plan assets at beginning of year $ 20,338 19,238 Actual gain on plan assets 2,611 1,104 Company contributions 66 66 Benefits paid (93 ) (70 ) Fair value of plan assets at end of year 22,922 20,338 Funded status at end of year $ 17,309 15,218
Amounts recognized in accumulated other comprehensive income	December 31, Amounts recognized in accumulated other comprehensive loss consist of the following as of: 2017 2016 Net actuarial gain $ (5,810 ) (4,581 ) Prior service credit (1,636 ) (1,547 ) Total $ (7,446 ) (6,128 )
Components of net periodic pension income and other amounts recognized in other comprehensive (loss) income	Components of Net Periodic Benefit Income and Other Amounts Recognized in Other Comprehensive (Loss) Income: For the years ended (dollars in thousands) 2017 2016 2015 Service cost $ 103 $ 116 165 Interest cost 218 221 268 Expected return on plan assets (761 ) (720 ) (722 ) Amortization of net actuarial gain (356 ) (274 ) (140 ) Amortization of prior service cost 90 90 90 Net periodic benefit credit (706 ) (567 ) (339 ) Net (gain) loss (1,584 ) (966 ) (602 ) Amortization of prior service cost (90 ) (90 ) (90 ) Amortization of net gain 356 274 140 Total amount recognized in other comprehensive (loss) income (1,318 ) (782 ) (552 ) Total amount recognized in net periodic benefit cost and other comprehensive (loss) income $ (2,024 ) $ (1,349 ) (891 )
Estimated future benefit payments	The following benefit payments are expected to be paid: (dollars in thousands) Year Postretirement Benefits 2018 98 2019 112 2020 117 2021 146 2022 158 2023 - 2027 1,040
Assumptions used to determine benefit obligation and net periodic expense	The discount rate assumption used to determine benefit obligations at December 31 is as follows: 2017 2016 2015 Discount rate 3.93 % 4.41 % 4.55 The assumptions used to determine net periodic pension expense (benefit) for the years ended December 31 are as follows: 2016 2015 2014 Discount rate 4.41 % 4.55 % 4.03 Expected long-term rate of return on assets, net of tax 3.75 3.75 3.75

Commitments and Contingent Li35

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingent Liabilities [Abstract]
Operating leases with minimum rental commitments	The Bank leases certain banking premises. These leases are accounted for as operating leases with minimum rental commitments in the amounts presented below. The majority of these leases contain options to renew. (dollars in thousands) 2018 $ 7,267 2019 7,178 2020 6,916 2021 6,720 2022 5,913 2023 and after 31,803 $ 65,797

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of the component parts of earnings per share	A reconciliation of the component parts of earnings per share for 2017, 2016 and 2015 follows: (dollars in thousands, except per share data) 2017 2016 2015 For the years ended December 31: Net income $ 43,145 42,601 42,238 Less: Net income allocated to participating securities - - - Net income allocated to common shareholders $ 43,145 42,601 42,238 Weighted average common shares outstanding including participating securities 96,111 95,548 95,103 Less: Participating securities - - - Weighted average common shares 96,111 95,548 95,103 Effect of Dilutive Securities: Stock Options 111 100 110 Weighted average common shares including potential dilutive shares 96,222 95,648 95,213 Basic EPS $ 0.449 0.446 0.444 Diluted EPS $ 0.448 0.445 0.444

Fair Value of Financial Instr37

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value of Financial Instruments [Abstract]
Assets and liabilities measured at fair value on a recurring basis	Assets and liabilities measured at fair value under ASC 820 on a recurring basis are summarized below: Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Securities available for sale: U.S. government sponsored enterprises $ 137,851 - $ 137,851 - State and political subdivisions 525 - 525 - Mortgage backed securities and collateralized mortgage obligations - residential 315,983 - 315,983 - Corporate bonds 40,162 - 40,162 - Small Business Administration- guaranteed participation securities 67,059 - 67,059 - Mortgage backed securities and collateralized mortgage obligations - commercial 9,700 - 9,700 - Other 685 35 650 - Total securities available for sale $ 571,965 $ 35 $ 571,930 $ - Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (dollars in thousands) Securities available for sale: U.S. government sponsored enterprises $ 117,266 $ - $ 117,266 $ - State and political subdivisions 886 - 886 - Mortgage backed securities and collateralized mortgage obligations - residential 372,308 - 372,308 - Corporate bonds 40,705 40,705 Small Business Administration- guaranteed participation securities 78,499 - 78,499 - Mortgage backed securities and collateralized mortgage obligations - commercial 10,011 - 10,011 - Other 685 35 650 - Total securities available for sale $ 620,360 $ 35 $ 620,325 $ -
Assets measured at fair value on a non-recurring basis	Assets measured at fair value on a non-recurring basis are summarized below: Fair Value Measurements at December 31, 2017 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Valuation technique Unobservable inputs Range (Weighted Average) (dollars in thousands) Other real estate owned $ 3,246 $ - $ - $ 3,246 Sales comparison approach Adjustments for differences between comparable sales 1% - 14% (7 %) Impaired loans: Commercial real estate - - - Sales comparison approach Adjustments for differences between comparable sales Real estate mortgage - 1 to 4 family 844 - - 844 Sales comparison approach Adjustments for differences between comparable sales 5% - 14% (10 %) Fair Value Measurements at December 31, 2016 Using: Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Valuation technique Unobservable inputs Range (Weighted Average) (dollars in thousands) Other real estate owned $ 4,268 $ - $ - $ 4,268 Sales comparison approach Adjustments for differences between comparable sales 1% - 14% (7 %) Impaired loans: Commercial real estate 1,250 - - 1,250 Sales comparison approach Adjustments for differences between comparable sales 7% - 35% (23 %) Real estate mortgage - 1 to 4 family 458 - - 458 Sales comparison approach Adjustments for differences between comparable sales 5% - 14% (10 %)
Carrying amounts and estimated fair values of financial instruments	In accordance with ASC 825, the carrying amounts and estimated fair values of financial instruments at December 31, 2017 and 2016 are as follows: (dollars in thousands) Carrying Fair Value Measurements at December 31, 2017 Using: Value Level 1 Level 2 Level 3 Total Financial assets: Cash and cash equivalents $ 612,740 612,740 - - 612,740 Securities available for sale 571,965 35 571,930 - 571,965 Held to maturity securities 27,551 - 28,701 - 28,701 Federal Reserve Bank and Federal Home Loan Bank stock 8,779 N/A N/A N/A N/A Net loans 3,592,237 - - 3,598,213 3,598,213 Accrued interest receivable 11,441 243 2,440 8,758 11,441 Financial liabilities: Demand deposits 398,399 398,399 - - 398,399 Interest bearing deposits 3,774,927 2,707,961 1,076,213 - 3,784,174 Short-term borrowings 242,991 - 242,991 - 242,991 Accrued interest payable 537 77 460 - 537 (dollars in thousands) Carrying Fair Value Measurements at December 31, 2016 Using: Value Level 1 Level 2 Level 3 Total Financial assets: Cash and cash equivalents $ 707,274 707,274 - - 707,274 Securities available for sale 620,360 35 620,325 - 620,360 Held to maturity securities 45,490 - 47,526 - 47,526 Federal Reserve Bank and Federal Home Loan Bank stock 9,579 N/A N/A N/A N/A Net loans 3,386,696 - - 3,370,976 3,370,976 Accrued interest receivable 11,070 145 2,654 8,271 11,070 Financial liabilities: Demand deposits 377,755 377,755 - - 377,755 Interest bearing deposits 3,818,408 2,658,945 1,156,025 - 3,814,970 Short-term borrowings 209,406 - 209,406 - 209,406 Accrued interest payable 526 82 444 - 526

Regulatory Capital Requiremen38

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Summary of actual capital amounts and ratios	The following is a summary of actual capital amounts and ratios as of December 31, 2017 and 2016, for Trustco Bank: (dollars in thousands) As of December 31, 2017 Well Adequately Amount Ratio Capitalized(1) Capitalized(1)(2) Tier 1 leverage ratio $ 444,931 9.152 % 5.000 % 4.000 % Common equity Tier 1 capital 444,931 17.460 6.500 5.750 Tier 1 risk-based capital 444,931 17.460 8.000 7.250 Total risk-based capital 476,942 18.720 10.000 9.250 (dollars in thousands) As of December 31, 2016 Well Adequately Amount Ratio Capitalized(1) Capitalized(1) Tier 1 leverage ratio $ 424,802 8.829 % 5.000 % 4.000 % Common equity Tier 1 capital 424,802 17.238 6.500 5.125 Tier 1 risk-based capital 424,802 17.238 8.000 6.625 Total risk-based capital 455,772 18.492 10.000 8.625 (1) Federal regulatory minimum requirements to be considered to be Well Capitalized and Adequately Capitalized (2) The December 31, 2016 common equity tier 1, tier 1 risk-based, and total risk-based capital ratios include a transition capital conservation buffer of 1.25 percent The following is a summary of actual capital amounts and ratios as of December 31, 2017 and 2016 for TrustCo on a consolidated basis. (dollars in thousands) As of December 31, 2017 Minimum for Amount Ratio Capital Adequacy plus Capital Conservation Buffer(1)(2) Tier 1 leverage ratio $ 459,561 9.449 % 4.000 % Common equity Tier 1 capital 459,561 18.020 5.750 Tier 1 risk-based capital 459,561 18.020 7.250 Total risk-based capital 491,590 19.280 9.250 (dollars in thousands) As of December 31, 2016 Minimum for Amount Ratio Capital Adequacy plus Capital Conservation Buffer(1)(2) Tier 1 leverage ratio $ 438,426 9.110 % 4.000 % Common equity Tier 1 capital 438,426 17.782 5.125 Tier 1 risk-based capital 438,426 17.782 6.625 Total risk-based capital 469,411 19.038 8.625 (1) Federal regulatory minimum requirements to be considered to be Well Capitalized and Adequately Capitalized (2) The December 31, 2017 and 2016 common equity tier 1, tier 1 risk-based, and total risk-based capital ratios include a transition capital conservation buffer of 1.25 percent, and 0.625 percent respectively.

Accumulated Other Comprehensi39

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Loss [Abstract]
Accumulated other comprehensive (loss) income, net of tax	The following is a summary of the accumulated other comprehensive loss balances, net of tax: For the year ended 12/31/17 (dollars in thousands) Balance at 12/31/2016 Other comprehensive income (loss) - before reclassifications Amount reclassified from accumulated other comprehensive loss Other comprehensive income (loss) - year ended 12/31/2017 Balance at 12/31/2017 Net unrealized holding loss on securities available for sale, net of tax $ (6,762 ) 1,732 1,732 (5,030 ) Net change in overfunded position in pension and postretirement plans arising during the year, net of tax 42 3,012 - 3,012 3,054 Net change in net actuarial loss and prior service cost on pension and postretirement benefit plans, net of tax 469 - (299 ) (299 ) 170 Accumulated other comprehensive loss, net of tax (6,251 ) 4,744 (299 ) 4,445 (1,806 ) For the year ended 12/31/16 (dollars in thousands) Balance at 12/31/2014 Other comprehensive (loss) income - before reclassifications Amount reclassified from accumulated other comprehensive loss Other comprehensive (loss) income - year ended 12/31/2016 Balance at 12/31/2016 Net unrealized holding gain (loss) on securities available for sale, net of tax $ (4,492 ) (1,869 ) (401 ) (2,270 ) (6,762 ) Net change in overfunded position in pension and postretirement plans arising during the year, net of tax (758 ) 800 - 800 42 Net change in net actuarial loss and prior service credit on pension and postretirement benefit plans, net of tax 469 - - - 469 Accumulated other comprehensive loss, net of tax (4,781 ) (1,069 ) (401 ) (1,470 ) (6,251 ) For the year ended 12/31/15 (dollars in thousands) Balance at 12/31/2014 Other comprehensive (loss) income - before reclassifications Amount reclassified from accumulated other comprehensive loss Other comprehensive (loss) Income- year ended 12/31/2015 Balance at 12/31/2015 Net unrealized holding gain (loss) on securities available for sale, net of tax $ (3,693 ) (648 ) (151 ) (799 ) (4,492 ) Net change in overfunded position in pension and postretirement plans arising during the year, net of tax (1,188 ) 430 - 430 (758 ) Net change in net actuarial loss and prior service credit on pension and postretirement benefit plans, net of tax 372 - 97 97 469 Accumulated other comprehensive loss, net of tax $ (4,509 ) (218 ) (54 ) (272 ) (4,781 )
Reclassifications out of accumulated other comprehensive income	The following represents the reclassifications out of accumulated other comprehensive loss for the years ended December 31, 2017,2016 and 2015: (dollars in thousands) Years Ended Affected Line Item 2017 2016 2015 in Financial Statements Unrealized gains on securities available for sale Realized gain on securities transactions $ - 668 251 Net gain on securities transactions Income tax expense - (267 ) (100 ) Income taxes Net of tax - 401 151 Amortization of pension and postretirement benefit items Amortization of net actuarial gain (loss) 289 90 (70 ) Salaries and employee benefits Amortization of prior service cost (90 ) (90 ) (90 ) Salaries and employee benefits Income tax benefit 100 - 63 Income taxes Net of tax 299 - (97 ) Total reclassifications, net of tax $ 299 401 54

Parent Company Only (Tables)

Parent Company Only (Tables)	12 Months Ended
	Dec. 31, 2017
Parent Company Only [Abstract]
Statements of Comprehensive Income	The following statements pertain to TrustCo Bank Corp NY (Parent Company): Statements of Comprehensive Income (dollars in thousands) Years Ended December 31, Income: 2017 2016 2015 Dividends and interest from subsidiaries $ 24,510 24,498 24,501 Net gain on securities transactions - - - Miscellaneous income - - - Total income 24,510 24,498 24,501 Expense: Operating supplies 26 21 33 Professional services 122 461 577 Miscellaneous expense 2,573 1,258 664 Total expense 2,721 1,740 1,274 Income before income taxes and subsidiaries' undistributed earnings 21,789 22,758 23,227 Income tax benefit (1,171 ) (578 ) (405 ) Income before subsidiaries' undistributed earnings 22,960 23,336 23,632 Equity in undistributed earnings of subsidiaries 20,185 19,265 18,606 Net income $ 43,145 42,601 42,238 Change in other comprehensive income (loss) 4,445 (1,470 ) (272 ) Comprehensive income $ 47,590 41,131 41,966
Statements of Condition	The following statements pertain to TrustCo Bank Corp NY (Parent Company): Statements of Condition (dollars in thousands) December 31, Assets: 2017 2016 Cash in subsidiary bank $ 21,773 19,886 Investments in subsidiaries 443,692 419,075 Securities available for sale 35 35 Other assets 771 824 Total assets 466,271 439,820 Liabilities and shareholders' equity: Accrued expenses and other liabilities 7,964 7,134 Total liabilities 7,964 7,134 Shareholders' equity 458,307 432,686 Total liabilities and shareholders' equity $ 466,271 439,820
Statements of Cash Flows	The following statements pertain to TrustCo Bank Corp NY (Parent Company): Statements of Cash Flows (dollars in thousands) Years Ended December 31, 2017 2016 2015 Increase/(decrease) in cash and cash equivalents: Cash flows from operating activities: Net income $ 43,145 42,601 42,238 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed earnings of subsidiaries (20,185 ) (19,265 ) (18,606 ) Stock based compensation expense 150 224 204 Net change in other assets and accrued expenses 853 (196 ) (140 ) Total adjustments (19,182 ) (19,237 ) (18,542 ) Net cash provided by operating activities 23,963 23,364 23,696 Cash flows from financing activities: Proceeds from exercise of stock options 5,236 1,368 147 Dividends paid (25,184 ) (25,055 ) (24,937 ) Payments to acquire treasury stock (4,608 ) (701 ) (147 ) Proceeds from sales of treasury stock 2,480 2,447 2,670 Net cash used in financing activities (22,076 ) (21,941 ) (22,267 ) Net increase in cash and cash equivalents 1,887 1,423 1,429 Cash and cash equivalents at beginning of year 19,886 18,463 17,034 Cash and cash equivalents at end of year $ 21,773 19,886 18,463

Basis of Presentation (Details)

Basis of Presentation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)PaymentSegment	Dec. 31, 2016USD ($)
Loans [Abstract]
Number of past due payments on loans classified as nonperforming | Payment	3
Non-payment period of loans moved to non-accrual status	90 days
Allowance for Loan Losses [Abstract]
Loan-to-value ratio applicable to additional allowance	90.00%
Other Real Estate Owned [Abstract]
Other real estate owned	$ 3.2	$ 4.3
Dividend Restrictions [Abstract]
Statutory amount available for dividend payments with regulatory approval	$ 68.2
Benefit Plans [Abstract]
Age at which company provides access to Medicare Supplemental program for retirees	65 years
Segment Reporting [Abstract]
Number of reportable segment | Segment	1
Buildings [Member] | Minimum [Member]
Bank Premises and Equipment [Abstract]
Premises and equipment, useful life	20 years
Buildings [Member] | Maximum [Member]
Bank Premises and Equipment [Abstract]
Premises and equipment, useful life	40 years
Furniture and Equipment [Member] | Minimum [Member]
Bank Premises and Equipment [Abstract]
Premises and equipment, useful life	3 years
Furniture and Equipment [Member] | Maximum [Member]
Bank Premises and Equipment [Abstract]
Premises and equipment, useful life	7 years

Balances at Other Banks (Detail

Balances at Other Banks (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Balances at Other Banks [Abstract]
Balances at other banks	$ 34.5	$ 32.3

Investment Securities, Availabl

Investment Securities, Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	$ 580,670	$ 631,590
Gross Unrealized Gains	121	136
Gross Unrealized Losses	8,861	11,401
Fair Value	571,930	620,325
Amortized cost and fair value of the equity securities available for sale [Abstract]
Amortized Cost	35	35
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	35	35
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	580,705	631,625
Gross Unrealized Gains	121	136
Gross Unrealized Losses	8,861	11,401
Fair Value	571,965	620,360
U. S. Government Sponsored Enterprises [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	139,890	119,887
Gross Unrealized Gains	27	0
Gross Unrealized Losses	2,066	2,621
Fair Value	137,851	117,266
State and Political Subdivisions [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	515	873
Gross Unrealized Gains	10	13
Gross Unrealized Losses	0	0
Fair Value	525	886
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	320,614	378,068
Gross Unrealized Gains	84	123
Gross Unrealized Losses	4,715	5,883
Fair Value	315,983	372,308
Corporate Bonds [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	40,270	40,956
Gross Unrealized Gains	0	0
Gross Unrealized Losses	108	251
Fair Value	40,162	40,705
Small Business Administration-Guaranteed Participation Securities [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	68,921	81,026
Gross Unrealized Gains	0	0
Gross Unrealized Losses	1,862	2,527
Fair Value	67,059	78,499
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Commercial [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	9,810	10,130
Gross Unrealized Gains	0	0
Gross Unrealized Losses	110	119
Fair Value	9,700	10,011
Other [Member]
Amortized cost and fair value of the debt securities available for sale [Abstract]
Amortized Cost	650	650
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 650	$ 650

Investment Securities, Availa44

Investment Securities, Available-for-sale Securities, Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortized Cost [Abstract]
Due in one year or less	$ 45,783
Due in one year through five years	135,483
Due after five years through ten years	59
Due after ten years	0
Amortized Cost	580,670	$ 631,590
Fair Value [Abstract]
Due in one year or less	45,739
Due in one year through five years	133,390
Due after five years through ten years	59
Due after ten years	0
Fair Value	571,930	620,325
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Amortized Cost [Abstract]
Securities, amortized cost	320,614
Amortized Cost	320,614	378,068
Fair Value [Abstract]
Securities, fair value	315,983
Fair Value	315,983	372,308
Small Business Administration-Guaranteed Participation Securities [Member]
Amortized Cost [Abstract]
Securities, amortized cost	68,921
Amortized Cost	68,921	81,026
Fair Value [Abstract]
Securities, fair value	67,059
Fair Value	67,059	78,499
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Commercial [Member]
Amortized Cost [Abstract]
Securities, amortized cost	9,810
Amortized Cost	9,810	10,130
Fair Value [Abstract]
Securities, fair value	9,700
Fair Value	$ 9,700	$ 10,011

Investment Securities, Availa45

Investment Securities, Available-for-sale Securities, Gross Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	$ 77,814	$ 577,164
12 months or more - Fair Value	481,405	18,653
Total - Fair Value	559,219	595,817
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	637	10,717
12 months or more - Gross Unrealized Loss	8,224	684
Total - Gross Unrealized Loss	8,861	11,401
U. S. Government Sponsored Enterprises [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	29,734	102,266
12 months or more - Fair Value	98,090	0
Total - Fair Value	127,824	102,266
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	266	2,621
12 months or more - Gross Unrealized Loss	1,800	0
Total - Gross Unrealized Loss	2,066	2,621
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	48,080	359,622
12 months or more - Fair Value	266,394	4,713
Total - Fair Value	314,474	364,335
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	371	5,766
12 months or more - Gross Unrealized Loss	4,344	117
Total - Gross Unrealized Loss	4,715	5,883
Corporate Bonds [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	0	40,705
12 months or more - Fair Value	40,162	0
Total - Fair Value	40,162	40,705
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	0	251
12 months or more - Gross Unrealized Loss	108	0
Total - Gross Unrealized Loss	108	251
Small Business Administration-Guaranteed Participation Securities [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	0	64,560
12 months or more - Fair Value	67,059	13,940
Total - Fair Value	67,059	78,500
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	0	1,960
12 months or more - Gross Unrealized Loss	1,862	567
Total - Gross Unrealized Loss	1,862	2,527
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Commercial [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	0	10,011
12 months or more - Fair Value	9,700	0
Total - Fair Value	9,700	10,011
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	0	119
12 months or more - Gross Unrealized Loss	110	0
Total - Gross Unrealized Loss	$ 110	$ 119

Investment Securities, Availa46

Investment Securities, Available-for-sale Securities, Transaction Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Proceeds from sales and calls of securities available for sale, gross realized gains and gross realized losses [Abstract]
Proceeds from sales	$ 0	$ 44,829	$ 22,945
Proceeds from calls	124,624	201,100	232,010
Gross realized gains	0	668	251
Gross realized losses	0	0	0
Income tax expense recognized on net gains on sales and calls of securities available for sale		267	$ 100
Securities available for sale pledged to secure short-term borrowings and for other purposes	$ 326,500	$ 264,800

Investment Securities, Held-to-

Investment Securities, Held-to-maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortized cost and fair value of the held to maturity securities [Abstract]
Amortized Cost	$ 27,551	$ 45,490
Gross Unrecognized Gains	1,150	2,036
Gross Unrecognized Losses	0	0
Fair Value	28,701	47,526
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Amortized cost and fair value of the held to maturity securities [Abstract]
Amortized Cost	27,551	35,500
Gross Unrecognized Gains	1,150	1,736
Gross Unrecognized Losses	0	0
Fair Value	28,701	37,236
Corporate Bonds [Member]
Amortized cost and fair value of the held to maturity securities [Abstract]
Amortized Cost	0	9,990
Gross Unrecognized Gains	0	300
Gross Unrecognized Losses	0	0
Fair Value	$ 0	$ 10,290

Investment Securities, Held-t48

Investment Securities, Held-to-maturity Securities, Maturity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Investment Securities [Abstract]
Sales and transfers of held to maturity securities	$ 0	$ 0
Amortized Cost [Abstract]
Amortized Cost	27,551	45,490
Fair Value [Abstract]
Fair Value	28,701	47,526
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Amortized Cost [Abstract]
Securities, amortized cost	27,551
Amortized Cost	27,551	35,500
Fair Value [Abstract]
Securities, fair value	28,701
Fair Value	$ 28,701	$ 37,236

Investment Securities, Concentr

Investment Securities, Concentrations (Details) $ in Thousands	Dec. 31, 2017USD ($)
Federal Home Loan Mortgage Corporation [Member]
Securities Held in Available for Sale and Held to Maturity Portfolios that Represent Greater than 10% of Shareholders Equity [Abstract]
Amortized Cost	$ 112,564
Fair Value	111,183
Federal National Mortgage Association [Member]
Securities Held in Available for Sale and Held to Maturity Portfolios that Represent Greater than 10% of Shareholders Equity [Abstract]
Amortized Cost	260,882
Fair Value	257,386
Government National Mortgage Association [Member]
Securities Held in Available for Sale and Held to Maturity Portfolios that Represent Greater than 10% of Shareholders Equity [Abstract]
Amortized Cost	68,921
Fair Value	67,059
Small Business Administration [Member]
Securities Held in Available for Sale and Held to Maturity Portfolios that Represent Greater than 10% of Shareholders Equity [Abstract]
Amortized Cost	50,000
Fair Value	$ 49,414

Loans and Allowance for Loan 50

Loans and Allowance for Loan Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		$ 3,636,407	$ 3,430,586
Less: Allowance for loan losses		44,170	43,890	$ 44,762	$ 46,327
Net loans		3,592,237	3,386,696
Due from officers		6,900	7,600
New loans		3,600
Repayments of loans		4,300
Reduction in outstanding loans		100
New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	2,795,993	2,692,335
Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		840,414	738,251
Real Estate Construction Loans [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		30,900	24,800
Residential Borrowers [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		21,100	16,300
Commercial Borrowers Residential Purpose [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		9,800	8,500
Commercial [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		186,207	191,194
Less: Allowance for loan losses		4,324	4,929	4,491	4,071
Commercial [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		172,974	178,905
Commercial [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		13,233	12,289
Commercial [Member] | Commercial Real Estate [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		161,892	163,609
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	149,368	151,366
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		12,524	12,243
Commercial [Member] | Other [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		24,315	27,585
Commercial [Member] | Other [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	23,606	27,539
Commercial [Member] | Other [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		709	46
Real Estate Mortgage - 1 to 4 Family [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		3,441,437	3,230,574
Less: Allowance for loan losses		39,077	38,231	39,753	42,088
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		3,052,077	2,824,087
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	2,286,148	2,158,904
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		765,929	665,183
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		80,444	71,646
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	66,455	60,892
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		13,989	10,754
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		308,916	334,841
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	263,275	286,586
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		45,641	48,255
Installment [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		8,763	8,818
Less: Allowance for loan losses		769	730	$ 518	$ 168
Installment [Member] | New York and Other States [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net	[1]	7,141	7,048
Installment [Member] | Florida [Member]
Loans and Leases Receivable, Net Amount [Abstract]
Total loans, net		$ 1,622	$ 1,770
[1]	Includes New York, New Jersey, Vermont, and Massachusetts.

Loans and Allowance for Loan 51

Loans and Allowance for Loan Losses, Non-accrual Loans, by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Non accrual loans by loan class [Abstract]
Total non-accrual loans	$ 24,339	$ 25,018
Restructured real estate mortgages - 1 to 4 family	38	42
Total nonperforming loans	24,377	25,060
Other real estate owned	2,700	3,500
New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	21,950	23,089
Restructured real estate mortgages - 1 to 4 family	38	42
Total nonperforming loans	21,988	23,131
Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	2,389	1,929
Restructured real estate mortgages - 1 to 4 family	0	0
Total nonperforming loans	2,389	1,929
Residential Real Estate [Member]
Non accrual loans by loan class [Abstract]
Non accrual residential mortgage loans in the process of foreclosure	12,600	12,500
Commercial [Member] | Commercial Real Estate [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	1,443	1,843
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	1,443	1,843
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	0	0
Commercial [Member] | Other [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	100	0
Commercial [Member] | Other [Member] | New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	100	0
Commercial [Member] | Other [Member] | Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	0	0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	18,913	19,386
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	16,654	17,727
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	2,259	1,659
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	93	95
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	93	95
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	3,733	3,646
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	3,603	3,376
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	130	270
Installment [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	57	48
Installment [Member] | New York and Other States [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	57	48
Installment [Member] | Florida [Member]
Non accrual loans by loan class [Abstract]
Total non-accrual loans	$ 0	$ 0

Loans and Allowance for Loan 52

Loans and Allowance for Loan Losses, Past Due (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 22,272	$ 27,065
Current		3,614,135	3,403,521
Total loans		3,636,407	3,430,586
Loans that are 90 days past due and still accruing interest		$ 0	$ 0
Number of days past due		90 days	90 days
New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 20,557	$ 23,588
Current		2,775,436	2,668,747
Total loans	[1]	2,795,993	2,692,335
Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,715	3,477
Current		838,699	734,774
Total loans		840,414	738,251
30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		6,673	9,189
30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		6,393	7,198
30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		280	1,991
60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,514	3,188
60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,509	3,113
60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		5	75
90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		14,085	14,688
90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		12,655	13,277
90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,430	1,411
Commercial [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		186,207	191,194
Commercial [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		172,974	178,905
Commercial [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		13,233	12,289
Commercial [Member] | Commercial Real Estate [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,689	1,799
Current		160,203	161,810
Total loans		161,892	163,609
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,689	1,799
Current		147,679	149,567
Total loans	[1]	149,368	151,366
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Current		12,524	12,243
Total loans		12,524	12,243
Commercial [Member] | Commercial Real Estate [Member] | 30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		183	50
Commercial [Member] | Commercial Real Estate [Member] | 30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		183	50
Commercial [Member] | Commercial Real Estate [Member] | 30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Commercial Real Estate [Member] | 60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		174	43
Commercial [Member] | Commercial Real Estate [Member] | 60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		174	43
Commercial [Member] | Commercial Real Estate [Member] | 60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,332	1,706
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,332	1,706
Commercial [Member] | Commercial Real Estate [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		100	0
Current		24,215	27,585
Total loans		24,315	27,585
Commercial [Member] | Other [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		100	0
Current		23,506	27,539
Total loans	[1]	23,606	27,539
Commercial [Member] | Other [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Current		709	46
Total loans		709	46
Commercial [Member] | Other [Member] | 30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		100	0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		100	0
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member]
Aging of the recorded investment in past due loans [Abstract]
Total loans		3,441,437	3,230,574
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		17,664	22,212
Current		3,034,413	2,801,875
Total loans		3,052,077	2,824,087
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		15,983	18,946
Current		2,270,165	2,139,958
Total loans	[1]	2,286,148	2,158,904
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,681	3,266
Current		764,248	661,917
Total loans		765,929	665,183
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		5,946	8,321
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		5,669	6,379
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		277	1,942
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,300	2,993
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,300	2,924
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	69
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		10,418	10,898
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		9,014	9,643
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		1,404	1,255
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		51	146
Current		80,393	71,500
Total loans		80,444	71,646
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		51	127
Current		66,404	60,765
Total loans	[1]	66,455	60,892
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	19
Current		13,989	10,735
Total loans		13,989	10,754
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		6	69
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		6	50
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	19
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	3
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	3
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		45	74
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		45	74
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,646	2,791
Current		306,270	332,050
Total loans		308,916	334,841
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,646	2,635
Current		260,629	283,951
Total loans	[1]	263,275	286,586
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	156
Current		45,641	48,099
Total loans		45,641	48,255
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		489	685
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		489	685
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		18	111
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		18	111
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,139	1,995
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		2,139	1,839
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		0	156
Installment [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		122	117
Current		8,641	8,701
Total loans		8,763	8,818
Installment [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		88	81
Current		7,053	6,967
Total loans	[1]	7,141	7,048
Installment [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		34	36
Current		1,588	1,734
Total loans		1,622	1,770
Installment [Member] | 30 to 59 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		49	64
Installment [Member] | 30 to 59 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		46	34
Installment [Member] | 30 to 59 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		3	30
Installment [Member] | 60 to 89 Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		22	38
Installment [Member] | 60 to 89 Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		17	32
Installment [Member] | 60 to 89 Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		5	6
Installment [Member] | 90+ Days Past Due [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		51	15
Installment [Member] | 90+ Days Past Due [Member] | New York and Other States [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		25	15
Installment [Member] | 90+ Days Past Due [Member] | Florida [Member]
Aging of the recorded investment in past due loans [Abstract]
Total 30+ days Past Due		$ 26	$ 0
[1]	Includes New York, New Jersey, Vermont, and Massachusetts.

Loans and Allowance for Loan 53

Loans and Allowance for Loan Losses, Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	$ 43,890	$ 44,762	$ 46,327
Loans charged off [Abstract]
Total loan charge offs	2,511	4,710	5,915
Recoveries of loans previously charged off [Abstract]
Total recoveries	791	888	650
Net loans charged off	1,720	3,822	5,265
Provision for loan losses	2,000	2,950	3,700
Balance at end of period	44,170	43,890	44,762
New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	2,325	4,545	5,578
Recoveries of loans previously charged off [Abstract]
Total recoveries	718	884	638
Florida [Member]
Loans charged off [Abstract]
Total loan charge offs	186	165	337
Recoveries of loans previously charged off [Abstract]
Total recoveries	73	4	12
Commercial [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	4,929	4,491	4,071
Loans charged off [Abstract]
Total loan charge offs	72	795	779
Recoveries of loans previously charged off [Abstract]
Total recoveries	96	207	27
Net loans charged off	(24)	588	752
Provision for loan losses	(629)	1,026	1,172
Balance at end of period	4,324	4,929	4,491
Commercial [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	72	795	779
Recoveries of loans previously charged off [Abstract]
Total recoveries	96	207	20
Commercial [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs	0	0	0
Recoveries of loans previously charged off [Abstract]
Total recoveries	0	0	7
Real Estate Mortgage - 1 to 4 Family [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	38,231	39,753	42,088
Loans charged off [Abstract]
Total loan charge offs	2,220	3,573	4,951
Recoveries of loans previously charged off [Abstract]
Total recoveries	669	617	577
Net loans charged off	1,551	2,956	4,374
Provision for loan losses	2,397	1,434	2,039
Balance at end of period	39,077	38,231	39,753
Real Estate Mortgage - 1 to 4 Family [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	2,053	3,447	4,631
Recoveries of loans previously charged off [Abstract]
Total recoveries	596	613	572
Real Estate Mortgage - 1 to 4 Family [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs	167	126	320
Recoveries of loans previously charged off [Abstract]
Total recoveries	73	4	5
Installment [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	730	518	168
Loans charged off [Abstract]
Total loan charge offs	219	342	185
Recoveries of loans previously charged off [Abstract]
Total recoveries	26	64	46
Net loans charged off	193	278	139
Provision for loan losses	232	490	489
Balance at end of period	769	730	518
Installment [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	200	303	168
Recoveries of loans previously charged off [Abstract]
Total recoveries	26	64	46
Installment [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs	19	39	17
Recoveries of loans previously charged off [Abstract]
Total recoveries	$ 0	$ 0	$ 0

Loans and Allowance for Loan 54

Loans and Allowance for Loan Losses, Based on Impairment Review Method (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	$ 0	$ 0
Collectively evaluated for impairment	44,170	43,890
Total ending allowance balance	44,170	43,890	$ 44,762	$ 46,327
Loans [Abstract]
Individually evaluated for impairment	24,280	24,025
Collectively evaluated for impairment	3,612,127	3,406,561
Total ending loans balance	3,636,407	3,430,586
Commercial [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	4,324	4,929
Total ending allowance balance	4,324	4,929	4,491	4,071
Loans [Abstract]
Individually evaluated for impairment	2,248	2,418
Collectively evaluated for impairment	183,959	188,776
Total ending loans balance	186,207	191,194
Real Estate Mortgage - 1 to 4 Family [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	39,077	38,231
Total ending allowance balance	39,077	38,231	39,753	42,088
Loans [Abstract]
Individually evaluated for impairment	22,032	21,607
Collectively evaluated for impairment	3,419,405	3,208,967
Total ending loans balance	3,441,437	3,230,574
Installment [Member]
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	769	730
Total ending allowance balance	769	730	$ 518	$ 168
Loans [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	8,763	8,818
Total ending loans balance	$ 8,763	$ 8,818

Loans and Allowance for Loan 55

Loans and Allowance for Loan Losses, Impaired Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Impaired loans by loans class [Abstract]
Recorded Investment	$ 24,280	$ 24,025
Unpaid Principal Balance	26,310	26,201
Related Allowance	0	0
Average Recorded Investment	24,750	22,408
New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	20,974	21,361
Unpaid Principal Balance	22,898	23,374
Related Allowance	0	0
Average Recorded Investment	21,762	19,936
Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	3,306	2,664
Unpaid Principal Balance	3,412	2,827
Related Allowance	0	0
Average Recorded Investment	2,988	2,472
Commercial [Member] | Commercial Real Estate [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,148	2,418
Unpaid Principal Balance	3,120	3,470
Related Allowance	0	0
Average Recorded Investment	2,711	2,214
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,148	2,418
Unpaid Principal Balance	3,120	3,470
Related Allowance	0	0
Average Recorded Investment	2,711	2,214
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Commercial [Member] | Other [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	100	0
Unpaid Principal Balance	100	0
Related Allowance	0	0
Average Recorded Investment	87	0
Commercial [Member] | Other [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	100	0
Unpaid Principal Balance	100	0
Related Allowance	0	0
Average Recorded Investment	87	0
Commercial [Member] | Other [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	18,557	18,684
Unpaid Principal Balance	19,353	19,539
Related Allowance	0	0
Average Recorded Investment	18,843	17,465
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	15,850	16,675
Unpaid Principal Balance	16,540	17,439
Related Allowance	0	0
Average Recorded Investment	16,508	15,665
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,707	2,009
Unpaid Principal Balance	2,813	2,100
Related Allowance	0	0
Average Recorded Investment	2,335	1,800
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	359	363
Unpaid Principal Balance	380	399
Related Allowance	0	0
Average Recorded Investment	355	332
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	270	269
Unpaid Principal Balance	291	305
Related Allowance	0	0
Average Recorded Investment	263	251
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	89	94
Unpaid Principal Balance	89	94
Related Allowance	0	0
Average Recorded Investment	92	81
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	3,116	2,560
Unpaid Principal Balance	3,357	2,793
Related Allowance	0	0
Average Recorded Investment	2,754	2,397
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	2,606	1,999
Unpaid Principal Balance	2,847	2,160
Related Allowance	0	0
Average Recorded Investment	2,193	1,806
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Impaired loans by loans class [Abstract]
Recorded Investment	510	561
Unpaid Principal Balance	510	633
Related Allowance	0	0
Average Recorded Investment	$ 561	$ 591

Loans and Allowance for Loan 56

Loans and Allowance for Loan Losses, Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)Contract	Dec. 31, 2015USD ($)Contract
Financing Receivable, Modifications [Line Items]
TDR's classifications from previously performing loans	$ 11,800	$ 11,500
New York and Other States [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	69	43	43
Pre-Modification Outstanding Recorded Investment	$ 7,003	$ 3,718	$ 5,440
Post-Modification Outstanding Recorded Investment	$ 7,003	$ 3,718	$ 5,440
Florida [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	12	6	10
Pre-Modification Outstanding Recorded Investment	$ 1,171	$ 555	$ 887
Post-Modification Outstanding Recorded Investment	$ 1,171	$ 555	$ 887
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	4	2	0
Pre-Modification Outstanding Recorded Investment	$ 426	$ 401	$ 0
Post-Modification Outstanding Recorded Investment	$ 426	$ 401	$ 0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	44	30	35
Pre-Modification Outstanding Recorded Investment	$ 5,653	$ 2,871	$ 4,797
Post-Modification Outstanding Recorded Investment	$ 5,653	$ 2,871	$ 4,797
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	10	4	6
Pre-Modification Outstanding Recorded Investment	$ 1,076	$ 504	$ 780
Post-Modification Outstanding Recorded Investment	$ 1,076	$ 504	$ 780
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | New York and Other States [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	3	1	1
Pre-Modification Outstanding Recorded Investment	$ 56	$ 44	$ 137
Post-Modification Outstanding Recorded Investment	$ 56	$ 44	$ 137
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Loans [Member] | Florida [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	0	1	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 45	$ 0
Post-Modification Outstanding Recorded Investment	$ 0	$ 45	$ 0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	18	10	7
Pre-Modification Outstanding Recorded Investment	$ 868	$ 402	$ 506
Post-Modification Outstanding Recorded Investment	$ 868	$ 402	$ 506
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Modified loans by class determined to be TDR's [Abstract]
Number of Contracts | Contract	2	1	4
Pre-Modification Outstanding Recorded Investment	$ 95	$ 6	$ 107
Post-Modification Outstanding Recorded Investment	$ 95	$ 6	$ 107

Loans and Allowance for Loan 57

Loans and Allowance for Loan Losses, Modified Loans Payment Status (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)Contract	Dec. 31, 2015USD ($)Contract
Loans modified for which there was payment default [Abstract]
Deferral period of chapter 13 bankruptcies	60 months
Number of days past due when loans are considered to be in payment default	90 days
Contractual past due period for loans to be in payment default	30 days
New York and Other States [Member]
Loans modified for which there was payment default [Abstract]
Number of Contracts | Contract	2	4	4
Recorded Investment | $	$ 75	$ 432	$ 172
Florida [Member]
Loans modified for which there was payment default [Abstract]
Number of Contracts | Contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | New York and Other States [Member]
Loans modified for which there was payment default [Abstract]
Number of Contracts | Contract	1	3	2
Recorded Investment | $	$ 72	$ 291	$ 148
Real Estate Mortgage - 1 to 4 Family [Member] | First Mortgages [Member] | Florida [Member]
Loans modified for which there was payment default [Abstract]
Number of Contracts | Contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | New York and Other States [Member]
Loans modified for which there was payment default [Abstract]
Number of Contracts | Contract	1	1	2
Recorded Investment | $	$ 3	$ 141	$ 24
Real Estate Mortgage - 1 to 4 Family [Member] | Home Equity Lines of Credit [Member] | Florida [Member]
Loans modified for which there was payment default [Abstract]
Number of Contracts | Contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0

Loans and Allowance for Loan 58

Loans and Allowance for Loan Losses, Risk Category of Loans (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		$ 3,636,407	$ 3,430,586
Impaired loans included in classified loans		1,500	1,800
New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net	[1]	2,795,993	2,692,335
Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		840,414	738,251
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		186,207	191,194
Commercial [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		172,974	178,905
Commercial [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		13,233	12,289
Commercial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		175,857	174,407
Commercial [Member] | Pass [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		162,742	162,118
Commercial [Member] | Pass [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		13,115	12,289
Commercial [Member] | Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		10,350	16,787
Commercial [Member] | Classified [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		10,232	16,787
Commercial [Member] | Classified [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		118	0
Commercial [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		161,892	163,609
Commercial [Member] | Commercial Real Estate [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net	[1]	149,368	151,366
Commercial [Member] | Commercial Real Estate [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		12,524	12,243
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		153,212	148,919
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		140,806	136,676
Commercial [Member] | Commercial Real Estate [Member] | Pass [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		12,406	12,243
Commercial [Member] | Commercial Real Estate [Member] | Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		8,680	14,690
Commercial [Member] | Commercial Real Estate [Member] | Classified [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		8,562	14,690
Commercial [Member] | Commercial Real Estate [Member] | Classified [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		118	0
Commercial [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		24,315	27,585
Commercial [Member] | Other [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net	[1]	23,606	27,539
Commercial [Member] | Other [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		709	46
Commercial [Member] | Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		22,645	25,488
Commercial [Member] | Other [Member] | Pass [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		21,936	25,442
Commercial [Member] | Other [Member] | Pass [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		709	46
Commercial [Member] | Other [Member] | Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		1,670	2,097
Commercial [Member] | Other [Member] | Classified [Member] | New York and Other States [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		1,670	2,097
Commercial [Member] | Other [Member] | Classified [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans, net		$ 0	$ 0
[1]	Includes New York, New Jersey, Vermont, and Massachusetts.

Bank Premises and Equipment (De

Bank Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total bank premises and equipment	$ 118,014	$ 115,123
Accumulated depreciation and amortization	(82,857)	(79,657)
Total	35,157	35,466
Depreciation and amortization expense	3,816	4,038	$ 4,554
Occupancy expense of the Bank's premises included rental expense	7,800	7,600	$ 7,500
Land [Member]
Property, Plant and Equipment [Line Items]
Total bank premises and equipment	2,308	2,308
Buildings [Member]
Property, Plant and Equipment [Line Items]
Total bank premises and equipment	34,599	33,617
Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total bank premises and equipment	50,832	49,503
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total bank premises and equipment	$ 30,275	$ 29,695

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Expense, Deposits [Abstract]
Interest bearing checking accounts	$ 478	$ 473	$ 448
Savings accounts	1,729	2,148	2,468
Time deposits and money market accounts	10,983	11,592	12,067
Total	13,190	14,213	$ 14,983
Maturity of Time Deposits [Abstract]
Under 1 year	652,270
1 to 2 years	392,618
2 to 3 years	15,849
3 to 4 years	1,585
4 to 5 years	4,474
Over 5 years	170
Total time deposits	1,066,966	1,159,463
Amount included in time deposits with balance in excess of $250,000	$ 136,800	$ 144,200

Short-Term Borrowings (Details)

Short-Term Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Amount outstanding	$ 242,991	$ 209,406
Federal Home Loan Bank of New York [Member]
Short-term Debt [Line Items]
Amount outstanding	0	0
Federal Reserve Bank of New York [Member]
Short-term Debt [Line Items]
Amount outstanding	0	0
Cash Management [Member]
Short-term Debt [Line Items]
Amount outstanding	242,991	209,406	$ 191,226
Maximum amount outstanding at any month end	252,996	209,406	194,738
Average amount outstanding	$ 228,086	$ 185,672	$ 184,725
Weighted average interest rate, For the year	0.61%	0.59%	0.66%
Weighted average interest rate, As of year end	0.62%	0.59%	0.60%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax expense [Abstract]
Federal		$ 26,510	$ 20,904	$ 19,864
State		2,221	1,524	1,647
Total current tax expense		28,731	22,428	21,511
Enactment of Federal Tax Reform		5,054	0	0
Deferred tax (benefit) expense		(183)	3,261	3,011
Total income tax expense		33,602	25,689	24,522
Components of deferred tax assets and liabilities [Abstract]
Benefits and deferred remuneration		(4,087)	(5,474)
Difference in reporting the allowance for loan losses, net		12,002	18,117
Other income or expense not yet reported for tax purposes		(327)	129
Depreciable assets		(325)	(638)
Net deferred tax asset at end of year		7,263	12,134	15,395
Net deferred tax asset at beginning of year	$ 7,263	12,134	15,395
Enactment of Federal Tax Reform		5,054	0	0
Deferred tax expense		(183)	3,261	$ 3,011
Deferred tax assets, unrealized losses on available-for-sale securities		2,300	4,400
Deferred tax liabilities, unrecognized overfunded position in company's pension and postretirement benefit plans		(1,200)	$ (339)
Income Tax Disclosure [Line Items]
Change in tax rate, Deferred tax asset, Provisional income tax expense		$ 5,100
Reconciliation from statutory federal income tax rate to effective tax rate [Abstract]
Statutory federal income tax rate		35.00%	35.00%	35.00%
Increase/(decrease) in taxes resulting from [Abstract]
Tax exempt income		(0.10%)	(0.10%)	(0.10%)
State income tax (including alternative minimum tax), net of federal tax benefit		1.60%	1.80%	1.80%
Enactment of Tax Reform		6.60%	0.00%	0.00%
Other items		0.70%	0.90%	0.00%
Effective income tax rate		43.80%	37.60%	36.70%
Open Tax Years [Abstract]
Annual deduction for compensation paid to employee		$ 1,000
Plan [Member]
Reconciliation from statutory federal income tax rate to effective tax rate [Abstract]
Statutory federal income tax rate	21.00%
Federal [Member] | Minimum [Member]
Open Tax Years [Abstract]
Open tax year		2,014
Federal [Member] | Maximum [Member]
Open Tax Years [Abstract]
Open tax year		2,017
New York State [Member] | Minimum [Member]
Open Tax Years [Abstract]
Open tax year		2,014
New York State [Member] | Maximum [Member]
Open Tax Years [Abstract]
Open tax year		2,017

Benefit Plans (Details)

Benefit Plans (Details) - Retirement Plan [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)h	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Requisite minimum period of employment	1 year
Requisite minimum hours of service | h	1,000
Number of consecutive years in highest compensation preceding retirement	5 years
Period preceding retirement considered in calculating benefits	10 years
Change in benefit obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 30,730	$ 30,889
Service cost	42	61	$ 60
Interest cost	1,303	1,371	1,329
Benefit payments and expected expenses	(2,050)	(1,782)
Net actuarial loss	1,194	191
Projected benefit obligation at end of year	$ 31,219	$ 30,730	$ 30,889

Benefit Plans, Plan Discosures

Benefit Plans, Plan Discosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Plan [Member]
Change in plan assets and reconciliation of funded status [Roll Forward]
Fair Value of plan assets at beginning of year	$ 43,100	$ 41,677
Actual gain on plan assets	6,169	3,187
Benefit payments and actual expenses	(2,042)	(1,764)
Fair value of plan assets at end of year	47,227	43,100	$ 41,677
Funded status at end of year	16,008	12,370
Amounts recognized in accumulated other comprehensive loss [Abstract]
Net actuarial loss	2,972	5,279
Accumulated benefit obligation for pension benefits	31,200	30,700
Components of the net periodic pension income and other amounts recognized in other comprehensive (loss) income [Abstract]
Service Cost	42	61	60
Interest cost	1,303	1,371	1,329
Expected return on plan assets	(2,742)	(2,648)	(2,735)
Amortization of net actuarial gain	67	184	210
Net periodic pension credit	(1,330)	(1,032)	(1,136)
Amortization of net loss	(67)	(184)	(210)
Net actuarial (gain) / loss included in other comprehensive (loss) income	(2,240)	(367)	(109)
Amortization of net gain	(67)	(184)	(210)
Total amount recognized in other comprehensive (loss) income	(2,307)	(551)	(319)
Total recognized in net periodic benefit (credit) cost and other comprehensive (loss) income	(3,637)	(1,583)	(1,455)
Amounts of Net Gain that will be amortized from accumulated other comprehensive income (loss) in next fiscal year	67
Postretirement Benefits [Member]
Change in plan assets and reconciliation of funded status [Roll Forward]
Fair Value of plan assets at beginning of year	20,338	19,238
Actual gain on plan assets	2,611	1,104
Company contributions	66	66
Benefits paid	(93)	(70)
Fair value of plan assets at end of year	22,922	20,338	19,238
Funded status at end of year	17,309	15,218
Amounts recognized in accumulated other comprehensive loss [Abstract]
Net actuarial loss	(5,810)	(4,581)
Prior service credit	(1,636)	(1,547)
Total	(7,446)	(6,128)
Accumulated benefit obligation for pension benefits	5,613	5,120	5,434
Components of the net periodic pension income and other amounts recognized in other comprehensive (loss) income [Abstract]
Service Cost	103	116	165
Interest cost	218	221	268
Expected return on plan assets	(761)	(720)	(722)
Amortization of net actuarial gain	(356)	(274)	(140)
Amortization of prior service cost	90	90	90
Net periodic pension credit	(706)	(567)	(339)
Amortization of net loss	356	274	140
Net actuarial (gain) / loss included in other comprehensive (loss) income	(1,584)	(966)	(602)
Amortization of prior service cost	(90)	(90)	(90)
Amortization of net gain	356	274	140
Total amount recognized in other comprehensive (loss) income	(1,318)	(782)	(552)
Total recognized in net periodic benefit (credit) cost and other comprehensive (loss) income	(2,024)	$ (1,349)	$ (891)
Amounts of Net Gain that will be amortized from accumulated other comprehensive income (loss) in next fiscal year	355
Amount of prior service cost that will be amortized from accumulated other comprehensive income (loss) in next fiscal year	$ 90

Benefit Plans, Estimated Future

Benefit Plans, Estimated Future Benefit Payments and Change in Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assumptions used to determine net periodic pension expense [Abstract]
Rabbi Trust	$ 5,600	$ 5,600
Retirement Plan [Member]
Estimated future benefit payments [Abstract]
2,018	1,773
2,019	1,802
2,020	1,839
2,021	1,894
2,022	1,875
2023 - 2027	$ 9,327
Assumptions used to determine benefit obligation [Abstract]
Discount rate	3.93%	4.41%	4.55%
Assumptions used to determine net periodic pension expense [Abstract]
Discount rate	4.41%	4.55%	4.03%
Expected long-term rate of return on assets	6.50%	6.50%	6.50%
Change in benefit obligation [Rollforward]
Accumulated benefit obligation at beginning of year	$ 30,700
Service cost	42	$ 61	$ 60
Interest cost	1,303	1,371	$ 1,329
Net actuarial loss (gain)	1,194	191
Accumulated benefit obligation at end of year	31,200	$ 30,700
Postretirement Benefits [Member]
Estimated future benefit payments [Abstract]
2,018	98
2,019	112
2,020	117
2,021	146
2,022	158
2023 - 2027	$ 1,040
Assumptions used to determine benefit obligation [Abstract]
Discount rate	3.93%	4.41%	4.55%
Assumptions used to determine net periodic pension expense [Abstract]
Discount rate	4.41%	4.55%	4.03%
Expected long-term rate of return on assets	3.75%	3.75%	3.75%
Change in benefit obligation [Rollforward]
Accumulated benefit obligation at beginning of year	$ 5,120	$ 5,434
Service cost	103	116	$ 165
Interest cost	218	221	268
Benefits paid	(93)	(70)
Net actuarial loss (gain)	265	(581)
Accumulated benefit obligation at end of year	5,613	5,120	5,434
Supplementary Pension Plan [Member]
Assumptions used to determine net periodic pension expense [Abstract]
Plan expense	1,100	1,000	$ 1,000
Change in benefit obligation [Rollforward]
Accumulated benefit obligation at beginning of year	5,600
Accumulated benefit obligation at end of year	$ 5,600	$ 5,600

Benefit Plans, Other Comprehens

Benefit Plans, Other Comprehensive Income Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in component of other comprehensive (loss) income related to the retirement plan or the post-retirement benefit plan [Abstract]
Change in overfunded position of pension and postretirement benefits	$ (3,824)	$ (1,333)	$ (711)
Amortization of net actuarial (loss) gain	289	90	(70)
Amortization of prior service cost	(90)	(90)	$ (90)
Total	(3,625)	(1,333)
Retirement Plan [Member]
Change in component of other comprehensive (loss) income related to the retirement plan or the post-retirement benefit plan [Abstract]
Change in overfunded position of pension and postretirement benefits	(2,240)	(367)
Amortization of net actuarial (loss) gain	(67)	(184)
Amortization of prior service cost	0	0
Total	(2,307)	(551)
Postretirement Benefits [Member]
Effect of one-percentage point change in assumed health care cost trend rates [Abstract]
Effect of one percentage point increase on in assumed health care cost	1,200
Effect of one percentage point decrease on in assumed health care cost	(907)
Effect of one percentage point increase on in interest and service components	68
Effect of one percentage point decrease on in interest and service components	(53)
Change in component of other comprehensive (loss) income related to the retirement plan or the post-retirement benefit plan [Abstract]
Change in overfunded position of pension and postretirement benefits	(1,584)	(966)
Amortization of net actuarial (loss) gain	356	274
Amortization of prior service cost	(90)	(90)
Total	$ (1,318)	$ (782)

Benefit Plans, Allocation of Pl

Benefit Plans, Allocation of Plan Assets (Details)	Dec. 31, 2017	Dec. 31, 2016
Retirement Plan [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	100.00%	100.00%
Retirement Plan [Member] | Debt Securities [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	29.00%	31.00%
Retirement Plan [Member] | Equity Securities [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	69.00%	64.00%
Retirement Plan [Member] | Other [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	2.00%	5.00%
Postretirement Benefits [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	100.00%	100.00%
Postretirement Benefits [Member] | Debt Securities [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	34.00%	33.00%
Postretirement Benefits [Member] | Equity Securities [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	64.00%	62.00%
Postretirement Benefits [Member] | Other [Member]
Major categories of pension and postretirement benefit plan assets [Abstract]
Total asset allocation	2.00%	6.00%
Pension and Postretirement Plans [Member] | Debt Securities [Member] | Minimum [Member]
Assets target allocations [Abstract]
Target allocations range	25.00%
Pension and Postretirement Plans [Member] | Debt Securities [Member] | Maximum [Member]
Assets target allocations [Abstract]
Target allocations range	40.00%
Pension and Postretirement Plans [Member] | Equity Securities [Member] | Minimum [Member]
Assets target allocations [Abstract]
Target allocations range	50.00%
Pension and Postretirement Plans [Member] | Equity Securities [Member] | Maximum [Member]
Assets target allocations [Abstract]
Target allocations range	70.00%
Pension and Postretirement Plans [Member] | Other [Member] | Minimum [Member]
Assets target allocations [Abstract]
Target allocations range	0.00%
Pension and Postretirement Plans [Member] | Other [Member] | Maximum [Member]
Assets target allocations [Abstract]
Target allocations range	10.00%

Benefit Plans, Fair Value of Pl

Benefit Plans, Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Plan [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	$ 47,227	$ 43,100	$ 41,677
Retirement Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	34,144	30,332
Retirement Plan [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	13,083	12,768
Retirement Plan [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	47,227	43,100
Retirement Plan [Member] | Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	1,034	2,027
Retirement Plan [Member] | Cash and Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Cash and Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Cash and Cash Equivalents [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	1,034	2,027
Retirement Plan [Member] | Equity Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	32,509	27,706
Retirement Plan [Member] | Equity Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Equity Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Equity Mutual Funds [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	32,509	27,706
Retirement Plan [Member] | U. S. Government Sponsored Enterprises [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | U. S. Government Sponsored Enterprises [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	6,920	4,233
Retirement Plan [Member] | U. S. Government Sponsored Enterprises [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | U. S. Government Sponsored Enterprises [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	6,920	4,233
Retirement Plan [Member] | Corporate Bonds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Corporate Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	6,163	8,535
Retirement Plan [Member] | Corporate Bonds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Corporate Bonds [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	6,163	8,535
Retirement Plan [Member] | Fixed Income Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	601	599
Retirement Plan [Member] | Fixed Income Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Fixed Income Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Retirement Plan [Member] | Fixed Income Mutual Funds [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	601	599
Postretirement Benefits [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	22,922	20,338	$ 19,238
Postretirement Benefits [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	15,112	13,712
Postretirement Benefits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	7,810	6,626
Postretirement Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	22,922	20,338
Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	406	1,172
Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	409	1,172
Postretirement Benefits [Member] | Equity Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	14,703	12,540
Postretirement Benefits [Member] | Equity Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Equity Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Equity Mutual Funds [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	14,703	12,540
Postretirement Benefits [Member] | U. S. Government Sponsored Enterprises [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | U. S. Government Sponsored Enterprises [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	3,512	2,049
Postretirement Benefits [Member] | U. S. Government Sponsored Enterprises [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | U. S. Government Sponsored Enterprises [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	3,512	2,049
Postretirement Benefits [Member] | Corporate Bonds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Corporate Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	3,610	3,127
Postretirement Benefits [Member] | Corporate Bonds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | Corporate Bonds [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	3,610	3,127
Postretirement Benefits [Member] | State and Political Subdivisions [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | State and Political Subdivisions [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	688	1,450
Postretirement Benefits [Member] | State and Political Subdivisions [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	0	0
Postretirement Benefits [Member] | State and Political Subdivisions [Member] | Carrying Value [Member]
Fair value of plan assets by asset category [Abstract]
Fair value of plan assets	$ 688	$ 1,450

Benefit Plans, Employee Service

Benefit Plans, Employee Service Share-based Compensation, Aggregate Disclosures (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock based compensation expense	$ 1,900	$ 857	$ 480
Number of awards in prior years (in shares)	1,500,000
Weighted average strike price (in dollars per share)	$ 8.81
Stock Options [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Options maximum term	5 years
Summary of the status of company's stock option, Outstanding options [Roll Forward]
Beginning balance (in shares)	2,084,041
New options awarded (in shares)	0
Expired options (in shares)	(553,000)
Options forfeited (in shares)	(4,900)
Exercised options (in shares)	(784,100)	(241,000)	(28,000)
Ending balance (in shares)	742,041	2,084,041
Summary of the status of company's stock option, Exercisable options [Roll Forward]
Ending balance (in shares)	531,641
Weighted average option price, Outstanding options [Roll Forward]
Beginning balance (in dollars per share)	$ 7.57
New options awarded (in dollars per share)	0
Expired options (in dollars per share)	0
Options forfeited (in dollars per share)	0
Exercised options (in dollars per share)	6.68
Ending balance (in dollars per share)	$ 6.78	$ 7.57
Weighted average remaining contractual life, options outstanding	5 years 9 months 18 days
Exercisable options, weighted average exercise price (in dollars per share)	$ 6.77
Weighted average remaining contractual life, exercisable outstanding	5 years 2 months 12 days
Intrinsic value of outstanding stock options	$ 1,600
Intrinsic value of vested stock options	$ 1,200
Stock Options [Member] | Maximum [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Options maximum term	10 years
Restricted Common Shares [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock based compensation expense	$ 150	$ 224	$ 204
Restricted Shares Units [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock based compensation expense	$ 633	610	324
Options maximum term	3 years
Performance Share Units [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock based compensation expense	$ 1,200	23	(48)
Options maximum term	3 years
Liability Awards [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock based compensation expense	$ 1,800	633	276
Equity Awards [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock based compensation expense	$ 151	224	204
401(k) Plan [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Employer matching contribution, first match	100.00%
Aggregate salary contribution matched by employer, first match	3.00%
Employer matching contribution, next matched	50.00%
Aggregate salary contribution matched by employer, next match	3.00%
Profit sharing contribution	$ 0	0	0
Expense related to 401(k) plan	1,000	986	944
Executive Incentive Plan [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Expense for officers and executive incentive plan	$ 1,900	$ 1,700	$ 715
2010 Employee Stock Option Plan [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Shares available for grant (in shares)	2,300,000
2010 Employee Stock Option Plan [Member] | Other Equity Based Cash Settled Awards [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Shares available for grant (in shares)	1,400,000
2010 Directors Stock Option Plan [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Shares available for grant (in shares)	250,000
2010 Directors Stock Option Plan [Member] | Other Equity Based Cash Settled Awards [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Shares available for grant (in shares)	250,000

Benefit Plans, Valuation, Stock

Benefit Plans, Valuation, Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Stock based compensation expense	$ 1,900	$ 857	$ 480
Income tax benefit related to stock-based compensation		343	192
Stock Options [Member]
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Income tax benefit related to stock-based compensation	$ 788
Options maximum term	5 years
Unrecognized stock-based compensation expense related to non-vested stock options	$ 184
Unrecognized compensation expense, period of recognition	2 years 2 months 1 day
Restricted Common Shares [Member]
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Stock based compensation expense	$ 150	224	204
Restricted Shares Units [Member]
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Stock based compensation expense	$ 633	$ 610	324
Options maximum term	3 years
Unrecognized stock-based compensation expense	$ 1,200
Unrecognized compensation expense, period of recognition	26 months
Shares [Roll Forward]
Balance, December 31, 2016 (in shares)	215,050
New awards granted (in shares)	70,650
Forfeited awards (in shares)	(9,200)
Awards settled (in shares)	(63,400)
Balance, December 31, 2017 (in shares)	213,100	215,050
Shares vested after term	100.00%
Liability related to awards	$ 749	$ 687
Performance Share Units [Member]
Employee Service Share-based Compensation, Non-vested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Stock based compensation expense	$ 1,200	$ 23	$ (48)
Options maximum term	3 years
Unrecognized stock-based compensation expense	$ 1,900
Unrecognized compensation expense, period of recognition	24 months
Shares [Roll Forward]
Balance, December 31, 2016 (in shares)	357,000
New awards granted (in shares)	94,600
Awards settled (in shares)	(81,500)
Balance, December 31, 2017 (in shares)	370,100	357,000
Shares vested after term	100.00%
Liability related to awards	$ 1,500	$ 323

Benefit Plans, Stock Based Comp

Benefit Plans, Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Based Compensation Expense [Abstract]
Stock based compensation expense	$ 1,900	$ 857	$ 480
Income tax benefit related to stock-based compensation		343	192
Liability Awards [Member]
Stock Based Compensation Expense [Abstract]
Stock based compensation expense	1,800	633	276
Equity Awards [Member]
Stock Based Compensation Expense [Abstract]
Stock based compensation expense	$ 151	$ 224	$ 204

Commitments and Contingent Li72

Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating leases with minimum rental commitments [Abstract]
2,018	$ 7,267
2,019	7,178
2,020	6,916
2,021	6,720
2,022	5,913
2023 and after	31,803
Total	65,797
Outsourced service expense	6,410	$ 6,216	$ 5,860
Third-Party Service Agreement [Member] | Minimum [Member]
Long-term Purchase Commitment [Line Items]
Outsource service expense	6,000
Third-Party Service Agreement [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Outsource service expense	$ 7,000

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of the component parts of earnings per share [Abstract]
Net income	$ 43,145	$ 42,601	$ 42,238
Less: Net income allocated to participating securities	0	0	0
Net income allocated to common shareholders	$ 43,145	$ 42,601	$ 42,238
Weighted average common shares outstanding including participating securities (in shares)	96,111	95,548	95,103
Less: Participating securities (in shares)	0	0	0
Weighted average common shares (in shares)	96,111	95,548	95,103
Effect of Dilutive Securities [Abstract]
Stock Options (in shares)	111	100	110
Weighted average common shares including potential dilutive shares (in shares)	96,222	95,648	95,213
Basic EPS (in dollars per share)	$ 0.449	$ 0.446	$ 0.444
Diluted EPS (in dollars per share)	$ 0.448	$ 0.445	$ 0.444
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of antidilutive stock options excluded from diluted earnings per share (in shares)	0	1,400	1,400

Off-Balance Sheet Financial I74

Off-Balance Sheet Financial Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet risks, amount	$ 414.3	$ 462.5
Variable rate product commitments	80.00%	80.00%
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet risks, amount	$ 3.8	$ 4.6
Off balance sheet instrument term	12 months

Fair Value of Financial Instr75

Fair Value of Financial Instruments, Part 1 (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Securities available for sale [Abstract]
Total securities available for sale	$ 571,965	$ 620,360
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale [Abstract]
Total securities available for sale	35	35
Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale [Abstract]
Total securities available for sale	571,930	620,325
Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale [Abstract]
Total securities available for sale	0	0
Carrying Value [Member]
Securities available for sale [Abstract]
Total securities available for sale	571,965	620,360
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale [Abstract]
U.S. government sponsored enterprises	0	0
State and political subdivisions	0	0
Mortgage backed securities and collateralized mortgage obligations - residential	0	0
Corporate bonds	0
Small Business Administration- guaranteed participation securities	0	0
Mortgage backed securities and collateralized mortgage obligations - commercial	0	0
Other	35	35
Total securities available for sale	35	35
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale [Abstract]
U.S. government sponsored enterprises	137,851	117,266
State and political subdivisions	525	886
Mortgage backed securities and collateralized mortgage obligations - residential	315,983	372,308
Corporate bonds	40,162	40,705
Small Business Administration- guaranteed participation securities	67,059	78,499
Mortgage backed securities and collateralized mortgage obligations - commercial	9,700	10,011
Other	650	650
Total securities available for sale	571,930	620,325
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale [Abstract]
U.S. government sponsored enterprises	0	0
State and political subdivisions	0	0
Mortgage backed securities and collateralized mortgage obligations - residential	0	0
Corporate bonds	0
Small Business Administration- guaranteed participation securities	0	0
Mortgage backed securities and collateralized mortgage obligations - commercial	0	0
Other	0	0
Total securities available for sale	0	0
Recurring [Member] | Carrying Value [Member]
Securities available for sale [Abstract]
U.S. government sponsored enterprises	137,851	117,266
State and political subdivisions	525	886
Mortgage backed securities and collateralized mortgage obligations - residential	315,983	372,308
Corporate bonds	40,162	40,705
Small Business Administration- guaranteed participation securities	67,059	78,499
Mortgage backed securities and collateralized mortgage obligations - commercial	9,700	10,011
Other	685	685
Total securities available for sale	$ 571,965	$ 620,360

Fair Value of Financial Instr76

Fair Value of Financial Instruments, Part 2 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Impaired loans [Abstract]
Fair value assets transfers from Level 1 to Level 2	$ 0	$ 0
Fair value assets transfers from Level 2 to Level 1	0	0
Other real estate owned, commercial real estate	541	756
Other real estate owned, residential real estate properties	2,700	3,500
Valuation charge on other real estate owned	1,100	1,200
Impaired loans	24,280	24,025
Collateral dependent impaired loans	844	1,700
Gross charge offs, commercial impaired loans		482
Gross charge offs, residential impaired loans	$ 151	$ 226
Nonrecurring [Member] | Sales Comparison Approach [Member] | Other Real Estate Owned [Member]
Impaired loans [Abstract]
Unobservable inputs	Adjustments for differences between comparable sales	Adjustments for differences between comparable sales
Nonrecurring [Member] | Sales Comparison Approach [Member] | Other Real Estate Owned [Member] | Minimum [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales	1.00%	1.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Other Real Estate Owned [Member] | Maximum [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales	14.00%	14.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Other Real Estate Owned [Member] | Weighted Average [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales	7.00%	7.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Real Estate Mortgage - 1 to 4 Family [Member]
Impaired loans [Abstract]
Unobservable inputs	Adjustments for differences between comparable sales	Adjustments for differences between comparable sales
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Real Estate Mortgage - 1 to 4 Family [Member] | Minimum [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales	5.00%	5.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Real Estate Mortgage - 1 to 4 Family [Member] | Maximum [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales	14.00%	14.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Real Estate Mortgage - 1 to 4 Family [Member] | Weighted Average [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales	10.00%	10.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Commercial Real Estate [Member]
Impaired loans [Abstract]
Unobservable inputs	Adjustments for differences between comparable sales	Adjustments for differences between comparable sales
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Commercial Real Estate [Member] | Minimum [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales		7.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Commercial Real Estate [Member] | Maximum [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales		35.00%
Nonrecurring [Member] | Sales Comparison Approach [Member] | Impaired Loan [Member] | Commercial Real Estate [Member] | Weighted Average [Member]
Impaired loans [Abstract]
Adjustments for differences between comparable sales		23.00%
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Other real estate owned [Abstract]
Other real estate owned	$ 0	$ 0
Impaired loans [Abstract]
Commercial real estate	0	0
Real estate mortgage - 1 to 4 family	0	0
Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Other real estate owned [Abstract]
Other real estate owned	0	0
Impaired loans [Abstract]
Commercial real estate	0	0
Real estate mortgage - 1 to 4 family	0	0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Other real estate owned [Abstract]
Other real estate owned	3,246	4,268
Impaired loans [Abstract]
Commercial real estate	0	1,250
Real estate mortgage - 1 to 4 family	844	458
Nonrecurring [Member] | Carrying Value [Member]
Other real estate owned [Abstract]
Other real estate owned	3,246	4,268
Impaired loans [Abstract]
Commercial real estate		1,250
Real estate mortgage - 1 to 4 family	$ 844	$ 458

Fair Value of Financial Instr77

Fair Value of Financial Instruments, Part 3 (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financial assets [Abstract]
Cash and cash equivalents	$ 612,740	$ 707,274	$ 718,156	$ 671,448
Securities available for sale	571,965	620,360
Held to maturity securities	28,701	47,526
Net loans	3,598,213	3,370,976
Accrued interest receivable	11,441	11,070
Financial liabilities [Abstract]
Demand deposits	398,399	377,755
Interest bearing deposits	3,784,174	3,814,970
Short-term borrowings	242,991	209,406
Accrued interest payable	537	526
Level 1 [Member]
Financial assets [Abstract]
Cash and cash equivalents	612,740	707,274
Securities available for sale	35	35
Held to maturity securities	0	0
Net loans	0	0
Accrued interest receivable	243	145
Financial liabilities [Abstract]
Demand deposits	398,399	377,755
Interest bearing deposits	2,707,961	2,658,945
Short-term borrowings	0	0
Accrued interest payable	77	82
Level 2 [Member]
Financial assets [Abstract]
Cash and cash equivalents	0	0
Securities available for sale	571,930	620,325
Held to maturity securities	28,701	47,526
Net loans	0	0
Accrued interest receivable	2,440	2,654
Financial liabilities [Abstract]
Demand deposits	0	0
Interest bearing deposits	1,076,213	1,156,025
Short-term borrowings	242,991	209,406
Accrued interest payable	460	444
Level 3 [Member]
Financial assets [Abstract]
Cash and cash equivalents	0	0
Securities available for sale	0	0
Held to maturity securities	0	0
Net loans	3,598,213	3,370,976
Accrued interest receivable	8,758	8,271
Financial liabilities [Abstract]
Demand deposits	0	0
Interest bearing deposits	0	0
Short-term borrowings	0	0
Accrued interest payable	0	0
Carrying Value [Member]
Financial assets [Abstract]
Cash and cash equivalents	612,740	707,274
Securities available for sale	571,965	620,360
Held to maturity securities	27,551	45,490
Federal Reserve Bank and Federal Home Loan Bank stock	8,779	9,579
Net loans	3,592,237	3,386,696
Accrued interest receivable	11,441	11,070
Financial liabilities [Abstract]
Demand deposits	398,399	377,755
Interest bearing deposits	3,774,927	3,818,408
Short-term borrowings	242,991	209,406
Accrued interest payable	$ 537	$ 526

Regulatory Capital Requiremen78

Regulatory Capital Requirements (Details) $ in Thousands		Dec. 31, 2017USD ($)Classification		Dec. 31, 2016USD ($)
Trustco Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Number of classifications for prompt corrective action regulations provide | Classification		5
Tier One Risk Based Capital [Abstract]
Tier 1 leverage capital		$ 444,931		$ 424,802
Common equity Tier 1 capital		444,931		424,802
Tier 1 risk-based capital		444,931		424,802
Total risk-based capital		$ 476,942		$ 455,772
Risk Based Ratios [Abstract]
Tier 1 leverage ratio, ratio		9.152%		8.829%
Common equity Tier 1 capital, ratio		17.46%		17.238%
Tier 1 risk-based capital, ratio		17.46%		17.238%
Total risk-based capital, ratio		18.72%		18.492%
Leverage Ratios [Abstract]
Tier 1 leverage ratio, well capitalized	[1]	5.00%		5.00%
Tier 1 leverage ratio, adequately capitalized	[1]	4.00%	[2]	4.00%
Common equity Tier 1 capital, well capitalized	[1]	6.50%		6.50%
Common equity Tier 1 capital, adequately capitalized	[1]	5.75%	[2]	5.125%
Tier 1 risk-based capital, well capitalized	[1]	8.00%		8.00%
Tier 1 risk-based capital, adequately capitalized	[1]	7.25%	[2]	6.625%
Total risk-based capital, well capitalized	[1]	10.00%		10.00%
Total risk-based capital, adequately capitalized	[1]	9.25%	[2]	8.625%
Common equity Tier 1 capital conservation buffer				1.25%
Tier 1 risk based capital ratio, capital conservation buffer				1.25%
Total risk based capital ratio, capital conservation buffer				1.25%
TrustCo Bank Corp NY [Member]
Tier One Risk Based Capital [Abstract]
Tier 1 leverage capital		$ 459,561		$ 438,426
Common equity Tier 1 capital		459,561		438,426
Tier 1 risk-based capital		459,561		438,426
Total risk-based capital		$ 491,590		$ 469,411
Risk Based Ratios [Abstract]
Tier 1 leverage ratio, ratio		9.449%		9.11%
Common equity Tier 1 capital, ratio		18.02%		17.782%
Tier 1 risk-based capital, ratio		18.02%		17.782%
Total risk-based capital, ratio		19.28%		19.038%
Leverage Ratios [Abstract]
Tier 1 leverage ratio, adequately capitalized	[1],[2]	4.00%		4.00%
Common equity Tier 1 capital, adequately capitalized	[1],[2]	5.75%		5.125%
Tier 1 risk-based capital, adequately capitalized	[1],[2]	7.25%		6.625%
Total risk-based capital, adequately capitalized	[1],[2]	9.25%		8.625%
Common equity Tier 1 capital conservation buffer		1.25%		0.625%
Tier 1 risk based capital ratio, capital conservation buffer		1.25%		0.625%
Total risk based capital ratio, capital conservation buffer		1.25%		0.625%
[1]	Federal regulatory minimum requirements to be considered to be Well Capitalized and Adequately Capitalized
[2]	The December 31, 2016 common equity tier 1, tier 1 risk-based, and total risk-based capital ratios include a transition capital conservation buffer of 1.25 percent

Accumulated Other Comprehensi79

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 432,686	$ 413,310	$ 393,444
Other comprehensive (loss) income - before reclassifications	4,744	(1,069)	(218)
Amount reclassified from accumulated other comprehensive loss	(299)	(401)	(54)
Other comprehensive income (loss), net of tax	4,445	(1,470)	(272)
Balance	458,308	432,686	413,310
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(6,251)	(4,781)	(4,509)
Other comprehensive income (loss), net of tax	4,445	(1,470)	(272)
Balance	(1,806)	(6,251)	(4,781)
Net Unrealized Holding Gain (Loss) on Securities Available for Sale, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(6,762)	(4,492)	(3,693)
Other comprehensive (loss) income - before reclassifications	1,732	(1,869)	(648)
Amount reclassified from accumulated other comprehensive loss		(401)	(151)
Other comprehensive income (loss), net of tax	1,732	(2,270)	(799)
Balance	(5,030)	(6,762)	(4,492)
Net Change in Overfunded Position in Pension and Postretirement Plans Arising During the Year, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	42	(758)	(1,188)
Other comprehensive (loss) income - before reclassifications	3,012	800	430
Amount reclassified from accumulated other comprehensive loss	0	0	0
Other comprehensive income (loss), net of tax	3,012	800	430
Balance	3,054	42	(758)
Net Change in Net Actuarial Gain and Prior Service Credit (Cost) on Pension and Postretirement Benefit Plans, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	469	469	372
Other comprehensive (loss) income - before reclassifications	0	0	0
Amount reclassified from accumulated other comprehensive loss	(299)	0	97
Other comprehensive income (loss), net of tax	(299)	0	97
Balance	$ 170	$ 469	$ 469

Accumulated Other Comprehensi80

Accumulated Other Comprehensive Loss, Reclassifications out of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net gain on securities transactions	$ 0	$ 668	$ 251
Salaries and employee benefits	40,665	36,508	32,521
Income tax effect	33,602	25,689	24,522
Net income	43,145	42,601	42,238
Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net income	299	401	54
Unrealized Gains on Securities Available for Sale [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net gain on securities transactions	0	668	251
Income tax effect	0	(267)	(100)
Net income	0	401	151
Amortization of Pension and Postretirement Benefit Items [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Income tax effect	100	0	63
Net income	299	0	(97)
Amortization of Net Actuarial Gain (Loss) [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	289	90	(70)
Amortization of Prior Service Cost [Member] | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ (90)	$ (90)	$ (90)

Agreement with the Office of 81

Agreement with the Office of the Comptroller of the Currency (Details)	Jul. 21, 2015Director
Agreement with the Office of the Comptroller of the Currency [Abstract]
Minimum number of directors to establish a committee	3

Parent Company Only, Statements

Parent Company Only, Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statements of Comprehensive Income [Abstract]
Net gain on securities transactions	$ 0	$ 668	$ 251
Expenses [Abstract]
Professional services	6,895	8,200	7,878
Total noninterest expense	93,994	93,827	90,560
Income before income taxes and subsidiaries' undistributed earnings	76,747	68,290	66,760
Income tax benefit	33,602	25,689	24,522
Net income	43,145	42,601	42,238
Change in other comprehensive income (loss)	4,445	(1,470)	(272)
Comprehensive income	47,590	41,131	41,966
TrustCo Bank Corp NY [Member]
Statements of Comprehensive Income [Abstract]
Dividends and interest from subsidiaries	24,510	24,498	24,501
Net gain on securities transactions	0	0	0
Miscellaneous income	0	0	0
Total income	24,510	24,498	24,501
Expenses [Abstract]
Operating supplies	26	21	33
Professional services	122	461	577
Miscellaneous expense	2,573	1,258	664
Total noninterest expense	2,721	1,740	1,274
Income before income taxes and subsidiaries' undistributed earnings	21,789	22,758	23,227
Income tax benefit	(1,171)	(578)	(405)
Income before subsidiaries' undistributed earnings	22,960	23,336	23,632
Equity in undistributed earnings of subsidiaries	20,185	19,265	18,606
Net income	43,145	42,601	42,238
Change in other comprehensive income (loss)	4,445	(1,470)	(272)
Comprehensive income	$ 47,590	$ 41,131	$ 41,966

Parent Company Only, Statemen83

Parent Company Only, Statements of Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets [Abstract]
Cash in subsidiary bank	$ 612,740	$ 707,274	$ 718,156	$ 671,448
Securities available for sale	571,965	620,360
Other assets	59,579	63,941
Total assets	4,908,008	4,868,806
Liabilities and shareholders' equity [Abstract]
Accrued expenses and other liabilities	33,383	30,551
Total liabilities	4,449,700	4,436,120
Shareholders' equity	458,308	432,686	413,310	393,444
Total liabilities and shareholders' equity	4,908,008	4,868,806
TrustCo Bank Corp NY [Member]
Assets [Abstract]
Cash in subsidiary bank	21,773	19,886	$ 18,463	$ 17,034
Investments in subsidiaries	443,692	419,075
Securities available for sale	35	35
Other assets	771	824
Total assets	466,271	439,820
Liabilities and shareholders' equity [Abstract]
Accrued expenses and other liabilities	7,964	7,134
Total liabilities	7,964	7,134
Shareholders' equity	458,307	432,686
Total liabilities and shareholders' equity	$ 466,271	$ 439,820

Parent Company Only, Statemen84

Parent Company Only, Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities [Abstract]
Net income	$ 43,145	$ 42,601	$ 42,238
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Stock based compensation expense	150	224	204
Total adjustments	18,545	12,293	17,770
Net cash provided by operating activities	61,690	54,894	60,008
Cash flows from financing activities [Abstract]
Proceeds from exercise of stock options	5,237	1,368	147
Dividends paid	(25,197)	(25,064)	(24,950)
Payments to acquire treasury stock	(4,608)	(701)	(147)
Proceeds from sales of treasury stock	2,480	2,447	2,670
Net cash (used in) provided by financing activities	(11,340)	92,015	47,967
Net (decrease) increase in cash and cash equivalents	(94,534)	(10,882)	46,708
Cash and cash equivalents at beginning of period	707,274	718,156	671,448
Cash and cash equivalents at end of period	612,740	707,274	718,156
TrustCo Bank Corp NY [Member]
Cash flows from operating activities [Abstract]
Net income	43,145	42,601	42,238
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Equity in undistributed earnings of subsidiaries	(20,185)	(19,265)	(18,606)
Stock based compensation expense	150	224	204
Net change in other assets and accrued expenses	853	(196)	(140)
Total adjustments	(19,182)	(19,237)	(18,542)
Net cash provided by operating activities	23,963	23,364	23,696
Cash flows from financing activities [Abstract]
Proceeds from exercise of stock options	5,236	1,368	147
Dividends paid	(25,184)	(25,055)	(24,937)
Payments to acquire treasury stock	(4,608)	(701)	(147)
Proceeds from sales of treasury stock	2,480	2,447	2,670
Net cash (used in) provided by financing activities	(22,076)	(21,941)	(22,267)
Net (decrease) increase in cash and cash equivalents	1,887	1,423	1,429
Cash and cash equivalents at beginning of period	19,886	18,463	17,034
Cash and cash equivalents at end of period	$ 21,773	$ 19,886	$ 18,463