Northwest Bancshares (NWBI) 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. 16, 2018	Jun. 30, 2017
Document and Entity Information
Entity Registrant Name	Northwest Bancshares, Inc.
Entity Central Index Key	1,471,265
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		102,549,072
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,595

CONSOLIDATED STATEMENTS OF FINA

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 77,710	$ 389,867
Marketable securities available-for-sale (amortized cost of $800,094 and $825,552)	792,535	826,200
Marketable securities held-to-maturity (fair value of $29,667 and $20,426)	29,678	19,978
Loans receivable, net of allowance for loan losses of $56,795 and $60,939	7,736,614	7,496,408
Assets held-for-sale	0	152,528
Accrued interest receivable	23,352	21,699
Real estate owned, net	5,666	4,889
Federal Home Loan Bank stock, at cost	11,733	7,390
Premises and equipment, net	151,944	161,185
Bank owned life insurance	171,547	171,449
Goodwill	307,420	307,420
Other intangible assets	25,669	32,433
Other assets	30,066	32,194
Total assets	9,363,934	9,623,640
Liabilities:
Deposits	7,826,989	7,882,321
Liabilities held-for-sale	0	215,657
Borrowed funds	108,238	142,899
Advances by borrowers for taxes and insurance	40,825	36,879
Accrued interest payable	460	635
Other liabilities	68,485	63,373
Junior subordinated deferrable interest debentures held by trusts that issued guaranteed capital debt securities	111,213	111,213
Total liabilities	8,156,210	8,452,977
Shareholders’ equity:
Preferred stock, $0.01 par value: 50,000,000 authorized, no shares issued	0	0
Common stock, $0.01 par value: 500,000,000 shares authorized, 102,687,811 and 101,699,406 shares issued, respectively	1,027	1,017
Paid-in capital	730,719	718,834
Retained earnings	508,058	478,803
Accumulated other comprehensive loss	(32,080)	(27,991)
Total shareholders’ equity	1,207,724	1,170,663
Total liabilities and shareholders’ equity	$ 9,363,934	$ 9,623,640

CONSOLIDATED STATEMENTS OF FIN3

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Marketable securities available-for-sale, amortized cost	$ 800,094	$ 825,552
Marketable securities held-to-maturity, fair value	29,667	20,426
Allowance for loan losses	$ 56,795	$ 60,939
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	102,394,828	101,699,406

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income:
Loans receivable	$ 339,992	$ 329,039	$ 298,665
Mortgage-backed securities	11,343	8,540	8,823
Taxable investment securities	3,749	3,409	4,520
Tax-free investment securities	2,023	2,732	4,313
FHLB dividends	250	1,371	2,828
Interest-earning deposits	1,499	543	431
Total interest income	358,856	345,634	319,580
Interest expense:
Deposits	23,057	23,465	24,055
Borrowed funds	5,014	14,834	32,272
Total interest expense	28,071	38,299	56,327
Net interest income	330,785	307,335	263,253
Provision for loan losses	19,751	13,542	9,712
Net interest income after provision for loan losses	311,034	293,793	253,541
Noninterest income:
Gain on sale of investments, net	1,148	625	1,037
Service charges and fees	49,717	44,113	38,362
Trust and other financial services income	17,987	14,103	12,342
Insurance commission income	9,013	10,522	9,526
Loss on real estate owned, net	(797)	(39)	(1,989)
Income from bank owned life insurance	6,093	5,361	4,338
Mortgage banking income	1,418	4,894	933
Gain on sale offices	17,186	0	0
Other operating income	8,715	5,781	4,287
Total noninterest income	110,480	85,360	68,836
Noninterest expense:
Compensation and employee benefits	150,228	140,927	119,818
Premises and occupancy costs	28,863	26,134	24,641
Office operations	16,342	14,898	12,337
Collections expense	2,849	2,431	3,247
Processing expenses	39,086	34,859	30,780
Marketing expenses	9,607	8,852	8,499
Federal deposit insurance premiums	3,518	4,404	5,109
Professional services	10,293	7,865	6,906
Amortization of intangible assets	6,764	4,259	1,688
Real estate owned expense	1,004	1,004	2,070
Restructuring/ acquisition expense	4,419	12,213	9,751
FHLB prepayment penalty	0	36,978	0
Other expense	12,630	13,014	9,031
Total noninterest expense	285,603	307,838	233,877
Income before income taxes	135,911	71,315	88,500
Provision for income taxes:
Federal	34,801	20,313	24,010
State	6,643	1,335	3,950
Total provision for income taxes	41,444	21,648	27,960
Net income	$ 94,467	$ 49,667	$ 60,540
Basic earnings per share (in dollars per share)	$ 0.94	$ 0.50	$ 0.64
Diluted earnings per share (in dollars per share)	$ 0.92	$ 0.49	$ 0.64

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income	$ 94,467	$ 49,667	$ 60,540
Net unrealized holding gains/ (losses) on marketable securities:
Unrealized holding gains/ (losses), net of tax of $1,915, $1,742 and $(204), respectively	(2,478)	(2,728)	315
Reclassification adjustment for gains included in net income, net of tax of $1,488, $129 and $289, respectively	(2,326)	(202)	(451)
Net unrealized holding losses on marketable securities	(4,804)	(2,930)	(136)
Change in fair value of interest rate swaps, net of tax of $(585), $(539) and $(699), respectively	1,087	1,001	1,299
Defined benefit plans:
Net loss, net of tax of $826, $3,061 and $1,408, respectively	(1,254)	(2,399)	(2,203)
Amortization of prior service costs, net of tax of $(613), $(606) and $(560), respectively	882	872	875
Net loss on defined benefit plans	(372)	(1,527)	(1,328)
Other comprehensive loss	(4,089)	(3,456)	(165)
Total comprehensive income	$ 90,378	$ 46,211	$ 60,375

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Income tax (expense) benefit related to unrealized holding gains/ losses on securities	$ 1,915	$ 1,742	$ (204)
Income tax (expense) benefit related to (gain) loss on securities	1,488	129	289
Income tax (expense) benefit related to derivatives qualifying as hedges	(585)	(539)	(699)
Income tax on defined benefit plan gain (loss)	826	3,061	1,408
Income tax expense (benefit) related to compensation and employee benefits	$ (613)	$ (606)	$ (560)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Retained earnings	Accumulated other comprehensive income/ (loss)	Unallocated common stock of ESOP
Balance at beginning of the period at Dec. 31, 2014	$ 1,062,647	$ 947	$ 626,134	$ 481,577	$ (24,370)	$ (21,641)
Comprehensive income:
Net Income	60,540			60,540
Other comprehensive loss, net of tax	(165)				(165)
Total comprehensive income	60,375			60,540	(165)
Shares issued to acquire LNB Bancorp, Inc.	90,608	70	90,538
Exercise of stock options	4,303	5	4,298
Share repurchases	(7,847)	(6)	(7,841)
Stock-based compensation expense including tax benefits	5,902	3	4,474			1,425
Dividends paid	(52,825)			(52,825)
Balance at end of the period at Dec. 31, 2015	1,163,163	1,019	717,603	489,292	(24,535)	(20,216)
Comprehensive income:
Net Income	49,667			49,667
Other comprehensive loss, net of tax	(3,456)				(3,456)
Total comprehensive income	46,211			49,667	(3,456)
ESOP termination	0	(14)	(13,896)			13,910
Exercise of stock options	10,856	11	10,845
Share repurchases	(1,752)	(2)	(1,750)
Stock-based compensation expense including tax benefits	12,341	3	6,032	0		6,306
Dividends paid	(60,156)			(60,156)
Balance at end of the period at Dec. 31, 2016	1,170,663	1,017	718,834	478,803	(27,991)	0
Comprehensive income:
Net Income	94,467			94,467
Other comprehensive loss, net of tax	(4,089)				(4,089)
Total comprehensive income	90,378			94,467	(4,089)
Exercise of stock options	7,001	6	6,995
Stock-based compensation expense including tax benefits	4,894	4	4,890			0
Dividends paid	(65,212)			(65,212)
Balance at end of the period at Dec. 31, 2017	$ 1,207,724	$ 1,027	$ 730,719	$ 508,058	$ (32,080)	$ 0

CONSOLIDATED STATEMENTS OF CHA8

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Other comprehensive income, tax	$ 3,031	$ 3,787	$ 234
Stock-based compensation expense, tax benefits		$ 1,425	$ 332
Dividends paid, per share (in dollars per share)	$ 0.64	$ 0.6	$ 0.56

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net Income	$ 94,467	$ 49,667	$ 60,540
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	19,751	13,542	9,712
Net gain on sale of assets	(627)	(4,499)	(921)
Net gain on sale offices	(17,186)	0	0
Net depreciation, amortization and accretion	14,293	15,424	8,958
Decrease in other assets	7,161	25,953	37,969
Increase/ (decrease) in other liabilities	11,694	4,801	(18,998)
Net amortization of premium on marketable securities	2,017	2,139	1,149
Noncash compensation expense related to stock benefit plans	4,894	10,916	5,570
Noncash impairment of real estate owned	1,231	1,481	2,923
Deferred income tax expense	11,317	2,734	6,290
FHLB prepayment penalty	0	24,520	0
Origination of loans held for sale	(66,058)	(252,204)	(2,504)
Proceeds from sale of loans held for sale	73,103	242,428	2,514
Net cash provided by operating activities	156,057	136,902	113,202
Investing activities:
Purchase of marketable securities held-to-maturity	(23,621)	0	0
Purchase of marketable securities available-for-sale	(218,292)	(238,673)	(59,980)
Proceeds from maturities and principal reductions of marketable securities held-to-maturity	13,902	11,700	72,265
Proceeds from maturities and principal reductions of marketable securities available-for-sale	206,089	278,621	280,277
Proceeds from sale of marketable securities available-for-sale	36,811	1,951	1,246
Net increase in loans	(120,076)	(33,434)	(319,088)
Net (purchases)/ redemptions of Federal Home Loan Bank stock	(4,343)	33,513	(3,770)
Proceeds from sale of real estate owned	4,342	8,113	13,961
Sale of real estate owned for investment	608	607	608
Purchases of premises and equipment	(3,719)	(15,227)	(13,223)
Acquisitions, net of cash received	0	1,102,237	(61,108)
Net cash provided by/ (used in) investing activities	(108,299)	1,149,408	(88,812)
Financing activities:
Net decrease in deposits	(270,989)	(157,457)	(60,236)
Proceeds from long-term borrowings	0	0	135,000
Repayments of long-term borrowings	0	(774,863)	(172,552)
Net increase/ (decrease) in short-term borrowings	(34,661)	(81,765)	61,281
Increase/ (decrease) in advances by borrowers for taxes and insurance	3,946	(139)	2,975
Redemption of Junior subordinated debentures	0	0	(8,119)
Share repurchases	0	(1,752)	(7,847)
Cash dividends paid on common stock	(65,212)	(60,156)	(52,825)
Proceeds from stock options exercised	7,001	10,856	4,303
Excess tax benefit from stock-based compensation	0	1,425	332
Net cash used in financing activities	(359,915)	(1,063,851)	(97,688)
Cash and cash equivalents at beginning of period	389,867	167,408	240,706
Net increase/ (decrease) in cash and cash equivalents	(312,157)	222,459	(73,298)
Cash and cash equivalents at end of period	77,710	389,867	167,408
Cash paid during the period for:
Interest on deposits and borrowings (including interest credited to deposit accounts of $22,385, $22,213 and $21,949, respectively)	28,254	39,649	55,270
Income taxes	32,270	9,710	16,719
Business acquisitions
Fair value of assets acquired	0	546,247	1,160,190
Net cash (paid)/ received	0	1,102,237	(61,108)
Liabilities assumed	0	1,648,484	1,099,082
Loan foreclosures and repossessions	8,130	6,252	7,633
Sale of real estate owned financed by the Company	$ 168	$ 498	$ 768

CONSOLIDATED STATEMENTS OF CA10

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Cash Flows [Abstract]
Interest on deposits and borrowings, interest credited to deposit accounts	$ 22,385	$ 22,213	$ 21,949

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a) Nature of Operations Northwest Bancshares, Inc., a Maryland corporation headquartered in Warren, Pennsylvania, is the federal savings and loan holding company for its wholly owned subsidiary, Northwest Bank. Northwest Bank, a Pennsylvania chartered savings bank, offers personal and business deposit and loan products as well as investment management and insurance services through its 172 banking locations in Pennsylvania, New York, and Ohio. (b) Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries after elimination of all intercompany accounts and transactions. (c) Cash and Cash Equivalents For purposes of the statements of financial condition and cash flows, cash and cash equivalents include cash and amounts due from banks, interest-bearing deposits in other financial institutions, federal funds sold, and other short-term investments with original maturities of three months or less. (d) Investment Securities We classify marketable securities at the time of purchase as held-to-maturity, available-for-sale, or trading. Securities for which management has the intent and ability to hold until maturity are classified as held-to-maturity and are carried at cost, adjusted for amortization of premiums and accretion of discounts on a level yield basis (amortized cost). If it is management’s intent at the time of purchase to hold securities for an indefinite period of time and/ or to use such securities as part of its asset/ liability management strategy, the securities are classified as available-for-sale and are carried at fair value, with unrealized gains and losses reported as accumulated other comprehensive income/ (loss), a separate component of shareholders’ equity, net of tax. Securities classified as available-for-sale include securities that may be sold in response to changes in interest rates, resultant prepayment risk, or other market factors. Securities that are bought and held principally for the purpose of selling them in the near term are classified as trading and are reported at fair value, with changes in fair value included in earnings. The cost of securities sold is determined on a specific identification basis. We held no securities classified as trading at or during the years ended December 31, 2017 and 2016 . On at least a quarterly basis, we review our investments for other-than-temporary impairment (“OTTI”). An investment security is deemed impaired if the fair value of the investment is less than its amortized cost. If an investment security is determined to be impaired, we evaluate whether the decline in value is other-than-temporary. We consider whether or not we expect to receive all of the contractual cash flows from the investment security based on factors that include, but are not limited to the creditworthiness of the issuer and the historical and projected performance of the underlying collateral. Also, we may evaluate the business and financial outlook of the issuer, as well as broader economic performance indicators. We consider both our intent to sell and the likelihood that we will not have to sell the investment securities before recovery of their cost basis during our evaluation. Impairment that is deemed credit related is recognized in earnings while impairment deemed noncredit related is recorded in accumulated other comprehensive income, if we do not intend to sell nor it is not likely we will be required to sell the investment security. If we intend to sell the investment security or if it is more likely than not that we will be required to sell the investment security, the entire impairment is recorded in earnings. (e) Loans Receivable Our loan segments consist of Personal Banking and Business Banking loans. Personal Banking loans include; residential mortgage, home equity and consumer loans. Business Banking loans include; commercial real estate and commercial loans. Originated loans are carried at their unpaid principal balance net of any deferred origination fees or costs and the allowance for loan losses. Interest income on loans is credited to income as earned. Interest earned on loans for which no payments were received during the month is accrued at month end. Accrued interest on loans more than 90 days delinquent is reversed and such loans are placed on nonaccrual status. All loans are placed on nonaccrual status when principal or interest is 90 days or more delinquent or when there is reasonable doubt that interest or principal will not be collected in accordance with the contractual terms. Interest receipts on all nonaccrual and impaired loans are recognized as interest income when it has been determined that all principal and interest will be collected or are applied to principal when collectability of contractual principal is in doubt. Nonaccrual loans generally are restored to an accrual basis when principal and interest become current and a period of performance has been established in accordance with the contractual terms, typically six months . A loan is considered to be a troubled debt restructured loan ("TDR") when the borrower is experiencing financial difficulties and the restructuring constitutes a concession. TDRs may include modifications of terms of loans, receipts of assets from borrowers in partial or full satisfaction of loans, or a combination thereof. TDRs are impaired loans. A modified loan is determined to be a TDR based on the contractual terms as specified by the original loan agreement or the most recent modification. Once classified a TDR, a loan is removed from such classification under three circumstances: (1) the loan is paid off, (2) the loan is charged off, or (3) if, at the beginning of the current fiscal year, the loan has performed in accordance with the modified terms for a minimum of six consecutive months and at the time of modification the loan’s interest rate represented a then current market interest rate for a loan of similar risk. Loan delinquency is measured based on the number of days since the payment due date. Past due status is measured using the loan’s contractual maturity date. Loan fees and certain direct loan origination costs are deferred and the net deferred fee or cost is then recognized using the level-yield method over the contractual life of the loan as an adjustment to interest income. We identify certain residential mortgage loans which will be sold prior to maturity, as loans held for sale. These loans are recorded at the lower of amortized cost or fair value less estimated cost to sell. At December 31, 2017 and 2016 , there were $3.1 million and $9.6 million residential mortgage loans classified as held for sale, respectively. Acquired loans are initially measured at fair value with no carryover of the related allowance for loan losses. Determining the fair value of the loans involves estimating the amount and timing of principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loan. The difference between contractually required payments at acquisition and the cash flows expected to be collected at acquisition is referred to as the nonaccretable discount. The nonaccretable discount represents estimated future credit losses expected to be incurred over the life of the loan. Subsequent decreases to the expected cash flows require us to evaluate the need for an allowance for loan losses. Subsequent improvements in expected cash flows result in the reversal of a corresponding amount of the nonaccretable discount which we then reclassify as accretable discount that is recognized into interest income over the remaining life of the loan using the interest method. Charge-offs of the principal amount on acquired loans would be first applied to the nonaccretable discount portion of the fair value adjustment. Acquired loans that met the criteria for nonaccrual of interest prior to the acquisition may be considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if we can reasonably estimate the timing and amount of the expected cash flows on such loans and if we expect to fully collect the new carrying value of the loans. As such, we may no longer consider the loan to be nonaccrual or nonperforming and may accrue interest on these loans, including the impact of any accretable discount. We have determined that we can reasonably estimate future cash flows on our current portfolio of acquired loans that are past due 90 days or more and on which we are accruing interest and we expect to fully collect the carrying value of the loans. (f) Allowance for Loan Losses and Provision for Loan Losses Provisions for estimated loan losses and the amount of the allowance for loan losses are based on losses inherent in the loan portfolio that are both probable and can be reasonably estimated at the date of the financial statements. We consider a loan to be impaired when it is probable that we will be unable to collect all amounts due according to the contractual terms of the loan agreement. In evaluating whether a loan is impaired, we consider not only the amount that we expect to collect but also the timing of collection. Generally, if a delay in payment is insignificant (e.g., less than 30 days ), a loan is not deemed to be impaired. Business Banking loans greater than or equal to $1.0 million are reviewed to determine if they should be individually evaluated for impairment. Smaller balance, homogeneous loans (e.g., primarily residential mortgage, home equity and consumer loans) are evaluated collectively for impairment. When a loan is considered to be impaired, the amount of impairment is measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s market price, or fair value of the collateral, less estimated cost to sell, if the loan is collateral dependent. Impairment losses are included in the allowance for loan losses. Impaired loans are charged-off or charged down when we believe that the ultimate collectability of a loan is not likely or the collateral value no longer supports the carrying value of the loan. Interest income on non-performing loans is recognized using the cash basis method. For non-performing loans interest collected is credited to income in the period of recovery or applied to reduce principal if there is sufficient doubt about the collectability of principal. The allowance for loan losses is shown as a valuation allowance to loans. The accounting policy for the determination of the adequacy of the allowance by portfolio segment requires us to make numerous complex and subjective estimates and assumptions relating to amounts which are inherently uncertain. The allowance for loan losses is maintained to absorb losses inherent in the loan portfolio as of the balance sheet date. The methodology used to determine the allowance for loan losses is designed to provide procedural discipline in assessing the appropriateness of the allowance for loan losses. Losses are charged against and recoveries are added to the allowance for loan losses. For Business Banking loans the allowance for loan losses consists of: • An allowance for impaired loans; • An allowance for homogenous loans based on historical losses; and • An allowance for homogenous loans based on environmental factors. The allowance for impaired loans is based on individual analysis of all nonperforming loans greater than or equal to $1.0 million . The allowance is measured by the difference between the recorded value of impaired loans and their impaired value. The impaired value is either the present value of the expected future cash flows from the borrower, the market value of the loan, or the fair value of the collateral, less estimated cost to sell. The allowance for homogeneous loans based on historical factors is a rolling three -year average of incurred losses, adjusted for a loss emergence period (the period of time from the event of loss to loss realization), applied to homogenous pools of loans categorized by similar risk characteristics, not including loans evaluated individually for impairment. The allowance for homogeneous loans based on environmental factors augments the historical loss factors for changes in: economic conditions, lending policies and procedures, the nature and volume of the loan portfolio, management, delinquency trends, loan administration, collateral values, concentrations of credit, and other external factors including legal and regulatory factors. For Personal Banking loans the allowance for loan losses consists of: • An allowance for loans 90 days or more delinquent; • An allowance for homogenous loans based on historical losses; and • An allowance for homogenous loans based on environmental factors. The allowance for loans 90 days or more delinquent is based on the loss history of loans that have become 90 days or more delinquent. We apply a historical loss factor to homogeneous pools of loans that are 90 days or more delinquent. The allowance for homogeneous loans based on historical losses is a rolling three -year average of actual losses incurred, adjusted for a loss realization period, applied to homogenous pools of loans categorized by similar risk characteristics, not including loans that are 90 days or more delinquent. The allocation of the allowance for loan losses is inherently subjective, and the entire allowance for loan losses is available to absorb loan losses regardless of the nature of the loss. Personal Banking loans are charged-off or charged down when they become 180 days delinquent, unless the borrower has filed for bankruptcy. Business Banking loans are charged-off or charged down when, in our opinion, they are no longer collectible or when it has been determined that the collateral value no longer supports the carrying value of the loan, for loans that are collateral dependent. We have not made any material changes to our methodology for the calculation of the allowance for loan losses during the current year. (g) Real Estate Owned Real estate owned is comprised of property either acquired through foreclosure or voluntarily conveyed by borrowers. These assets are recorded on the date acquired at the lower of the loan balance or fair value of the collateral, less estimated disposition costs, with the fair value being determined by an appraisal. Any initial write-down is charged to the allowance for loan losses. Subsequently, foreclosed assets are valued at the lower of the amount recorded at acquisition date or the current fair value, less estimated disposition costs. Any subsequent write-down or gains or losses realized from the disposition of such property are credited or charged to noninterest income. (h) Restricted Investment in Federal Home Loan Bank Stock Federal law requires a member institution of the Federal Home Loan Bank ("FHLB") system to hold stock of its district FHLB according to a predetermined formula. FHLB stock is carried at cost and evaluated or impairment based on the ultimate recoverability of the par value. FHLB stock can only be purchased, redeemed and transferred at par value. Dividends are reported in interest income in the Consolidated Statements of Income. (i) Premises and Equipment Premises and equipment are carried at cost, less accumulated depreciation and amortization. Depreciation is accumulated on a straight-line basis over the estimated useful lives of the related assets. Estimated lives range from three to 39 years . Amortization of leasehold improvements is accumulated on a straight-line basis over the terms of the related leases or the useful lives of the related assets, whichever is shorter. (j) Goodwill Goodwill is generated from the premium paid for an acquisition and is allocated to reporting units, which are either our reportable segments or one level below. Reporting units are identified based upon analyzing each individual operating segment. A reporting unit is defined as a distinct, separately identifiable component of an operating segment for which complete, discrete financial information is available that management regularly reviews. Goodwill is not subject to amortization but is tested for impairment at least annually and possibly more frequently if certain events occur or changes in circumstances arise. In testing goodwill for impairment, we have the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If, after assessing all events and circumstances, we determine it is not more likely than not that the fair value of a reporting unit is less than its carrying value, then performing the two-step impairment test would be unnecessary. However, if we conclude otherwise, it would then be required to perform the first step of the goodwill impairment test, and continue to the second step, if necessary. Step 1 requires the fair value of each reporting unit be compared to its carrying amount, including goodwill. Determining the fair value of a reporting unit requires a high degree of subjective judgment, including developing cash flow projections, selecting appropriate discount rates, identifying relevant market comparables, incorporating general economic and market conditions and selecting an appropriate control premium. We conducted our annual impairment assessment as of June 30, 2017 by first performing a qualitative assessment of goodwill to determine if it was more likely than not that the fair value was less than the carrying value. In performing a qualitative analysis, factors considered include, but are not limited to, macroeconomic conditions, industry and market conditions and overall financial performance. The results of the qualitative assessment for 2017 indicated that it was not more likely than not that the fair value of the reporting unit was less than the carrying value. Consequently, no additional quantitative two-step impairment test was required, and no impairment was recorded in 2017. As of June 30, 2016, we performed a quantitative impairment test that did not result in any impairment. Future events could cause us to conclude that goodwill has become impaired, which would result in recording an impairment loss. There were no changes in our operations that would cause us to update the assessment performed as of June 30, 2017 and 2016. Accordingly, we have determined that goodwill is not impaired as of December 31, 2017 and 2016. (k) Core Deposit and Other Identifiable Intangibles Through the assistance of an independent third party, we analyze and prepare a core deposit study for all bank acquisitions or other identifiable intangible asset study, such as customer lists, for all non-bank acquisitions. The core deposit study reflects the cumulative present value benefit of acquiring deposits versus an alternative source of funding. The other identifiable intangible asset study reflects the cumulative present value benefit of acquiring the income stream from an existing customer base versus developing new business relationships. Based upon analysis, the amount of the premium related to the core deposits or other identifiable intangibles of the business purchased is calculated along with the estimated life of the intangible. The intangible, which is recorded in other intangible assets, is then amortized to expense on an accelerated basis over an approximate life of typically between seven to eleven years. (l) Bank-Owned Life Insurance We own insurance on the lives of a certain group of current and former employees and directors. The policies were purchased to help offset the increase in the costs of various benefit plans, including healthcare, as well as the directors deferred compensation plan. The cash surrender value of these policies is included as an asset on the consolidated statements of financial condition, and any increases in the cash surrender value are recorded as tax-free noninterest income on the consolidated statements of income. In the event of the death of an insured individual covered by these policies, after distribution to the insured’s beneficiaries, if any, we receive a tax-free death benefit, which is recorded as noninterest income. (m) Deposits Interest on deposits is accrued and charged to expense monthly and is paid or credited in accordance with the terms of the accounts. (n) Pension Plans We maintain multiple noncontributory defined benefit pension plans for substantially all of our employees. The net periodic pension cost has been calculated using service cost, interest cost, expected returns on plan assets and net amortization. (o) Income Taxes We join with our wholly owned subsidiaries in filing a consolidated federal income tax return. In accordance with an intercompany tax allocation agreement, the applicable federal income tax expense or benefit is allocated to each subsidiary based upon taxable income or loss calculated on a separate company basis. Each subsidiary is responsible for payment of its own federal income tax liability or receives reimbursement of federal income tax benefit. In addition, deferred taxes are calculated and maintained on a separate company basis. We account for income taxes under the asset and liability method. The objective of the asset and liability method is to establish deferred tax assets and liabilities for temporary differences between the financial reporting and tax basis of our assets and liabilities based on the tax rates expected to be in effect when such amounts are realized or settled. The effect on deferred tax assets and liabilities with regard to a change in tax rates is recognized in the tax provision in the period the change is enacted. (p) Stock-Related Compensation We determine the fair value of each option award, estimated on the grant date, using the Black-Scholes-Merton option-pricing model. The Black-Scholes-Merton option-pricing model uses variables including; expected volatilities, expected term, risk-free discount rate and annual rate of quarterly dividends. Expected volatilities are based on historical volatility of the Company’s stock. The expected terms are based upon actual exercise and forfeiture experience of previous option grants. The risk-free rate is based on yields on U.S. Treasury securities of a similar maturity to the expected term of the options. For options outstanding at December 31, 2017 the following assumptions were used to determine the options fair value: (1) annual rate of quarterly dividends ranging from 3.2% to 5.1% based on historical dividends and market prices; (2) expected volatility of 17.0% to 22.0% based on historical average monthly volatility; (3) risk-free discount rates ranging from 1.7% to 3.1% ; and (4) expected lives of seven to nine years based on previous grants. During the year ended December 31, 2017 , we awarded 754,210 stock options to employees and 64,800 stock options to directors. Option awards are generally granted with an exercise price equal to the closing market price of the Company’s stock on the day before the grant date. The options granted in 2017 vest over a ten -year period, with the first vesting occurring on the grant date. New shares are issued when options are exercised. During the year ended December 31, 2017 , we awarded 353,750 common shares to employees and 24,300 common shares to directors. The common share awards granted in 2017 vest over a ten -year period, with the first vesting occurring on the grant date. For additional information regarding grants of stock options and common shares see note 14. Stock-based employee compensation expense related to common share awards of $3.8 million , $3.5 million and $3.0 million was included in income before income taxes during the years ended December 31, 2017 , 2016 and 2015 , respectively. The effect on net income for the years ended December 31, 2017 , 2016 and 2015 was a reduction of $2.3 million , $2.2 million and $1.8 million , respectively. Total compensation expense for unvested stock options of $4.1 million has yet to be recognized as of December 31, 2017 . The weighted average period over which this remaining stock option expense will be recognized is approximately 4 years . (q) Segment Reporting As a result of the closure of the Northwest Consumer Discount Company in the third quarter 2017, we have determined that we have one reportable segment beginning in the fourth quarter 2017. The Company provides services traditionally offered by full-service community banks, including business and personal deposit accounts and business and personal loans, as well as insurance, brokerage and investment management and trust services. The Company’s non-banking activities are immaterial and, therefore, separate information has not been disclosed. (r) Derivative financial instruments We recognize all derivative financial instruments as either assets or liabilities in the balance sheet and measure those instruments at fair value. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and the resulting designation. An entity that elects to use hedge accounting is required, at inception, to establish the method it will use for assessing the effectiveness of the hedging derivative and the measurement approach for determining the ineffective aspect of the hedge. Those methods must be consistent with our approach to managing risk. We utilize interest rate swap agreements as part of the management of interest rate risk to hedge the interest rate risk on our trust preferred debentures. Amounts receivable or payable are recognized as accrued under the terms of the agreements and the differential is recorded as an adjustment to interest expense. The interest rate swaps are designated as cash flow hedges, with the effective portion of the derivative’s unrealized gain or loss recorded as a component of other comprehensive income which is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The ineffective portion of the unrealized gain or loss, if any, would be recorded in other expense. For derivatives that are not designated as hedging instruments, any gain or loss is recognized immediately in earnings. (s) Off-Balance-Sheet Instruments In the normal course of business, we extend credit in the form of loan commitments, undisbursed lines of credit, and standby letters of credit. These off-balance-sheet instruments involve, to various degrees, elements of credit and interest rate risk not reported in the consolidated statement of financial condition. We utilize the same underwriting standards for these instruments as other extensions of credit. (t) Use of Estimates The preparation of financial statements, in conformity with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amount of revenues and expenses during the reporting period. The estimates and assumptions that we deem important to our financial statements relate to the allowance for loan losses, the accounting treatment and valuation of our investment securities portfolio, the analysis of the carrying value of goodwill, pension and income taxes. These estimates and assumptions are based on management’s best estimates and judgment and we evaluate them using historical experience and other factors, including the current economic environment. We adjust our estimates and assumptions when facts and circumstances dictate. As future events cannot be determined, actual results could differ significantly from our estimates. (u) Reclassification of Prior Years’ Statements Certain items previously reported have been reclassified to conform with the current year’s reporting format.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014 the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606)”. This guidance supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance. The core principle of this guidance requires an entity to recognize revenue upon 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 and provides five steps to be analyzed to accomplish the core principle. This guidance is effective retrospectively for annual reporting periods beginning after December 15, 2017, including interim periods within those years and early adoption is not permitted. Our revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. With respect to non-interest income we are complete with our overall assessment of revenue streams and review of related contracts potentially affected by the ASU, including service charges and fees, trust and other financial services income, insurance commission income, and other operating income. The adoption of this ASU will not materially change the method in which we currently recognize revenue for these revenue streams. We are also complete with our evaluation of certain costs related to these revenue streams to determine whether such costs should be presented as expenses or contra-revenue (i.e., gross vs. net). We adopted ASU No. 2014-09 on January 1, 2018 utilizing the modified retrospective approach. Since there was no net income impact, a cumulative effect adjustment to opening retained earnings was deemed not necessary. We are completing our evaluation of the ASU's expanded disclosure requirements and expect them to be primarily qualitative in nature, such as providing greater detail on revenue streams and related performance obligations. In January 2016 the FASB issued ASU 2016-01, “Financial Instruments - Overall (Subtopic 825-10)” . This guidance requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. Additionally, this guidance requires entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We do not expected this guidance to have a material impact on our results of operations and financial position. In February 2016 the FASB issued ASU 2016-2, “Leases” . This guidance requires a lessee to recognize in the statement of financial condition a liability to make lease payments and a right-of-use asset representing the right to use the underlying asset for the term of the lease. Optional periods should only be recognized if the lessee is reasonably certain to exercise the option. For leases with a term of twelve months or less, the lessee is permitted not to recognize lease assets and lease liabilities and should recognize lease expense for such leases generally on a straight-line basis over the term of the lease. This guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those years and early adoption is permitted. We are currently evaluating the impact this guidance will have on our results of operations and financial position. In June 2016, the FASB issued ASU 2016-13, " Financial Instruments - Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments" , which eliminates the probable initial recognition threshold for credit losses requiring, instead, that all financial assets (or group of financial assets) measured at amortized cost be presented at the net amount expected to be collected inclusive of the entity’s current estimate of all lifetime expected credit losses. This guidance also applies to certain off-balance-sheet credit exposures such as unfunded commitments and non-derivative financial guarantees. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) in order to present the net carrying value at the amount expected to be collected on the financial asset. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The income statement under this guidance will reflect the initial recognition of current expected credit losses for newly recognized assets, as well as any increases or decreases of expected credit losses that have occurred during the period. This guidance retains many currently-existing disclosures related to the credit quality of an entity’s assets and the related allowance for credit losses amended to reflect the change to an expected credit loss methodology, as well as enhanced disclosures to provide information to users at a more disaggregated level. Upon adoption, ASU 2016-13 provides for a modified retrospective transition by means of a cumulative-effect adjustment to equity as of the beginning of the period in which the guidance is effective, except for debt securities for which an other-than-temporary impairment has previously been recognized. For these debt securities, a prospective transition is provided in order to maintain the same amortized cost prior to and subsequent to the effective date of the ASU. This guidance is effective for annual reporting periods beginning after December 15, 2019, and interim periods within those annual periods with early adoption permitted for fiscal years beginning after December 15, 2018, and interim periods within those annual periods. Management created a formal working group to govern the implementation of these amendments consisting of key stakeholders from finance, risk, and accounting. We are currently in the process of designing current expected credit loss estimation methodologies and systems, and collecting data to be able to comply with the standard. We are also evaluating the effect this guidance will have on our results of operations, financial position and related disclosures. The impact of the ASU will depend upon the state of the economy and the nature of our portfolios at the date of adoption. In August 2016, the FASB issued ASU No. 2016-15, “ Classification of Certain Cash Receipts and Cash Payments ”. The main objective of this ASU is to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The amendments in this Update provide guidance on the following eight specific cash flow issues: debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of bank-owned life insurance (BOLI) policies, distributions received from equity method investments, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. This guidance is effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption is permitted, provided that all of the amendments are adopted in the same period. The provisions of this ASU will not materially impact our results of operations and financial position. In January 2017 the FASB issued ASU 2017-04, "Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment" . This guidance eliminates the requirement to determine the fair value of individual assets and liabilities of a reporting unit to measure goodwill impairment. Under this guidance goodwill impairment testing will be performed by comparing the fair value of the reporting unit with its carrying amount and recognizing an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. This guidance is effective for annual and interim goodwill impairment tests in fiscal years beginning after December 15, 2019, and should be applied on a prospective basis. Early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. We do not expected this guidance to have a material impact on our consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-07, “Compensation Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Costs and Net Periodic Postretirement Benefit Costs". This guidance provides financial statement users with clearer and disaggregated information related to the components of net periodic benefit cost and improve transparency of the presentation of net periodic benefit cost in the financial statements. This guidance is effective for annual and interim periods beginning after December 15, 2017. Early adoption is permitted and this guidance should be applied retrospectively. We intend to early adopt the provisions of this standard effective with our March 31, 2018 quarterly report on Form 10-Q and do not anticipate that the adoption of this guidance will not have a material impact on our results of operations, however it will impact the presentation of our Consolidated Statements of Income. In March 2017 the FASB issued ASU 2017-08, "Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities" . This guidance shortens the amortization period for certain callable debt securities held at a premium to the earliest call date from the maturity date. This guidance is effective for annual and interim periods beginning after December 15, 2018. Early adoption is permitted in any interim period. We intend to early adopt the provisions of this standard effective with our March 31, 2018 quarterly report on Form 10-Q and do not expect the adoption to have a material impact on our results of operations or financial position. In May 2017 the FASB issued ASU 2017-09, “Compensation - Stock Compensation (Topic 718) - Scope of Modification Accounting”. This guidance clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award's fair value, (ii) the award's vesting conditions and (iii) the award's classification as an equity or liability instrument. This guidance is effective for annual and interim periods beginning after December 15, 2017 and is not expected to have a material impact on our consolidated financial statements. 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." This guidance permits a reclassification from accumulated other comprehensive income to retained earnings of the stranded tax effects resulting from the Tax Cuts and Jobs Act. This guidance is effective for annual or interim reporting periods beginning after December 15, 2018. Early adoption is permitted and the guidance should be applied either in the period of adoption or retrospectively to each period impacted by the change in the Federal corporate income tax rate change. We intend to early adopt the provisions of this standard effective with our March 31, 2018 quarterly report on Form 10-Q and do not expect the adoption to have a material impact on our consolidated financial statements

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities Marketable securities available-for-sale at December 31, 2017 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Debt issued by the U.S. government and agencies: Due in one year or less $ 1 — — 1 Debt issued by government sponsored enterprises: 3 Due in one year or less 66,566 14 (289 ) 66,291 Due after one year through five years 140,624 — (2,402 ) 138,222 Due after five years through ten years — — — — Due after ten years 4,833 — (77 ) 4,756 Equity securities 551 29 (6 ) 574 Municipal securities: Due in one year or less 2,492 7 (1 ) 2,498 Due after one year through five years 7,072 82 (6 ) 7,148 Due after five years through ten years 14,576 171 — 14,747 Due after ten years 26,371 292 — 26,663 Corporate debt issues: Due after ten years 909 — — 909 Residential mortgage-backed securities: Fixed rate pass-through 144,411 1,108 (2,817 ) 142,702 Variable rate pass-through 33,079 1,464 (6 ) 34,537 Fixed rate non-agency CMOs 15 — — 15 Fixed rate agency CMOs 284,320 37 (5,271 ) 279,086 Variable rate agency CMOs 74,274 249 (137 ) 74,386 Total residential mortgage-backed securities 536,099 2,858 (8,231 ) 530,726 Total marketable securities available-for-sale $ 800,094 3,453 (11,012 ) 792,535 Marketable securities held to maturity at December 31, 2017 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Residential mortgage-backed securities: Fixed rate pass-through $ 3,760 140 — 3,900 Variable rate pass-through 2,283 64 — 2,347 Fixed rate agency CMOs 22,906 20 (248 ) 22,678 Variable rate agency CMOs 729 13 — 742 Total residential mortgage-backed securities 29,678 237 (248 ) 29,667 Total marketable securities held-to-maturity $ 29,678 237 (248 ) 29,667 Marketable securities available-for-sale at December 31, 2016 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Debt issued by the U.S. government and agencies: Due in one year or less $ 6 — — 6 Debt issued by government sponsored enterprises: Due in one year or less 74,980 5 (33 ) 74,952 Due after one year through five years 220,937 203 (2,504 ) 218,636 Due after five years through ten years 585 — (3 ) 582 Due after ten years — — — — Equity securities 3,351 1,095 (6 ) 4,440 Municipal securities: Due in one year or less 2,449 7 — 2,456 Due after one year through five years 9,448 105 (21 ) 9,532 Due after five years through ten years 11,794 137 (1 ) 11,930 Due after ten years 38,141 1,027 (16 ) 39,152 Corporate debt issues: Due after ten years 14,367 2,935 (322 ) 16,980 Residential mortgage-backed securities: Fixed rate pass-through 175,398 1,849 (2,680 ) 174,567 Variable rate pass-through 43,587 2,007 (6 ) 45,588 Fixed rate non-agency CMOs 100 1 — 101 Fixed rate agency CMOs 165,535 185 (3,455 ) 162,265 Variable rate agency CMOs 64,874 306 (167 ) 65,013 Total residential mortgage-backed securities 449,494 4,348 (6,308 ) 447,534 Total marketable securities available-for-sale $ 825,552 9,862 (9,214 ) 826,200 Marketable securities held to maturity at December 31, 2016 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Municipal securities: Due after ten years $ 4,808 65 — 4,873 Residential mortgage-backed securities: Fixed rate pass-through 4,807 217 — 5,024 Variable rate pass-through 2,848 58 — 2,906 Fixed rate agency CMOs 6,674 94 — 6,768 Variable rate agency CMOs 841 14 — 855 Total residential mortgage-backed securities 15,170 383 — 15,553 Total marketable securities held-to-maturity $ 19,978 448 — 20,426 The following table presents information regarding the issuers and the carrying values of our mortgage-backed securities at December 31, 2017 and 2016 : December 31, 2017 2016 Residential mortgage backed securities: FNMA $ 286,031 210,373 GNMA 37,796 42,221 FHLMC 236,007 202,822 SBA — 6,608 Other (including non-agency) 570 680 Total residential mortgage-backed securities $ 560,404 462,704 Marketable securities having a carrying value of $161.6 million at December 31, 2017 , were pledged under collateral agreements. During the year ended December 31, 2017 , we sold marketable securities classified as available-for-sale for $36.8 million , with gross realized gains of $1.8 million and gross realized losses of $626,000 . During the year ended December 31, 2016 , we sold marketable securities classified as available-for-sale for $2.0 million , with gross realized gains of $268,000 and gross realized losses of $0 . During the year ended December 31, 2015 , we sold marketable securities classified as available-for-sale for $1.2 million , with gross realized gains of $121,000 and gross realized losses of $ 67,000 . During the years ended December 31, 2017 , 2016 and 2015 , we did not recognize non-cash credit related other-than-temporary-impairment in our investment portfolio. The following table shows the fair value and gross unrealized losses on investment securities, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position at December 31, 2017 : Less than 12 months 12 months or more Total Unrealized Unrealized Unrealized Fair value loss Fair value loss Fair value loss Government sponsored enterprises $ 5,006 (7 ) 197,695 (2,761 ) 202,701 (2,768 ) Corporate debt issues — — — — — — Equity securities — — 544 (6 ) 544 (6 ) Municipal securities 4,563 (7 ) — — 4,563 (7 ) Residential mortgage-backed securities - agency 239,703 (2,522 ) 202,344 (5,957 ) 442,047 (8,479 ) Total temporarily impaired securities $ 249,272 (2,536 ) 400,583 (8,724 ) 649,855 (11,260 ) The following table shows the fair value and gross unrealized losses on investment securities, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position at December 31, 2016 : Less than 12 months 12 months or more Total Unrealized Unrealized Unrealized Fair value loss Fair value loss Fair value loss Government sponsored enterprises $ 238,003 (2,448 ) 9,205 (92 ) 247,208 (2,540 ) Corporate debt issues — — 2,107 (322 ) 2,107 (322 ) Equity securities — — 544 (6 ) 544 (6 ) Municipal securities 5,621 (37 ) 66 (1 ) 5,687 (38 ) Residential mortgage-backed securities - agency 213,662 (3,837 ) 87,723 (2,471 ) 301,385 (6,308 ) Total temporarily impaired securities $ 457,286 (6,322 ) 99,645 (2,892 ) 556,931 (9,214 ) We perform an assessment to determine whether there have been any events or economic circumstances that indicate a security which has an unrealized loss is impaired other-than-temporarily. The assessment considers many factors including the severity and duration of the impairment; recent events specific to the issuer or industry; and for debt securities, external credit ratings, underlying collateral position and recent downgrades. For asset backed securities, we evaluate current characteristics of each security such as delinquency and foreclosure levels, credit enhancement and projected losses and coverage. It is possible that the underlying collateral of these securities will perform worse than current expectations, which may lead to adverse changes in cash flows on these securities and potential future losses. Events that may trigger material declines in fair values for these securities in the future would be, but are not limited to: deterioration of credit metrics, significantly higher levels of default and severity of loss on the underlying collateral, deteriorating credit enhancement and loss coverage ratios, or further illiquidity. For debt securities, credit related other-than-temporary impairment is recognized in earnings, while noncredit related other-than-temporary impairment on securities not expected to be sold, or otherwise disposed of, is recognized in other comprehensive income. We assert that we do not have the intent to sell these securities and it is more likely than not that we will not have to sell these securities before a recovery of our cost basis. For these reasons, we consider the unrealized losses to be temporary impairment losses. There are approximately 173 positions that are temporarily impaired at December 31, 2017 . The aggregate carrying amount of cost-method investments, including both held-to-maturity and available-for-sale, at December 31, 2017 was $822.2 million , of which all were evaluated for impairment. The following table sets forth the categories of investment securities as of December 31, 2017 on which other-than-temporary impairment charges have been recorded in earnings: Total Accumulated Category Amortized cost Fair value Unrealized gain impairment charges Freddie Mac preferred shares $ 1 30 29 119 Trust preferred investments — — — 352 Total $ 1 30 29 471 The table below shows a cumulative roll forward of credit related impairment losses recognized in earnings for debt securities held and not intended to be sold: December 31, 2017 2016 Beginning balance as of January 1, (1) $ 7,942 8,436 Credit losses on debt securities for which other-than-temporary impairment was not previously recognized — — Credit losses on debt securities for which other-than-temporary impairment was previously recognized (7,265 ) (494 ) Reduction for securities sold realized during the year (325 ) — Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized — — Ending balance as of December 31, $ 352 7,942 (1) The beginning balance represents credit losses included in other-than-temporary impairment charges recognized on debt securities in prior periods.

Loans Receivable and Allowance

Loans Receivable and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Loans Receivable and Allowance for Loan Losses	Loans Receivable and Allowance for Loan Losses Loans receivable at December 31, 2017 and 2016 are summarized in the table below: December 31, 2017 December 31, 2016 Originated Acquired Total Originated Acquired Total Personal Banking: Residential mortgage loans (1) $ 2,658,726 113,823 2,772,549 2,565,620 133,511 2,699,131 Home equity loans 1,051,558 258,797 1,310,355 1,042,913 302,457 1,345,370 Consumer finance loans (2) 18,619 — 18,619 48,981 — 48,981 Consumer loans 540,832 97,877 638,709 418,656 163,622 582,278 Total Personal Banking 4,269,735 470,497 4,740,232 4,076,170 599,590 4,675,760 Commercial Banking: Commercial real estate loans 2,303,179 296,161 2,599,340 2,140,678 372,991 2,513,669 Commercial loans 572,341 60,822 633,163 481,543 75,676 557,219 Total Commercial Banking 2,875,520 356,983 3,232,503 2,622,221 448,667 3,070,888 Total loans receivable, gross 7,145,255 827,480 7,972,735 6,698,391 1,048,257 7,746,648 Deferred loan costs 26,255 1,527 27,782 20,081 2,294 22,375 Allowance for loan losses (50,572 ) (6,223 ) (56,795 ) (55,293 ) (5,646 ) (60,939 ) Undisbursed loan proceeds: Residential mortgage loans (10,067 ) — (10,067 ) (11,638 ) — (11,638 ) Commercial real estate loans (141,967 ) (2,647 ) (144,614 ) (168,595 ) (2,985 ) (171,580 ) Commercial loans (51,143 ) (1,284 ) (52,427 ) (26,168 ) (2,290 ) (28,458 ) Total loans receivable, net $ 6,917,761 818,853 7,736,614 6,456,778 1,039,630 7,496,408 (1) Includes $3.1 million and $9.6 million of loans held for sale at December 31, 2017 and 2016 , respectively. (2) Represents loans from our consumer finance subsidiary that was closed in 2017 which are no longer being originated. As of December 31, 2017 , 2016 and 2015 , we serviced loans for others approximating $887.3 million , $918.9 million and $776.0 million , respectively. These loans serviced for others are not our assets and are not included in our financial statements. As of December 31, 2017 and 2016 , approximately 60% and 62% , respectively, of our loan portfolio was secured by properties located in Pennsylvania. We do not believe we have significant concentrations of credit risk to any one group of borrowers given our underwriting and collateral requirements. Loans receivable as of December 31, 2017 and 2016 include $2.856 billion and $2.755 billion , respectively, of adjustable rate loans and $5.117 billion and $4.992 billion , respectively, of fixed rate loans. The following table provides information related to the outstanding principal balance and related carrying value of acquired loans for the dates indicated: December 31, 2017 2016 Acquired loans evaluated individually for future credit losses: Outstanding principal balance $ 9,735 16,108 Carrying value 6,875 12,665 Acquired loans evaluated collectively for future credit losses: Outstanding principal balance 824,205 1,040,378 Carrying value 818,201 1,032,611 Total acquired loans: Outstanding principal balance 833,940 1,056,486 Carrying value 825,076 1,045,276 The following table provides information related to the changes in the accretable discount, which includes income recognized from contractual cash flows for the dates indicated: Total Balance at December 31, 2015 $ 2,019 Accretion (1,170 ) Net reclassification from nonaccretable yield 1,338 Balance at December 31, 2016 2,187 Accretion (1,318 ) Net reclassification from nonaccretable yield 671 Balance at December 31, 2017 $ 1,540 The following table provides information related to purchased credit impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2017 : Carrying value Outstanding principal balance Related impairment reserve Average recorded investment in impaired loans Interest income/ accretion recognized Personal Banking: Residential mortgage loans $ 1,182 1,880 24 1,251 181 Home equity loans 1,143 2,219 21 1,253 157 Consumer loans 59 160 4 97 51 Total Personal Banking 2,384 4,259 49 2,601 389 Commercial Banking: Commercial real estate loans 4,388 5,363 39 6,992 914 Commercial loans 103 113 — 177 15 Total Commercial Banking 4,491 5,476 39 7,169 929 Total $ 6,875 9,735 88 9,770 1,318 The following table provides information related to purchased credit impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2016 : Carrying Outstanding Related Average Interest Personal Banking: Residential mortgage loans $ 1,319 2,062 204 1,650 202 Home equity loans 1,363 2,669 8 1,724 185 Consumer loans 136 303 3 201 51 Total Personal Banking 2,818 5,034 215 3,575 438 Commercial Banking: Commercial real estate loans 9,596 10,809 52 10,942 721 Commercial loans 251 265 — 249 11 Total Commercial Banking 9,847 11,074 52 11,191 732 Total $ 12,665 16,108 267 14,766 1,170 The following table provides information related to changes in the allowance for losses on loans receivable for the year ended December 31, 2017 : Balance Provision Charge-offs Recoveries Balance Originated loans Personal Banking: Residential mortgage loans $ 3,824 (390 ) (834 ) 392 4,656 Home equity loans 4,072 1,474 (1,080 ) 192 3,486 Consumer finance loans 3,968 8,444 (8,369 ) 448 3,445 Consumer loans 8,475 13,601 (11,128 ) 1,473 4,529 Total Personal Banking 20,339 23,129 (21,411 ) 2,505 16,116 Commercial Banking: Commercial real estate loans 19,911 (3,663 ) (1,344 ) 1,251 23,667 Commercial loans 10,322 (4,777 ) (2,462 ) 2,051 15,510 Total Commercial Banking 30,233 (8,440 ) (3,806 ) 3,302 39,177 Total originated loans 50,572 14,689 (25,217 ) 5,807 55,293 Acquired loans Personal Banking: Residential mortgage loans 131 185 (205 ) 80 71 Home equity loans 762 503 (1,179 ) 391 1,047 Consumer loans 890 765 (795 ) 267 653 Total Personal Banking 1,783 1,453 (2,179 ) 738 1,771 Commercial Banking: Commercial real estate loans 3,549 2,631 (2,830 ) 740 3,008 Commercial loans 891 978 (1,028 ) 74 867 Total Commercial Banking 4,440 3,609 (3,858 ) 814 3,875 Total acquired loans 6,223 5,062 (6,037 ) 1,552 5,646 Total $ 56,795 19,751 (31,254 ) 7,359 60,939 The following table provides information related to changes in the allowance for losses on loans receivable for the year ended December 31, 2016 : Balance Provision Charge-offs Recoveries Balance Originated loans Personal Banking: Residential mortgage loans $ 4,656 2,906 (3,228 ) 286 4,692 Home equity loans 3,486 293 (1,090 ) 342 3,941 Consumer finance loans 3,445 3,117 (3,323 ) 376 3,275 Consumer loans 4,529 5,935 (6,902 ) 1,283 4,213 Total Personal Banking 16,116 12,251 (14,543 ) 2,287 16,121 Commercial Banking: Commercial real estate loans 23,667 (9,819 ) (2,403 ) 3,541 32,348 Commercial loans 15,510 4,834 (4,165 ) 2,340 12,501 Total Commercial Banking 39,177 (4,985 ) (6,568 ) 5,881 44,849 Total originated loans 55,293 7,266 (21,111 ) 8,168 60,970 Acquired loans Personal Banking: Residential mortgage loans 71 146 (252 ) 159 18 Home equity loans 1,047 2,065 (1,449 ) 330 101 Consumer loans 653 1,072 (680 ) 151 110 Total Personal Banking 1,771 3,283 (2,381 ) 640 229 Commercial Banking: Commercial real estate loans 3,008 2,116 (1,337 ) 790 1,439 Commercial loans 867 877 (52 ) 8 34 Total Commercial Banking 3,875 2,993 (1,389 ) 798 1,473 Total acquired loans 5,646 6,276 (3,770 ) 1,438 1,702 Total $ 60,939 13,542 (24,881 ) 9,606 62,672 The following table provides information related to changes in the allowance for losses on loans receivable for the year ended December 31, 2015 : Balance Provision Charge-offs Recoveries Balance Originated loans Personal Banking: Residential mortgage loans $ 4,692 (96 ) (1,057 ) 264 5,581 Home equity loans 3,941 693 (1,716 ) 414 4,550 Consumer finance loans 3,275 2,853 (3,056 ) 404 3,074 Consumer loans 4,213 5,132 (5,017 ) 1,054 3,044 Total Personal Banking 16,121 8,582 (10,846 ) 2,136 16,249 Commercial Banking: Commercial real estate loans 32,348 540 (5,741 ) 4,160 33,389 Commercial loans 12,501 2,768 (7,814 ) 4,032 13,515 Total Commercial Banking 44,849 3,308 (13,555 ) 8,192 46,904 Unallocated — (4,365 ) — — 4,365 Total originated loans 60,970 7,525 (24,401 ) 10,328 67,518 Acquired loans Personal Banking: Residential mortgage loans 18 47 (69 ) 40 — Home equity loans 101 247 (708 ) 562 — Other consumer loans 110 188 (201 ) 123 — Total Personal Banking 229 482 (978 ) 725 — Business Banking: Commercial real estate loans 1,439 1,545 (585 ) 479 — Commercial loans 34 160 (369 ) 243 — Total Business Banking 1,473 1,705 (954 ) 722 — Total acquired loans 1,702 2,187 (1,932 ) 1,447 — Total $ 62,672 9,712 (26,333 ) 11,775 67,518 While we use available information to provide for losses, future additions to the allowance may be necessary based on changes in economic conditions. In addition, various regulatory agencies, as an integral part of their examination process, periodically review our allowance for loan losses. Such agencies may require us to recognize additions to the allowance based on their judgments about information available to them at the time of their examination. Management believes, to the best of their knowledge, that all known losses as of the balance sheet dates have been recorded. The following table provides information related to the loan portfolio by portfolio segment and by class of financing receivable as of December 31, 2017 : Recorded investment in loans receivable Allowance for loan losses Recorded investment in loans on nonaccrual (1) Recorded investment in loans 90 days or more past maturity and still accruing TDRs (1) Allowance for loan losses related to TDRs Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,776,203 3,955 14,791 — 8,000 815 — Home equity loans 1,310,355 4,834 8,907 120 1,716 462 4 Consumer finance loans 18,619 3,968 199 3 — — — Consumer loans 652,770 9,365 4,673 379 — — — Total Personal Banking 4,757,947 22,122 28,570 502 9,716 1,277 4 Commercial Banking: Commercial real estate loans 2,454,726 23,460 28,473 — 15,691 1,125 235 Commercial loans 580,736 11,213 7,412 — 6,697 742 8 Total Commercial Banking 3,035,462 34,673 35,885 — 22,388 1,867 243 Total $ 7,793,409 56,795 64,455 502 32,104 3,144 247 (1) Includes $12.3 million of nonaccrual TDRs. The following table provides information related to the loan portfolio by portfolio segment and by class of financing receivable as of December 31, 2016 : Recorded investment in loans receivable Allowance for loan losses Recorded investment in loans on nonaccrual (1) Recorded TDRs (1) Allowance Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,698,166 4,727 18,264 — 7,299 708 — Home equity loans 1,345,370 4,533 7,865 — 1,813 450 4 Consumer finance loans 48,981 3,445 743 — — — — Consumer loans 593,980 5,182 4,366 85 — — — Total Personal Banking 4,686,497 17,887 31,238 85 9,112 1,158 4 Commercial Banking: Commercial real estate loans 2,342,089 26,675 38,724 564 24,483 2,072 417 Commercial loans 528,761 16,377 9,574 — 9,331 1,360 17 Total Commercial Banking 2,870,850 43,052 48,298 564 33,814 3,432 434 Total $ 7,557,347 60,939 79,536 649 42,926 4,590 438 (1) Includes $16.3 million of nonaccrual TDRs. A loan is considered to be impaired, when, based on current information and events it is probable that we will be unable to collect all amounts due according to the contractual terms of the loan agreement including both contractual principal and interest payments. This includes non-accrual loans, loans more than 90 days delinquent and still accruing interest, loans for which we perform an impairment review and TDRs. Impairment is measured using one of three methods: (1) the present value of expected future cash flows discounted at the loan’s effective interest rate; (2) the loan’s observable market price; or (3) the fair value of collateral if the loan is collateral dependent, less costs of sale or disposition. If the measure of the impaired loan is less than the recorded investment in the loan, a specific allowance is allocated for the impairment. The following table provides information related to the composition of impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2017 : Nonaccrual loans 90 or more days delinquent Nonaccrual loans less than 90 days delinquent Loans less than 90 days delinquent reviewed for impairment TDRs less than 90 days delinquent not included elsewhere Total impaired loans Average recorded investment in impaired loans Interest income recognized on impaired loans Personal Banking: Residential mortgage loans $ 13,509 1,282 — 6,814 21,605 21,531 892 Home equity loans 7,251 1,656 — 1,449 10,356 9,150 452 Consumer finance loans 199 — — — 199 379 20 Consumer loans 3,617 1,056 — — 4,673 4,042 188 Total Personal Banking 24,576 3,994 — 8,263 36,833 35,102 1,552 Commercial Banking: Commercial real estate loans 15,361 13,112 4,431 4,123 37,027 49,981 1,758 Commercial loans 3,140 4,272 906 2,447 10,765 12,110 672 Total Commercial Banking 18,501 17,384 5,337 6,570 47,792 62,091 2,430 Total $ 43,077 21,378 5,337 14,833 84,625 97,193 3,982 The following table provides information related to the composition of impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2016 : Nonaccrual loans 90 or more days delinquent Nonaccrual loans less than 90 days delinquent Loans less than 90 days delinquent reviewed for impairment TDRs less than 90 days delinquent not included elsewhere Total impaired loans Average recorded investment in impaired loans Interest income recognized on impaired loans Personal Banking: Residential mortgage loans $ 13,169 5,095 — 5,929 24,193 24,483 1,079 Home equity loans 5,552 2,313 — 1,439 9,304 9,234 496 Consumer finance loans 743 — — — 743 772 35 Consumer loans 3,080 1,286 — — 4,366 2,931 131 Total Personal Banking 22,544 8,694 — 7,368 38,606 37,420 1,741 Commercial Banking: Commercial real estate loans 19,264 19,460 3,622 11,582 53,928 64,350 2,864 Commercial loans 3,373 6,201 2,837 3,116 15,527 16,905 991 Total Commercial Banking 22,637 25,661 6,459 14,698 69,455 81,255 3,855 Total $ 45,181 34,355 6,459 22,066 108,061 118,675 5,596 The following table provides information related to the composition of impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2015 : Nonaccrual loans 90 or more days delinquent Nonaccrual loans less than 90 days delinquent Loans less than 90 days delinquent reviewed for impairment TDRs less than 90 days delinquent not included elsewhere Total impaired loans Average recorded investment in impaired loans Interest income recognized on impaired loans Personal Banking: Residential mortgage loans $ 15,810 3,962 — 5,086 24,858 24,554 944 Home equity loans 5,650 1,872 — 1,847 9,369 9,644 497 Consumer finance loans 792 — — — 792 768 29 Consumer loans 2,108 552 — — 2,660 2,209 72 Total Personal Banking 24,360 6,386 — 6,933 37,679 37,175 1,542 Commercial Banking: Commercial real estate loans 16,449 16,972 16,121 16,467 66,009 77,166 3,226 Commercial loans 2,459 5,036 2,014 4,654 14,163 16,187 694 Total Commercial Banking 18,908 22,008 18,135 21,121 80,172 93,353 3,920 Total $ 43,268 28,394 18,135 28,054 117,851 130,528 5,462 The following table provides information related to the evaluation of impaired loans by portfolio segment and by class of financing receivable as of and for the year ended December 31, 2017 : Loans collectively evaluated for impairment Loans individually evaluated for impairment Loans individually evaluated for impairment for which there is a related impairment reserve Related impairment reserve Loans individually evaluated for impairment for which there is no related reserve Personal Banking: Residential mortgage loans $ 2,767,635 8,568 8,568 816 — Home equity loans 1,308,639 1,716 1,716 461 — Consumer finance loans 18,619 — — — — Consumer loans 652,685 85 85 25 — Total Personal Banking 4,747,578 10,369 10,369 1,302 — Commercial Banking: Commercial real estate loans 2,433,755 20,971 18,470 1,859 2,501 Commercial loans 571,412 9,324 8,572 829 752 Total Commercial Banking 3,005,167 30,295 27,042 2,688 3,253 Total $ 7,752,745 40,664 37,411 3,990 3,253 The following table provides information related to the evaluation of impaired loans by portfolio segment and by class of financing receivable as of and for the year ended December 31, 2016 : Loans collectively evaluated for impairment Loans individually evaluated for impairment Loans individually evaluated for impairment for which there is a related impairment reserve Related impairment reserve Loans individually evaluated for impairment for which there is no related reserve Personal Banking: Residential mortgage loans $ 2,689,886 8,280 8,280 709 — Home equity loans 1,343,556 1,814 1,814 450 — Consumer finance loans 48,981 — — — — Consumer loans 593,854 126 126 29 — Total Personal Banking 4,676,277 10,220 10,220 1,188 — Commercial Banking: Commercial real estate loans 2,309,186 32,903 27,594 3,545 5,309 Commercial loans 518,449 10,312 10,242 1,390 70 Total Commercial Banking 2,827,635 43,215 37,836 4,935 5,379 Total $ 7,503,912 53,435 48,056 6,123 5,379 Our loan portfolios include certain loans that have been modified in a TDR, where economic concessions have been granted to borrowers who have experienced financial difficulties. These concessions typically result from our loss mitigation activities and could include: extending the note’s maturity date, permitting interest only payments, reducing the interest rate to a rate lower than current market rates for new debt with similar risk, reducing the principal payment, principal forbearance or other actions. These concessions are applicable to all loan segments and classes. Certain TDRs are classified as nonperforming at the time of restructuring and typically are returned to performing status after considering the borrower’s sustained repayment performance for a reasonable period of at least six consecutive months. When we modify loans in a TDR, we evaluate any possible impairment similar to other impaired loans based on the present value of expected future cash flows, discounted at the contractual interest rate of the original loan agreement, the loan’s observable market price or the current fair value of the collateral, less selling costs, for collateral dependent loans. If we determine that the value of the modified loan is less than the recorded investment in the loan (net of previous charge-offs, deferred loan fees or costs and unamortized premium or discount), impairment is recognized through an allowance estimate or a charge-off to the allowance. In periods subsequent to modification, we evaluate all TDRs, including those that have payment defaults, for possible impairment, using ASC 310-10. As a result, loans modified in a TDR may have the financial effect of increasing the specific allowance associated with the loan. Loans modified in a TDR are closely monitored for delinquency as an early indicator of possible future default. If loans modified in a TDR subsequently default, we evaluate the loan for possible further impairment. The allowance may be increased, adjustments may be made in the allocation of the allowance, partial charge-offs may be taken to further write-down the carrying value of the loan, or the loan may be charged-off completely. The following table provides a roll forward of troubled debt restructurings for the periods indicated: For the years ended December 31, 2017 2016 Number of Amount Number of Amount Beginning TDR balance: 225 $ 42,926 227 $ 51,115 New TDRs 24 5,450 34 6,365 Re-modified TDRs 5 2,099 7 3,414 Net paydowns (11,538 ) (9,037 ) Charge-offs: Residential mortgage loans 1 (77 ) — — Home equity loans 1 (48 ) — — Commercial real estate loans 2 (2,498 ) 1 (120 ) Commercial loans 6 (259 ) 2 (142 ) Paid-off loans: Residential mortgage loans — — 4 (151 ) Home equity loans 8 (62 ) 7 (534 ) Commercial real estate loans 15 (1,633 ) 12 (6,170 ) Commercial loans 11 (2,256 ) 10 (1,814 ) Ending TDR balance: 205 $ 32,104 225 $ 42,926 Accruing TDRs $ 19,819 $ 26,580 Non-accrual TDRs 12,285 16,346 The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable during the year ended December 31, 2017 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 8 $ 1,604 1,555 158 Home equity loans 3 152 148 40 Total Personal Banking 11 1,756 1,703 198 Commercial Banking: Commercial real estate loans 11 5,232 4,889 364 Commercial loans 7 561 526 37 Total Commercial Banking 18 5,793 5,415 401 Total 29 $ 7,549 7,118 599 Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings modified within the previous twelve months that have subsequently defaulted: Personal Banking: Residential mortgage loans 1 $ 336 334 34 Home equity loans — — — — Total Personal Banking 1 336 334 34 Commercial Banking: Commercial real estate loans 2 438 426 35 Commercial loans — — — — Total Commercial Banking 2 438 426 35 Total 3 $ 774 760 69 The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable during the year ended December 31, 2016 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 7 $ 1,199 1,177 114 Home equity loans 7 475 471 110 Total Personal Banking 14 1,674 1,648 224 Commercial Banking: Commercial real estate loans 7 3,729 3,643 485 Commercial loans 20 4,376 2,218 508 Total Commercial Banking 27 8,105 5,861 993 Total 41 $ 9,779 7,509 1,217 Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings modified within the previous twelve months that have subsequently defaulted: Personal Banking: Residential mortgage loans — $ — — — Home equity loans — — — — Total Personal Banking — — — — Commercial Banking: Commercial real estate loans 1 429 425 31 Commercial loans 3 533 533 533 Total Business Banking 4 962 958 564 Total 4 $ 962 958 564 The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable during the year ended December 31, 2015 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 6 $ 364 357 21 Home equity loans 3 101 97 21 Total Personal Banking 9 465 454 42 Commercial Banking: Commercial real estate loans 11 12,258 12,243 1,047 Commercial loans 9 2,200 2,184 156 Total Commercial Banking 20 14,458 14,427 1,203 Total 29 $ 14,923 14,881 1,245 At December 31, 2015, no TDRs that were modified in the previous twelve months had subsequently defaulted. The following table provides information for troubled debt restructurings (including re-modified TDRs) by type of modification, by portfolio segment and class of financing receivable during the year ended December 31, 2017 : Number of Type of modification contracts Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 8 $ 359 — 8 1,188 1,555 Home equity loans 3 118 — — 30 148 Total Personal Banking 11 477 — 8 1,218 1,703 Commercial Banking: Commercial real estate loans 11 — 2,688 2,201 — 4,889 Commercial loans 7 — — 422 104 526 Total Commercial Banking 18 — 2,688 2,623 104 5,415 Total 29 $ 477 2,688 2,631 1,322 7,118 The following table provides information for troubled debt restructurings (including re-modified TDRs) by type of modification, by portfolio segment and class of financing receivable during the year ended December 31, 2016 : Number of Type of modification contracts Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 7 $ 358 — 771 48 1,177 Home equity loans 7 120 — 3 348 471 Total Personal Banking 14 478 — 774 396 1,648 Commercial Banking: Commercial real estate loans 7 — 425 1,980 1,238 3,643 Commercial loans 20 — 328 1,178 712 2,218 Total Commercial Banking 27 — 753 3,158 1,950 5,861 Total 41 $ 478 753 3,932 2,346 7,509 The following table provides information related to re-modified troubled debt restructurings by portfolio segment and by class of financing receivable for the year ended December 31, 2017 : Number of re-modified Type of re-modification TDRs Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 2 $ 250 — — 429 679 Home equity loans 1 12 — — — 12 Total Personal Banking 3 262 — — 429 691 Commercial Banking: Commercial real estate loans 1 — — 1,299 — 1,299 Commercial loans 1 — — 83 — 83 Total Commercial Banking 2 — — 1,382 — 1,382 Total 5 $ 262 — 1,382 429 2,073 The following table provides information related to re-modified troubled debt restructurings by portfolio segment and by class of financing receivable for the year ended December 31, 2016 : Number of Type of re-modification TDRs Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans — $ — — — — — Home equity loans 1 — — — 192 192 Total Personal Banking 1 — — — 192 192 Commercial Banking: Commercial real estate loans 2 — — 1,329 173 1,502 Commercial loans 4 — 502 — — 502 Total Commercial Banking 6 — 502 1,329 173 2,004 Total 7 $ — 502 1,329 365 2,196 The following table provides information related to loan delinquencies as of December 31, 2017 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 23,786 6,030 12,613 42,429 2,619,951 2,662,380 — Home equity loans 6,094 2,333 6,043 14,470 1,037,088 1,051,558 — Consumer finance loans 2,128 1,113 199 3,440 15,179 18,619 — Consumer loans 9,762 2,834 3,274 15,870 537,496 553,366 — Total Personal Banking 41,770 12,310 22,129 76,209 4,209,714 4,285,923 — Commercial Banking: Commercial real estate loans 5,520 2,133 10,629 18,282 2,142,930 2,161,212 — Commercial loans 1,469 204 2,806 4,479 516,719 521,198 — Total Commercial Banking 6,989 2,337 13,435 22,761 2,659,649 2,682,410 — Total originated loans 48,759 14,647 35,564 98,970 6,869,363 6,968,333 — Acquired loans Personal Banking: Residential mortgage loans 1,998 205 1,277 3,480 110,343 113,823 381 Home equity loans 1,367 538 1,306 3,211 255,586 258,797 98 Consumer loans 1,150 517 353 2,020 97,384 99,404 10 Total Personal Banking 4,515 1,260 2,936 8,711 463,313 472,024 489 Commercial Banking: Commercial real estate loans 2,795 406 5,655 8,856 284,658 293,514 923 Commercial loans 396 237 334 967 58,571 59,538 — Total Commercial Banking 3,191 643 5,989 9,823 343,229 353,052 923 Total acquired loans 7,706 1,903 8,925 18,534 806,542 825,076 1,412 Total loans $ 56,465 16,550 44,489 117,504 7,675,905 7,793,409 1,412 (1) Represents acquired loans that were originally recorded at fair value upon acquisition. These loans are considered to be accruing because we can reasonably estimate future cash flows and expect to fully collect the carrying value of these loans. Therefore, we are accreting the difference between the carrying value and their expected cash flows into interest income. The following table provides information related to loan delinquencies as of December 31, 2016 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 26,212 5,806 12,792 44,810 2,519,845 2,564,655 — Home equity loans 5,785 1,305 4,783 11,873 1,031,040 1,042,913 — Consumer finance loans 1,255 766 743 2,764 46,217 48,981 Consumer loans 7,343 2,438 2,775 12,556 415,508 428,064 — Total Personal Banking 40,595 10,315 21,093 72,003 4,012,610 4,084,613 — Commercial Banking: Commercial real estate loans 7,674 3,674 16,508 27,856 1,944,227 1,972,083 — Commercial loans 1,067 1,957 3,107 6,131 449,244 455,375 — Total Commercial Banking 8,741 5,631 19,615 33,987 2,393,471 2,427,458 — Total originated loans 49,336 15,946 40,708 105,990 6,406,081 6,512,071 — Acquired loans Personal Banking: Residential mortgage loans 1,174 421 829 2,424 131,087 133,511 452 Home equity loans 1,020 258 973 2,251 300,206 302,457 204 Consumer loans 1,270 405 320 1,995 163,921 165,916 15 Total Personal Banking 3,464 1,084 2,122 6,670 595,214 601,884 671 Commercial Banking: Commercial real estate loans 2,703 821 4,762 8,286 361,720 370,006 2,006 Commercial loans 111 124 413 648 72,738 73,386 147 Total Commercial Banking 2,814 945 5,175 8,934 434,458 443,392 2,153 Total acquired loans 6,278 2,029 7,297 15,604 1,029,672 1,045,276 2,824 Total loans $ 55,614 17,975 48,005 121,594 7,435,753 7,557,347 2,824 (1) Represents acquired loans that were originally recorded at fair value upon acquisition. These loans are considered to be accruing because we can reasonably estimate future cash flows and expect to fully collect the carrying value of these loans. Therefore, we are accreting the difference between the carrying value and their expected cash flows into interest income. Credit quality indicators: We categorize 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. We analyze business loans individually by classifying the loans by credit risk. Relationships greater than or equal to $1.0 million classified as special mention or substandard are reviewed quarterly for further deterioration or improvement to determine if the loan is appropriately classified. We use the following definitions for risk ratings other than pass: Special mention — Loans designated as special mention have specific, well-defined risk issues, which create a high level of uncertainty regarding the long-term viability of the business. Loans in this class are considered to have high-risk characteristics. A special mention loan exhibits material negative financial trends due to company-specific or systemic conditions. If these potential weaknesses are not mitigated, they threaten the borrower’s capacity to meet its debt obligations. Special mention loans still demonstrate sufficient financial flexibility to react to and positively address the root cause of the adverse financial trends without significant deviations from their current business strategy. Their potential weaknesses deserve our close attention and warrant enhanced monitoring. Substandard — Loans classified as substandard are inadequately protected by the current net worth and payment capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that we will sustain some loss if the deficiencies are not corrected. Doubtful — Loans classified as doubtful have all the weaknesses inherent in those classified as substandard. In addition, those weaknesses make collection or liquidation in full highly questionable and improbable. A loan classified as doubtful exhibits discernible loss potential, but a complete loss seems very unlikely. The possibility of a loss on a doubtful loan is high, but because of certain important and reasonably specific pending factors that may strengthen the loan, its classification as an estimated loss is deferred until a more exact status can be determined. Loss — Loans classified as loss are considered uncollectible and of such value that the continuance as a loan is not warranted. A loss classification does not mean that the loan has no recovery or salvage value; instead, it means that it is not practical or desirable to defer writing off all or a portion of a basically worthless loan even though partial recovery may be affected in the future. The following table sets forth information about credit quality indicators as of December 31, 2017 : Pass Special mention Substandard Doubtful Loss Total Originated loans Personal Banking: Residential mortgage loans $ 2,645,475 — 16,905 — — 2,662,380 Home equity loans 1,042,965 — 8,593 — — 1,051,558 Consumer finance loans 18,420 — 199 — — 18,619 Con

Accrued Interest Receivable

Accrued Interest Receivable	12 Months Ended
	Dec. 31, 2017
Interest Receivable and Other Assets [Abstract]
Accrued Interest Receivable	Accrued Interest Receivable Accrued interest receivable as of December 31, 2017 and 2016 is presented in the following table: December 31, 2017 2016 Investment securities $ 1,260 1,613 Mortgage-backed securities 1,107 910 Loans receivable 20,985 19,176 $ 23,352 21,699

Federal Home Loan Bank Stock

Federal Home Loan Bank Stock	12 Months Ended
	Dec. 31, 2017
Federal Home Loan Banks [Abstract]
Federal Home Loan Bank Stock	Federal Home Loan Bank Stock Northwest Bank is a member of the Federal Home Loan Bank system. As a member, we are required to maintain an investment in the capital stock of the FHLB of Pittsburgh in accordance with their 2015 Capital Plan, at cost, in two subclasses based on the following ranges: Membership stock purchase (Subclass B-1) ranging from 0.05 % to 1.0 % of the member asset value as defined by the FHLB, currently at 0.10 %; and Activity-based stock purchase (Subclass B-2) ranging from 2.0 % to 6.0 % of outstanding advances, currently at 4.0 %; 0.0 % to 6.0 % of acquired member assets, currently at 4.0 %; 0.0 % to 4.0 % of certain letters of credit, currently at 0.75 %; and 0.0 % to 6.0 % of outstanding advance commitments settling more than 30 days after trade, currently at 0.0 %. We received dividends on capital stock during the years ended December 31, 2017 and 2016 of $250,000 and $1.4 million , respectively. Future dividends may be established at different rates for the two subclasses of capital stock.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment Premises and equipment at December 31, 2017 and 2016 are summarized by major classification in the following table: December 31, 2017 2016 Land and land improvements $ 21,563 21,229 Office buildings and improvements 150,056 156,162 Furniture, fixtures and equipment 125,347 120,391 Leasehold improvements 19,909 19,859 Total, at cost 316,875 317,641 Less accumulated depreciation and amortization (164,931 ) (156,456 ) Premises and equipment, net $ 151,944 161,185 Depreciation and amortization expense for the years ended December 31, 2017 , 2016 and 2015 was $12.4 million , $13.7 million and $13.3 million , respectively. Premises used by certain of our offices are occupied under formal operating lease arrangements. The leases expire on various dates through 2027. Minimum annual rentals by fiscal year are summarized in the following table: 2018 $ 4,395 2019 3,300 2020 2,726 2021 2,232 2022 1,620 Thereafter 7,413 Total $ 21,686 Rental expense for the years ended December 31, 2017 , 2016 and 2015 was $5.6 million , $5.3 million and $4.6 million , respectively.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The following table provides information for intangible assets subject to amortization for the years ended December 31, 2017 and 2016 : December 31, 2017 2016 Amortizable intangible assets: Core deposit intangibles - gross $ 63,685 37,953 Acquisitions — 25,732 Less: accumulated amortization (40,029 ) (34,378 ) Core deposit intangibles - net $ 23,656 29,307 Customer and Contract intangible assets - gross $ 10,474 8,496 Acquisitions — 1,978 Less: accumulated amortization (8,461 ) (7,348 ) Customer and Contract intangible assets - net $ 2,013 3,126 The following information shows the actual aggregate amortization expense for the years ended December 31, 2017 , 2016 and 2015 as well as the estimated aggregate amortization expense, based upon current levels of intangible assets, for each of the five succeeding fiscal years: For the year ended December 31, 2015 $ 1,688 For the year ended December 31, 2016 4,259 For the year ended December 31, 2017 6,764 For the year ending December 31, 2018 5,848 For the year ending December 31, 2019 4,933 For the year ending December 31, 2020 4,017 For the year ending December 31, 2021 3,188 For the year ending December 31, 2022 2,456 The following table provides information for the changes in the carrying amount of goodwill: Total Balance at December 31, 2015 $ 261,736 Goodwill acquired 45,684 Balance at December 31, 2016 307,420 Goodwill acquired — Balance at December 31, 2017 $ 307,420 We have determined that goodwill is not impaired as of December 31, 2017 and 2016 . There were no changes in our operations that would cause us to update the goodwill impairment test performed as of June 30, 2017 .

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Deposits	Deposits Deposit balances at December 31, 2017 and 2016 are shown in the table below: December 31, 2017 2016 Savings deposits $ 1,653,579 1,622,879 Interest-bearing demand deposits 1,442,928 1,428,317 Noninterest-bearing demand deposits 1,610,409 1,448,972 Money market deposit accounts 1,707,450 1,841,567 Time deposits 1,412,623 1,540,586 Total deposits $ 7,826,989 7,882,321 The aggregate amount of time deposits with a minimum denomination of $100,000 at December 31, 2017 and 2016 was $436.4 million and $451.6 million , respectively. Generally, deposits in excess of $250,000 are not federally insured. At December 31, 2017 we had $1.639 billion of deposits in accounts exceeding $250,000 . The following table summarizes the contractual maturity of time deposits at December 31, 2017 and 2016 : December 31, 2017 2016 Due within 12 months $ 666,348 836,525 Due between 12 and 24 months 226,171 311,976 Due between 24 and 36 months 201,654 153,708 Due between 36 and 48 months 131,530 90,777 Due between 48 and 60 months 174,704 134,687 After 60 months 12,216 12,913 Total time deposits $ 1,412,623 1,540,586 The following table summarizes the interest expense incurred on the respective deposits for the years ended December 31, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Savings deposits $ 3,062 3,218 3,387 Interest-bearing demand deposits 1,027 462 568 Money market deposit accounts 4,203 3,621 3,222 Time deposits 14,765 16,164 16,878 Total interest expense $ 23,057 23,465 24,055

Borrowed Funds

Borrowed Funds	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowed Funds	Borrowed Funds (a) Borrowings Borrowed funds at December 31, 2017 and 2016 are presented in the following table: December 31, 2017 2016 Amount Average rate Amount Average rate Collateralized borrowings, due within one year $ 108,238 0.20 % $ 142,899 0.17 % Borrowings from the FHLB of Pittsburgh, if any, are secured by our residential first mortgage and other qualifying loans. Certain of these borrowings are subject to restrictions or penalties in the event of prepayment. The revolving line of credit with the FHLB of Pittsburgh carries a commitment of $150.0 million . The rate is adjusted daily by the FHLB of Pittsburgh, and any borrowings on this line may be repaid at any time without penalty. At December 31, 2017 collateralized borrowings, due within one year were $108.2 million , and $142.9 million at December 31, 2016 . The collateralized borrowings are collateralized by various securities held in safekeeping by the FHLB of Pittsburgh. The market value of these securities exceeds the value of the collateralized borrowings. The average amount of collateralized borrowings outstanding in the years ended December 31, 2017 , 2016 and 2015 was $121.0 million , $141.6 million and $144.7 million , respectively. The maximum amount of collateralized borrowings outstanding during the years ended December 31, 2017 , 2016 and 2015 was $137.2 million , $158.4 million and $166.4 million , respectively. (b) Trust Preferred Securities We have three statutory business trusts: Northwest Bancorp Capital Trust III, a Delaware statutory business trust, Northwest Bancorp Statutory Trust IV, a Connecticut statutory business trust and LNB Trust II, a Delaware statutory business trusts (the Trusts). The trusts exist solely to issue preferred securities to third parties for cash, issue common securities to the Company in exchange for capitalization of the Trusts, invest the proceeds from the sale of trust securities in an equivalent amount of debentures of the Company, and engage in other activities that are incidental to those previously listed. Northwest Bancorp Capital Trust III issued 50,000 cumulative trust preferred securities in a private transaction to a pooled investment vehicle on December 5, 2005 (liquidation value of $1,000 per preferred security or $50,000,000 ) with a stated maturity of December 30, 2035 and a floating rate of interest, which is reset quarterly, equal to three-month LIBOR plus 1.38% . Northwest Bancorp Statutory Trust IV issued 50,000 cumulative trust preferred securities in a private transaction to a pooled investment vehicle on December 15, 2005 (liquidation value of $1,000 per preferred security or $50,000,000 ) with a stated maturity of December 15, 2035 and a floating rate of interest, which is reset quarterly, equal to three-month LIBOR plus 1.38% . LNB Trust II had 7,875 cumulative trust preferred securities outstanding (liquidation value of $1,000 per preferred security or $7,875,000 ) with a stated maturity of June 15, 2037 an a floating rate of interest, which resets quarterly, equal to three-month LIBOR plus 1.48% . As the shareholders of the trust preferred securities are the primary beneficiaries of the Trusts, the Trusts are not consolidated in our financial statements. The Trusts have invested the proceeds of the offerings in junior subordinated deferrable interest debentures issued by the Company. The structure of these debentures mirrors the structure of the trust-preferred securities. Northwest Bancorp Capital Trust III holds $51,547,000 of the Company’s junior subordinated debentures due December 30, 2035 with a floating rate of interest, reset quarterly, of three-month LIBOR plus 1.38% . The rate in effect at December 31, 2017 was 3.07% . Northwest Bancorp Statutory Trust IV holds $51,547,000 of the Company’s junior subordinated debentures due December 15, 2035 with a floating rate of interest, reset quarterly, of three-month LIBOR plus 1.38% . The rate in effect at December 31, 2017 was 2.97% . LNB Trust II holds $8,119,000 of the Company's junior subordinated debentures due June 15, 2037, with a floating rate of interest, reset quarterly, of three-month LIBOR plus 1.48% . The rate in effect at December 31, 2017 was 3.07% . Cash distributions on the trust securities are made on a quarterly basis to the extent interest on the debentures is received by the Trusts. We have the right to defer payment of interest on the subordinated debentures at any time, or from time-to-time, for periods not exceeding 5 years . If interest payments on the subordinated debentures are deferred, the distributions on the trust securities also are deferred. To date there have been no interest deferrals. Interest on the subordinated debentures and distributions on the trust securities is cumulative. Our obligation constitutes a full, irrevocable, and unconditional guarantee on a subordinated basis of the obligations of the trust under the preferred securities. The Trusts must redeem the preferred securities when the debentures are paid at maturity or upon an earlier redemption of the debentures to the extent the debentures are redeemed. All or part of the debentures may be redeemed at any time. Also, the debentures may be redeemed at any time if existing laws or regulations, or the interpretation or application of these laws or regulations, change causing: • the interest on the debentures to no longer be deductible by the Company for federal income tax purposes; • the trust to become subject to federal income tax or to certain other taxes or governmental charges; • the trust to register as an investment company; or • the preferred securities do not qualify as Tier I capital. We may, at any time, dissolve any of the Trusts and distribute the debentures to the trust security holders, subject to receipt of any required regulatory approval(s). The following table sets forth a summary of guaranteed capital debt securities and junior subordinated deferrable interest debentures held by the trusts as of December 31, 2017 and 2016 : Capital debt December 31, securities 2017 2016 Northwest Bancorp Capital Trust III $ 50,000 51,547 51,547 Northwest Bancorp Statutory Trust IV 50,000 51,547 51,547 LNB Trust II 7,875 8,119 8,119 Total $ 107,875 111,213 111,213

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Total income tax was allocated for the years ended December 31, 2017 , 2016 and 2015 as follows: Years ended December 31, 2017 2016 2015 Income before income taxes $ 41,444 21,648 27,960 Shareholders’ equity for unrealized (loss)/ gain on securities available-for-sale (3,403 ) (1,871 ) (85 ) Shareholders’ equity for tax benefit for excess of fair value above cost of stock benefit plans — (1,425 ) (332 ) Shareholders’ equity for pension adjustment (213 ) (2,455 ) (848 ) Shareholders’ equity for swap fair value adjustment 585 539 699 Unallocated income tax $ 38,413 16,436 27,394 Income tax expense applicable to income before taxes consists of: Years ended December 31, 2017 2016 2015 Current $ 30,127 18,914 21,670 Deferred 11,317 2,734 6,290 Total income tax expense $ 41,444 21,648 27,960 A reconciliation of the expected federal statutory income tax rate to the effective rate, expressed as a percentage of pretax income for the years ended December 31, 2017 , 2016 and 2015 , is as follows: Years ended December 31, 2017 2016 2015 Expected tax rate 35.0 % 35.0 % 35.0 % Tax-exempt interest income (1.5 )% (3.3 )% (3.0 )% State income tax, net of federal benefit 3.2 % 1.2 % 2.9 % Bank-owned life insurance (1.6 )% (2.6 )% (1.7 )% Stock-based compensation (0.9 )% — % — % Dividends on stock plans (1.1 )% (2.0 )% (0.8 )% Low income housing and historic tax credits (0.5 )% (1.0 )% (1.4 )% Non-deductible acquisition expense — % — % 0.5 % ESOP termination — % 3.4 % — % Adjustment to net deferred tax liabilities for enacted changes in tax laws and rates (2.3 )% — % — % Other 0.2 % (0.3 )% 0.1 % Effective tax rate 30.5 % 30.4 % 31.6 % 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 presented below: December 31, 2017 2016 Deferred tax assets: Deferred rent $ 87 187 Deferred compensation expense 1,040 2,893 Bad debts 10,277 18,823 Other reserves 953 1,823 Accrued postretirement benefit cost 413 641 Stock benefit plans 744 1,085 Writedown of investment securities 104 2,875 Accrued expenses 35 95 Pension and postretirement benefits 13,033 18,491 Unrealized loss on the fair value of derivatives 223 958 Unrealized loss on the fair value of securities available-for-sale 2,160 — Purchase accounting — 1,215 Deferred income 1,001 253 Other 141 153 Total deferred tax assets 30,211 49,492 Deferred tax liabilities: Pension expense 5,542 8,689 Unrealized gain on the fair value of securities available-for-sale — 252 Purchase accounting 303 — Intangible assets 13,546 21,927 Mortgage servicing rights 777 1,559 Fixed assets 4,940 8,107 Net deferred loan fees 4,690 — Other 274 635 Total deferred tax liabilities 30,072 41,169 Net deferred tax asset $ 139 8,323 We recorded a valuation allowance against state deferred tax assets of a Northwest subsidiary since the subsidiary is not expected to utilize its deferred tax assets in the foreseeable future. This valuation allowance is netted against other deferred tax assets in the preceding table. Other than stated above, we have determined that no valuation allowance is necessary for the deferred tax assets because it is more likely than not that these assets will be realized through future reversals of existing temporary differences and through future taxable income. We will continue to review the criteria related to the recognition of deferred tax assets on a regular basis. We utilize a comprehensive model to recognize, measure, present and disclose in our financial statements uncertain tax positions that the company has taken or expects to take on a tax return. At December 31, 2017 , there were no unrecognized tax benefits that, if recognized, would favorably affect the effective income tax rate. We recognize interest accrued and penalties (if any) related to unrecognized tax benefits in income tax expense. During the year ended December 31, 2017 , we did not accrue any interest. At December 31, 2017 , we had no amount accrued for interest or the payment of penalties. We are subject to routine audits of our tax returns by the Internal Revenue Service as well as all states in which we conduct business. We are subject to audit by the Internal Revenue Service for the tax periods ended December 31, 2017 , 2016 , 2015 and 2014 and subject to audit by any state in which we conduct business for the tax periods ended December 31, 2017 , 2016 , 2015 and 2014 . The New York State audit of the Company's 2011to 2014 tax years was finalized in 2016, resulting in an additional tax liability of $ 444,000 . The Internal Revenue Service audit of the 2013 tax year of LNB was concluded in 2016 and resulted in no additional tax liability. The Act reduces our corporate federal tax rate from 35.0% to 21.0% effective January 1, 2018. As a result we are required to re-measure, through income tax expense, 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 liability resulted in a 2017 income tax benefit of $ 3.1 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 effects 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 from the Act’s enactment date to complete the necessary accounting. We recorded provisional amounts of deferred income taxes using reasonable estimates in five areas where information necessary to complete the accounting was not available, prepared, or analyzed: (i) our 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 purchased and placed in service after September 27, 2017; (ii) our deferred tax asset for temporary differences 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; (iii) our deferred tax liability for temporary differences associated with equity investments in partnerships is awaiting receipt of Schedules K-1 from outside preparers, which is necessary to determine our 2017 tax impact from these investments; (iv) our deferred tax liability for temporary differences related to our qualified pension plan is based upon actuarial reports from our third party provider, however we are still in the process of determining if a contribution related to the 2017 plan year will be made; (v) our deferred tax liability for temporary differences related to deferred loans fees is based upon the assumption the IRS will accept the tax treatment requested in the consent change in tax accounting method filed in 2017. In a sixth area, we 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. There is uncertainty in applying the newly-enacted rules to existing contracts, and we are seeking further clarifications before completing our analysis. We will complete and record the income tax effects of these provisional items during the period the necessary information becomes available. This measurement period will not extend beyond December 22, 2018.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity Retained earnings are partially restricted in connection with regulations related to the insurance of deposit accounts, which requires Northwest to maintain certain statutory reserves. Northwest may not pay dividends on or repurchase any of its common stock if the effect thereof would reduce retained earnings below the level of adequate capitalization as defined by federal and state regulators. In tax years prior to fiscal 1997, Northwest was permitted, under the Internal Revenue Code ("IRC"), to deduct an annual addition to a reserve for bad debts in determining taxable income, subject to certain limitations. Bad debt deductions for income tax purposes are included in taxable income of later years only if the bad debt reserve is used subsequently for purposes other than to absorb bad debt losses. Because Northwest does not intend to use the reserve for purposes other than to absorb losses, no deferred income taxes have been provided prior to fiscal 1987. Retained earnings at December 31, 2017 and 2016 include approximately $39.1 million representing such bad debt deductions for which no deferred income taxes have been provided.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per common share ("EPS") is computed by dividing net income available to common shareholders by the weighted average number of common shares outstanding for the period, without considering any dilutive items. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in our earnings. All stock options outstanding during the years ended December 31, 2017 and 2016 were included in the computation of diluted earnings per share because the stock options exercise price was less than the average market price of the common shares of $16.64 and $14.79 , respectively. For the year ended December 31, 2015 there were 524,250 options outstanding with a weighted average exercise price of $13.15 per share that were excluded in the computation of diluted earnings per share because the stock options’ exercise price was greater than the average market price of the common shares of $12.64 . The computation of basic and diluted earnings per share for the years ended December 31, 2017 , 2016 and 2015 follows: Years ended December 31, 2017 2016 2015 Net income available to common shareholders $ 94,467 49,667 60,540 Weighted average common shares outstanding 101,015,083 99,439,174 94,314,420 Dilutive potential shares due to effect of stock options 1,549,822 1,225,514 515,369 Total weighted average common shares and dilutive potential shares 102,564,905 100,664,688 94,829,789 Basic earnings per share (1) $ 0.94 0.50 0.64 Diluted earnings per share (1) $ 0.92 0.49 0.64 (1) Not in thousands.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans (a) Pension Plans We maintain noncontributory defined benefit pension plans covering substantially all employees and members of our board of directors. Retirement benefits are based on certain compensation levels, age, and length of service. Contributions are based on an actuarially determined amount to fund not only benefits attributed to service to date but also for those expected to be earned in the future. In addition, we have an unfunded Supplemental Executive Retirement Plan (“SERP”) to compensate those executive participants eligible for the defined benefit pension plan whose benefits are limited by Section 415 of the IRC. We also sponsor a retirement savings plan in which substantially all employees participate. We provide a matching contribution of 100% of each employee’s contribution to a maximum of 4% of the employee’s compensation. Total expense for all retirement plans, including defined benefit pension plans, was approximately $6.8 million , $5.8 million and $4.6 million , for the years ended December 31, 2017 , 2016 and 2015 , respectively. Components of net periodic pension cost and other amounts recognized in other comprehensive income: The following table sets forth the net periodic pension cost for the defined benefit pension plans for the years ended December 31, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Service cost $ 6,149 5,496 5,721 Interest cost 6,879 6,781 6,125 Expected return on plan assets (10,512 ) (9,897 ) (10,371 ) Net amortization and deferral 1,388 1,388 1,375 Net periodic pension cost $ 3,904 3,768 2,850 The following table sets forth other changes in the defined benefit pension plans’ plan assets and benefit obligations recognized in other comprehensive income: Years ended December 31, 2017 2016 2015 Net loss/ (gain) $ (1,647 ) 1,550 (420 ) Prior service cost/ (credit) — — — Amortization of prior service cost 2,323 2,323 2,323 Total recognized in other comprehensive income $ 676 3,873 1,903 Total recognized in net periodic pension cost and other comprehensive income/ (loss) $ 4,580 7,641 4,753 The estimated net loss and prior service credit for the defined benefit pension plan that will be amortized from accumulated other comprehensive income into net periodic cost over the next year is $3.3 million and $(2.3) million , respectively. The following table sets forth information for the defined benefit pension plans’ funded status at December 31, 2017 and 2016 : December 31, 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 172,208 162,133 Service cost 6,149 5,496 Interest cost 6,879 6,781 Acquisition — — Actuarial (gain)/ loss 14,807 4,267 Benefits paid (6,901 ) (6,469 ) Benefit obligation at end of year $ 193,142 172,208 Change in plan assets: Fair value of plan assets at beginning of year $ 152,625 143,655 Actual return on plan assets 23,255 8,903 Employer contributions 4,689 6,536 Acquisition — — Benefits paid (6,901 ) (6,469 ) Fair value of plan assets at end of period $ 173,668 152,625 Funded status at end of year $ (19,474 ) (19,583 ) The following table sets forth the assumptions used to develop the net periodic pension cost: Years ended December 31, 2017 2016 2015 Discount rate 4.06 % 4.25 % 3.89 % Expected long-term rate of return on assets 7.00 % 7.00 % 7.50 % Rate of increase in compensation levels 3.00 % 3.00 % 3.00 % The following table sets forth the assumptions used to determine benefit obligations at the end of each period: Years ended December 31, 2017 2016 2015 Discount rate 3.53 % 4.06 % 4.25 % Expected long-term rate of return on assets 7.00 % 7.00 % 7.00 % Rate of increase in compensation levels 3.00 % 3.00 % 3.00 % The expected long-term rate of return on assets is based on the expected return of each of the asset categories, weighted based on the median of the target allocation for each category. We use the Citigroup Pension Liability Index rates matching the duration of our benefit payments as of the measurement date to determine the discount rate. The accumulated benefit obligation for the funded defined benefit pension plan was $186.9 million , $165.9 million and $155.9 million at December 31, 2017 , 2016 and 2015 , respectively. The accumulated benefit obligation for all unfunded defined benefit plans was $6.2 million , $6.3 million and $6.3 million at December 31, 2017 , 2016 and 2015 , respectively. The following table sets forth certain information related to our pension plans: December 31, 2017 2016 Projected benefit obligation $ 193,142 172,208 Accumulated benefit obligation 193,142 172,208 Fair value of plan assets 173,668 152,625 We anticipate making a contribution to our defined benefit pension plan of $4.0 million to $6.0 million during the year ending December 31, 2018 . The investment policy as established by the Plan Administrative Committee, to be followed by the Trustee, is to invest assets based on the target allocations shown in the table below. To meet target allocation ranges set forth by the Plan Administrative Committee, periodically, the assets are reallocated by the Trustee. The investment policy is reviewed periodically to determine if the policy should be changed. Pension assets are conservatively invested with the goal of providing market or better returns with below market risks. Assets are invested in a balanced portfolio composed primarily of equities, fixed income, and cash or cash equivalent investments. The Trustee tries to maintain an approximate asset mix position of 30% to 60% equities and 20% to 50% bonds. A maximum of 10% may be invested in any one stock, including the stock of Northwest Bancshares, Inc. The objective of holding equity securities is to provide capital appreciation consistent with the ownership of the common stocks of medium to large companies. Acceptable bond investments are direct or agency obligations of the U.S. Government or investment grade corporate bonds. The average maturity of the bond portfolio shall not exceed 10 years . The following table sets forth the weighted average asset allocation of defined benefit plans: Target December 31, allocation 2017 2016 Debt securities 20 – 50% 23 % 23 % Equity securities 30 – 60% 73 % 72 % Other 5 – 50% 4 % 5 % Total 100 % 100 % All of the assets held by the defined benefit pension plan are measured and recorded at estimated fair value on our balance sheet on a recurring basis as Level 1 assets, as defined by the fair value hierarchy defined in note 15. The following table sets forth the pension plan assets as of December 31, 2017 and 2016 : December 31, 2017 2016 Mutual funds - debt $ 40,010 35,224 Mutual funds - equity 125,871 110,078 Cash and cash equivalents 7,787 7,322 The benefits expected to be paid in each year from 2018 to 2022 are $5.9 million , $6.4 million , $6.6 million , $7.0 million and $7.5 million , respectively. The aggregate benefits expected to be paid in the five years from 2023 to 2027 are $42.6 million . The expected benefits to be paid are based on the same assumptions used to measure our benefit obligations at December 31, 2017 and include estimated future employee service. (b) Postretirement Healthcare Plan In addition to pension benefits, we provide postretirement healthcare benefits for certain employees who were employed as of October 1, 1993 and were at least 55 years of age on that date. We use the accrual method of accounting for postretirement benefits other than pensions. Components of net periodic benefit cost and other amounts recognized in other comprehensive income: The following table sets forth the net periodic benefit cost for the postretirement healthcare benefits plan for the years ended December 31, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Service cost $ — — — Interest cost 68 70 58 Amortization of net loss 108 90 60 Net period benefit cost $ 176 160 118 The following table sets forth other changes in the postretirement healthcare plan’s plan assets and benefit obligations recognized in other comprehensive income: Years ended December 31, 2017 2016 2015 Net loss/ (gain) $ (156 ) 109 273 Total recognized in other comprehensive income $ (156 ) 109 273 Total recognized in net periodic benefit cost and other comprehensive income $ 20 269 391 The estimated net loss for the postretirement healthcare benefit plan that will be amortized from accumulated other comprehensive income into net periodic benefit cost over the year ending December 31, 2018 is $98,000 . The following table sets forth the funded status of the postretirement healthcare benefit plan at December 31, 2017 and 2016 : December 31, 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 1,779 1,737 Service cost — — Interest cost 68 70 Actuarial loss (48 ) 200 Benefits paid (162 ) (228 ) Benefit obligation at end of year $ 1,637 1,779 Change in plan assets: Fair value of plan assets at beginning of year $ — — Employer contributions 162 228 Benefits paid (162 ) (228 ) Fair value of plan assets at end of year $ — — Funded status at year end $ (1,637 ) (1,779 ) The assumptions used to develop the preceding information for postretirement healthcare benefits are as follows: Years ended December 31, 2017 2016 2015 Discount rate 4.06 % 4.25 % 3.89 % Monthly cost of healthcare insurance per beneficiary (1) $ 548 539 470 Annual rate of increase in healthcare costs 4.00 % 4.00 % 4.00 % (1) Not in thousands If the assumed rate of increase in healthcare costs was increased by one percentage point to 5% from the level presented above, the interest cost component of net periodic postretirement healthcare benefit cost would increase by $8,000 and the accumulated postretirement benefit obligation for healthcare benefits would increase by $58,000 . The following table sets forth information for plans with an accumulated benefit obligation in excess of plan assets: December 31, 2017 2016 Projected benefit obligation $ 1,637 1,779 Accumulated benefit obligation 1,637 1,779 Fair value of plan assets — — (c) Employee Stock Ownership Plan On September 30, 2016, the Northwest Savings Bank Employee Stock Ownership Plan ("ESOP") was terminated and merged into the Northwest Bank 401(k) Plan. ESOP compensation expense was $0 , $6.3 million and $335,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. Compensation expense related to the ESOP was recognized at an amount equal to the number of common shares committed to be released by the ESOP to participants’ accounts multiplied by the average fair value of the common stock during the reporting period. The difference between the fair value of the shares of the common stock committed to be allocated by the ESOP to participants’ accounts for the period and the average cost of those common shares is recorded as an adjustment to either additional paid-in capital or retained earnings. (d) Common Stock Awards On April 20, 2011, we established the Northwest Bancshares, Inc. 2011 Equity Incentive Plan with 2,806,233 common shares authorized. On May 20, 2015, we awarded employees 282,050 common shares and outside directors 24,300 common shares with a grant date fair value of $12.31 per share (total market value of $3.8 million at issuance). On May 18, 2016, we awarded employees 310,160 common shares and outside directors 24,300 common shares with a grant date fair value of $14.51 per share (total market value of $4.9 million at issuance). On May 17, 2017, we awarded employees 378,050 common shares and outside directors 24,300 common shares with a grant date fair value of $15.24 per share (total market value of $5.8 million at issuance). Total common shares forfeited from the 2011 plan were 415,154 , of which, 105,600 shares were forfeited during the year ended December 31, 2017 . Forfeited shares may be awarded to other eligible recipients in future grants until the plan termination date in 2021. Common shares vest over a 10 -year period with the first vesting occurring on the grant date. As of December 31, 2017 , 30% of the 2015 issuances have vested, 20% of the 2016 issuances have vested and 10% of the 2017 issuances have vested. Once shares have vested, they are no longer restricted. Compensation expense, in the amount of the fair market value of the common stock at the date of the grant, will be recognized pro rata over the periods in which the shares vest. While restricted, the recipients are entitled to all shareholder rights, except that the shares may not be sold, pledged, or otherwise disposed of and are required to be held in a trust. (e) Stock Option Plans The Northwest Bancshares, Inc. 2011 Equity Incentive Plan also authorizes the granting of 7,015,583 stock options. On May 20, 2015, we granted employees 660,570 stock options and outside directors 64,800 stock options with an exercise price of $12.37 per share. On May 18, 2016, we granted employees 660,600 stock options and outside directors 64,800 stock options with an exercise price of $14.15 per share. On May 17, 2017, we granted employees 754,210 stock options and outside directors 64,800 stock options with an exercise price of $15.57 per share. Awarded stock options vest over a ten -year period with the first vesting occurring on the grant date with a ten year exercise period from the grant date. The following table summarizes the activity in our option plans during the years ended December 31, 2017 , 2016 and 2015 (amounts in this table are not in thousands): Years ended December 31, 2017 2016 2015 Number Weighted average exercise price Number Weighted average exercise price Number Weighted average exercise price Balance at beginning of year 5,804,105 $ 12.25 6,306,496 $ 11.81 6,402,407 $ 11.65 Granted (1) 819,010 15.57 725,400 14.15 665,370 12.37 Exercised (2) (630,591 ) 11.66 (1,081,072 ) 11.01 (474,253 ) 10.27 Forfeited/ expired (296,954 ) 12.43 (146,719 ) 12.71 (287,028 ) 12.26 Balance at end of year 5,695,570 12.75 5,804,105 12.25 6,306,496 11.81 Exercisable at end of year 3,016,367 11.99 3,035,718 11.71 3,431,113 11.42 (1) Weighted average fair value of options at grant date: $1.55 , $1.52 and $1.14 , respectively. (2) The total intrinsic value of options exercised was $3.5 million , $5.1 million and $1.2 million , respectively. The aggregate intrinsic value of all options expected to vest and fully vested options at December 31, 2017 is $8.6 million and $14.3 million , respectively. The following table summarizes the number of options outstanding, number of options exercisable, and weighted average remaining life of all option grants as of December 31, 2017 : Exercise Exercise Exercise Exercise Exercise Exercise Exercise Options outstanding: Number of options 164,289 143,224 48,027 260,456 384,380 342,789 14,500 Weighted average remaining contract life (years) 1.25 1.00 0.25 2.25 4.50 3.25 3.50 Options exercisable: Number of options 164,289 143,224 48,027 260,456 237,916 299,253 13,000 Weighted average remaining term - vested (years) 1.25 1.00 0.25 2.25 4.50 3.25 3.50 Exercise Exercise Exercise Exercise Exercise Exercise Total Options outstanding: Number of options 1,537,329 522,750 427,090 440,653 643,998 766,085 5,695,570 Weighted average remaining contract life (years) 3.50 7.50 5.50 6.50 8.50 9.50 5.46 Options exercisable: Number of options 1,079,159 163,646 226,292 178,091 126,374 76,640 3,016,367 Weighted average remaining term - vested (years) 3.50 7.50 5.50 6.50 8.50 9.50 4.04

Disclosures About Fair Value of

Disclosures About Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Disclosures About Fair Value of Financial Instruments	Disclosures About Fair Value of Financial Instruments We are required to disclose fair value information about financial instruments whether or not recognized in the consolidated statement of financial condition. Fair value information of certain financial instruments and all nonfinancial instruments is not required to be disclosed. Accordingly, the aggregate fair value amounts presented do not represent the underlying value of the Company. Financial assets and liabilities recognized or disclosed at fair value on a recurring basis and certain financial assets and liabilities on a non-recurring basis are accounted for using a three-level hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. This hierarchy gives the highest priority to quoted prices with readily available independent data in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable market inputs (Level 3). When various inputs for measurement fall within different levels of the fair value hierarchy, the lowest level input that has a significant impact on fair value measurement is used. Financial assets and liabilities are categorized based upon the following characteristics or inputs to the valuation techniques: • Level 1 - Financial assets and liabilities for which inputs are observable and are obtained from reliable quoted prices for identical assets or liabilities in actively traded markets. This is the most reliable fair value measurement and includes, for example, active exchange-traded equity securities. • Level 2 - Financial assets and liabilities for which values are based on quoted prices in markets that are not active or for which values are based on similar assets or liabilities that are actively traded. Level 2 also includes pricing models in which the inputs are corroborated by market data, for example, matrix pricing. • Level 3 - Financial assets and liabilities for which values are based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. Level 3 inputs include the following: • Quotes from brokers or other external sources that are not considered binding; • Quotes from brokers or other external sources where it cannot be determined that market participants would in fact transact for the asset or liability at the quoted price; • Quotes and other information from brokers or other external sources where the inputs are not deemed observable. We are responsible for the valuation process and as part of this process may use data from outside sources in establishing fair value. We perform due diligence to understand the inputs used or how the data was calculated or derived. We also corroborate the reasonableness of external inputs in the valuation process. The carrying amounts reported in the consolidated statement of financial condition approximate fair value for the following financial instruments: cash on hand, interest-earning deposits in other institutions, federal funds sold and other short-term investments, accrued interest receivable, accrued interest payable, and marketable securities available-for-sale. Marketable Securities Where available, market values are based on quoted market prices, dealer quotes, and prices obtained from independent pricing services. Debt securities — available-for-sale - Generally, debt securities are valued using pricing for similar securities, recently executed transactions and other pricing models utilizing observable inputs. The valuation for most debt securities is classified as Level 2. Securities within Level 2 include corporate bonds, municipal bonds, mortgage-backed securities and US government obligations. Certain debt securities which were AAA rated at purchase do not have an active market and as such we have used an alternative method to determine the fair value of these securities. The fair value has been determined using a discounted cash flow model using market assumptions, which generally include cash flow, collateral and other market assumptions. As such, securities which otherwise would have been classified as level 2 securities if an active market for those assets or similar assets existed are included herein as level 3 assets. Other debt securities, pooled trust preferred securities rated below AA at purchase, have a fair value based on a discounted cash flow model using similar assumptions to those noted above and accordingly are classified as level 3 assets. Equity securities — available-for-sale - Level 1 securities include publicly traded securities valued using quoted market prices. We consider the financial condition of the issuer to determine if the securities have indicators of impairment. Debt securities — held-to-maturity - The fair value of debt securities held to maturity is determined in the same manner as debt securities available for sale. Loans Receivable Loans with comparable characteristics including collateral and re-pricing structures are segregated for valuation purposes. Each loan pool is separately valued utilizing a discounted cash flow analysis. Projected monthly cash flows are discounted to present value using a market rate for comparable loans, which is not considered an exit price. Characteristics of comparable loans include remaining term, coupon interest, and estimated prepayment speeds. Delinquent loans are separately evaluated given the impact delinquency has on the projected future cash flow of the loan including the approximate discount or market rate, which is not considered an exit price. FHLB Stock Due to the restrictions placed on the transferability of FHLB stock it is not practical to determine the fair value. Deposit Liabilities The estimated fair value of deposits with no stated maturity, which includes demand deposits, money market, and other savings accounts, is the amount payable on demand. Although market premiums paid for depository institutions reflect an additional value for these low-cost deposits, adjusting fair value for any value expected to be derived from retaining those deposits for a future period of time or from the benefit that results from the ability to fund interest-earning assets with these deposit liabilities is prohibited. The fair value estimates of deposit liabilities do not include the benefit that results from the low-cost funding provided by these deposits compared to the cost of borrowing funds in the market. Fair values for time deposits are estimated using a discounted cash flow calculation that applies contractual cost currently being offered in the existing portfolio to current market rates being offered locally for deposits of similar remaining maturities. The valuation adjustment for the portfolio consists of the present value of the difference of these two cash flows, discounted at the assumed market rate of the corresponding maturity. Borrowed Funds Fixed rate advances are valued by comparing their contractual cost to the prevailing market cost. The carrying amount of repurchase agreements approximates fair value. Junior Subordinated Debentures The fair value of junior subordinated debentures is calculated using the discounted cash flows at the prevailing rate of interest. Interest rate and foreign exchange swap agreements The fair value of the interest rate swaps is based upon the present value of the expected future cash flows using the LIBOR swap curve, the basis for the underlying interest rate. To price interest rate swaps, cash flows are first projected for each payment date using the fixed rate for the fixed side of the swap and the forward rates for the floating side of the swap. These swap cash flows are then discounted to time zero using LIBOR zero-coupon interest rates. The sum of the present value of both legs is the fair market value of the interest rate swap. These valuations have been derived from our third party vendor’s proprietary models rather than actual market quotations. The proprietary models are based upon financial principles and assumptions that we believe to be reasonable. The fair value of the foreign exchange swap is derived from proprietary models rather than actual market quotations. The proprietary models are based upon financial principles and assumptions we believe to be reasonable. Off-Balance Sheet Financial Instruments These financial instruments generally are not sold or traded, and estimated fair values are not readily available. However, the fair value of commitments to extend credit and standby letters of credit is estimated using the fees currently charged to enter into similar agreements. Commitments to extend credit are generally short-term in nature and, if drawn upon, are issued under current market terms. At December 31, 2017 and 2016 , there was no significant unrealized appreciation or depreciation on these financial instruments. The following table sets forth the carrying amount and estimated fair value of our financial instruments included in the consolidated statement of financial condition at December 31, 2017 and 2016 : December 31, 2017 Carrying Estimated amount fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 77,710 77,710 77,710 — — Securities available-for-sale 792,535 792,535 574 791,961 — Securities held-to-maturity 29,678 29,667 — 29,667 — Loans receivable, net 7,736,614 7,762,562 3,128 — 7,759,434 Accrued interest receivable 23,352 23,352 23,352 — — Interest rate swaps 214 214 — 214 — FHLB Stock 11,733 11,733 — — — Total financial assets $ 8,671,836 8,697,773 104,764 821,842 7,759,434 Financial liabilities: Savings and checking accounts $ 6,414,366 6,414,366 6,414,366 — — Time deposits 1,412,623 1,433,380 — — 1,433,380 Borrowed funds 108,238 108,238 108,238 — — Junior subordinated debentures 111,213 110,954 — — 110,954 Interest rate swaps 1,278 1,278 — 1,278 — Foreign exchange swaps 61 61 — 61 — Accrued interest payable 460 460 460 — — Total financial liabilities $ 8,048,239 8,068,737 6,523,064 1,339 1,544,334 December 31, 2016 Carrying Estimated amount fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 389,867 389,867 389,867 — — Securities available-for-sale 826,200 826,200 4,440 812,394 9,366 Securities held-to-maturity 19,978 20,426 — 20,426 — Loans receivable, net 7,496,408 7,878,815 9,625 — 7,869,190 Accrued interest receivable 21,699 21,699 21,699 — — Interest rate swaps 238 238 — 238 — FHLB Stock 7,390 7,390 — — — Total financial assets $ 8,761,780 9,144,635 425,631 833,058 7,878,556 Financial liabilities: Savings and checking accounts $ 6,341,735 6,341,735 6,341,735 — — Time deposits 1,540,586 1,626,434 — — 1,626,434 Borrowed funds 142,899 142,899 142,899 — — Junior subordinated debentures 111,213 113,313 — — 113,313 Interest rate swaps 2,974 2,974 — 2,974 — Accrued interest payable 643 643 643 — — Total financial liabilities $ 8,140,050 8,227,998 6,485,277 2,974 1,739,747 Fair value estimates are made at a point-in-time, based on relevant market data and information about the instrument. The preceding methods and assumptions were used in estimating the fair value of financial instruments at December 31, 2017 and 2016 . There were no transfers of financial instruments between Level 1 and Level 2 during the years ended December 31, 2017 and 2016 . The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 : Level 1 Level 2 Level 3 Total at fair value Assets Equity securities $ 574 — — 574 Debt securities: U.S. government and agencies — 1 — 1 Government sponsored enterprises — 209,269 — 209,269 States and political subdivisions — 51,056 — 51,056 Corporate — 909 — 909 Total debt securities — 261,235 — 261,235 Residential mortgage-backed securities: GNMA — 29,695 — 29,695 FNMA — 82,969 — 82,969 FHLMC — 64,021 — 64,021 Non-agency — 555 — 555 Collateralized mortgage obligations: GNMA — 4,769 — 4,769 FNMA — 191,512 — 191,512 FHLMC — 157,190 — 157,190 Non-agency — 15 — 15 Total mortgage-backed securities — 530,726 — 530,726 Interest rate swaps — 214 — 214 Total assets $ 574 792,175 — 792,749 Liabilities Interest rate swaps $ — 1,278 — 1,278 Foreign exchange swaps — 61 — 61 Total liabilities $ — 1,339 — 1,339 The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2016 : Level 1 Level 2 Level 3 Total at fair value Assets Equity securities $ 4,440 — — 4,440 Debt securities: U.S. government and agencies — 6 — 6 Government sponsored enterprises — 294,170 — 294,170 States and political subdivisions — 63,070 — 63,070 Corporate — 7,614 9,366 16,980 Total debt securities — 364,860 9,366 374,226 Residential mortgage-backed securities: GNMA — 30,883 — 30,883 FNMA — 106,578 — 106,578 FHLMC — 82,115 — 82,115 Non-agency — 579 — 579 Collateralized mortgage obligations: GNMA — 6,287 — 6,287 FNMA — 95,186 — 95,186 FHLMC — 119,197 — 119,197 SBA — 6,608 — 6,608 Non-agency — 101 — 101 Total mortgage-backed securities — 447,534 — 447,534 Interest rate swaps — 238 — 238 Total assets $ 4,440 812,632 9,366 826,438 Liabilities Interest rate swaps $ — 2,974 — 2,974 Total liabilities $ — 2,974 — 2,974 The table below presents a reconciliation of all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the year ended December 31, 2017 and 2016 : December 31, 2017 2016 Debt securities Beginning balance January 1, $ 9,366 8,955 Total net realized investment gains/ (losses) and net change in unrealized appreciation/ (depreciation): Included in net income as OTTI — — Included in other comprehensive income 1,282 411 Purchases — — Sales (10,648 ) — Transfers into Level 3 — — Transfers out of Level 3 — — Ending balance December 31, $ — 9,366 Certain assets and liabilities are measured at fair value on a nonrecurring basis after initial recognition such as loans held for sale, loans measured for impairment, real estate owned, and mortgage servicing rights. The following table represents the fair market measurement for only those nonrecurring assets that had a fair market value below the carrying amount as of December 31, 2017 : Level 1 Level 2 Level 3 Total assets at fair value Loans evaluated for impairment $ — — 33,421 33,421 Real estate owned — — 5,666 5,666 Total assets $ — — 39,087 39,087 The following table represents the fair market measurement for only those nonrecurring assets that had a fair market value below the carrying amount as of December 31, 2016 : Level 1 Level 2 Level 3 Total assets at fair value Loans evaluated for impairment $ — — 41,933 41,933 Mortgage servicing rights — — 246 246 Real estate owned — — 4,889 4,889 Total assets $ — — 47,068 47,068 Loans measured for impairment - A loan is considered to be impaired as described in note 1(f). We classify impaired loans as nonrecurring Level 3. Mortgage servicing rights - Mortgage servicing rights represent the value of servicing residential mortgage loans, when the mortgage loans have been sold into the secondary market and the associated servicing has been retained. The value is determined through a discounted cash flow analysis, which uses interest rates, prepayment speeds and delinquency rate assumptions as inputs. All of these assumptions require a significant degree of management judgment. Servicing rights and the related mortgage loans are segregated into categories or homogeneous pools based upon common characteristics. Adjustments are only made when the estimated discounted future cash flows are less than the carrying value, as determined by individual pool. As such, mortgage servicing rights are classified as nonrecurring Level 3. Real estate owned - Real estate owned is comprised of property acquired through foreclosure or voluntarily conveyed by borrowers. These assets are recorded on the date acquired at the lower of the related loan balance or fair value, less estimated disposition costs, with the fair value being determined by appraisal. Subsequently, foreclosed assets are valued at the lower of the amount recorded at acquisition date or fair value, less estimated disposition costs. We classify real estate owned as nonrecurring Level 3. The following table presents additional quantitative information about assets measured at fair value on a recurring and nonrecurring basis and for which we have utilized Level 3 inputs to determine fair value at December 31, 2017 : Fair value Valuation techniques Significant unobservable inputs Range (weighted average) Loans measured for impairment $ 33,421 Appraisal Estimated costs to sell 10% value (1) Discounted cash Discount rate 4.25% to 10.0% (7.50%) flow Real estate owned 5,666 Appraisal Estimated costs to sell 10% value (1) (1) Fair value is generally determined through independent appraisals of the underlying collateral, which may include Level 3 inputs that are not identifiable, or by using the discounted cash flow method if the loan is not collateral dependent.

Regulatory Capital Requirements

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Regulatory Capital Requirements	Regulatory Capital Requirements We and our banking subsidiary are subject to various regulatory capital requirements administered by the federal and state banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory, and possibly additional discretionary actions by the regulators that, if undertaken, could have a direct material effect on our financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, specific capital guidelines that involve quantitative measures of assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices must be met. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. In July 2013, the FDIC and the other federal regulatory agencies issued a final rule that revised their leverage and risk-based capital requirements and the method for calculating risk-weighted assets to make them consistent with agreements that were reached by the Basel Committee on Banking Supervision and certain provisions of the Dodd-Frank Act. The rule limits an organization’s capital distributions and certain discretionary bonus payments if the organization does not hold a “capital conservation buffer” consisting of 2.5% of Total, Tier 1 and Common Equity Tier 1 ("CET1") capital to risk-weighted assets in addition to the amount necessary to meet its minimum risk-based capital requirements. Quantitative measures established by regulation to ensure capital adequacy require us and our banking subsidiary to maintain minimum amounts and ratios (set forth in the table below) of total, Tier 1, and CET1 capital (as defined in the regulations) to risk-weighted assets (as defined) and of Tier I capital to average assets (as defined). As of December 31, 2017 and 2016 , we and our banking subsidiary exceeded all capital adequacy requirements to which we were subject. As of December 15, 2017 , the most recent notification from the FDIC categorized Northwest Bank as “well capitalized” under the regulatory framework for prompt corrective action. To be categorized as “well capitalized,” the bank must maintain total risk-based, Tier 1 risk-based, CET 1 risk-based, and Tier 1 leverage ratios as set forth in the table. There are no conditions or events since that notification that management believes have changed the bank’s categories. The actual, required, and well capitalized levels as of December 31, 2017 and 2016 were as follows: At December 31, 2017 Minimum capital Well capitalized Actual requirements (1) requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,136,076 15.831 % $ 663,823 9.250 % $ 717,647 10.000 % Northwest Bank 1,017,251 14.189 % 663,179 9.250 % 716,951 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,079,270 15.039 % 520,294 7.250 % 574,117 8.000 % Northwest Bank 960,443 13.396 % 519,789 7.250 % 573,560 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 971,395 13.536 % 412,647 5.750 % 466,470 6.500 % Northwest Bank 960,443 13.396 % 412,247 5.750 % 430,170 6.000 % Tier 1 capital (leverage) (to average assets) Northwest Bancshares, Inc. 1,079,270 11.676 % 369,735 4.000 % 462,169 5.000 % Northwest Bank 960,443 10.400 % 369,482 4.000 % 461,853 5.000 % (1) Amounts and ratios include the 2017 capital conservation buffer of 1.250% with the exception of Tier 1 capital to average assets. For further information related to the capital conservation buffer, see Item 1. Business - "Supervision and Regulation". At December 31, 2016 Minimum capital Well capitalized Actual requirements (1) requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,051,582 14.873 % $ 609,835 8.625 % $ 707,056 10.000 % Northwest Bank 961,279 13.609 % 609,248 8.625 % 706,375 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 990,153 14.004 % 468,424 6.625 % 565,644 8.000 % Northwest Bank 900,328 12.746 % 467,973 6.625 % 565,100 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 882,278 12.478 % 362,366 5.125 % 459,586 6.500 % Northwest Bank 900,328 12.746 % 362,017 5.125 % 459,144 6.500 % Tier I capital (leverage) (to average assets) Northwest Bancshares, Inc. 990,153 10.530 % 376,116 4.000 % 470,145 5.000 % Northwest Bank 900,328 9.585 % 375,735 4.000 % 469,669 5.000 % (1) Amounts and ratios include the 2016 capital conservation buffer of 0.625% with the exception of Tier 1 capital to average assets. For further information related to the capital conservation buffer, see Item 1. Business - "Supervision and Regulation".

Contingent Liabilities

Contingent Liabilities	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities	Contingent Liabilities We and our subsidiaries are subject to a number of asserted and unasserted claims encountered in the normal course of business. Management believes that the aggregate liability, if any, that may result from such potential litigation will not have a material adverse effect on our financial statements. However, we cannot presently determine whether or not any claims against us will have a material adverse effect on our results of operations in any future reporting period.

Legal Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	Legal Proceedings We establish accruals for legal proceedings when information related to the loss contingencies represented by those matters indicates both that a loss is probable and that the amount of loss can be reasonably estimated. As of December 31, 2017 we have not accrued for legal proceedings based on our analysis of currently available information which is subject to significant judgment and a variety of assumptions and uncertainties. Any such accruals are adjusted thereafter as appropriate to reflect changes in circumstances. Due to the inherent subjectivity of assessments and unpredictability of outcomes of legal proceedings, any amounts accrued may not represent the ultimate loss to us from legal proceedings.

Components of Accumulated Other

Components of Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of Accumulated Other Comprehensive Income	Components of Accumulated Other Comprehensive Income The following table sets forth the components of accumulated other comprehensive income as of December 31, 2017 and 2016 : December 31, 2017 2016 Unrealized gain on marketable securities available-for-sale $ (4,409 ) 395 Fair value of interest rate swaps (691 ) (1,778 ) Defined benefit pension plans (26,980 ) (26,608 ) Accumulated other comprehensive income $ (32,080 ) (27,991 ) The following table shows the changes in accumulated other comprehensive income by component for the year ended December 31, 2017 : Unrealized gains and losses on securities available-for- sale Change in fair value of interest rate swaps Change in defined benefit pension plans Total Balance as of January 1, $ 395 (1,778 ) (26,608 ) (27,991 ) Other comprehensive income/ (loss) before reclassification adjustments (2,478 ) 1,087 (1,254 ) (2,645 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (2,326 ) — 882 (1,444 ) Net other comprehensive income/ (loss) (4,804 ) 1,087 (372 ) (4,089 ) Balance as of December 31, $ (4,409 ) (691 ) (26,980 ) (32,080 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $3,814 , net of tax (income tax expense) of $1,488 . (2) Consists of amortization of prior service cost (compensation and employee benefits) of $2,323 and amortization of net loss (compensation and employee benefits) of $(3,818) , net of tax (income tax expense) of $613 . The following table shows the changes in accumulated other comprehensive income by component for the year ended December 31, 2016 : Unrealized gains and losses on securities available-for- sale Change in fair value of interest rate swaps Change in defined benefit pension plans Total Balance as of January 1, $ 3,325 (2,779 ) (25,081 ) (24,535 ) Other comprehensive income/ (loss) before reclassification adjustments (2,728 ) 1,001 (2,399 ) (4,126 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (202 ) — 872 670 Net other comprehensive income/ (loss) (2,930 ) 1,001 (1,527 ) (3,456 ) Balance as of December 31, $ 395 (1,778 ) (26,608 ) (27,991 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $331 net of tax (income tax expense) of $(129) . (2) Consists of amortization of prior service cost (compensation and employee benefits) of $2,323 and amortization of net loss (compensation and employee benefits) of $(3,801) , net of tax (income tax expense) of $606 . The following table shows the changes in accumulated other comprehensive income by component for the year ended December 31, 2015 : Unrealized gains and losses on securities available-for- sale Change in fair value of interest rate swaps Change in defined benefit pension plans Total Balance as of January 1, $ 3,461 (4,078 ) (23,753 ) (24,370 ) Other comprehensive income/ (loss) before reclassification adjustments 315 1,299 (2,203 ) (589 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (451 ) — 875 424 Net other comprehensive income/ (loss) (136 ) 1,299 (1,328 ) (165 ) Balance as of December 31, $ 3,325 (2,779 ) (25,081 ) (24,535 ) (1) Consists of realized losses on securities (gain on sales of investments, net) of $740 net of tax (income tax expense) of $(289) . (2) Consists of amortization of prior service cost (compensation and employee benefits) of $2,323 and amortization of net loss (compensation and employee benefits) of $(3,758) , net of tax (income tax expense) of $560 .

Parent Company Only Financial S

Parent Company Only Financial Statements - Condensed	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Only Financial Statements - Condensed	Parent Company Only Financial Statements - Condensed Statements of Financial Condition December 31, 2017 2016 Assets Cash and cash equivalents $ 26,088 34,521 Marketable securities available-for-sale 545 4,413 Investment in bank subsidiary 1,200,799 1,193,175 Other assets 92,712 52,645 Total assets $ 1,320,144 1,284,754 Liabilities and Shareholders’ Equity Liabilities: Debentures payable $ 111,213 111,213 Other liabilities 1,207 2,878 Total liabilities 112,420 114,091 Shareholders’ equity 1,207,724 1,170,663 Total liabilities and shareholders’ equity $ 1,320,144 1,284,754 Statements of Income Years ended December 31, 2017 2016 2015 Income: Interest income $ 137 737 1,258 Other income 2,297 709 659 Dividends from bank subsidiary 90,000 50,000 135,000 Undistributed earnings from equity investment in bank subsidiary 7,255 2,760 (70,854 ) Total income 99,689 54,206 66,063 Expense: Compensation and benefits 1,282 1,129 1,061 Other expense 553 561 1,356 Interest expense 4,666 4,560 4,926 Total expense 6,501 6,250 7,343 Income before income taxes 93,188 47,956 58,720 Federal and state income taxes (1,279 ) (1,711 ) (1,820 ) Net income $ 94,467 49,667 60,540 Statements of Cash Flows Years ended December 31, 2017 2016 2015 Operating activities: Net income $ 94,467 49,667 60,540 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed earnings of subsidiary (7,255 ) (2,760 ) 70,854 Noncash stock benefit plan compensation expense 4,894 10,916 5,654 Gain on sale of marketable securities (1,615 ) (43 ) (54 ) Net change in other assets and liabilities (43,513 ) (63,533 ) (5,824 ) Net cash provided by/ (used in) operating activities 46,978 (5,753 ) 131,170 Investing activities: Net sale of marketable securities 2,800 (1,952 ) 1,192 Acquisition, net of cash received — — (89,398 ) Net cash provided by/ (used in) investing activities 2,800 (1,952 ) (88,206 ) Financing activities: Cash dividends paid (65,212 ) (60,156 ) (52,825 ) Share repurchases — (1,752 ) (7,847 ) Repayment of loan to ESOP — 797 1,549 Redemption of junior subordinated debt — — (8,119 ) Excess tax benefit from stock-based compensation — 1,425 332 Proceeds from options exercised 7,001 10,856 4,303 Net cash used in financing activities (58,211 ) (48,830 ) (62,607 ) Net decrease in cash and cash equivalents $ (8,433 ) (56,535 ) (19,643 ) Cash and cash equivalents at beginning of year $ 34,521 91,056 110,699 Net decrease in cash and cash equivalents (8,433 ) (56,535 ) (19,643 ) Cash and cash equivalents at end of year $ 26,088 34,521 91,056

Derivative Financial Instrument

Derivative Financial Instruments Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments We are a party to derivative financial instruments in the normal course of business to manage our own exposure to fluctuations in interest rates and to meet the needs of our customers. The primary derivatives that we use are interest rate swaps and caps and foreign exchange contracts, which are entered into with counterparties that meet established credit standards. We believe that the credit risk inherent in all of our derivative contracts is minimal based on our credit standards and the netting and collateral provisions of the interest rate swap agreements (a) Derivatives Designated in Hedging Relationships We are currently a counterparty to two interest rate swap agreements (swaps), designating the swaps as cash flow hedges. The swaps are intended to protect against the variability of cash flows associated with Northwest Bancorp Capital Trust III and Northwest Bancorp Capital Trust IV. The first swap modifies the re-pricing characteristics of Northwest Bancorp Capital Trust III, wherein for a 10 years period expiring in September 2018, the Company receives interest of three-month LIBOR from a counterparty and pays a fixed rate of 4.61% to the same counterparty calculated on a notional amount of $25.0 million . The second swap modifies the re-pricing characteristics of Northwest Bancorp Capital Trust IV, wherein for a ten years period expiring in December 2018, the Company receives interest of three-month LIBOR from a counterparty and pays a fixed rate of 4.09% to the same counterparty calculated on a notional amount of $25.0 million . The swap agreements were entered into with a counterparty that met our credit standards and the agreements contain collateral provisions protecting the at-risk party. We believe that the credit risk inherent in the contracts is not significant. At December 31, 2017 , $1.6 million of cash was pledged as collateral to the counterparty. These cash flow hedges are recorded within other liabilities on the consolidated statement of financial condition at their estimated fair value. At December 31, 2017 , the fair value of the swap agreements was $( 1.1 ) million, and there was no hedge ineffectiveness for any of the swaps discussed above. During the next twelve months, as the swaps expire, we estimate that $ 700,000 will be reclassified from accumulated other comprehensive income into interest expense. (b) Derivatives Not Designated in Hedge Relationships In addition to our derivatives designated in hedge relationships, we act as an interest rate or foreign exchange swap counterparty for certain commercial borrowers in the normal course of servicing our customers, which are accounted for at fair value. We manage our exposure to such interest rate or foreign exchange swaps by entering into corresponding and offsetting interest rate swaps with third parties that mirror the terms of the swaps we have with the commercial borrowers. These positions (referred to as “customer swaps”) directly offset each other and our exposure is fair value of the derivatives due to changes in credit risk of our commercial borrowers and third parties. Customer swaps are recorded within other assets or other liabilities on the consolidated statement of financial condition at their estimated fair value. Changes to the fair value of assets and liabilities arising from these derivatives are included, net, in other operating income in the consolidated statement of income. The following table presents information regarding our derivative financial instruments, at December 31, : Asset derivatives Liability derivatives Notional amount Fair value Notional amount Fair value 2017: Derivatives designated as hedging instruments: Interest rate swap agreements $ — — 50,000 1,064 Derivatives not designated as hedging instruments: Interest rate swap agreements 92,631 214 92,631 214 Foreign exchange swap agreements — — 12,344 61 Total derivatives $ 92,631 214 154,975 1,339 2016: Derivatives designated as hedging instruments: Interest rate swap agreements $ — — 50,000 2,736 Derivatives not designated as hedging instruments: Interest rate swap agreements 10,559 238 10,559 238 Foreign exchange swap agreements — — — — Total derivatives $ 10,559 238 60,559 2,974 The following table indicates the gain or loss recognized in income on derivatives for the periods indicated: For the years ended December 31, 2017 2016 2015 Non-hedging swap derivatives: Increase/ (decrease) in other income $ (373 ) — — Hedging interest rate derivatives: Increase in interest expense 1,599 1,866 2,922

Selected Quarterly Financial Da

Selected Quarterly Financial Data - Unaudited	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data - Unaudited	Selected Quarterly Financial Data - Unaudited Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2017: Interest income $ 87,267 89,797 90,231 91,561 Interest expense 6,690 7,066 6,994 7,321 Net interest income 80,577 82,731 83,237 84,240 Provision for loan losses 4,637 5,562 3,027 6,525 Noninterest income 21,504 41,477 24,594 22,905 Noninterest expenses 71,646 73,262 68,799 71,896 Income before income taxes 25,798 45,384 36,005 28,724 Income tax expense 8,052 14,402 12,414 6,576 Net income $ 17,746 30,982 23,591 22,148 Basic earnings per share $ 0.18 0.31 0.23 0.22 Diluted earnings per share $ 0.17 0.30 0.23 0.22 Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2016: Interest income $ 85,298 85,555 84,748 90,033 Interest expense 13,746 10,008 7,454 7,091 Net interest income 71,552 75,547 77,294 82,942 Provision for loan losses 1,660 4,199 5,538 2,145 Noninterest income 19,448 20,275 20,818 24,819 Noninterest expenses 63,275 102,122 73,680 68,761 Income before income taxes 26,065 (10,499 ) 18,894 36,855 Income tax expense 8,081 (3,491 ) 4,697 12,361 Net income $ 17,984 (7,008 ) 14,197 24,494 Basic earnings per share $ 0.18 (0.07 ) 0.14 0.24 Diluted earnings per share $ 0.18 (0.07 ) 0.14 0.24 Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2015: Interest income $ 76,880 75,970 81,091 85,639 Interest expense 13,899 13,792 14,150 14,486 Net interest income 62,981 62,178 66,941 71,153 Provision for loan losses 900 1,050 3,167 4,595 Noninterest income 14,625 16,525 18,140 19,546 Noninterest expenses 53,711 55,135 63,804 61,227 Income before income taxes 22,995 22,518 18,110 24,877 Income tax expense 6,825 7,213 5,238 8,684 Net income $ 16,170 15,305 12,872 16,193 Basic earnings per share $ 0.18 0.17 0.14 0.16 Diluted earnings per share $ 0.18 0.17 0.13 0.16

Summary of Significant Accoun33

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations Northwest Bancshares, Inc., a Maryland corporation headquartered in Warren, Pennsylvania, is the federal savings and loan holding company for its wholly owned subsidiary, Northwest Bank. Northwest Bank, a Pennsylvania chartered savings bank, offers personal and business deposit and loan products as well as investment management and insurance services through its 172 banking locations in Pennsylvania, New York, and Ohio.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries after elimination of all intercompany accounts and transactions.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of the statements of financial condition and cash flows, cash and cash equivalents include cash and amounts due from banks, interest-bearing deposits in other financial institutions, federal funds sold, and other short-term investments with original maturities of three months or less.
Investment Securities	Investment Securities We classify marketable securities at the time of purchase as held-to-maturity, available-for-sale, or trading. Securities for which management has the intent and ability to hold until maturity are classified as held-to-maturity and are carried at cost, adjusted for amortization of premiums and accretion of discounts on a level yield basis (amortized cost). If it is management’s intent at the time of purchase to hold securities for an indefinite period of time and/ or to use such securities as part of its asset/ liability management strategy, the securities are classified as available-for-sale and are carried at fair value, with unrealized gains and losses reported as accumulated other comprehensive income/ (loss), a separate component of shareholders’ equity, net of tax. Securities classified as available-for-sale include securities that may be sold in response to changes in interest rates, resultant prepayment risk, or other market factors. Securities that are bought and held principally for the purpose of selling them in the near term are classified as trading and are reported at fair value, with changes in fair value included in earnings. The cost of securities sold is determined on a specific identification basis. We held no securities classified as trading at or during the years ended December 31, 2017 and 2016 . On at least a quarterly basis, we review our investments for other-than-temporary impairment (“OTTI”). An investment security is deemed impaired if the fair value of the investment is less than its amortized cost. If an investment security is determined to be impaired, we evaluate whether the decline in value is other-than-temporary. We consider whether or not we expect to receive all of the contractual cash flows from the investment security based on factors that include, but are not limited to the creditworthiness of the issuer and the historical and projected performance of the underlying collateral. Also, we may evaluate the business and financial outlook of the issuer, as well as broader economic performance indicators. We consider both our intent to sell and the likelihood that we will not have to sell the investment securities before recovery of their cost basis during our evaluation. Impairment that is deemed credit related is recognized in earnings while impairment deemed noncredit related is recorded in accumulated other comprehensive income, if we do not intend to sell nor it is not likely we will be required to sell the investment security. If we intend to sell the investment security or if it is more likely than not that we will be required to sell the investment security, the entire impairment is recorded in earnings.
Loans Receivable	Loans Receivable Our loan segments consist of Personal Banking and Business Banking loans. Personal Banking loans include; residential mortgage, home equity and consumer loans. Business Banking loans include; commercial real estate and commercial loans. Originated loans are carried at their unpaid principal balance net of any deferred origination fees or costs and the allowance for loan losses. Interest income on loans is credited to income as earned. Interest earned on loans for which no payments were received during the month is accrued at month end. Accrued interest on loans more than 90 days delinquent is reversed and such loans are placed on nonaccrual status. All loans are placed on nonaccrual status when principal or interest is 90 days or more delinquent or when there is reasonable doubt that interest or principal will not be collected in accordance with the contractual terms. Interest receipts on all nonaccrual and impaired loans are recognized as interest income when it has been determined that all principal and interest will be collected or are applied to principal when collectability of contractual principal is in doubt. Nonaccrual loans generally are restored to an accrual basis when principal and interest become current and a period of performance has been established in accordance with the contractual terms, typically six months . A loan is considered to be a troubled debt restructured loan ("TDR") when the borrower is experiencing financial difficulties and the restructuring constitutes a concession. TDRs may include modifications of terms of loans, receipts of assets from borrowers in partial or full satisfaction of loans, or a combination thereof. TDRs are impaired loans. A modified loan is determined to be a TDR based on the contractual terms as specified by the original loan agreement or the most recent modification. Once classified a TDR, a loan is removed from such classification under three circumstances: (1) the loan is paid off, (2) the loan is charged off, or (3) if, at the beginning of the current fiscal year, the loan has performed in accordance with the modified terms for a minimum of six consecutive months and at the time of modification the loan’s interest rate represented a then current market interest rate for a loan of similar risk. Loan delinquency is measured based on the number of days since the payment due date. Past due status is measured using the loan’s contractual maturity date. Loan fees and certain direct loan origination costs are deferred and the net deferred fee or cost is then recognized using the level-yield method over the contractual life of the loan as an adjustment to interest income. We identify certain residential mortgage loans which will be sold prior to maturity, as loans held for sale. These loans are recorded at the lower of amortized cost or fair value less estimated cost to sell. At December 31, 2017 and 2016 , there were $3.1 million and $9.6 million residential mortgage loans classified as held for sale, respectively. Acquired loans are initially measured at fair value with no carryover of the related allowance for loan losses. Determining the fair value of the loans involves estimating the amount and timing of principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loan. The difference between contractually required payments at acquisition and the cash flows expected to be collected at acquisition is referred to as the nonaccretable discount. The nonaccretable discount represents estimated future credit losses expected to be incurred over the life of the loan. Subsequent decreases to the expected cash flows require us to evaluate the need for an allowance for loan losses. Subsequent improvements in expected cash flows result in the reversal of a corresponding amount of the nonaccretable discount which we then reclassify as accretable discount that is recognized into interest income over the remaining life of the loan using the interest method. Charge-offs of the principal amount on acquired loans would be first applied to the nonaccretable discount portion of the fair value adjustment. Acquired loans that met the criteria for nonaccrual of interest prior to the acquisition may be considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if we can reasonably estimate the timing and amount of the expected cash flows on such loans and if we expect to fully collect the new carrying value of the loans. As such, we may no longer consider the loan to be nonaccrual or nonperforming and may accrue interest on these loans, including the impact of any accretable discount. We have determined that we can reasonably estimate future cash flows on our current portfolio of acquired loans that are past due 90 days or more and on which we are accruing interest and we expect to fully collect the carrying value of the loans.
Allowance for Loan Losses and Provision for Loan Losses	Allowance for Loan Losses and Provision for Loan Losses Provisions for estimated loan losses and the amount of the allowance for loan losses are based on losses inherent in the loan portfolio that are both probable and can be reasonably estimated at the date of the financial statements. We consider a loan to be impaired when it is probable that we will be unable to collect all amounts due according to the contractual terms of the loan agreement. In evaluating whether a loan is impaired, we consider not only the amount that we expect to collect but also the timing of collection. Generally, if a delay in payment is insignificant (e.g., less than 30 days ), a loan is not deemed to be impaired. Business Banking loans greater than or equal to $1.0 million are reviewed to determine if they should be individually evaluated for impairment. Smaller balance, homogeneous loans (e.g., primarily residential mortgage, home equity and consumer loans) are evaluated collectively for impairment. When a loan is considered to be impaired, the amount of impairment is measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s market price, or fair value of the collateral, less estimated cost to sell, if the loan is collateral dependent. Impairment losses are included in the allowance for loan losses. Impaired loans are charged-off or charged down when we believe that the ultimate collectability of a loan is not likely or the collateral value no longer supports the carrying value of the loan. Interest income on non-performing loans is recognized using the cash basis method. For non-performing loans interest collected is credited to income in the period of recovery or applied to reduce principal if there is sufficient doubt about the collectability of principal. The allowance for loan losses is shown as a valuation allowance to loans. The accounting policy for the determination of the adequacy of the allowance by portfolio segment requires us to make numerous complex and subjective estimates and assumptions relating to amounts which are inherently uncertain. The allowance for loan losses is maintained to absorb losses inherent in the loan portfolio as of the balance sheet date. The methodology used to determine the allowance for loan losses is designed to provide procedural discipline in assessing the appropriateness of the allowance for loan losses. Losses are charged against and recoveries are added to the allowance for loan losses. For Business Banking loans the allowance for loan losses consists of: • An allowance for impaired loans; • An allowance for homogenous loans based on historical losses; and • An allowance for homogenous loans based on environmental factors. The allowance for impaired loans is based on individual analysis of all nonperforming loans greater than or equal to $1.0 million . The allowance is measured by the difference between the recorded value of impaired loans and their impaired value. The impaired value is either the present value of the expected future cash flows from the borrower, the market value of the loan, or the fair value of the collateral, less estimated cost to sell. The allowance for homogeneous loans based on historical factors is a rolling three -year average of incurred losses, adjusted for a loss emergence period (the period of time from the event of loss to loss realization), applied to homogenous pools of loans categorized by similar risk characteristics, not including loans evaluated individually for impairment. The allowance for homogeneous loans based on environmental factors augments the historical loss factors for changes in: economic conditions, lending policies and procedures, the nature and volume of the loan portfolio, management, delinquency trends, loan administration, collateral values, concentrations of credit, and other external factors including legal and regulatory factors. For Personal Banking loans the allowance for loan losses consists of: • An allowance for loans 90 days or more delinquent; • An allowance for homogenous loans based on historical losses; and • An allowance for homogenous loans based on environmental factors. The allowance for loans 90 days or more delinquent is based on the loss history of loans that have become 90 days or more delinquent. We apply a historical loss factor to homogeneous pools of loans that are 90 days or more delinquent. The allowance for homogeneous loans based on historical losses is a rolling three -year average of actual losses incurred, adjusted for a loss realization period, applied to homogenous pools of loans categorized by similar risk characteristics, not including loans that are 90 days or more delinquent. The allocation of the allowance for loan losses is inherently subjective, and the entire allowance for loan losses is available to absorb loan losses regardless of the nature of the loss. Personal Banking loans are charged-off or charged down when they become 180 days delinquent, unless the borrower has filed for bankruptcy. Business Banking loans are charged-off or charged down when, in our opinion, they are no longer collectible or when it has been determined that the collateral value no longer supports the carrying value of the loan, for loans that are collateral dependent. We have not made any material changes to our methodology for the calculation of the allowance for loan losses during the current year.
Real Estate Owned	Real Estate Owned Real estate owned is comprised of property either acquired through foreclosure or voluntarily conveyed by borrowers. These assets are recorded on the date acquired at the lower of the loan balance or fair value of the collateral, less estimated disposition costs, with the fair value being determined by an appraisal. Any initial write-down is charged to the allowance for loan losses. Subsequently, foreclosed assets are valued at the lower of the amount recorded at acquisition date or the current fair value, less estimated disposition costs. Any subsequent write-down or gains or losses realized from the disposition of such property are credited or charged to noninterest income.
Restricted Investment in Federal Home Loan Bank Stock	Restricted Investment in Federal Home Loan Bank Stock Federal law requires a member institution of the Federal Home Loan Bank ("FHLB") system to hold stock of its district FHLB according to a predetermined formula. FHLB stock is carried at cost and evaluated or impairment based on the ultimate recoverability of the par value. FHLB stock can only be purchased, redeemed and transferred at par value. Dividends are reported in interest income in the Consolidated Statements of Income.
Premises and Equipment	Premises and Equipment Premises and equipment are carried at cost, less accumulated depreciation and amortization. Depreciation is accumulated on a straight-line basis over the estimated useful lives of the related assets. Estimated lives range from three to 39 years . Amortization of leasehold improvements is accumulated on a straight-line basis over the terms of the related leases or the useful lives of the related assets, whichever is shorter.
Goodwill	Goodwill Goodwill is generated from the premium paid for an acquisition and is allocated to reporting units, which are either our reportable segments or one level below. Reporting units are identified based upon analyzing each individual operating segment. A reporting unit is defined as a distinct, separately identifiable component of an operating segment for which complete, discrete financial information is available that management regularly reviews. Goodwill is not subject to amortization but is tested for impairment at least annually and possibly more frequently if certain events occur or changes in circumstances arise. In testing goodwill for impairment, we have the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. If, after assessing all events and circumstances, we determine it is not more likely than not that the fair value of a reporting unit is less than its carrying value, then performing the two-step impairment test would be unnecessary. However, if we conclude otherwise, it would then be required to perform the first step of the goodwill impairment test, and continue to the second step, if necessary. Step 1 requires the fair value of each reporting unit be compared to its carrying amount, including goodwill. Determining the fair value of a reporting unit requires a high degree of subjective judgment, including developing cash flow projections, selecting appropriate discount rates, identifying relevant market comparables, incorporating general economic and market conditions and selecting an appropriate control premium. We conducted our annual impairment assessment as of June 30, 2017 by first performing a qualitative assessment of goodwill to determine if it was more likely than not that the fair value was less than the carrying value. In performing a qualitative analysis, factors considered include, but are not limited to, macroeconomic conditions, industry and market conditions and overall financial performance. The results of the qualitative assessment for 2017 indicated that it was not more likely than not that the fair value of the reporting unit was less than the carrying value. Consequently, no additional quantitative two-step impairment test was required, and no impairment was recorded in 2017. As of June 30, 2016, we performed a quantitative impairment test that did not result in any impairment. Future events could cause us to conclude that goodwill has become impaired, which would result in recording an impairment loss. There were no changes in our operations that would cause us to update the assessment performed as of June 30, 2017 and 2016. Accordingly, we have determined that goodwill is not impaired as of December 31, 2017 and 2016.
Core Deposit and Other Identifiable Intangibles	Core Deposit and Other Identifiable Intangibles Through the assistance of an independent third party, we analyze and prepare a core deposit study for all bank acquisitions or other identifiable intangible asset study, such as customer lists, for all non-bank acquisitions. The core deposit study reflects the cumulative present value benefit of acquiring deposits versus an alternative source of funding. The other identifiable intangible asset study reflects the cumulative present value benefit of acquiring the income stream from an existing customer base versus developing new business relationships. Based upon analysis, the amount of the premium related to the core deposits or other identifiable intangibles of the business purchased is calculated along with the estimated life of the intangible. The intangible, which is recorded in other intangible assets, is then amortized to expense on an accelerated basis over an approximate life of typically between seven to eleven years.
Bank-Owned Life Insurance	Bank-Owned Life Insurance We own insurance on the lives of a certain group of current and former employees and directors. The policies were purchased to help offset the increase in the costs of various benefit plans, including healthcare, as well as the directors deferred compensation plan. The cash surrender value of these policies is included as an asset on the consolidated statements of financial condition, and any increases in the cash surrender value are recorded as tax-free noninterest income on the consolidated statements of income. In the event of the death of an insured individual covered by these policies, after distribution to the insured’s beneficiaries, if any, we receive a tax-free death benefit, which is recorded as noninterest income.
Deposits	Deposits Interest on deposits is accrued and charged to expense monthly and is paid or credited in accordance with the terms of the accounts.
Pension Plans	Pension Plans We maintain multiple noncontributory defined benefit pension plans for substantially all of our employees. The net periodic pension cost has been calculated using service cost, interest cost, expected returns on plan assets and net amortization.
Income Taxes	Income Taxes We join with our wholly owned subsidiaries in filing a consolidated federal income tax return. In accordance with an intercompany tax allocation agreement, the applicable federal income tax expense or benefit is allocated to each subsidiary based upon taxable income or loss calculated on a separate company basis. Each subsidiary is responsible for payment of its own federal income tax liability or receives reimbursement of federal income tax benefit. In addition, deferred taxes are calculated and maintained on a separate company basis. We account for income taxes under the asset and liability method. The objective of the asset and liability method is to establish deferred tax assets and liabilities for temporary differences between the financial reporting and tax basis of our assets and liabilities based on the tax rates expected to be in effect when such amounts are realized or settled. The effect on deferred tax assets and liabilities with regard to a change in tax rates is recognized in the tax provision in the period the change is enacted.
Stock-Related Compensation	Stock-Related Compensation We determine the fair value of each option award, estimated on the grant date, using the Black-Scholes-Merton option-pricing model. The Black-Scholes-Merton option-pricing model uses variables including; expected volatilities, expected term, risk-free discount rate and annual rate of quarterly dividends. Expected volatilities are based on historical volatility of the Company’s stock. The expected terms are based upon actual exercise and forfeiture experience of previous option grants. The risk-free rate is based on yields on U.S. Treasury securities of a similar maturity to the expected term of the options.
Segment Reporting	Segment Reporting As a result of the closure of the Northwest Consumer Discount Company in the third quarter 2017, we have determined that we have one reportable segment beginning in the fourth quarter 2017. The Company provides services traditionally offered by full-service community banks, including business and personal deposit accounts and business and personal loans, as well as insurance, brokerage and investment management and trust services. The Company’s non-banking activities are immaterial and, therefore, separate information has not been disclosed.
Derivative financial instruments	Derivative financial instruments We recognize all derivative financial instruments as either assets or liabilities in the balance sheet and measure those instruments at fair value. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and the resulting designation. An entity that elects to use hedge accounting is required, at inception, to establish the method it will use for assessing the effectiveness of the hedging derivative and the measurement approach for determining the ineffective aspect of the hedge. Those methods must be consistent with our approach to managing risk. We utilize interest rate swap agreements as part of the management of interest rate risk to hedge the interest rate risk on our trust preferred debentures. Amounts receivable or payable are recognized as accrued under the terms of the agreements and the differential is recorded as an adjustment to interest expense. The interest rate swaps are designated as cash flow hedges, with the effective portion of the derivative’s unrealized gain or loss recorded as a component of other comprehensive income which is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. The ineffective portion of the unrealized gain or loss, if any, would be recorded in other expense. For derivatives that are not designated as hedging instruments, any gain or loss is recognized immediately in earnings.
Off-Balance-Sheet Instruments	Off-Balance-Sheet Instruments In the normal course of business, we extend credit in the form of loan commitments, undisbursed lines of credit, and standby letters of credit. These off-balance-sheet instruments involve, to various degrees, elements of credit and interest rate risk not reported in the consolidated statement of financial condition. We utilize the same underwriting standards for these instruments as other extensions of credit.
Use of Estimates	Use of Estimates The preparation of financial statements, in conformity with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amount of revenues and expenses during the reporting period. The estimates and assumptions that we deem important to our financial statements relate to the allowance for loan losses, the accounting treatment and valuation of our investment securities portfolio, the analysis of the carrying value of goodwill, pension and income taxes. These estimates and assumptions are based on management’s best estimates and judgment and we evaluate them using historical experience and other factors, including the current economic environment. We adjust our estimates and assumptions when facts and circumstances dictate. As future events cannot be determined, actual results could differ significantly from our estimates.
Reclassification of Prior Years' Statements	Reclassification of Prior Years’ Statements Certain items previously reported have been reclassified to conform with the current year’s reporting format.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014 the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606)”. This guidance supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance. The core principle of this guidance requires an entity to recognize revenue upon 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 and provides five steps to be analyzed to accomplish the core principle. This guidance is effective retrospectively for annual reporting periods beginning after December 15, 2017, including interim periods within those years and early adoption is not permitted. Our revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. With respect to non-interest income we are complete with our overall assessment of revenue streams and review of related contracts potentially affected by the ASU, including service charges and fees, trust and other financial services income, insurance commission income, and other operating income. The adoption of this ASU will not materially change the method in which we currently recognize revenue for these revenue streams. We are also complete with our evaluation of certain costs related to these revenue streams to determine whether such costs should be presented as expenses or contra-revenue (i.e., gross vs. net). We adopted ASU No. 2014-09 on January 1, 2018 utilizing the modified retrospective approach. Since there was no net income impact, a cumulative effect adjustment to opening retained earnings was deemed not necessary. We are completing our evaluation of the ASU's expanded disclosure requirements and expect them to be primarily qualitative in nature, such as providing greater detail on revenue streams and related performance obligations. In January 2016 the FASB issued ASU 2016-01, “Financial Instruments - Overall (Subtopic 825-10)” . This guidance requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. Additionally, this guidance requires entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. This guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We do not expected this guidance to have a material impact on our results of operations and financial position. In February 2016 the FASB issued ASU 2016-2, “Leases” . This guidance requires a lessee to recognize in the statement of financial condition a liability to make lease payments and a right-of-use asset representing the right to use the underlying asset for the term of the lease. Optional periods should only be recognized if the lessee is reasonably certain to exercise the option. For leases with a term of twelve months or less, the lessee is permitted not to recognize lease assets and lease liabilities and should recognize lease expense for such leases generally on a straight-line basis over the term of the lease. This guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those years and early adoption is permitted. We are currently evaluating the impact this guidance will have on our results of operations and financial position. In June 2016, the FASB issued ASU 2016-13, " Financial Instruments - Credit Losses (Topic 326) - Measurement of Credit Losses on Financial Instruments" , which eliminates the probable initial recognition threshold for credit losses requiring, instead, that all financial assets (or group of financial assets) measured at amortized cost be presented at the net amount expected to be collected inclusive of the entity’s current estimate of all lifetime expected credit losses. This guidance also applies to certain off-balance-sheet credit exposures such as unfunded commitments and non-derivative financial guarantees. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) in order to present the net carrying value at the amount expected to be collected on the financial asset. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The income statement under this guidance will reflect the initial recognition of current expected credit losses for newly recognized assets, as well as any increases or decreases of expected credit losses that have occurred during the period. This guidance retains many currently-existing disclosures related to the credit quality of an entity’s assets and the related allowance for credit losses amended to reflect the change to an expected credit loss methodology, as well as enhanced disclosures to provide information to users at a more disaggregated level. Upon adoption, ASU 2016-13 provides for a modified retrospective transition by means of a cumulative-effect adjustment to equity as of the beginning of the period in which the guidance is effective, except for debt securities for which an other-than-temporary impairment has previously been recognized. For these debt securities, a prospective transition is provided in order to maintain the same amortized cost prior to and subsequent to the effective date of the ASU. This guidance is effective for annual reporting periods beginning after December 15, 2019, and interim periods within those annual periods with early adoption permitted for fiscal years beginning after December 15, 2018, and interim periods within those annual periods. Management created a formal working group to govern the implementation of these amendments consisting of key stakeholders from finance, risk, and accounting. We are currently in the process of designing current expected credit loss estimation methodologies and systems, and collecting data to be able to comply with the standard. We are also evaluating the effect this guidance will have on our results of operations, financial position and related disclosures. The impact of the ASU will depend upon the state of the economy and the nature of our portfolios at the date of adoption. In August 2016, the FASB issued ASU No. 2016-15, “ Classification of Certain Cash Receipts and Cash Payments ”. The main objective of this ASU is to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The amendments in this Update provide guidance on the following eight specific cash flow issues: debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of bank-owned life insurance (BOLI) policies, distributions received from equity method investments, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. This guidance is effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption is permitted, provided that all of the amendments are adopted in the same period. The provisions of this ASU will not materially impact our results of operations and financial position. In January 2017 the FASB issued ASU 2017-04, "Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment" . This guidance eliminates the requirement to determine the fair value of individual assets and liabilities of a reporting unit to measure goodwill impairment. Under this guidance goodwill impairment testing will be performed by comparing the fair value of the reporting unit with its carrying amount and recognizing an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. This guidance is effective for annual and interim goodwill impairment tests in fiscal years beginning after December 15, 2019, and should be applied on a prospective basis. Early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. We do not expected this guidance to have a material impact on our consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-07, “Compensation Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Costs and Net Periodic Postretirement Benefit Costs". This guidance provides financial statement users with clearer and disaggregated information related to the components of net periodic benefit cost and improve transparency of the presentation of net periodic benefit cost in the financial statements. This guidance is effective for annual and interim periods beginning after December 15, 2017. Early adoption is permitted and this guidance should be applied retrospectively. We intend to early adopt the provisions of this standard effective with our March 31, 2018 quarterly report on Form 10-Q and do not anticipate that the adoption of this guidance will not have a material impact on our results of operations, however it will impact the presentation of our Consolidated Statements of Income. In March 2017 the FASB issued ASU 2017-08, "Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities" . This guidance shortens the amortization period for certain callable debt securities held at a premium to the earliest call date from the maturity date. This guidance is effective for annual and interim periods beginning after December 15, 2018. Early adoption is permitted in any interim period. We intend to early adopt the provisions of this standard effective with our March 31, 2018 quarterly report on Form 10-Q and do not expect the adoption to have a material impact on our results of operations or financial position. In May 2017 the FASB issued ASU 2017-09, “Compensation - Stock Compensation (Topic 718) - Scope of Modification Accounting”. This guidance clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award's fair value, (ii) the award's vesting conditions and (iii) the award's classification as an equity or liability instrument. This guidance is effective for annual and interim periods beginning after December 15, 2017 and is not expected to have a material impact on our consolidated financial statements.

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of the portfolio of investment securities available-for-sale	Marketable securities available-for-sale at December 31, 2017 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Debt issued by the U.S. government and agencies: Due in one year or less $ 1 — — 1 Debt issued by government sponsored enterprises: 3 Due in one year or less 66,566 14 (289 ) 66,291 Due after one year through five years 140,624 — (2,402 ) 138,222 Due after five years through ten years — — — — Due after ten years 4,833 — (77 ) 4,756 Equity securities 551 29 (6 ) 574 Municipal securities: Due in one year or less 2,492 7 (1 ) 2,498 Due after one year through five years 7,072 82 (6 ) 7,148 Due after five years through ten years 14,576 171 — 14,747 Due after ten years 26,371 292 — 26,663 Corporate debt issues: Due after ten years 909 — — 909 Residential mortgage-backed securities: Fixed rate pass-through 144,411 1,108 (2,817 ) 142,702 Variable rate pass-through 33,079 1,464 (6 ) 34,537 Fixed rate non-agency CMOs 15 — — 15 Fixed rate agency CMOs 284,320 37 (5,271 ) 279,086 Variable rate agency CMOs 74,274 249 (137 ) 74,386 Total residential mortgage-backed securities 536,099 2,858 (8,231 ) 530,726 Total marketable securities available-for-sale $ 800,094 3,453 (11,012 ) 792,535 Marketable securities available-for-sale at December 31, 2016 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Debt issued by the U.S. government and agencies: Due in one year or less $ 6 — — 6 Debt issued by government sponsored enterprises: Due in one year or less 74,980 5 (33 ) 74,952 Due after one year through five years 220,937 203 (2,504 ) 218,636 Due after five years through ten years 585 — (3 ) 582 Due after ten years — — — — Equity securities 3,351 1,095 (6 ) 4,440 Municipal securities: Due in one year or less 2,449 7 — 2,456 Due after one year through five years 9,448 105 (21 ) 9,532 Due after five years through ten years 11,794 137 (1 ) 11,930 Due after ten years 38,141 1,027 (16 ) 39,152 Corporate debt issues: Due after ten years 14,367 2,935 (322 ) 16,980 Residential mortgage-backed securities: Fixed rate pass-through 175,398 1,849 (2,680 ) 174,567 Variable rate pass-through 43,587 2,007 (6 ) 45,588 Fixed rate non-agency CMOs 100 1 — 101 Fixed rate agency CMOs 165,535 185 (3,455 ) 162,265 Variable rate agency CMOs 64,874 306 (167 ) 65,013 Total residential mortgage-backed securities 449,494 4,348 (6,308 ) 447,534 Total marketable securities available-for-sale $ 825,552 9,862 (9,214 ) 826,200
Schedule of the portfolio of investment securities held-to-maturity	Marketable securities held to maturity at December 31, 2016 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Municipal securities: Due after ten years $ 4,808 65 — 4,873 Residential mortgage-backed securities: Fixed rate pass-through 4,807 217 — 5,024 Variable rate pass-through 2,848 58 — 2,906 Fixed rate agency CMOs 6,674 94 — 6,768 Variable rate agency CMOs 841 14 — 855 Total residential mortgage-backed securities 15,170 383 — 15,553 Total marketable securities held-to-maturity $ 19,978 448 — 20,426 Marketable securities held to maturity at December 31, 2017 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Residential mortgage-backed securities: Fixed rate pass-through $ 3,760 140 — 3,900 Variable rate pass-through 2,283 64 — 2,347 Fixed rate agency CMOs 22,906 20 (248 ) 22,678 Variable rate agency CMOs 729 13 — 742 Total residential mortgage-backed securities 29,678 237 (248 ) 29,667 Total marketable securities held-to-maturity $ 29,678 237 (248 ) 29,667
Information regarding the issuers and the carrying values of the entity's mortgage-backed securities	The following table presents information regarding the issuers and the carrying values of our mortgage-backed securities at December 31, 2017 and 2016 : December 31, 2017 2016 Residential mortgage backed securities: FNMA $ 286,031 210,373 GNMA 37,796 42,221 FHLMC 236,007 202,822 SBA — 6,608 Other (including non-agency) 570 680 Total residential mortgage-backed securities $ 560,404 462,704
Schedule of the fair value and gross unrealized losses on investment securities, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position	The following table shows the fair value and gross unrealized losses on investment securities, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position at December 31, 2017 : Less than 12 months 12 months or more Total Unrealized Unrealized Unrealized Fair value loss Fair value loss Fair value loss Government sponsored enterprises $ 5,006 (7 ) 197,695 (2,761 ) 202,701 (2,768 ) Corporate debt issues — — — — — — Equity securities — — 544 (6 ) 544 (6 ) Municipal securities 4,563 (7 ) — — 4,563 (7 ) Residential mortgage-backed securities - agency 239,703 (2,522 ) 202,344 (5,957 ) 442,047 (8,479 ) Total temporarily impaired securities $ 249,272 (2,536 ) 400,583 (8,724 ) 649,855 (11,260 ) The following table shows the fair value and gross unrealized losses on investment securities, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position at December 31, 2016 : Less than 12 months 12 months or more Total Unrealized Unrealized Unrealized Fair value loss Fair value loss Fair value loss Government sponsored enterprises $ 238,003 (2,448 ) 9,205 (92 ) 247,208 (2,540 ) Corporate debt issues — — 2,107 (322 ) 2,107 (322 ) Equity securities — — 544 (6 ) 544 (6 ) Municipal securities 5,621 (37 ) 66 (1 ) 5,687 (38 ) Residential mortgage-backed securities - agency 213,662 (3,837 ) 87,723 (2,471 ) 301,385 (6,308 ) Total temporarily impaired securities $ 457,286 (6,322 ) 99,645 (2,892 ) 556,931 (9,214 )
Schedule of categories of investment securities on which other-than-temporary impairment charges have been recorded in earnings	The following table sets forth the categories of investment securities as of December 31, 2017 on which other-than-temporary impairment charges have been recorded in earnings: Total Accumulated Category Amortized cost Fair value Unrealized gain impairment charges Freddie Mac preferred shares $ 1 30 29 119 Trust preferred investments — — — 352 Total $ 1 30 29 471
Schedule of the cumulative roll forward of credit related impairment losses recognized in earnings for debt securities held and not intended to be sold	The table below shows a cumulative roll forward of credit related impairment losses recognized in earnings for debt securities held and not intended to be sold: December 31, 2017 2016 Beginning balance as of January 1, (1) $ 7,942 8,436 Credit losses on debt securities for which other-than-temporary impairment was not previously recognized — — Credit losses on debt securities for which other-than-temporary impairment was previously recognized (7,265 ) (494 ) Reduction for securities sold realized during the year (325 ) — Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized — — Ending balance as of December 31, $ 352 7,942 (1) The beginning balance represents credit losses included in other-than-temporary impairment charges recognized on debt securities in prior periods.

Loans Receivable and Allowanc35

Loans Receivable and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Summary of loans receivable	Loans receivable at December 31, 2017 and 2016 are summarized in the table below: December 31, 2017 December 31, 2016 Originated Acquired Total Originated Acquired Total Personal Banking: Residential mortgage loans (1) $ 2,658,726 113,823 2,772,549 2,565,620 133,511 2,699,131 Home equity loans 1,051,558 258,797 1,310,355 1,042,913 302,457 1,345,370 Consumer finance loans (2) 18,619 — 18,619 48,981 — 48,981 Consumer loans 540,832 97,877 638,709 418,656 163,622 582,278 Total Personal Banking 4,269,735 470,497 4,740,232 4,076,170 599,590 4,675,760 Commercial Banking: Commercial real estate loans 2,303,179 296,161 2,599,340 2,140,678 372,991 2,513,669 Commercial loans 572,341 60,822 633,163 481,543 75,676 557,219 Total Commercial Banking 2,875,520 356,983 3,232,503 2,622,221 448,667 3,070,888 Total loans receivable, gross 7,145,255 827,480 7,972,735 6,698,391 1,048,257 7,746,648 Deferred loan costs 26,255 1,527 27,782 20,081 2,294 22,375 Allowance for loan losses (50,572 ) (6,223 ) (56,795 ) (55,293 ) (5,646 ) (60,939 ) Undisbursed loan proceeds: Residential mortgage loans (10,067 ) — (10,067 ) (11,638 ) — (11,638 ) Commercial real estate loans (141,967 ) (2,647 ) (144,614 ) (168,595 ) (2,985 ) (171,580 ) Commercial loans (51,143 ) (1,284 ) (52,427 ) (26,168 ) (2,290 ) (28,458 ) Total loans receivable, net $ 6,917,761 818,853 7,736,614 6,456,778 1,039,630 7,496,408 (1) Includes $3.1 million and $9.6 million of loans held for sale at December 31, 2017 and 2016 , respectively. (2) Represents loans from our consumer finance subsidiary that was closed in 2017 which are no longer being originated.
Schedule of information related to the outstanding principal balance and related carrying value of acquired loans	The following table provides information related to the outstanding principal balance and related carrying value of acquired loans for the dates indicated: December 31, 2017 2016 Acquired loans evaluated individually for future credit losses: Outstanding principal balance $ 9,735 16,108 Carrying value 6,875 12,665 Acquired loans evaluated collectively for future credit losses: Outstanding principal balance 824,205 1,040,378 Carrying value 818,201 1,032,611 Total acquired loans: Outstanding principal balance 833,940 1,056,486 Carrying value 825,076 1,045,276
Schedule of the changes in the accretable discount	The following table provides information related to the changes in the accretable discount, which includes income recognized from contractual cash flows for the dates indicated: Total Balance at December 31, 2015 $ 2,019 Accretion (1,170 ) Net reclassification from nonaccretable yield 1,338 Balance at December 31, 2016 2,187 Accretion (1,318 ) Net reclassification from nonaccretable yield 671 Balance at December 31, 2017 $ 1,540
Schedule of the composition of impaired loans by portfolio segment and by class of financing receivable	The following table provides information related to the composition of impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2017 : Nonaccrual loans 90 or more days delinquent Nonaccrual loans less than 90 days delinquent Loans less than 90 days delinquent reviewed for impairment TDRs less than 90 days delinquent not included elsewhere Total impaired loans Average recorded investment in impaired loans Interest income recognized on impaired loans Personal Banking: Residential mortgage loans $ 13,509 1,282 — 6,814 21,605 21,531 892 Home equity loans 7,251 1,656 — 1,449 10,356 9,150 452 Consumer finance loans 199 — — — 199 379 20 Consumer loans 3,617 1,056 — — 4,673 4,042 188 Total Personal Banking 24,576 3,994 — 8,263 36,833 35,102 1,552 Commercial Banking: Commercial real estate loans 15,361 13,112 4,431 4,123 37,027 49,981 1,758 Commercial loans 3,140 4,272 906 2,447 10,765 12,110 672 Total Commercial Banking 18,501 17,384 5,337 6,570 47,792 62,091 2,430 Total $ 43,077 21,378 5,337 14,833 84,625 97,193 3,982 The following table provides information related to the composition of impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2016 : Nonaccrual loans 90 or more days delinquent Nonaccrual loans less than 90 days delinquent Loans less than 90 days delinquent reviewed for impairment TDRs less than 90 days delinquent not included elsewhere Total impaired loans Average recorded investment in impaired loans Interest income recognized on impaired loans Personal Banking: Residential mortgage loans $ 13,169 5,095 — 5,929 24,193 24,483 1,079 Home equity loans 5,552 2,313 — 1,439 9,304 9,234 496 Consumer finance loans 743 — — — 743 772 35 Consumer loans 3,080 1,286 — — 4,366 2,931 131 Total Personal Banking 22,544 8,694 — 7,368 38,606 37,420 1,741 Commercial Banking: Commercial real estate loans 19,264 19,460 3,622 11,582 53,928 64,350 2,864 Commercial loans 3,373 6,201 2,837 3,116 15,527 16,905 991 Total Commercial Banking 22,637 25,661 6,459 14,698 69,455 81,255 3,855 Total $ 45,181 34,355 6,459 22,066 108,061 118,675 5,596 The following table provides information related to the composition of impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2015 : Nonaccrual loans 90 or more days delinquent Nonaccrual loans less than 90 days delinquent Loans less than 90 days delinquent reviewed for impairment TDRs less than 90 days delinquent not included elsewhere Total impaired loans Average recorded investment in impaired loans Interest income recognized on impaired loans Personal Banking: Residential mortgage loans $ 15,810 3,962 — 5,086 24,858 24,554 944 Home equity loans 5,650 1,872 — 1,847 9,369 9,644 497 Consumer finance loans 792 — — — 792 768 29 Consumer loans 2,108 552 — — 2,660 2,209 72 Total Personal Banking 24,360 6,386 — 6,933 37,679 37,175 1,542 Commercial Banking: Commercial real estate loans 16,449 16,972 16,121 16,467 66,009 77,166 3,226 Commercial loans 2,459 5,036 2,014 4,654 14,163 16,187 694 Total Commercial Banking 18,908 22,008 18,135 21,121 80,172 93,353 3,920 Total $ 43,268 28,394 18,135 28,054 117,851 130,528 5,462 The following table provides information related to purchased credit impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2017 : Carrying value Outstanding principal balance Related impairment reserve Average recorded investment in impaired loans Interest income/ accretion recognized Personal Banking: Residential mortgage loans $ 1,182 1,880 24 1,251 181 Home equity loans 1,143 2,219 21 1,253 157 Consumer loans 59 160 4 97 51 Total Personal Banking 2,384 4,259 49 2,601 389 Commercial Banking: Commercial real estate loans 4,388 5,363 39 6,992 914 Commercial loans 103 113 — 177 15 Total Commercial Banking 4,491 5,476 39 7,169 929 Total $ 6,875 9,735 88 9,770 1,318 The following table provides information related to purchased credit impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2016 : Carrying Outstanding Related Average Interest Personal Banking: Residential mortgage loans $ 1,319 2,062 204 1,650 202 Home equity loans 1,363 2,669 8 1,724 185 Consumer loans 136 303 3 201 51 Total Personal Banking 2,818 5,034 215 3,575 438 Commercial Banking: Commercial real estate loans 9,596 10,809 52 10,942 721 Commercial loans 251 265 — 249 11 Total Commercial Banking 9,847 11,074 52 11,191 732 Total $ 12,665 16,108 267 14,766 1,170
Schedule of the changes in the allowance for losses on loans receivable	The following table provides information related to changes in the allowance for losses on loans receivable for the year ended December 31, 2017 : Balance Provision Charge-offs Recoveries Balance Originated loans Personal Banking: Residential mortgage loans $ 3,824 (390 ) (834 ) 392 4,656 Home equity loans 4,072 1,474 (1,080 ) 192 3,486 Consumer finance loans 3,968 8,444 (8,369 ) 448 3,445 Consumer loans 8,475 13,601 (11,128 ) 1,473 4,529 Total Personal Banking 20,339 23,129 (21,411 ) 2,505 16,116 Commercial Banking: Commercial real estate loans 19,911 (3,663 ) (1,344 ) 1,251 23,667 Commercial loans 10,322 (4,777 ) (2,462 ) 2,051 15,510 Total Commercial Banking 30,233 (8,440 ) (3,806 ) 3,302 39,177 Total originated loans 50,572 14,689 (25,217 ) 5,807 55,293 Acquired loans Personal Banking: Residential mortgage loans 131 185 (205 ) 80 71 Home equity loans 762 503 (1,179 ) 391 1,047 Consumer loans 890 765 (795 ) 267 653 Total Personal Banking 1,783 1,453 (2,179 ) 738 1,771 Commercial Banking: Commercial real estate loans 3,549 2,631 (2,830 ) 740 3,008 Commercial loans 891 978 (1,028 ) 74 867 Total Commercial Banking 4,440 3,609 (3,858 ) 814 3,875 Total acquired loans 6,223 5,062 (6,037 ) 1,552 5,646 Total $ 56,795 19,751 (31,254 ) 7,359 60,939 The following table provides information related to changes in the allowance for losses on loans receivable for the year ended December 31, 2016 : Balance Provision Charge-offs Recoveries Balance Originated loans Personal Banking: Residential mortgage loans $ 4,656 2,906 (3,228 ) 286 4,692 Home equity loans 3,486 293 (1,090 ) 342 3,941 Consumer finance loans 3,445 3,117 (3,323 ) 376 3,275 Consumer loans 4,529 5,935 (6,902 ) 1,283 4,213 Total Personal Banking 16,116 12,251 (14,543 ) 2,287 16,121 Commercial Banking: Commercial real estate loans 23,667 (9,819 ) (2,403 ) 3,541 32,348 Commercial loans 15,510 4,834 (4,165 ) 2,340 12,501 Total Commercial Banking 39,177 (4,985 ) (6,568 ) 5,881 44,849 Total originated loans 55,293 7,266 (21,111 ) 8,168 60,970 Acquired loans Personal Banking: Residential mortgage loans 71 146 (252 ) 159 18 Home equity loans 1,047 2,065 (1,449 ) 330 101 Consumer loans 653 1,072 (680 ) 151 110 Total Personal Banking 1,771 3,283 (2,381 ) 640 229 Commercial Banking: Commercial real estate loans 3,008 2,116 (1,337 ) 790 1,439 Commercial loans 867 877 (52 ) 8 34 Total Commercial Banking 3,875 2,993 (1,389 ) 798 1,473 Total acquired loans 5,646 6,276 (3,770 ) 1,438 1,702 Total $ 60,939 13,542 (24,881 ) 9,606 62,672 The following table provides information related to changes in the allowance for losses on loans receivable for the year ended December 31, 2015 : Balance Provision Charge-offs Recoveries Balance Originated loans Personal Banking: Residential mortgage loans $ 4,692 (96 ) (1,057 ) 264 5,581 Home equity loans 3,941 693 (1,716 ) 414 4,550 Consumer finance loans 3,275 2,853 (3,056 ) 404 3,074 Consumer loans 4,213 5,132 (5,017 ) 1,054 3,044 Total Personal Banking 16,121 8,582 (10,846 ) 2,136 16,249 Commercial Banking: Commercial real estate loans 32,348 540 (5,741 ) 4,160 33,389 Commercial loans 12,501 2,768 (7,814 ) 4,032 13,515 Total Commercial Banking 44,849 3,308 (13,555 ) 8,192 46,904 Unallocated — (4,365 ) — — 4,365 Total originated loans 60,970 7,525 (24,401 ) 10,328 67,518 Acquired loans Personal Banking: Residential mortgage loans 18 47 (69 ) 40 — Home equity loans 101 247 (708 ) 562 — Other consumer loans 110 188 (201 ) 123 — Total Personal Banking 229 482 (978 ) 725 — Business Banking: Commercial real estate loans 1,439 1,545 (585 ) 479 — Commercial loans 34 160 (369 ) 243 — Total Business Banking 1,473 1,705 (954 ) 722 — Total acquired loans 1,702 2,187 (1,932 ) 1,447 — Total $ 62,672 9,712 (26,333 ) 11,775 67,518
Schedule of loan portfolio by portfolio segment and by class of financing receivable	The following table provides information related to the loan portfolio by portfolio segment and by class of financing receivable as of December 31, 2017 : Recorded investment in loans receivable Allowance for loan losses Recorded investment in loans on nonaccrual (1) Recorded investment in loans 90 days or more past maturity and still accruing TDRs (1) Allowance for loan losses related to TDRs Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,776,203 3,955 14,791 — 8,000 815 — Home equity loans 1,310,355 4,834 8,907 120 1,716 462 4 Consumer finance loans 18,619 3,968 199 3 — — — Consumer loans 652,770 9,365 4,673 379 — — — Total Personal Banking 4,757,947 22,122 28,570 502 9,716 1,277 4 Commercial Banking: Commercial real estate loans 2,454,726 23,460 28,473 — 15,691 1,125 235 Commercial loans 580,736 11,213 7,412 — 6,697 742 8 Total Commercial Banking 3,035,462 34,673 35,885 — 22,388 1,867 243 Total $ 7,793,409 56,795 64,455 502 32,104 3,144 247 (1) Includes $12.3 million of nonaccrual TDRs. The following table provides information related to the loan portfolio by portfolio segment and by class of financing receivable as of December 31, 2016 : Recorded investment in loans receivable Allowance for loan losses Recorded investment in loans on nonaccrual (1) Recorded TDRs (1) Allowance Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,698,166 4,727 18,264 — 7,299 708 — Home equity loans 1,345,370 4,533 7,865 — 1,813 450 4 Consumer finance loans 48,981 3,445 743 — — — — Consumer loans 593,980 5,182 4,366 85 — — — Total Personal Banking 4,686,497 17,887 31,238 85 9,112 1,158 4 Commercial Banking: Commercial real estate loans 2,342,089 26,675 38,724 564 24,483 2,072 417 Commercial loans 528,761 16,377 9,574 — 9,331 1,360 17 Total Commercial Banking 2,870,850 43,052 48,298 564 33,814 3,432 434 Total $ 7,557,347 60,939 79,536 649 42,926 4,590 438 (1) Includes $16.3 million of nonaccrual TDRs.
Schedule of the evaluation of impaired loans by portfolio segment and by class of financing receivable	The following table provides information related to the evaluation of impaired loans by portfolio segment and by class of financing receivable as of and for the year ended December 31, 2017 : Loans collectively evaluated for impairment Loans individually evaluated for impairment Loans individually evaluated for impairment for which there is a related impairment reserve Related impairment reserve Loans individually evaluated for impairment for which there is no related reserve Personal Banking: Residential mortgage loans $ 2,767,635 8,568 8,568 816 — Home equity loans 1,308,639 1,716 1,716 461 — Consumer finance loans 18,619 — — — — Consumer loans 652,685 85 85 25 — Total Personal Banking 4,747,578 10,369 10,369 1,302 — Commercial Banking: Commercial real estate loans 2,433,755 20,971 18,470 1,859 2,501 Commercial loans 571,412 9,324 8,572 829 752 Total Commercial Banking 3,005,167 30,295 27,042 2,688 3,253 Total $ 7,752,745 40,664 37,411 3,990 3,253 The following table provides information related to the evaluation of impaired loans by portfolio segment and by class of financing receivable as of and for the year ended December 31, 2016 : Loans collectively evaluated for impairment Loans individually evaluated for impairment Loans individually evaluated for impairment for which there is a related impairment reserve Related impairment reserve Loans individually evaluated for impairment for which there is no related reserve Personal Banking: Residential mortgage loans $ 2,689,886 8,280 8,280 709 — Home equity loans 1,343,556 1,814 1,814 450 — Consumer finance loans 48,981 — — — — Consumer loans 593,854 126 126 29 — Total Personal Banking 4,676,277 10,220 10,220 1,188 — Commercial Banking: Commercial real estate loans 2,309,186 32,903 27,594 3,545 5,309 Commercial loans 518,449 10,312 10,242 1,390 70 Total Commercial Banking 2,827,635 43,215 37,836 4,935 5,379 Total $ 7,503,912 53,435 48,056 6,123 5,379
Schedule of roll forward of troubled debt restructurings	The following table provides a roll forward of troubled debt restructurings for the periods indicated: For the years ended December 31, 2017 2016 Number of Amount Number of Amount Beginning TDR balance: 225 $ 42,926 227 $ 51,115 New TDRs 24 5,450 34 6,365 Re-modified TDRs 5 2,099 7 3,414 Net paydowns (11,538 ) (9,037 ) Charge-offs: Residential mortgage loans 1 (77 ) — — Home equity loans 1 (48 ) — — Commercial real estate loans 2 (2,498 ) 1 (120 ) Commercial loans 6 (259 ) 2 (142 ) Paid-off loans: Residential mortgage loans — — 4 (151 ) Home equity loans 8 (62 ) 7 (534 ) Commercial real estate loans 15 (1,633 ) 12 (6,170 ) Commercial loans 11 (2,256 ) 10 (1,814 ) Ending TDR balance: 205 $ 32,104 225 $ 42,926 Accruing TDRs $ 19,819 $ 26,580 Non-accrual TDRs 12,285 16,346
Schedule of troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable	The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable during the year ended December 31, 2017 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 8 $ 1,604 1,555 158 Home equity loans 3 152 148 40 Total Personal Banking 11 1,756 1,703 198 Commercial Banking: Commercial real estate loans 11 5,232 4,889 364 Commercial loans 7 561 526 37 Total Commercial Banking 18 5,793 5,415 401 Total 29 $ 7,549 7,118 599 Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings modified within the previous twelve months that have subsequently defaulted: Personal Banking: Residential mortgage loans 1 $ 336 334 34 Home equity loans — — — — Total Personal Banking 1 336 334 34 Commercial Banking: Commercial real estate loans 2 438 426 35 Commercial loans — — — — Total Commercial Banking 2 438 426 35 Total 3 $ 774 760 69 The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable during the year ended December 31, 2016 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 7 $ 1,199 1,177 114 Home equity loans 7 475 471 110 Total Personal Banking 14 1,674 1,648 224 Commercial Banking: Commercial real estate loans 7 3,729 3,643 485 Commercial loans 20 4,376 2,218 508 Total Commercial Banking 27 8,105 5,861 993 Total 41 $ 9,779 7,509 1,217 Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings modified within the previous twelve months that have subsequently defaulted: Personal Banking: Residential mortgage loans — $ — — — Home equity loans — — — — Total Personal Banking — — — — Commercial Banking: Commercial real estate loans 1 429 425 31 Commercial loans 3 533 533 533 Total Business Banking 4 962 958 564 Total 4 $ 962 958 564 The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable during the year ended December 31, 2015 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 6 $ 364 357 21 Home equity loans 3 101 97 21 Total Personal Banking 9 465 454 42 Commercial Banking: Commercial real estate loans 11 12,258 12,243 1,047 Commercial loans 9 2,200 2,184 156 Total Commercial Banking 20 14,458 14,427 1,203 Total 29 $ 14,923 14,881 1,245
Schedule of troubled debt restructurings (including re-modified TDRs) by type of modification by portfolio segment and by class of financing receivable	The following table provides information for troubled debt restructurings (including re-modified TDRs) by type of modification, by portfolio segment and class of financing receivable during the year ended December 31, 2017 : Number of Type of modification contracts Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 8 $ 359 — 8 1,188 1,555 Home equity loans 3 118 — — 30 148 Total Personal Banking 11 477 — 8 1,218 1,703 Commercial Banking: Commercial real estate loans 11 — 2,688 2,201 — 4,889 Commercial loans 7 — — 422 104 526 Total Commercial Banking 18 — 2,688 2,623 104 5,415 Total 29 $ 477 2,688 2,631 1,322 7,118 The following table provides information for troubled debt restructurings (including re-modified TDRs) by type of modification, by portfolio segment and class of financing receivable during the year ended December 31, 2016 : Number of Type of modification contracts Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 7 $ 358 — 771 48 1,177 Home equity loans 7 120 — 3 348 471 Total Personal Banking 14 478 — 774 396 1,648 Commercial Banking: Commercial real estate loans 7 — 425 1,980 1,238 3,643 Commercial loans 20 — 328 1,178 712 2,218 Total Commercial Banking 27 — 753 3,158 1,950 5,861 Total 41 $ 478 753 3,932 2,346 7,509
Schedule of re-modified troubled debt restructurings by portfolio segment and by class of financing receivable	The following table provides information related to re-modified troubled debt restructurings by portfolio segment and by class of financing receivable for the year ended December 31, 2017 : Number of re-modified Type of re-modification TDRs Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 2 $ 250 — — 429 679 Home equity loans 1 12 — — — 12 Total Personal Banking 3 262 — — 429 691 Commercial Banking: Commercial real estate loans 1 — — 1,299 — 1,299 Commercial loans 1 — — 83 — 83 Total Commercial Banking 2 — — 1,382 — 1,382 Total 5 $ 262 — 1,382 429 2,073 The following table provides information related to re-modified troubled debt restructurings by portfolio segment and by class of financing receivable for the year ended December 31, 2016 : Number of Type of re-modification TDRs Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans — $ — — — — — Home equity loans 1 — — — 192 192 Total Personal Banking 1 — — — 192 192 Commercial Banking: Commercial real estate loans 2 — — 1,329 173 1,502 Commercial loans 4 — 502 — — 502 Total Commercial Banking 6 — 502 1,329 173 2,004 Total 7 $ — 502 1,329 365 2,196
Schedule of loan delinquencies	The following table provides information related to loan delinquencies as of December 31, 2017 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 23,786 6,030 12,613 42,429 2,619,951 2,662,380 — Home equity loans 6,094 2,333 6,043 14,470 1,037,088 1,051,558 — Consumer finance loans 2,128 1,113 199 3,440 15,179 18,619 — Consumer loans 9,762 2,834 3,274 15,870 537,496 553,366 — Total Personal Banking 41,770 12,310 22,129 76,209 4,209,714 4,285,923 — Commercial Banking: Commercial real estate loans 5,520 2,133 10,629 18,282 2,142,930 2,161,212 — Commercial loans 1,469 204 2,806 4,479 516,719 521,198 — Total Commercial Banking 6,989 2,337 13,435 22,761 2,659,649 2,682,410 — Total originated loans 48,759 14,647 35,564 98,970 6,869,363 6,968,333 — Acquired loans Personal Banking: Residential mortgage loans 1,998 205 1,277 3,480 110,343 113,823 381 Home equity loans 1,367 538 1,306 3,211 255,586 258,797 98 Consumer loans 1,150 517 353 2,020 97,384 99,404 10 Total Personal Banking 4,515 1,260 2,936 8,711 463,313 472,024 489 Commercial Banking: Commercial real estate loans 2,795 406 5,655 8,856 284,658 293,514 923 Commercial loans 396 237 334 967 58,571 59,538 — Total Commercial Banking 3,191 643 5,989 9,823 343,229 353,052 923 Total acquired loans 7,706 1,903 8,925 18,534 806,542 825,076 1,412 Total loans $ 56,465 16,550 44,489 117,504 7,675,905 7,793,409 1,412 (1) Represents acquired loans that were originally recorded at fair value upon acquisition. These loans are considered to be accruing because we can reasonably estimate future cash flows and expect to fully collect the carrying value of these loans. Therefore, we are accreting the difference between the carrying value and their expected cash flows into interest income. The following table provides information related to loan delinquencies as of December 31, 2016 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 26,212 5,806 12,792 44,810 2,519,845 2,564,655 — Home equity loans 5,785 1,305 4,783 11,873 1,031,040 1,042,913 — Consumer finance loans 1,255 766 743 2,764 46,217 48,981 Consumer loans 7,343 2,438 2,775 12,556 415,508 428,064 — Total Personal Banking 40,595 10,315 21,093 72,003 4,012,610 4,084,613 — Commercial Banking: Commercial real estate loans 7,674 3,674 16,508 27,856 1,944,227 1,972,083 — Commercial loans 1,067 1,957 3,107 6,131 449,244 455,375 — Total Commercial Banking 8,741 5,631 19,615 33,987 2,393,471 2,427,458 — Total originated loans 49,336 15,946 40,708 105,990 6,406,081 6,512,071 — Acquired loans Personal Banking: Residential mortgage loans 1,174 421 829 2,424 131,087 133,511 452 Home equity loans 1,020 258 973 2,251 300,206 302,457 204 Consumer loans 1,270 405 320 1,995 163,921 165,916 15 Total Personal Banking 3,464 1,084 2,122 6,670 595,214 601,884 671 Commercial Banking: Commercial real estate loans 2,703 821 4,762 8,286 361,720 370,006 2,006 Commercial loans 111 124 413 648 72,738 73,386 147 Total Commercial Banking 2,814 945 5,175 8,934 434,458 443,392 2,153 Total acquired loans 6,278 2,029 7,297 15,604 1,029,672 1,045,276 2,824 Total loans $ 55,614 17,975 48,005 121,594 7,435,753 7,557,347 2,824 (1) Represents acquired loans that were originally recorded at fair value upon acquisition. These loans are considered to be accruing because we can reasonably estimate future cash flows and expect to fully collect the carrying value of these loans. Therefore, we are accreting the difference between the carrying value and their expected cash flows into interest income.
Schedule of credit quality indicators	The following table sets forth information about credit quality indicators as of December 31, 2017 : Pass Special mention Substandard Doubtful Loss Total Originated loans Personal Banking: Residential mortgage loans $ 2,645,475 — 16,905 — — 2,662,380 Home equity loans 1,042,965 — 8,593 — — 1,051,558 Consumer finance loans 18,420 — 199 — — 18,619 Consumer loans 549,550 — 3,816 — — 553,366 Total Personal Banking 4,256,410 — 29,513 — — 4,285,923 Commercial Banking: Commercial real estate loans 1,964,565 78,699 117,948 — — 2,161,212 Commercial loans 461,962 15,510 43,726 — — 521,198 Total Commercial Banking 2,426,527 94,209 161,674 — — 2,682,410 Total originated loans 6,682,937 94,209 191,187 — — 6,968,333 Acquired loans Personal Banking: Residential mortgage loans 112,990 — 833 — — 113,823 Home equity loans 257,312 — 1,485 — — 258,797 Consumer loans 98,659 — 745 — — 99,404 Total Personal Banking 468,961 — 3,063 — — 472,024 Commercial Banking: Commercial real estate loans 251,761 4,838 36,915 — — 293,514 Commercial loans 49,073 3,787 6,678 — — 59,538 Total Commercial Banking 300,834 8,625 43,593 — — 353,052 Total acquired loans 769,795 8,625 46,656 — — 825,076 Total loans $ 7,452,732 102,834 237,843 — — 7,793,409 The following table sets forth information about credit quality indicators as of December 31, 2016 : Pass Special mention Substandard Doubtful Loss Total Originated loans Personal Banking: Residential mortgage loans $ 2,548,390 — 16,265 — — 2,564,655 Home equity loans 1,035,496 — 7,417 — — 1,042,913 Consumer finance loans 48,238 — 743 — — 48,981 Consumer loans 425,712 — 2,352 — — 428,064 Total Personal Banking 4,057,836 — 26,777 — — 4,084,613 Commercial Banking: Commercial real estate loans 1,821,548 36,321 114,214 — — 1,972,083 Commercial loans 401,866 15,203 38,306 — — 455,375 Total Commercial Banking 2,223,414 51,524 152,520 — — 2,427,458 Total originated loans 6,281,250 51,524 179,297 — — 6,512,071 Acquired loans Personal Banking: Residential mortgage loans 131,717 — 1,794 — — 133,511 Home equity loans 300,100 — 2,357 — — 302,457 Consumer loans 165,094 — 822 — — 165,916 Total Personal Banking 596,911 — 4,973 — — 601,884 Commercial Banking: Commercial real estate loans 331,780 7,403 30,823 — — 370,006 Commercial loans 68,127 1,989 3,270 — — 73,386 Total Commercial Banking 399,907 9,392 34,093 — — 443,392 Total acquired loans 996,818 9,392 39,066 — — 1,045,276 Total loans $ 7,278,068 60,916 218,363 — — 7,557,347
Schedule of financial instruments with off-balance-sheet risk	Financial instruments with off-balance-sheet risk as of December 31, 2017 and 2016 are presented in the following table: December 31, 2017 2016 Loan commitments $ 181,058 109,032 Undisbursed lines of credit 872,700 843,457 Standby letters of credit 25,718 25,039 Total $ 1,079,476 977,528
Schedule of changes in mortgage servicing rights	The following table shows changes in MSRs as of and for the years ended December 31, 2017 and 2016 : Servicing rights Valuation allowance Net carrying value and fair value Balance at December 31, 2015 $ 1,666 — 1,666 Additions 3,523 (4 ) 3,519 Amortization (950 ) — (950 ) Balance at December 31, 2016 4,239 (4 ) 4,235 Additions 833 4 837 Amortization (1,549 ) — (1,549 ) Balance at December 31, 2017 $ 3,523 — 3,523

Accrued Interest Receivable (Ta

Accrued Interest Receivable (Tables)	12 Months Ended
	Dec. 31, 2017
Interest Receivable and Other Assets [Abstract]
Schedule of accrued interest receivable	Accrued interest receivable as of December 31, 2017 and 2016 is presented in the following table: December 31, 2017 2016 Investment securities $ 1,260 1,613 Mortgage-backed securities 1,107 910 Loans receivable 20,985 19,176 $ 23,352 21,699

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of premises and equipment	Premises and equipment at December 31, 2017 and 2016 are summarized by major classification in the following table: December 31, 2017 2016 Land and land improvements $ 21,563 21,229 Office buildings and improvements 150,056 156,162 Furniture, fixtures and equipment 125,347 120,391 Leasehold improvements 19,909 19,859 Total, at cost 316,875 317,641 Less accumulated depreciation and amortization (164,931 ) (156,456 ) Premises and equipment, net $ 151,944 161,185
Schedule of minimum annual rentals	Minimum annual rentals by fiscal year are summarized in the following table: 2018 $ 4,395 2019 3,300 2020 2,726 2021 2,232 2022 1,620 Thereafter 7,413 Total $ 21,686

Goodwill and Other Intangible38

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of intangible assets subject to amortization	The following table provides information for intangible assets subject to amortization for the years ended December 31, 2017 and 2016 : December 31, 2017 2016 Amortizable intangible assets: Core deposit intangibles - gross $ 63,685 37,953 Acquisitions — 25,732 Less: accumulated amortization (40,029 ) (34,378 ) Core deposit intangibles - net $ 23,656 29,307 Customer and Contract intangible assets - gross $ 10,474 8,496 Acquisitions — 1,978 Less: accumulated amortization (8,461 ) (7,348 ) Customer and Contract intangible assets - net $ 2,013 3,126
Schedule of the actual aggregate amortization expense as well as estimated aggregate amortization expense, based upon current levels of intangible assets	The following information shows the actual aggregate amortization expense for the years ended December 31, 2017 , 2016 and 2015 as well as the estimated aggregate amortization expense, based upon current levels of intangible assets, for each of the five succeeding fiscal years: For the year ended December 31, 2015 $ 1,688 For the year ended December 31, 2016 4,259 For the year ended December 31, 2017 6,764 For the year ending December 31, 2018 5,848 For the year ending December 31, 2019 4,933 For the year ending December 31, 2020 4,017 For the year ending December 31, 2021 3,188 For the year ending December 31, 2022 2,456
Schedule of the changes in carrying amount of goodwill	The following table provides information for the changes in the carrying amount of goodwill: Total Balance at December 31, 2015 $ 261,736 Goodwill acquired 45,684 Balance at December 31, 2016 307,420 Goodwill acquired — Balance at December 31, 2017 $ 307,420

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Schedule of deposit balances	Deposit balances at December 31, 2017 and 2016 are shown in the table below: December 31, 2017 2016 Savings deposits $ 1,653,579 1,622,879 Interest-bearing demand deposits 1,442,928 1,428,317 Noninterest-bearing demand deposits 1,610,409 1,448,972 Money market deposit accounts 1,707,450 1,841,567 Time deposits 1,412,623 1,540,586 Total deposits $ 7,826,989 7,882,321
Summarizes the contractual maturity of the certificate accounts	The following table summarizes the contractual maturity of time deposits at December 31, 2017 and 2016 : December 31, 2017 2016 Due within 12 months $ 666,348 836,525 Due between 12 and 24 months 226,171 311,976 Due between 24 and 36 months 201,654 153,708 Due between 36 and 48 months 131,530 90,777 Due between 48 and 60 months 174,704 134,687 After 60 months 12,216 12,913 Total time deposits $ 1,412,623 1,540,586
Summarizes the interest expense incurred on the deposits	The following table summarizes the interest expense incurred on the respective deposits for the years ended December 31, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Savings deposits $ 3,062 3,218 3,387 Interest-bearing demand deposits 1,027 462 568 Money market deposit accounts 4,203 3,621 3,222 Time deposits 14,765 16,164 16,878 Total interest expense $ 23,057 23,465 24,055

Borrowed Funds (Tables)

Borrowed Funds (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of borrowed funds	Borrowed funds at December 31, 2017 and 2016 are presented in the following table: December 31, 2017 2016 Amount Average rate Amount Average rate Collateralized borrowings, due within one year $ 108,238 0.20 % $ 142,899 0.17 %
Schedule of capital debt securities and junior subordinated deferrable interest debentures	The following table sets forth a summary of guaranteed capital debt securities and junior subordinated deferrable interest debentures held by the trusts as of December 31, 2017 and 2016 : Capital debt December 31, securities 2017 2016 Northwest Bancorp Capital Trust III $ 50,000 51,547 51,547 Northwest Bancorp Statutory Trust IV 50,000 51,547 51,547 LNB Trust II 7,875 8,119 8,119 Total $ 107,875 111,213 111,213

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of allocation of income tax	Total income tax was allocated for the years ended December 31, 2017 , 2016 and 2015 as follows: Years ended December 31, 2017 2016 2015 Income before income taxes $ 41,444 21,648 27,960 Shareholders’ equity for unrealized (loss)/ gain on securities available-for-sale (3,403 ) (1,871 ) (85 ) Shareholders’ equity for tax benefit for excess of fair value above cost of stock benefit plans — (1,425 ) (332 ) Shareholders’ equity for pension adjustment (213 ) (2,455 ) (848 ) Shareholders’ equity for swap fair value adjustment 585 539 699 Unallocated income tax $ 38,413 16,436 27,394
Schedule of income tax expense (benefit) applicable to income before taxes	Income tax expense applicable to income before taxes consists of: Years ended December 31, 2017 2016 2015 Current $ 30,127 18,914 21,670 Deferred 11,317 2,734 6,290 Total income tax expense $ 41,444 21,648 27,960
Schedule of reconciliation of the expected federal statutory rate to the effective rate	A reconciliation of the expected federal statutory income tax rate to the effective rate, expressed as a percentage of pretax income for the years ended December 31, 2017 , 2016 and 2015 , is as follows: Years ended December 31, 2017 2016 2015 Expected tax rate 35.0 % 35.0 % 35.0 % Tax-exempt interest income (1.5 )% (3.3 )% (3.0 )% State income tax, net of federal benefit 3.2 % 1.2 % 2.9 % Bank-owned life insurance (1.6 )% (2.6 )% (1.7 )% Stock-based compensation (0.9 )% — % — % Dividends on stock plans (1.1 )% (2.0 )% (0.8 )% Low income housing and historic tax credits (0.5 )% (1.0 )% (1.4 )% Non-deductible acquisition expense — % — % 0.5 % ESOP termination — % 3.4 % — % Adjustment to net deferred tax liabilities for enacted changes in tax laws and rates (2.3 )% — % — % Other 0.2 % (0.3 )% 0.1 % Effective tax rate 30.5 % 30.4 % 31.6 %
Tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities	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 presented below: December 31, 2017 2016 Deferred tax assets: Deferred rent $ 87 187 Deferred compensation expense 1,040 2,893 Bad debts 10,277 18,823 Other reserves 953 1,823 Accrued postretirement benefit cost 413 641 Stock benefit plans 744 1,085 Writedown of investment securities 104 2,875 Accrued expenses 35 95 Pension and postretirement benefits 13,033 18,491 Unrealized loss on the fair value of derivatives 223 958 Unrealized loss on the fair value of securities available-for-sale 2,160 — Purchase accounting — 1,215 Deferred income 1,001 253 Other 141 153 Total deferred tax assets 30,211 49,492 Deferred tax liabilities: Pension expense 5,542 8,689 Unrealized gain on the fair value of securities available-for-sale — 252 Purchase accounting 303 — Intangible assets 13,546 21,927 Mortgage servicing rights 777 1,559 Fixed assets 4,940 8,107 Net deferred loan fees 4,690 — Other 274 635 Total deferred tax liabilities 30,072 41,169 Net deferred tax asset $ 139 8,323

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per share	The computation of basic and diluted earnings per share for the years ended December 31, 2017 , 2016 and 2015 follows: Years ended December 31, 2017 2016 2015 Net income available to common shareholders $ 94,467 49,667 60,540 Weighted average common shares outstanding 101,015,083 99,439,174 94,314,420 Dilutive potential shares due to effect of stock options 1,549,822 1,225,514 515,369 Total weighted average common shares and dilutive potential shares 102,564,905 100,664,688 94,829,789 Basic earnings per share (1) $ 0.94 0.50 0.64 Diluted earnings per share (1) $ 0.92 0.49 0.64 (1) Not in thousands.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of net periodic costs for the defined benefit pension plans and the post retirement healthcare plans	The following table sets forth the net periodic pension cost for the defined benefit pension plans for the years ended December 31, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Service cost $ 6,149 5,496 5,721 Interest cost 6,879 6,781 6,125 Expected return on plan assets (10,512 ) (9,897 ) (10,371 ) Net amortization and deferral 1,388 1,388 1,375 Net periodic pension cost $ 3,904 3,768 2,850 The following table sets forth the net periodic benefit cost for the postretirement healthcare benefits plan for the years ended December 31, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Service cost $ — — — Interest cost 68 70 58 Amortization of net loss 108 90 60 Net period benefit cost $ 176 160 118
Schedule of other changes in the defined benefit pension plans' plan assets and benefit obligations recognized in other comprehensive income	The following table sets forth other changes in the defined benefit pension plans’ plan assets and benefit obligations recognized in other comprehensive income: Years ended December 31, 2017 2016 2015 Net loss/ (gain) $ (1,647 ) 1,550 (420 ) Prior service cost/ (credit) — — — Amortization of prior service cost 2,323 2,323 2,323 Total recognized in other comprehensive income $ 676 3,873 1,903 Total recognized in net periodic pension cost and other comprehensive income/ (loss) $ 4,580 7,641 4,753 The following table sets forth other changes in the postretirement healthcare plan’s plan assets and benefit obligations recognized in other comprehensive income: Years ended December 31, 2017 2016 2015 Net loss/ (gain) $ (156 ) 109 273 Total recognized in other comprehensive income $ (156 ) 109 273 Total recognized in net periodic benefit cost and other comprehensive income $ 20 269 391
Schedule of defined benefit pension plans' funded status	The following table sets forth information for the defined benefit pension plans’ funded status at December 31, 2017 and 2016 : December 31, 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 172,208 162,133 Service cost 6,149 5,496 Interest cost 6,879 6,781 Acquisition — — Actuarial (gain)/ loss 14,807 4,267 Benefits paid (6,901 ) (6,469 ) Benefit obligation at end of year $ 193,142 172,208 Change in plan assets: Fair value of plan assets at beginning of year $ 152,625 143,655 Actual return on plan assets 23,255 8,903 Employer contributions 4,689 6,536 Acquisition — — Benefits paid (6,901 ) (6,469 ) Fair value of plan assets at end of period $ 173,668 152,625 Funded status at end of year $ (19,474 ) (19,583 ) The following table sets forth the funded status of the postretirement healthcare benefit plan at December 31, 2017 and 2016 : December 31, 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 1,779 1,737 Service cost — — Interest cost 68 70 Actuarial loss (48 ) 200 Benefits paid (162 ) (228 ) Benefit obligation at end of year $ 1,637 1,779 Change in plan assets: Fair value of plan assets at beginning of year $ — — Employer contributions 162 228 Benefits paid (162 ) (228 ) Fair value of plan assets at end of year $ — — Funded status at year end $ (1,637 ) (1,779 )
Schedule of assumptions used to develop the net periodic pension cost	The assumptions used to develop the preceding information for postretirement healthcare benefits are as follows: Years ended December 31, 2017 2016 2015 Discount rate 4.06 % 4.25 % 3.89 % Monthly cost of healthcare insurance per beneficiary (1) $ 548 539 470 Annual rate of increase in healthcare costs 4.00 % 4.00 % 4.00 % (1) Not in thousands The following table sets forth the assumptions used to develop the net periodic pension cost: Years ended December 31, 2017 2016 2015 Discount rate 4.06 % 4.25 % 3.89 % Expected long-term rate of return on assets 7.00 % 7.00 % 7.50 % Rate of increase in compensation levels 3.00 % 3.00 % 3.00 %
Schedule of assumptions used to determine benefit obligations	The following table sets forth the assumptions used to determine benefit obligations at the end of each period: Years ended December 31, 2017 2016 2015 Discount rate 3.53 % 4.06 % 4.25 % Expected long-term rate of return on assets 7.00 % 7.00 % 7.00 % Rate of increase in compensation levels 3.00 % 3.00 % 3.00 %
Schedule of certain information related to pension plans	The following table sets forth certain information related to our pension plans: December 31, 2017 2016 Projected benefit obligation $ 193,142 172,208 Accumulated benefit obligation 193,142 172,208 Fair value of plan assets 173,668 152,625
Schedule of weighted average asset allocation of defined benefit plans	The following table sets forth the weighted average asset allocation of defined benefit plans: Target December 31, allocation 2017 2016 Debt securities 20 – 50% 23 % 23 % Equity securities 30 – 60% 73 % 72 % Other 5 – 50% 4 % 5 % Total 100 % 100 %
Schedule of allocation of plan assets	The following table sets forth the pension plan assets as of December 31, 2017 and 2016 : December 31, 2017 2016 Mutual funds - debt $ 40,010 35,224 Mutual funds - equity 125,871 110,078 Cash and cash equivalents 7,787 7,322
Schedule of accumulated benefit obligation in excess of plan assets	The following table sets forth information for plans with an accumulated benefit obligation in excess of plan assets: December 31, 2017 2016 Projected benefit obligation $ 1,637 1,779 Accumulated benefit obligation 1,637 1,779 Fair value of plan assets — —
Schedule of activity under option plans	The following table summarizes the activity in our option plans during the years ended December 31, 2017 , 2016 and 2015 (amounts in this table are not in thousands): Years ended December 31, 2017 2016 2015 Number Weighted average exercise price Number Weighted average exercise price Number Weighted average exercise price Balance at beginning of year 5,804,105 $ 12.25 6,306,496 $ 11.81 6,402,407 $ 11.65 Granted (1) 819,010 15.57 725,400 14.15 665,370 12.37 Exercised (2) (630,591 ) 11.66 (1,081,072 ) 11.01 (474,253 ) 10.27 Forfeited/ expired (296,954 ) 12.43 (146,719 ) 12.71 (287,028 ) 12.26 Balance at end of year 5,695,570 12.75 5,804,105 12.25 6,306,496 11.81 Exercisable at end of year 3,016,367 11.99 3,035,718 11.71 3,431,113 11.42 (1) Weighted average fair value of options at grant date: $1.55 , $1.52 and $1.14 , respectively. (2) The total intrinsic value of options exercised was $3.5 million , $5.1 million and $1.2 million , respectively.
Schedule of number of options outstanding, number of options exercisable, and weighted average remaining life of all option grants	The following table summarizes the number of options outstanding, number of options exercisable, and weighted average remaining life of all option grants as of December 31, 2017 : Exercise Exercise Exercise Exercise Exercise Exercise Exercise Options outstanding: Number of options 164,289 143,224 48,027 260,456 384,380 342,789 14,500 Weighted average remaining contract life (years) 1.25 1.00 0.25 2.25 4.50 3.25 3.50 Options exercisable: Number of options 164,289 143,224 48,027 260,456 237,916 299,253 13,000 Weighted average remaining term - vested (years) 1.25 1.00 0.25 2.25 4.50 3.25 3.50 Exercise Exercise Exercise Exercise Exercise Exercise Total Options outstanding: Number of options 1,537,329 522,750 427,090 440,653 643,998 766,085 5,695,570 Weighted average remaining contract life (years) 3.50 7.50 5.50 6.50 8.50 9.50 5.46 Options exercisable: Number of options 1,079,159 163,646 226,292 178,091 126,374 76,640 3,016,367 Weighted average remaining term - vested (years) 3.50 7.50 5.50 6.50 8.50 9.50 4.04

Disclosures About Fair Value 44

Disclosures About Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of the carrying amount and estimated fair value of the entity's financial instruments included in the consolidated statement of financial condition	The following table sets forth the carrying amount and estimated fair value of our financial instruments included in the consolidated statement of financial condition at December 31, 2017 and 2016 : December 31, 2017 Carrying Estimated amount fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 77,710 77,710 77,710 — — Securities available-for-sale 792,535 792,535 574 791,961 — Securities held-to-maturity 29,678 29,667 — 29,667 — Loans receivable, net 7,736,614 7,762,562 3,128 — 7,759,434 Accrued interest receivable 23,352 23,352 23,352 — — Interest rate swaps 214 214 — 214 — FHLB Stock 11,733 11,733 — — — Total financial assets $ 8,671,836 8,697,773 104,764 821,842 7,759,434 Financial liabilities: Savings and checking accounts $ 6,414,366 6,414,366 6,414,366 — — Time deposits 1,412,623 1,433,380 — — 1,433,380 Borrowed funds 108,238 108,238 108,238 — — Junior subordinated debentures 111,213 110,954 — — 110,954 Interest rate swaps 1,278 1,278 — 1,278 — Foreign exchange swaps 61 61 — 61 — Accrued interest payable 460 460 460 — — Total financial liabilities $ 8,048,239 8,068,737 6,523,064 1,339 1,544,334 December 31, 2016 Carrying Estimated amount fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 389,867 389,867 389,867 — — Securities available-for-sale 826,200 826,200 4,440 812,394 9,366 Securities held-to-maturity 19,978 20,426 — 20,426 — Loans receivable, net 7,496,408 7,878,815 9,625 — 7,869,190 Accrued interest receivable 21,699 21,699 21,699 — — Interest rate swaps 238 238 — 238 — FHLB Stock 7,390 7,390 — — — Total financial assets $ 8,761,780 9,144,635 425,631 833,058 7,878,556 Financial liabilities: Savings and checking accounts $ 6,341,735 6,341,735 6,341,735 — — Time deposits 1,540,586 1,626,434 — — 1,626,434 Borrowed funds 142,899 142,899 142,899 — — Junior subordinated debentures 111,213 113,313 — — 113,313 Interest rate swaps 2,974 2,974 — 2,974 — Accrued interest payable 643 643 643 — — Total financial liabilities $ 8,140,050 8,227,998 6,485,277 2,974 1,739,747
Schedule of assets and liabilities measured at fair value on a recurring basis	The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 : Level 1 Level 2 Level 3 Total at fair value Assets Equity securities $ 574 — — 574 Debt securities: U.S. government and agencies — 1 — 1 Government sponsored enterprises — 209,269 — 209,269 States and political subdivisions — 51,056 — 51,056 Corporate — 909 — 909 Total debt securities — 261,235 — 261,235 Residential mortgage-backed securities: GNMA — 29,695 — 29,695 FNMA — 82,969 — 82,969 FHLMC — 64,021 — 64,021 Non-agency — 555 — 555 Collateralized mortgage obligations: GNMA — 4,769 — 4,769 FNMA — 191,512 — 191,512 FHLMC — 157,190 — 157,190 Non-agency — 15 — 15 Total mortgage-backed securities — 530,726 — 530,726 Interest rate swaps — 214 — 214 Total assets $ 574 792,175 — 792,749 Liabilities Interest rate swaps $ — 1,278 — 1,278 Foreign exchange swaps — 61 — 61 Total liabilities $ — 1,339 — 1,339 The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2016 : Level 1 Level 2 Level 3 Total at fair value Assets Equity securities $ 4,440 — — 4,440 Debt securities: U.S. government and agencies — 6 — 6 Government sponsored enterprises — 294,170 — 294,170 States and political subdivisions — 63,070 — 63,070 Corporate — 7,614 9,366 16,980 Total debt securities — 364,860 9,366 374,226 Residential mortgage-backed securities: GNMA — 30,883 — 30,883 FNMA — 106,578 — 106,578 FHLMC — 82,115 — 82,115 Non-agency — 579 — 579 Collateralized mortgage obligations: GNMA — 6,287 — 6,287 FNMA — 95,186 — 95,186 FHLMC — 119,197 — 119,197 SBA — 6,608 — 6,608 Non-agency — 101 — 101 Total mortgage-backed securities — 447,534 — 447,534 Interest rate swaps — 238 — 238 Total assets $ 4,440 812,632 9,366 826,438 Liabilities Interest rate swaps $ — 2,974 — 2,974 Total liabilities $ — 2,974 — 2,974
Schedule of reconciliation of debt securities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)	The table below presents a reconciliation of all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the year ended December 31, 2017 and 2016 : December 31, 2017 2016 Debt securities Beginning balance January 1, $ 9,366 8,955 Total net realized investment gains/ (losses) and net change in unrealized appreciation/ (depreciation): Included in net income as OTTI — — Included in other comprehensive income 1,282 411 Purchases — — Sales (10,648 ) — Transfers into Level 3 — — Transfers out of Level 3 — — Ending balance December 31, $ — 9,366
Schedule of fair value measurement for nonrecurring assets	The following table represents the fair market measurement for only those nonrecurring assets that had a fair market value below the carrying amount as of December 31, 2017 : Level 1 Level 2 Level 3 Total assets at fair value Loans evaluated for impairment $ — — 33,421 33,421 Real estate owned — — 5,666 5,666 Total assets $ — — 39,087 39,087 The following table represents the fair market measurement for only those nonrecurring assets that had a fair market value below the carrying amount as of December 31, 2016 : Level 1 Level 2 Level 3 Total assets at fair value Loans evaluated for impairment $ — — 41,933 41,933 Mortgage servicing rights — — 246 246 Real estate owned — — 4,889 4,889 Total assets $ — — 47,068 47,068
Schedule of quantitative information about assets measured at fair value on a recurring and nonrecurring basis for Level 3 Fair Value Measurements	The following table presents additional quantitative information about assets measured at fair value on a recurring and nonrecurring basis and for which we have utilized Level 3 inputs to determine fair value at December 31, 2017 : Fair value Valuation techniques Significant unobservable inputs Range (weighted average) Loans measured for impairment $ 33,421 Appraisal Estimated costs to sell 10% value (1) Discounted cash Discount rate 4.25% to 10.0% (7.50%) flow Real estate owned 5,666 Appraisal Estimated costs to sell 10% value (1) (1) Fair value is generally determined through independent appraisals of the underlying collateral, which may include Level 3 inputs that are not identifiable, or by using the discounted cash flow method if the loan is not collateral dependent.

Regulatory Capital Requiremen45

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Schedule of actual, required, and well capitalized levels	The actual, required, and well capitalized levels as of December 31, 2017 and 2016 were as follows: At December 31, 2017 Minimum capital Well capitalized Actual requirements (1) requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,136,076 15.831 % $ 663,823 9.250 % $ 717,647 10.000 % Northwest Bank 1,017,251 14.189 % 663,179 9.250 % 716,951 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,079,270 15.039 % 520,294 7.250 % 574,117 8.000 % Northwest Bank 960,443 13.396 % 519,789 7.250 % 573,560 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 971,395 13.536 % 412,647 5.750 % 466,470 6.500 % Northwest Bank 960,443 13.396 % 412,247 5.750 % 430,170 6.000 % Tier 1 capital (leverage) (to average assets) Northwest Bancshares, Inc. 1,079,270 11.676 % 369,735 4.000 % 462,169 5.000 % Northwest Bank 960,443 10.400 % 369,482 4.000 % 461,853 5.000 % (1) Amounts and ratios include the 2017 capital conservation buffer of 1.250% with the exception of Tier 1 capital to average assets. For further information related to the capital conservation buffer, see Item 1. Business - "Supervision and Regulation". At December 31, 2016 Minimum capital Well capitalized Actual requirements (1) requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,051,582 14.873 % $ 609,835 8.625 % $ 707,056 10.000 % Northwest Bank 961,279 13.609 % 609,248 8.625 % 706,375 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 990,153 14.004 % 468,424 6.625 % 565,644 8.000 % Northwest Bank 900,328 12.746 % 467,973 6.625 % 565,100 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 882,278 12.478 % 362,366 5.125 % 459,586 6.500 % Northwest Bank 900,328 12.746 % 362,017 5.125 % 459,144 6.500 % Tier I capital (leverage) (to average assets) Northwest Bancshares, Inc. 990,153 10.530 % 376,116 4.000 % 470,145 5.000 % Northwest Bank 900,328 9.585 % 375,735 4.000 % 469,669 5.000 % (1) Amounts and ratios include the 2016 capital conservation buffer of 0.625% with the exception of Tier 1 capital to average assets. For further information related to the capital conservation buffer, see Item 1. Business - "Supervision and Regulation".

Components of Accumulated Oth46

Components of Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of the components of accumulated other comprehensive income	The following table sets forth the components of accumulated other comprehensive income as of December 31, 2017 and 2016 : December 31, 2017 2016 Unrealized gain on marketable securities available-for-sale $ (4,409 ) 395 Fair value of interest rate swaps (691 ) (1,778 ) Defined benefit pension plans (26,980 ) (26,608 ) Accumulated other comprehensive income $ (32,080 ) (27,991 )
Schedule of the changes in accumulated other comprehensive income by component	The following table shows the changes in accumulated other comprehensive income by component for the year ended December 31, 2017 : Unrealized gains and losses on securities available-for- sale Change in fair value of interest rate swaps Change in defined benefit pension plans Total Balance as of January 1, $ 395 (1,778 ) (26,608 ) (27,991 ) Other comprehensive income/ (loss) before reclassification adjustments (2,478 ) 1,087 (1,254 ) (2,645 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (2,326 ) — 882 (1,444 ) Net other comprehensive income/ (loss) (4,804 ) 1,087 (372 ) (4,089 ) Balance as of December 31, $ (4,409 ) (691 ) (26,980 ) (32,080 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $3,814 , net of tax (income tax expense) of $1,488 . (2) Consists of amortization of prior service cost (compensation and employee benefits) of $2,323 and amortization of net loss (compensation and employee benefits) of $(3,818) , net of tax (income tax expense) of $613 . The following table shows the changes in accumulated other comprehensive income by component for the year ended December 31, 2016 : Unrealized gains and losses on securities available-for- sale Change in fair value of interest rate swaps Change in defined benefit pension plans Total Balance as of January 1, $ 3,325 (2,779 ) (25,081 ) (24,535 ) Other comprehensive income/ (loss) before reclassification adjustments (2,728 ) 1,001 (2,399 ) (4,126 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (202 ) — 872 670 Net other comprehensive income/ (loss) (2,930 ) 1,001 (1,527 ) (3,456 ) Balance as of December 31, $ 395 (1,778 ) (26,608 ) (27,991 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $331 net of tax (income tax expense) of $(129) . (2) Consists of amortization of prior service cost (compensation and employee benefits) of $2,323 and amortization of net loss (compensation and employee benefits) of $(3,801) , net of tax (income tax expense) of $606 . The following table shows the changes in accumulated other comprehensive income by component for the year ended December 31, 2015 : Unrealized gains and losses on securities available-for- sale Change in fair value of interest rate swaps Change in defined benefit pension plans Total Balance as of January 1, $ 3,461 (4,078 ) (23,753 ) (24,370 ) Other comprehensive income/ (loss) before reclassification adjustments 315 1,299 (2,203 ) (589 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (451 ) — 875 424 Net other comprehensive income/ (loss) (136 ) 1,299 (1,328 ) (165 ) Balance as of December 31, $ 3,325 (2,779 ) (25,081 ) (24,535 ) (1) Consists of realized losses on securities (gain on sales of investments, net) of $740 net of tax (income tax expense) of $(289) . (2) Consists of amortization of prior service cost (compensation and employee benefits) of $2,323 and amortization of net loss (compensation and employee benefits) of $(3,758) , net of tax (income tax expense) of $560 .

Parent Company Only Financial47

Parent Company Only Financial Statements - Condensed (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule of statements of financial condition	December 31, 2017 2016 Assets Cash and cash equivalents $ 26,088 34,521 Marketable securities available-for-sale 545 4,413 Investment in bank subsidiary 1,200,799 1,193,175 Other assets 92,712 52,645 Total assets $ 1,320,144 1,284,754 Liabilities and Shareholders’ Equity Liabilities: Debentures payable $ 111,213 111,213 Other liabilities 1,207 2,878 Total liabilities 112,420 114,091 Shareholders’ equity 1,207,724 1,170,663 Total liabilities and shareholders’ equity $ 1,320,144 1,284,754
Schedule of statements of income	Years ended December 31, 2017 2016 2015 Income: Interest income $ 137 737 1,258 Other income 2,297 709 659 Dividends from bank subsidiary 90,000 50,000 135,000 Undistributed earnings from equity investment in bank subsidiary 7,255 2,760 (70,854 ) Total income 99,689 54,206 66,063 Expense: Compensation and benefits 1,282 1,129 1,061 Other expense 553 561 1,356 Interest expense 4,666 4,560 4,926 Total expense 6,501 6,250 7,343 Income before income taxes 93,188 47,956 58,720 Federal and state income taxes (1,279 ) (1,711 ) (1,820 ) Net income $ 94,467 49,667 60,540
Schedule of statements of cash flows	Years ended December 31, 2017 2016 2015 Operating activities: Net income $ 94,467 49,667 60,540 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed earnings of subsidiary (7,255 ) (2,760 ) 70,854 Noncash stock benefit plan compensation expense 4,894 10,916 5,654 Gain on sale of marketable securities (1,615 ) (43 ) (54 ) Net change in other assets and liabilities (43,513 ) (63,533 ) (5,824 ) Net cash provided by/ (used in) operating activities 46,978 (5,753 ) 131,170 Investing activities: Net sale of marketable securities 2,800 (1,952 ) 1,192 Acquisition, net of cash received — — (89,398 ) Net cash provided by/ (used in) investing activities 2,800 (1,952 ) (88,206 ) Financing activities: Cash dividends paid (65,212 ) (60,156 ) (52,825 ) Share repurchases — (1,752 ) (7,847 ) Repayment of loan to ESOP — 797 1,549 Redemption of junior subordinated debt — — (8,119 ) Excess tax benefit from stock-based compensation — 1,425 332 Proceeds from options exercised 7,001 10,856 4,303 Net cash used in financing activities (58,211 ) (48,830 ) (62,607 ) Net decrease in cash and cash equivalents $ (8,433 ) (56,535 ) (19,643 ) Cash and cash equivalents at beginning of year $ 34,521 91,056 110,699 Net decrease in cash and cash equivalents (8,433 ) (56,535 ) (19,643 ) Cash and cash equivalents at end of year $ 26,088 34,521 91,056

Derivative Financial Instrume48

Derivative Financial Instruments Derivative Fainncial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The following table presents information regarding our derivative financial instruments, at December 31, : Asset derivatives Liability derivatives Notional amount Fair value Notional amount Fair value 2017: Derivatives designated as hedging instruments: Interest rate swap agreements $ — — 50,000 1,064 Derivatives not designated as hedging instruments: Interest rate swap agreements 92,631 214 92,631 214 Foreign exchange swap agreements — — 12,344 61 Total derivatives $ 92,631 214 154,975 1,339 2016: Derivatives designated as hedging instruments: Interest rate swap agreements $ — — 50,000 2,736 Derivatives not designated as hedging instruments: Interest rate swap agreements 10,559 238 10,559 238 Foreign exchange swap agreements — — — — Total derivatives $ 10,559 238 60,559 2,974
Gain (Loss) on Derivative Instruments	The following table indicates the gain or loss recognized in income on derivatives for the periods indicated: For the years ended December 31, 2017 2016 2015 Non-hedging swap derivatives: Increase/ (decrease) in other income $ (373 ) — — Hedging interest rate derivatives: Increase in interest expense 1,599 1,866 2,922

Selected Quarterly Financial 49

Selected Quarterly Financial Data - Unaudited (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of selected quarterly financial data	Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2017: Interest income $ 87,267 89,797 90,231 91,561 Interest expense 6,690 7,066 6,994 7,321 Net interest income 80,577 82,731 83,237 84,240 Provision for loan losses 4,637 5,562 3,027 6,525 Noninterest income 21,504 41,477 24,594 22,905 Noninterest expenses 71,646 73,262 68,799 71,896 Income before income taxes 25,798 45,384 36,005 28,724 Income tax expense 8,052 14,402 12,414 6,576 Net income $ 17,746 30,982 23,591 22,148 Basic earnings per share $ 0.18 0.31 0.23 0.22 Diluted earnings per share $ 0.17 0.30 0.23 0.22 Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2016: Interest income $ 85,298 85,555 84,748 90,033 Interest expense 13,746 10,008 7,454 7,091 Net interest income 71,552 75,547 77,294 82,942 Provision for loan losses 1,660 4,199 5,538 2,145 Noninterest income 19,448 20,275 20,818 24,819 Noninterest expenses 63,275 102,122 73,680 68,761 Income before income taxes 26,065 (10,499 ) 18,894 36,855 Income tax expense 8,081 (3,491 ) 4,697 12,361 Net income $ 17,984 (7,008 ) 14,197 24,494 Basic earnings per share $ 0.18 (0.07 ) 0.14 0.24 Diluted earnings per share $ 0.18 (0.07 ) 0.14 0.24 Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2015: Interest income $ 76,880 75,970 81,091 85,639 Interest expense 13,899 13,792 14,150 14,486 Net interest income 62,981 62,178 66,941 71,153 Provision for loan losses 900 1,050 3,167 4,595 Noninterest income 14,625 16,525 18,140 19,546 Noninterest expenses 53,711 55,135 63,804 61,227 Income before income taxes 22,995 22,518 18,110 24,877 Income tax expense 6,825 7,213 5,238 8,684 Net income $ 16,170 15,305 12,872 16,193 Basic earnings per share $ 0.18 0.17 0.14 0.16 Diluted earnings per share $ 0.18 0.17 0.13 0.16

Summary of Significant Accoun50

Summary of Significant Accounting Policies - Loans Receivable and Allowance for Loan Losses and Other Narrative Information (Details)	12 Months Ended
	Dec. 31, 2017USD ($)bank	Dec. 31, 2016USD ($)
Nature of Operations
Number of banking locations | bank	172
Investment Securities
Securities classified as trading	$ 0	$ 0
Loans Receivable
Number of days in delinquency for accrued interest on loans to be considered for reversal, minimum	90 days
Number of days delinquent for loans to be placed on non-accrual status, minimum	90 days
Period of time to return TDRs included in impaired loans to performing status through the fulfilling of contractual terms	6 months
Residential mortgage loans classified as held-for-sale	$ 3,100,000	$ 9,600,000
Allowance for Loan Losses and Provision for Loan Losses
Number of days for loans not deemed to be impaired	30 days
Commercial Banking
Allowance for Loan Losses and Provision for Loan Losses
Financing receivable, individually evaluated for impairment, threshold amount for analysis	$ 1,000,000
Actual losses incurred through average number of rolling years	3 years
Personal Banking
Allowance for Loan Losses and Provision for Loan Losses
Actual losses incurred through average number of rolling years	3 years
Number of days delinquent for allowance for loans	90 days
Number of days delinquent for loans to be charged off or charged down unless that borrower has filed for bankruptcy	180 days

Summary of Significant Accoun51

Summary of Significant Accounting Policies - Premises and Equipment and Goodwill (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Premises and Equipment
Estimated lives	3 years
Core Deposit Intangibles
Useful life of core deposit intangibles	7 years
Maximum
Premises and Equipment
Estimated lives	39 years
Core Deposit Intangibles
Useful life of core deposit intangibles	11 years

Summary of Significant Accoun52

Summary of Significant Accounting Policies - Stock Related Compensation and Segments (Details) $ in Millions	May 17, 2017shares	May 18, 2016shares	May 20, 2015shares	Dec. 31, 2017USD ($)segmentshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Segment Reporting
Number of reportable segments | segment				1
Stock options
Stock Related Compensation
Expected volatility, minimum (as a percent)				17.00%
Expected volatility, maximum (as a percent)				22.00%
Risk-free interest rates, minimum (as a percent)				1.70%
Risk-free interest rates, maximum (as a percent)				3.10%
Number of shares awarded				819,010	725,400	665,370
Vesting period				10 years
Stock-based aggregate disclosure
Compensation expense for unvested common share awards which is yet to be recognized | $				$ 4.1
Weighted average period over which stock option expense will be recognized				4 years
Stock options | Minimum
Stock Related Compensation
Dividend yields (as a percent)				3.20%
Expected lives				7 years
Stock options | Maximum
Stock Related Compensation
Dividend yields (as a percent)				5.10%
Expected lives				9 years
Stock options | Employees
Stock Related Compensation
Number of shares awarded	754,210	660,600	660,570	754,210
Stock options | Director
Stock Related Compensation
Number of shares awarded	64,800	64,800	64,800	64,800
Restricted common shares
Stock Related Compensation
Vesting period				10 years
Stock-based aggregate disclosure
Stock-based employee compensation expense | $				$ 3.8	$ 3.5	$ 3
Effect of compensation expense on net income included in income before income taxes | $				$ 2.3	$ 2.2	$ 1.8
Restricted common shares | Employees
Stock Related Compensation
Number of shares awarded	378,050	310,160	282,050	353,750
Restricted common shares | Director
Stock Related Compensation
Number of shares awarded	24,300	24,300	24,300	24,300

Marketable Securities - Availab

Marketable Securities - Available For Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortized cost
Marketable securities available-for-sale, amortized cost	$ 800,094	$ 825,552
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	3,453	9,862
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(11,012)	(9,214)
Fair value
Marketable securities available-for-sale, total fair value	792,535	826,200
U.S. Government and agencies
Amortized cost
Due in one year or less	1	6
Gross unrealized holding gains
Due in one year or less	0	0
Gross unrealized holding losses
Due in one year or less	0	0
Fair value
Due in one year or less	1	6
Government sponsored enterprises
Amortized cost
Due in one year or less	66,566	74,980
Due after one year through five years	140,624	220,937
Due after five years through ten years	0	585
Due after ten years	4,833	0
Gross unrealized holding gains
Due in one year or less	14	5
Due after one year through five years	0	203
Due after five years through ten years	0	0
Due after ten years	0	0
Gross unrealized holding losses
Due in one year or less	(289)	(33)
Due after one year through five years	(2,402)	(2,504)
Due after five years through ten years	0	(3)
Due after ten years	(77)	0
Fair value
Due in one year or less	66,291	74,952
Due after one year through five years	138,222	218,636
Due after five years through ten years	0	582
Due after ten years	4,756	0
Equity securities
Amortized cost
Marketable securities available-for-sale, amortized cost	551	3,351
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	29	1,095
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(6)	(6)
Fair value
Marketable securities available-for-sale, total fair value	574	4,440
Municipal securities
Amortized cost
Due in one year or less	2,492	2,449
Due after one year through five years	7,072	9,448
Due after five years through ten years	14,576	11,794
Due after ten years	26,371	38,141
Gross unrealized holding gains
Due in one year or less	7	7
Due after one year through five years	82	105
Due after five years through ten years	171	137
Due after ten years	292	1,027
Gross unrealized holding losses
Due in one year or less	(1)	0
Due after one year through five years	(6)	(21)
Due after five years through ten years	0	(1)
Due after ten years	0	(16)
Fair value
Due in one year or less	2,498	2,456
Due after one year through five years	7,148	9,532
Due after five years through ten years	14,747	11,930
Due after ten years	26,663	39,152
Corporate debt issues
Amortized cost
Due after ten years	909	14,367
Gross unrealized holding gains
Due after ten years	0	2,935
Gross unrealized holding losses
Due after ten years	0	(322)
Fair value
Due after ten years	909	16,980
Residential mortgage-backed securities
Amortized cost
Marketable securities available-for-sale, amortized cost	536,099	449,494
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	2,858	4,348
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(8,231)	(6,308)
Fair value
Marketable securities available-for-sale, total fair value	530,726	447,534
Fixed rate | Pass-through
Amortized cost
Marketable securities available-for-sale, amortized cost	144,411	175,398
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	1,108	1,849
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(2,817)	(2,680)
Fair value
Marketable securities available-for-sale, total fair value	142,702	174,567
Fixed rate | Non-agency CMOs
Amortized cost
Marketable securities available-for-sale, amortized cost	15	100
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	0	1
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	0	0
Fair value
Marketable securities available-for-sale, total fair value	15	101
Fixed rate | Agency CMOs
Amortized cost
Marketable securities available-for-sale, amortized cost	284,320	165,535
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	37	185
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(5,271)	(3,455)
Fair value
Marketable securities available-for-sale, total fair value	279,086	162,265
Variable rate | Pass-through
Amortized cost
Marketable securities available-for-sale, amortized cost	33,079	43,587
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	1,464	2,007
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(6)	(6)
Fair value
Marketable securities available-for-sale, total fair value	34,537	45,588
Variable rate | Agency CMOs
Amortized cost
Marketable securities available-for-sale, amortized cost	74,274	64,874
Gross unrealized holding gains
Marketable securities available-for-sale, gross unrealized holding gains	249	306
Gross unrealized holding losses
Marketable securities available-for-sale, gross unrealized holding losses	(137)	(167)
Fair value
Marketable securities available-for-sale, total fair value	$ 74,386	$ 65,013

Marketable Securities - Held To

Marketable Securities - Held To Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortized cost
Held-to-maturity securities, amortized cost	$ 29,678	$ 19,978
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	237	448
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	(248)	0
Fair value
Held-to-maturity securities, fair value	29,667	20,426
Municipal securities
Amortized cost
Due after ten years		4,808
Gross unrealized holding gains
Due after ten years		65
Gross unrealized holding losses
Due after ten years		0
Fair value
Due after ten years		4,873
Residential mortgage-backed securities
Amortized cost
Held-to-maturity securities, amortized cost	29,678	15,170
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	237	383
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	(248)	0
Fair value
Held-to-maturity securities, fair value	29,667	15,553
Fixed rate | Pass-through
Amortized cost
Held-to-maturity securities, amortized cost	3,760	4,807
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	140	217
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	0
Fair value
Held-to-maturity securities, fair value	3,900	5,024
Fixed rate | Agency CMOs
Amortized cost
Held-to-maturity securities, amortized cost	22,906	6,674
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	20	94
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	(248)	0
Fair value
Held-to-maturity securities, fair value	22,678	6,768
Variable rate | Pass-through
Amortized cost
Held-to-maturity securities, amortized cost	2,283	2,848
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	64	58
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	0
Fair value
Held-to-maturity securities, fair value	2,347	2,906
Variable rate | Agency CMOs
Amortized cost
Held-to-maturity securities, amortized cost	729	841
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	13	14
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	0
Fair value
Held-to-maturity securities, fair value	$ 742	$ 855

Marketable Securities - Issuers

Marketable Securities - Issuers and the Carrying Values of Mortgage-Backed Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Marketable securities
Carrying value of marketable securities pledged	$ 161,600,000
Marketable securities classified as available-for-sale sold	36,811,000	$ 1,951,000	$ 1,246,000
Gross realized gains	1,800,000	268,000	121,000
Gross realized losses	626,000	0	67,000
Non-cash credit related other-than-temporary impairment	0	0	$ 0
Residential mortgage-backed securities
Marketable securities
Total residential mortgage-backed securities	560,404,000	462,704,000
Residential mortgage-backed securities | FNMA
Marketable securities
Total residential mortgage-backed securities	286,031,000	210,373,000
Residential mortgage-backed securities | GNMA
Marketable securities
Total residential mortgage-backed securities	37,796,000	42,221,000
Residential mortgage-backed securities | FHLMC
Marketable securities
Total residential mortgage-backed securities	236,007,000	202,822,000
Residential mortgage-backed securities | SBA
Marketable securities
Total residential mortgage-backed securities	0	6,608,000
Residential mortgage-backed securities | Other (including non-agency)
Marketable securities
Total residential mortgage-backed securities	$ 570,000	$ 680,000

Marketable Securities - Fair Va

Marketable Securities - Fair Value and Gross Unrealized Losses on Investment Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)investment	Dec. 31, 2016USD ($)
Marketable securities
Less than 12 months - Fair value	$ 249,272	$ 457,286
Less than 12 months - Unrealized loss	(2,536)	(6,322)
12 months or more - Fair value	400,583	99,645
12 months or more - Unrealized loss	(8,724)	(2,892)
Total - Fair value	649,855	556,931
Total - Unrealized loss	$ (11,260)	(9,214)
Number of investments that are temporarily impaired | investment	173
Aggregate carrying amount of cost-method investment	$ 822,200
Government sponsored enterprises
Marketable securities
Less than 12 months - Fair value	5,006	238,003
Less than 12 months - Unrealized loss	(7)	(2,448)
12 months or more - Fair value	197,695	9,205
12 months or more - Unrealized loss	(2,761)	(92)
Total - Fair value	202,701	247,208
Total - Unrealized loss	(2,768)	(2,540)
Corporate debt issues
Marketable securities
Less than 12 months - Fair value	0	0
Less than 12 months - Unrealized loss	0	0
12 months or more - Fair value	0	2,107
12 months or more - Unrealized loss	0	(322)
Total - Fair value	0	2,107
Total - Unrealized loss	0	(322)
Equity securities
Marketable securities
Less than 12 months - Fair value	0	0
Less than 12 months - Unrealized loss	0	0
12 months or more - Fair value	544	544
12 months or more - Unrealized loss	(6)	(6)
Total - Fair value	544	544
Total - Unrealized loss	(6)	(6)
Municipal securities
Marketable securities
Less than 12 months - Fair value	4,563	5,621
Less than 12 months - Unrealized loss	(7)	(37)
12 months or more - Fair value	0	66
12 months or more - Unrealized loss	0	(1)
Total - Fair value	4,563	5,687
Total - Unrealized loss	(7)	(38)
Residential mortgage-backed securities - agency | Agency CMOs
Marketable securities
Less than 12 months - Fair value	239,703	213,662
Less than 12 months - Unrealized loss	(2,522)	(3,837)
12 months or more - Fair value	202,344	87,723
12 months or more - Unrealized loss	(5,957)	(2,471)
Total - Fair value	442,047	301,385
Total - Unrealized loss	$ (8,479)	$ (6,308)

Marketable Securities - Categor

Marketable Securities - Categories of Investment Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Marketable securities
Total - Amortized cost	$ 1
Total - Fair value	30
Total - Unrealized gain	29
Accumulated impairment charges	(471)
Freddie Mac preferred shares
Marketable securities
Total - Amortized cost	1
Total - Fair value	30
Total - Unrealized gain	29
Accumulated impairment charges	(119)
Trust preferred investments
Marketable securities
Total - Amortized cost	0
Total - Fair value	0
Total - Unrealized gain	0
Accumulated impairment charges	$ (352)

Marketable Securities - Cumulat

Marketable Securities - Cumulative Roll Forward of Credit Related Impairment Losses Recognized in Earnings for Debt Securities Held and Not Intended to be Sold (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cumulative roll forward of credit related impairment losses recognized in earnings for debt securities held and not intended to be sold:
Beginning balance	$ 7,942	$ 8,436
Credit losses on debt securities for which other-than-temporary impairment was not previously recognized	0	0
Credit losses on debt securities for which other-than-temporary impairment was previously recognized	(7,265)	(494)
Reduction for securities sold realized during the year	(325)	0
Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized	0	0
Ending balance	$ 352	$ 7,942

Loans Receivable and Allowanc59

Loans Receivable and Allowance for Loan Losses - Summary of Originated and Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	$ 7,972,735	$ 7,746,648
Deferred loan costs	27,782	22,375
Allowance for loan losses	(56,795)	(60,939)	$ (62,672)	$ (67,518)
Loans Receivable, Net	7,736,614	7,496,408
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(10,067)	(11,638)
Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(144,614)	(171,580)
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(52,427)	(28,458)
Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	4,740,232	4,675,760
Allowance for loan losses		(16,116)	(16,121)
Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,772,549	2,699,131
Allowance for loan losses		(4,656)	(4,692)
Loans held-for-sale	3,100	9,600
Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,310,355	1,345,370
Allowance for loan losses		(3,486)	(3,941)
Personal Banking | Consumer Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	18,619	48,981
Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	638,709	582,278
Allowance for loan losses		(4,529)	(4,213)
Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	3,232,503	3,070,888
Allowance for loan losses		(39,177)	(44,849)
Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,599,340	2,513,669
Allowance for loan losses		(23,667)	(32,348)
Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	633,163	557,219
Allowance for loan losses		(15,510)	(12,501)
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	7,145,255	6,698,391
Deferred loan costs	26,255	20,081
Allowance for loan losses	(50,572)	(55,293)	(60,970)	(67,518)
Loans Receivable, Net	6,917,761	6,456,778
Originated | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(10,067)	(11,638)
Originated | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(141,967)	(168,595)
Originated | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(51,143)	(26,168)
Originated | Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	4,269,735	4,076,170
Allowance for loan losses	(20,339)	(16,116)	(16,121)	(16,249)
Originated | Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,658,726	2,565,620
Allowance for loan losses	(3,824)	(4,656)	(4,692)	(5,581)
Originated | Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,051,558	1,042,913
Allowance for loan losses	(4,072)	(3,486)	(3,941)	(4,550)
Originated | Personal Banking | Consumer Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	18,619	48,981
Originated | Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	540,832	418,656
Allowance for loan losses	(8,475)	(4,529)	(4,213)	(3,044)
Originated | Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,875,520	2,622,221
Allowance for loan losses	(30,233)	(39,177)	(44,849)	(46,904)
Originated | Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,303,179	2,140,678
Allowance for loan losses	(19,911)	(23,667)	(32,348)	(33,389)
Originated | Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	572,341	481,543
Allowance for loan losses	(10,322)	(15,510)	(12,501)	(13,515)
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	827,480	1,048,257
Deferred loan costs	1,527	2,294
Allowance for loan losses	(6,223)	(5,646)	(1,702)	0
Loans Receivable, Net	818,853	1,039,630
Acquired | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	0	0
Acquired | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(2,647)	(2,985)
Acquired | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(1,284)	(2,290)
Acquired | Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	470,497	599,590
Allowance for loan losses	(1,783)	(1,771)	(229)	0
Acquired | Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	113,823	133,511
Allowance for loan losses	(131)	(71)	(18)	0
Acquired | Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	258,797	302,457
Allowance for loan losses	(762)	(1,047)	(101)	0
Acquired | Personal Banking | Consumer Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	0	0
Acquired | Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	97,877	163,622
Allowance for loan losses	(890)	(653)	(110)	0
Acquired | Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	356,983	448,667
Allowance for loan losses	(4,440)	(3,875)	(1,473)	0
Acquired | Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	296,161	372,991
Allowance for loan losses	(3,549)	(3,008)	(1,439)	0
Acquired | Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	60,822	75,676
Allowance for loan losses	$ (891)	$ (867)	$ (34)	$ 0

Loans Receivable and Allowanc60

Loans Receivable and Allowance for Loan Losses - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Serviced loans for others	$ 887.3	$ 918.9	$ 776
Percentage of loan portfolio secured by properties located in Pennsylvania	60.00%	62.00%
Adjustable rate loans	$ 2,856	$ 2,755
Fixed rate loans	$ 5,117	$ 4,992

Loans Receivable and Allowanc61

Loans Receivable and Allowance for Loan Losses - Outstanding Principal Balance and Related Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	$ 833,940	$ 1,056,486
Carrying value	825,076	1,045,276
Acquired loans evaluated individually for future credit losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	9,735	16,108
Carrying value	6,875	12,665
Acquired loans evaluated collectively for future credit losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	824,205	1,040,378
Carrying value	$ 818,201	$ 1,032,611

Loans Receivable and Allowanc62

Loans Receivable and Allowance for Loan Losses - Changes in the Accretable Discount (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Beginning balance	$ 2,187	$ 2,019
Accretion	(1,318)	(1,170)
Net reclassification from nonaccretable yield	671	1,338
Ending balance	$ 1,540	$ 2,187

Loans Receivable and Allowanc63

Loans Receivable and Allowance for Loan Losses - Composition of Acquired Impaired Loans by Portfolio Segment and by Class of Financing Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	$ 84,625	$ 108,061	$ 117,851
Average recorded investment in impaired loans	97,193	118,675	130,528
Interest income/ accretion recognized	3,982	5,596	5,462
Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	6,875	12,665
Outstanding principal balance	9,735	16,108
Related impairment reserve	88	267
Average recorded investment in impaired loans	9,770	14,766
Interest income/ accretion recognized	1,318	1,170
Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	36,833	38,606	37,679
Average recorded investment in impaired loans	35,102	37,420	37,175
Interest income/ accretion recognized	1,552	1,741	1,542
Personal Banking | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	2,384	2,818
Outstanding principal balance	4,259	5,034
Related impairment reserve	49	215
Average recorded investment in impaired loans	2,601	3,575
Interest income/ accretion recognized	389	438
Personal Banking | Residential mortgage loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	21,605	24,193	24,858
Average recorded investment in impaired loans	21,531	24,483	24,554
Interest income/ accretion recognized	892	1,079	944
Personal Banking | Residential mortgage loans | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	1,182	1,319
Outstanding principal balance	1,880	2,062
Related impairment reserve	24	204
Average recorded investment in impaired loans	1,251	1,650
Interest income/ accretion recognized	181	202
Personal Banking | Home equity loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	10,356	9,304	9,369
Average recorded investment in impaired loans	9,150	9,234	9,644
Interest income/ accretion recognized	452	496	497
Personal Banking | Home equity loans | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	1,143	1,363
Outstanding principal balance	2,219	2,669
Related impairment reserve	21	8
Average recorded investment in impaired loans	1,253	1,724
Interest income/ accretion recognized	157	185
Personal Banking | Consumer loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	4,673	4,366	2,660
Average recorded investment in impaired loans	4,042	2,931	2,209
Interest income/ accretion recognized	188	131	72
Personal Banking | Consumer loans | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	59	136
Outstanding principal balance	160	303
Related impairment reserve	4	3
Average recorded investment in impaired loans	97	201
Interest income/ accretion recognized	51	51
Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	47,792	69,455	80,172
Average recorded investment in impaired loans	62,091	81,255	93,353
Interest income/ accretion recognized	2,430	3,855	3,920
Commercial Banking | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	4,491	9,847
Outstanding principal balance	5,476	11,074
Related impairment reserve	39	52
Average recorded investment in impaired loans	7,169	11,191
Interest income/ accretion recognized	929	732
Commercial Banking | Commercial real estate loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	37,027	53,928	66,009
Average recorded investment in impaired loans	49,981	64,350	77,166
Interest income/ accretion recognized	1,758	2,864	3,226
Commercial Banking | Commercial real estate loans | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	4,388	9,596
Outstanding principal balance	5,363	10,809
Related impairment reserve	39	52
Average recorded investment in impaired loans	6,992	10,942
Interest income/ accretion recognized	914	721
Commercial Banking | Commercial loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	10,765	15,527	14,163
Average recorded investment in impaired loans	12,110	16,905	16,187
Interest income/ accretion recognized	672	991	$ 694
Commercial Banking | Commercial loans | Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	103	251
Outstanding principal balance	113	265
Related impairment reserve	0	0
Average recorded investment in impaired loans	177	249
Interest income/ accretion recognized	$ 15	$ 11

Loans Receivable and Allowanc64

Loans Receivable and Allowance for Loan Losses - Changes in the Allowance for Losses on Loans Receivable (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				$ 60,939				$ 62,672				$ 67,518	$ 60,939	$ 62,672	$ 67,518
Provision	$ 6,525	$ 3,027	$ 5,562	4,637	$ 2,145	$ 5,538	$ 4,199	1,660	$ 4,595	$ 3,167	$ 1,050	900	19,751	13,542	9,712
Charge-offs													(31,254)	(24,881)	(26,333)
Recoveries													7,359	9,606	11,775
Balance at the end of the period	56,795				60,939				62,672				56,795	60,939	62,672
Personal Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				16,116				16,121					16,116	16,121
Provision														12,251
Charge-offs														(14,543)
Recoveries														2,287
Balance at the end of the period					16,116				16,121					16,116	16,121
Personal Banking | Residential mortgage loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				4,656				4,692					4,656	4,692
Provision														2,906
Charge-offs														(3,228)
Recoveries														286
Balance at the end of the period					4,656				4,692					4,656	4,692
Personal Banking | Home equity loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,486				3,941					3,486	3,941
Provision														293
Charge-offs														(1,090)
Recoveries														342
Balance at the end of the period					3,486				3,941					3,486	3,941
Personal Banking | Consumer Finance Loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,445				3,275					3,445	3,275
Provision														3,117
Charge-offs														(3,323)
Recoveries														376
Balance at the end of the period					3,445				3,275					3,445	3,275
Personal Banking | Consumer loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				4,529				4,213					4,529	4,213
Provision														5,935
Charge-offs														(6,902)
Recoveries														1,283
Balance at the end of the period					4,529				4,213					4,529	4,213
Commercial Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				39,177				44,849					39,177	44,849
Provision														(4,985)
Charge-offs														(6,568)
Recoveries														5,881
Balance at the end of the period					39,177				44,849					39,177	44,849
Commercial Banking | Commercial real estate loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				23,667				32,348					23,667	32,348
Provision														(9,819)
Charge-offs														(2,403)
Recoveries														3,541
Balance at the end of the period					23,667				32,348					23,667	32,348
Commercial Banking | Commercial loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				15,510				12,501					15,510	12,501
Provision														4,834
Charge-offs														(4,165)
Recoveries														2,340
Balance at the end of the period					15,510				12,501					15,510	12,501
Originated
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				55,293				60,970				67,518	55,293	60,970	67,518
Provision													14,689	7,266	7,525
Charge-offs													(25,217)	(21,111)	(24,401)
Recoveries													5,807	8,168	10,328
Balance at the end of the period	50,572				55,293				60,970				50,572	55,293	60,970
Originated | Personal Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				16,116				16,121				16,249	16,116	16,121	16,249
Provision													23,129		8,582
Charge-offs													(21,411)		(10,846)
Recoveries													2,505		2,136
Balance at the end of the period	20,339				16,116				16,121				20,339	16,116	16,121
Originated | Personal Banking | Residential mortgage loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				4,656				4,692				5,581	4,656	4,692	5,581
Provision													(390)		(96)
Charge-offs													(834)		(1,057)
Recoveries													392		264
Balance at the end of the period	3,824				4,656				4,692				3,824	4,656	4,692
Originated | Personal Banking | Home equity loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,486				3,941				4,550	3,486	3,941	4,550
Provision													1,474		693
Charge-offs													(1,080)		(1,716)
Recoveries													192		414
Balance at the end of the period	4,072				3,486				3,941				4,072	3,486	3,941
Originated | Personal Banking | Consumer Finance Loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,445				3,275				3,074	3,445	3,275	3,074
Provision													8,444		2,853
Charge-offs													(8,369)		(3,056)
Recoveries													448		404
Balance at the end of the period	3,968				3,445				3,275				3,968	3,445	3,275
Originated | Personal Banking | Consumer loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				4,529				4,213				3,044	4,529	4,213	3,044
Provision													13,601		5,132
Charge-offs													(11,128)		(5,017)
Recoveries													1,473		1,054
Balance at the end of the period	8,475				4,529				4,213				8,475	4,529	4,213
Originated | Commercial Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				39,177				44,849				46,904	39,177	44,849	46,904
Provision													(8,440)		3,308
Charge-offs													(3,806)		(13,555)
Recoveries													3,302		8,192
Balance at the end of the period	30,233				39,177				44,849				30,233	39,177	44,849
Originated | Commercial Banking | Commercial real estate loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				23,667				32,348				33,389	23,667	32,348	33,389
Provision													(3,663)		540
Charge-offs													(1,344)		(5,741)
Recoveries													1,251		4,160
Balance at the end of the period	19,911				23,667				32,348				19,911	23,667	32,348
Originated | Commercial Banking | Commercial loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				15,510				12,501				13,515	15,510	12,501	13,515
Provision													(4,777)		2,768
Charge-offs													(2,462)		(7,814)
Recoveries													2,051		4,032
Balance at the end of the period	10,322				15,510				12,501				10,322	15,510	12,501
Originated | Unallocated
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period								0				4,365		0	4,365
Provision															(4,365)
Charge-offs															0
Recoveries															0
Balance at the end of the period									0						0
Acquired
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				5,646				1,702				0	5,646	1,702	0
Provision													5,062	6,276	2,187
Charge-offs													(6,037)	(3,770)	(1,932)
Recoveries													1,552	1,438	1,447
Balance at the end of the period	6,223				5,646				1,702				6,223	5,646	1,702
Acquired | Personal Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				1,771				229				0	1,771	229	0
Provision													1,453	3,283	482
Charge-offs													(2,179)	(2,381)	(978)
Recoveries													738	640	725
Balance at the end of the period	1,783				1,771				229				1,783	1,771	229
Acquired | Personal Banking | Residential mortgage loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				71				18				0	71	18	0
Provision													185	146	47
Charge-offs													(205)	(252)	(69)
Recoveries													80	159	40
Balance at the end of the period	131				71				18				131	71	18
Acquired | Personal Banking | Home equity loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				1,047				101				0	1,047	101	0
Provision													503	2,065	247
Charge-offs													(1,179)	(1,449)	(708)
Recoveries													391	330	562
Balance at the end of the period	762				1,047				101				762	1,047	101
Acquired | Personal Banking | Consumer loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				653				110				0	653	110	0
Provision													765	1,072	188
Charge-offs													(795)	(680)	(201)
Recoveries													267	151	123
Balance at the end of the period	890				653				110				890	653	110
Acquired | Commercial Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,875				1,473				0	3,875	1,473	0
Provision													3,609	2,993	1,705
Charge-offs													(3,858)	(1,389)	(954)
Recoveries													814	798	722
Balance at the end of the period	4,440				3,875				1,473				4,440	3,875	1,473
Acquired | Commercial Banking | Commercial real estate loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,008				1,439				0	3,008	1,439	0
Provision													2,631	2,116	1,545
Charge-offs													(2,830)	(1,337)	(585)
Recoveries													740	790	479
Balance at the end of the period	3,549				3,008				1,439				3,549	3,008	1,439
Acquired | Commercial Banking | Commercial loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				$ 867				$ 34				$ 0	867	34	0
Provision													978	877	160
Charge-offs													(1,028)	(52)	(369)
Recoveries													74	8	243
Balance at the end of the period	$ 891				$ 867				$ 34				$ 891	$ 867	$ 34

Loans Receivable and Allowanc65

Loans Receivable and Allowance for Loan Losses - Loan Portfolio by Portfolio Segment and by Class of Financing Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	$ 7,793,409	$ 7,557,347
Allowance for loan losses	56,795	60,939
Recorded investment in loans on nonaccrual	64,455	79,536
Recorded investment in loans 90 days or more past maturity and still accruing	502	649
TDRs	32,104	42,926	$ 51,115
Allowance for loan losses related to TDRs	3,144	4,590
Additional commitments to customers with loans classified as TDRs	247	438
Nonaccrual TDRs	12,285	16,346
Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	4,757,947	4,686,497
Allowance for loan losses	22,122	17,887
Recorded investment in loans on nonaccrual	28,570	31,238
Recorded investment in loans 90 days or more past maturity and still accruing	502	85
TDRs	9,716	9,112
Allowance for loan losses related to TDRs	1,277	1,158
Additional commitments to customers with loans classified as TDRs	4	4
Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	2,776,203	2,698,166
Allowance for loan losses	3,955	4,727
Recorded investment in loans on nonaccrual	14,791	18,264
Recorded investment in loans 90 days or more past maturity and still accruing	0	0
TDRs	8,000	7,299
Allowance for loan losses related to TDRs	815	708
Additional commitments to customers with loans classified as TDRs	0	0
Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	1,310,355	1,345,370
Allowance for loan losses	4,834	4,533
Recorded investment in loans on nonaccrual	8,907	7,865
Recorded investment in loans 90 days or more past maturity and still accruing	120	0
TDRs	1,716	1,813
Allowance for loan losses related to TDRs	462	450
Additional commitments to customers with loans classified as TDRs	4	4
Personal Banking | Consumer Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	18,619	48,981
Allowance for loan losses	3,968	3,445
Recorded investment in loans on nonaccrual	199	743
Recorded investment in loans 90 days or more past maturity and still accruing	3	0
TDRs	0	0
Allowance for loan losses related to TDRs	0	0
Additional commitments to customers with loans classified as TDRs	0	0
Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	652,770	593,980
Allowance for loan losses	9,365	5,182
Recorded investment in loans on nonaccrual	4,673	4,366
Recorded investment in loans 90 days or more past maturity and still accruing	379	85
TDRs	0	0
Allowance for loan losses related to TDRs	0	0
Additional commitments to customers with loans classified as TDRs	0	0
Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	3,035,462	2,870,850
Allowance for loan losses	34,673	43,052
Recorded investment in loans on nonaccrual	35,885	48,298
Recorded investment in loans 90 days or more past maturity and still accruing	0	564
TDRs	22,388	33,814
Allowance for loan losses related to TDRs	1,867	3,432
Additional commitments to customers with loans classified as TDRs	243	434
Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	2,454,726	2,342,089
Allowance for loan losses	23,460	26,675
Recorded investment in loans on nonaccrual	28,473	38,724
Recorded investment in loans 90 days or more past maturity and still accruing	0	564
TDRs	15,691	24,483
Allowance for loan losses related to TDRs	1,125	2,072
Additional commitments to customers with loans classified as TDRs	235	417
Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in loans receivable	580,736	528,761
Allowance for loan losses	11,213	16,377
Recorded investment in loans on nonaccrual	7,412	9,574
Recorded investment in loans 90 days or more past maturity and still accruing	0	0
TDRs	6,697	9,331
Allowance for loan losses related to TDRs	742	1,360
Additional commitments to customers with loans classified as TDRs	$ 8	$ 17

Loans Receivable and Allowanc66

Loans Receivable and Allowance for Loan Losses - Composition of Impaired Loans by Portfolio Segment and Class of Financing Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	$ 64,455	$ 79,536
Total impaired loans	84,625	108,061	$ 117,851
Average recorded investment in impaired loans	97,193	118,675	130,528
Interest income/ accretion recognized	3,982	5,596	5,462
Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	28,570	31,238
Total impaired loans	36,833	38,606	37,679
Average recorded investment in impaired loans	35,102	37,420	37,175
Interest income/ accretion recognized	1,552	1,741	1,542
Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	35,885	48,298
Total impaired loans	47,792	69,455	80,172
Average recorded investment in impaired loans	62,091	81,255	93,353
Interest income/ accretion recognized	2,430	3,855	3,920
Residential mortgage loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	14,791	18,264
Total impaired loans	21,605	24,193	24,858
Average recorded investment in impaired loans	21,531	24,483	24,554
Interest income/ accretion recognized	892	1,079	944
Home equity loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	8,907	7,865
Total impaired loans	10,356	9,304	9,369
Average recorded investment in impaired loans	9,150	9,234	9,644
Interest income/ accretion recognized	452	496	497
Consumer Finance Loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	199	743
Total impaired loans	199	743	792
Average recorded investment in impaired loans	379	772	768
Interest income/ accretion recognized	20	35	29
Consumer loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	4,673	4,366
Total impaired loans	4,673	4,366	2,660
Average recorded investment in impaired loans	4,042	2,931	2,209
Interest income/ accretion recognized	188	131	72
Commercial real estate loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	28,473	38,724
Total impaired loans	37,027	53,928	66,009
Average recorded investment in impaired loans	49,981	64,350	77,166
Interest income/ accretion recognized	1,758	2,864	3,226
Commercial loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	7,412	9,574
Total impaired loans	10,765	15,527	14,163
Average recorded investment in impaired loans	12,110	16,905	16,187
Interest income/ accretion recognized	672	991	694
90 days or greater delinquent
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	43,077	45,181	43,268
90 days or greater delinquent | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	24,576	22,544	24,360
90 days or greater delinquent | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	18,501	22,637	18,908
90 days or greater delinquent | Residential mortgage loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	13,509	13,169	15,810
90 days or greater delinquent | Home equity loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	7,251	5,552	5,650
90 days or greater delinquent | Consumer Finance Loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	199	743	792
90 days or greater delinquent | Consumer loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	3,617	3,080	2,108
90 days or greater delinquent | Commercial real estate loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	15,361	19,264	16,449
90 days or greater delinquent | Commercial loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	3,140	3,373	2,459
Less than 90 days delinquent
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	21,378	34,355	28,394
Loans less than 90 days delinquent reviewed for impairment	5,337	6,459	18,135
TDRs less than 90 days delinquent not included elsewhere	14,833	22,066	28,054
Less than 90 days delinquent | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	3,994	8,694	6,386
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	8,263	7,368	6,933
Less than 90 days delinquent | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	17,384	25,661	22,008
Loans less than 90 days delinquent reviewed for impairment	5,337	6,459	18,135
TDRs less than 90 days delinquent not included elsewhere	6,570	14,698	21,121
Less than 90 days delinquent | Residential mortgage loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	1,282	5,095	3,962
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	6,814	5,929	5,086
Less than 90 days delinquent | Home equity loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	1,656	2,313	1,872
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	1,449	1,439	1,847
Less than 90 days delinquent | Consumer Finance Loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	0	0	0
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	0	0	0
Less than 90 days delinquent | Consumer loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	1,056	1,286	552
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	0	0	0
Less than 90 days delinquent | Commercial real estate loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	13,112	19,460	16,972
Loans less than 90 days delinquent reviewed for impairment	4,431	3,622	16,121
TDRs less than 90 days delinquent not included elsewhere	4,123	11,582	16,467
Less than 90 days delinquent | Commercial loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	4,272	6,201	5,036
Loans less than 90 days delinquent reviewed for impairment	906	2,837	2,014
TDRs less than 90 days delinquent not included elsewhere	$ 2,447	$ 3,116	$ 4,654

Loans Receivable and Allowanc67

Loans Receivable and Allowance for Loan Losses - Evaluation of Impaired Loans by Portfolio Segment and by Class of Financing Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	$ 7,752,745	$ 7,503,912
Loans individually evaluated for impairment	40,664	53,435
Loans individually evaluated for impairment for which there is a related impairment reserve	37,411	48,056
Related impairment reserve	3,990	6,123
Loans individually evaluated for impairment for which there is no related reserve	3,253	5,379
Personal Banking
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	4,747,578	4,676,277
Loans individually evaluated for impairment	10,369	10,220
Loans individually evaluated for impairment for which there is a related impairment reserve	10,369	10,220
Related impairment reserve	1,302	1,188
Loans individually evaluated for impairment for which there is no related reserve	0	0
Personal Banking | Residential mortgage loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	2,767,635	2,689,886
Loans individually evaluated for impairment	8,568	8,280
Loans individually evaluated for impairment for which there is a related impairment reserve	8,568	8,280
Related impairment reserve	816	709
Loans individually evaluated for impairment for which there is no related reserve	0	0
Personal Banking | Home equity loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	1,308,639	1,343,556
Loans individually evaluated for impairment	1,716	1,814
Loans individually evaluated for impairment for which there is a related impairment reserve	1,716	1,814
Related impairment reserve	461	450
Loans individually evaluated for impairment for which there is no related reserve	0	0
Personal Banking | Consumer Finance Loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	18,619	48,981
Loans individually evaluated for impairment	0	0
Loans individually evaluated for impairment for which there is a related impairment reserve	0	0
Related impairment reserve	0	0
Loans individually evaluated for impairment for which there is no related reserve	0	0
Personal Banking | Consumer loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	652,685	593,854
Loans individually evaluated for impairment	85	126
Loans individually evaluated for impairment for which there is a related impairment reserve	85	126
Related impairment reserve	25	29
Loans individually evaluated for impairment for which there is no related reserve	0	0
Commercial Banking
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	3,005,167	2,827,635
Loans individually evaluated for impairment	30,295	43,215
Loans individually evaluated for impairment for which there is a related impairment reserve	27,042	37,836
Related impairment reserve	2,688	4,935
Loans individually evaluated for impairment for which there is no related reserve	3,253	5,379
Commercial Banking | Commercial real estate loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	2,433,755	2,309,186
Loans individually evaluated for impairment	20,971	32,903
Loans individually evaluated for impairment for which there is a related impairment reserve	18,470	27,594
Related impairment reserve	1,859	3,545
Loans individually evaluated for impairment for which there is no related reserve	2,501	5,309
Commercial Banking | Commercial loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	571,412	518,449
Loans individually evaluated for impairment	9,324	10,312
Loans individually evaluated for impairment for which there is a related impairment reserve	8,572	10,242
Related impairment reserve	829	1,390
Loans individually evaluated for impairment for which there is no related reserve	$ 752	$ 70

Loans Receivable and Allowanc68

Loans Receivable and Allowance for Loan Losses - Roll Forward of Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)contract	Dec. 31, 2016USD ($)contract
Number of contract
Beginning balance | contract	225	227
Number of contracts new TDRs | contract	24	34
Number of re-modified TDRs | contract	5	7
Ending balance | contract	205	225
Roll forward of troubled debt restructurings
Beginning TDR balance:	$ 42,926	$ 51,115
New TDRs	5,450	6,365
Re-modified TDRs	2,099	3,414
Net paydowns	(11,538)	(9,037)
Ending TDR balance:	32,104	42,926
Accruing TDRs	19,819	26,580
Non-accrual TDRs	$ 12,285	$ 16,346
Residential mortgage loans
Number of contract
Number of contracts charged off | contract	1	0
Number of contracts paid off | contract	0	4
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ (77)	$ 0
Amount of contracts paid off	$ 0	$ (151)
Home equity loans
Number of contract
Number of contracts charged off | contract	1	0
Number of contracts paid off | contract	8	7
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ (48)	$ 0
Amount of contracts paid off	$ (62)	$ (534)
Commercial real estate loans
Number of contract
Number of contracts charged off | contract	2	1
Number of contracts paid off | contract	15	12
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ (2,498)	$ (120)
Amount of contracts paid off	$ (1,633)	$ (6,170)
Commercial loans
Number of contract
Number of contracts charged off | contract	6	2
Number of contracts paid off | contract	11	10
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ (259)	$ (142)
Amount of contracts paid off	$ (2,256)	$ (1,814)

Loans Receivable and Allowanc69

Loans Receivable and Allowance for Loan Losses - Troubled Debt Restructuring (Including Re-Modified TDRs) by Portfolio Segment and by Class of Financing Receivable (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)contract	Dec. 31, 2016USD ($)contract	Dec. 31, 2015USD ($)contract
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	29	41	29
Recorded investment at the time of modification	$ 7,549	$ 9,779	$ 14,923
Current recorded investment	7,118	7,509	14,881
Current allowance	$ 599	$ 1,217	$ 1,245
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	3	4
Recorded investment at the time of modification	$ 774	$ 962
Current recorded investment	760	958
Current allowance	$ 69	$ 564
Personal Banking
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	11	14	9
Recorded investment at the time of modification	$ 1,756	$ 1,674	$ 465
Current recorded investment	1,703	1,648	454
Current allowance	$ 198	$ 224	$ 42
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	1	0
Recorded investment at the time of modification	$ 336	$ 0
Current recorded investment	334	0
Current allowance	$ 34	$ 0
Personal Banking | Residential mortgage loans
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	8	7	6
Recorded investment at the time of modification	$ 1,604	$ 1,199	$ 364
Current recorded investment	1,555	1,177	357
Current allowance	$ 158	$ 114	$ 21
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	1	0
Recorded investment at the time of modification	$ 336	$ 0
Current recorded investment	334	0
Current allowance	$ 34	$ 0
Personal Banking | Home equity loans
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	3	7	3
Recorded investment at the time of modification	$ 152	$ 475	$ 101
Current recorded investment	148	471	97
Current allowance	$ 40	$ 110	$ 21
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	0	0
Recorded investment at the time of modification	$ 0	$ 0
Current recorded investment	0	0
Current allowance	$ 0	$ 0
Personal Banking | Commercial real estate loans
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	2
Commercial Banking
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	18	27	20
Recorded investment at the time of modification	$ 5,793	$ 8,105	$ 14,458
Current recorded investment	5,415	5,861	14,427
Current allowance	$ 401	$ 993	$ 1,203
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	2	4
Recorded investment at the time of modification	$ 438	$ 962
Current recorded investment	426	958
Current allowance	$ 35	$ 564
Commercial Banking | Commercial real estate loans
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	11	7	11
Recorded investment at the time of modification	$ 5,232	$ 3,729	$ 12,258
Current recorded investment	4,889	3,643	12,243
Current allowance	364	$ 485	$ 1,047
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract		1
Recorded investment at the time of modification	438	$ 429
Current recorded investment	426	425
Current allowance	$ 35	$ 31
Commercial Banking | Commercial loans
Financing Receivable, Modifications [Line Items]
Number of contracts | contract	7	20	9
Recorded investment at the time of modification	$ 561	$ 4,376	$ 2,200
Current recorded investment	526	2,218	2,184
Current allowance	$ 37	$ 508	$ 156
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract	0	3
Recorded investment at the time of modification	$ 0	$ 533
Current recorded investment	0	533
Current allowance	$ 0	$ 533

Loans Receivable and Allowanc70

Loans Receivable and Allowance for Loan Losses - Troubled Debt Restructurings by Type of Modification (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)contract	Dec. 31, 2016USD ($)contract	Dec. 31, 2015USD ($)contract
Troubled debt restructurings
Number of contracts | contract	29	41	29
Total	$ 7,118	$ 7,509	$ 14,881
Number of re-modified TDRs | contract	5	7
Total	$ 2,073	$ 2,196
Rate
Troubled debt restructurings
Total	477	478
Total	262	0
Payment
Troubled debt restructurings
Total	2,688	753
Total	0	502
Maturity date
Troubled debt restructurings
Total	2,631	3,932
Total	1,382	1,329
Other
Troubled debt restructurings
Total	1,322	2,346
Total	$ 429	$ 365
Personal Banking
Troubled debt restructurings
Number of contracts | contract	11	14	9
Total	$ 1,703	$ 1,648	$ 454
Number of re-modified TDRs | contract	3	1
Total	$ 691	$ 192
Personal Banking | Rate
Troubled debt restructurings
Total	477	478
Total	262	0
Personal Banking | Payment
Troubled debt restructurings
Total	0	0
Total	0	0
Personal Banking | Maturity date
Troubled debt restructurings
Total	8	774
Total	0	0
Personal Banking | Other
Troubled debt restructurings
Total	1,218	396
Total	$ 429	$ 192
Personal Banking | Residential mortgage loans
Troubled debt restructurings
Number of contracts | contract	8	7	6
Total	$ 1,555	$ 1,177	$ 357
Number of re-modified TDRs | contract	2	0
Total	$ 679	$ 0
Personal Banking | Residential mortgage loans | Rate
Troubled debt restructurings
Total	359	358
Total	250	0
Personal Banking | Residential mortgage loans | Payment
Troubled debt restructurings
Total	0	0
Total	0	0
Personal Banking | Residential mortgage loans | Maturity date
Troubled debt restructurings
Total	8	771
Total	0	0
Personal Banking | Residential mortgage loans | Other
Troubled debt restructurings
Total	1,188	48
Total	$ 429	$ 0
Personal Banking | Home equity loans
Troubled debt restructurings
Number of contracts | contract	3	7	3
Total	$ 148	$ 471	$ 97
Number of re-modified TDRs | contract	1	1
Total	$ 12	$ 192
Personal Banking | Home equity loans | Rate
Troubled debt restructurings
Total	118	120
Total	12	0
Personal Banking | Home equity loans | Payment
Troubled debt restructurings
Total	0	0
Total	0	0
Personal Banking | Home equity loans | Maturity date
Troubled debt restructurings
Total	0	3
Total	0	0
Personal Banking | Home equity loans | Other
Troubled debt restructurings
Total	30	348
Total	$ 0	$ 192
Commercial Banking
Troubled debt restructurings
Number of contracts | contract	18	27	20
Total	$ 5,415	$ 5,861	$ 14,427
Number of re-modified TDRs | contract	2	6
Total	$ 1,382	$ 2,004
Commercial Banking | Rate
Troubled debt restructurings
Total	0	0
Total	0	0
Commercial Banking | Payment
Troubled debt restructurings
Total	2,688	753
Total	0	502
Commercial Banking | Maturity date
Troubled debt restructurings
Total	2,623	3,158
Total	1,382	1,329
Commercial Banking | Other
Troubled debt restructurings
Total	104	1,950
Total	$ 0	$ 173
Commercial Banking | Commercial real estate loans
Troubled debt restructurings
Number of contracts | contract	11	7	11
Total	$ 4,889	$ 3,643	$ 12,243
Number of re-modified TDRs | contract	1	2
Total	$ 1,299	$ 1,502
Commercial Banking | Commercial real estate loans | Rate
Troubled debt restructurings
Total	0	0
Total	0	0
Commercial Banking | Commercial real estate loans | Payment
Troubled debt restructurings
Total	2,688	425
Total	0	0
Commercial Banking | Commercial real estate loans | Maturity date
Troubled debt restructurings
Total	2,201	1,980
Total	1,299	1,329
Commercial Banking | Commercial real estate loans | Other
Troubled debt restructurings
Total	0	1,238
Total	$ 0	$ 173
Commercial Banking | Commercial loans
Troubled debt restructurings
Number of contracts | contract	7	20	9
Total	$ 526	$ 2,218	$ 2,184
Number of re-modified TDRs | contract	1	4
Total	$ 83	$ 502
Commercial Banking | Commercial loans | Rate
Troubled debt restructurings
Total	0	0
Total	0	0
Commercial Banking | Commercial loans | Payment
Troubled debt restructurings
Total	0	328
Total	0	502
Commercial Banking | Commercial loans | Maturity date
Troubled debt restructurings
Total	422	1,178
Total	83	0
Commercial Banking | Commercial loans | Other
Troubled debt restructurings
Total	104	712
Total	$ 0	$ 0

Loans Receivable and Allowanc71

Loans Receivable and Allowance for Loan Losses - Loan Delinquencies (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loan payment delinquencies
Total delinquency	$ 117,504	$ 121,594
Current	7,675,905	7,435,753
Total loans	7,793,409	7,557,347
90 days or greater delinquent and accruing	1,412	2,824
Personal Banking
Loan payment delinquencies
Total loans	4,757,947	4,686,497
Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total loans	2,776,203	2,698,166
Personal Banking | Home equity loans
Loan payment delinquencies
Total loans	1,310,355	1,345,370
Personal Banking | Consumer Finance Loans
Loan payment delinquencies
Total loans	18,619	48,981
Personal Banking | Consumer loans
Loan payment delinquencies
Total loans	652,770	593,980
Commercial Banking
Loan payment delinquencies
Total loans	3,035,462	2,870,850
Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total loans	2,454,726	2,342,089
Commercial Banking | Commercial loans
Loan payment delinquencies
Total loans	580,736	528,761
Originated
Loan payment delinquencies
Total delinquency	98,970	105,990
Current	6,869,363	6,406,081
Total loans	6,968,333	6,512,071
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking
Loan payment delinquencies
Total delinquency	76,209	72,003
Current	4,209,714	4,012,610
Total loans	4,285,923	4,084,613
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	42,429	44,810
Current	2,619,951	2,519,845
Total loans	2,662,380	2,564,655
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	14,470	11,873
Current	1,037,088	1,031,040
Total loans	1,051,558	1,042,913
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Consumer Finance Loans
Loan payment delinquencies
Total delinquency	3,440	2,764
Current	15,179	46,217
Total loans	18,619	48,981
90 days or greater delinquent and accruing	0
Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	15,870	12,556
Current	537,496	415,508
Total loans	553,366	428,064
90 days or greater delinquent and accruing	0	0
Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	22,761	33,987
Current	2,659,649	2,393,471
Total loans	2,682,410	2,427,458
90 days or greater delinquent and accruing	0	0
Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	18,282	27,856
Current	2,142,930	1,944,227
Total loans	2,161,212	1,972,083
90 days or greater delinquent and accruing	0	0
Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	4,479	6,131
Current	516,719	449,244
Total loans	521,198	455,375
90 days or greater delinquent and accruing	0	0
Acquired
Loan payment delinquencies
Total delinquency	18,534	15,604
Current	806,542	1,029,672
Total loans	825,076	1,045,276
90 days or greater delinquent and accruing	1,412	2,824
Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	8,711	6,670
Current	463,313	595,214
Total loans	472,024	601,884
90 days or greater delinquent and accruing	489	671
Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	3,480	2,424
Current	110,343	131,087
Total loans	113,823	133,511
90 days or greater delinquent and accruing	381	452
Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	3,211	2,251
Current	255,586	300,206
Total loans	258,797	302,457
90 days or greater delinquent and accruing	98	204
Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	2,020	1,995
Current	97,384	163,921
Total loans	99,404	165,916
90 days or greater delinquent and accruing	10	15
Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	9,823	8,934
Current	343,229	434,458
Total loans	353,052	443,392
90 days or greater delinquent and accruing	923	2,153
Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	8,856	8,286
Current	284,658	361,720
Total loans	293,514	370,006
90 days or greater delinquent and accruing	923	2,006
Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	967	648
Current	58,571	72,738
Total loans	59,538	73,386
90 days or greater delinquent and accruing	0	147
30-59 days delinquent
Loan payment delinquencies
Total delinquency	56,465	55,614
30-59 days delinquent | Originated
Loan payment delinquencies
Total delinquency	48,759	49,336
30-59 days delinquent | Originated | Personal Banking
Loan payment delinquencies
Total delinquency	41,770	40,595
30-59 days delinquent | Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	23,786	26,212
30-59 days delinquent | Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	6,094	5,785
30-59 days delinquent | Originated | Personal Banking | Consumer Finance Loans
Loan payment delinquencies
Total delinquency	2,128	1,255
30-59 days delinquent | Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	9,762	7,343
30-59 days delinquent | Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	6,989	8,741
30-59 days delinquent | Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	5,520	7,674
30-59 days delinquent | Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	1,469	1,067
30-59 days delinquent | Acquired
Loan payment delinquencies
Total delinquency	7,706	6,278
30-59 days delinquent | Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	4,515	3,464
30-59 days delinquent | Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	1,998	1,174
30-59 days delinquent | Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	1,367	1,020
30-59 days delinquent | Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	1,150	1,270
30-59 days delinquent | Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	3,191	2,814
30-59 days delinquent | Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	2,795	2,703
30-59 days delinquent | Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	396	111
60-89 days delinquent
Loan payment delinquencies
Total delinquency	16,550	17,975
60-89 days delinquent | Originated
Loan payment delinquencies
Total delinquency	14,647	15,946
60-89 days delinquent | Originated | Personal Banking
Loan payment delinquencies
Total delinquency	12,310	10,315
60-89 days delinquent | Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	6,030	5,806
60-89 days delinquent | Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	2,333	1,305
60-89 days delinquent | Originated | Personal Banking | Consumer Finance Loans
Loan payment delinquencies
Total delinquency	1,113	766
60-89 days delinquent | Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	2,834	2,438
60-89 days delinquent | Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	2,337	5,631
60-89 days delinquent | Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	2,133	3,674
60-89 days delinquent | Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	204	1,957
60-89 days delinquent | Acquired
Loan payment delinquencies
Total delinquency	1,903	2,029
60-89 days delinquent | Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	1,260	1,084
60-89 days delinquent | Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	205	421
60-89 days delinquent | Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	538	258
60-89 days delinquent | Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	517	405
60-89 days delinquent | Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	643	945
60-89 days delinquent | Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	406	821
60-89 days delinquent | Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	237	124
90 days or greater delinquent
Loan payment delinquencies
Total delinquency	44,489	48,005
90 days or greater delinquent | Originated
Loan payment delinquencies
Total delinquency	35,564	40,708
90 days or greater delinquent | Originated | Personal Banking
Loan payment delinquencies
Total delinquency	22,129	21,093
90 days or greater delinquent | Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	12,613	12,792
90 days or greater delinquent | Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	6,043	4,783
90 days or greater delinquent | Originated | Personal Banking | Consumer Finance Loans
Loan payment delinquencies
Total delinquency	199	743
90 days or greater delinquent | Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	3,274	2,775
90 days or greater delinquent | Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	13,435	19,615
90 days or greater delinquent | Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	10,629	16,508
90 days or greater delinquent | Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	2,806	3,107
90 days or greater delinquent | Acquired
Loan payment delinquencies
Total delinquency	8,925	7,297
90 days or greater delinquent | Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	2,936	2,122
90 days or greater delinquent | Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	1,277	829
90 days or greater delinquent | Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	1,306	973
90 days or greater delinquent | Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	353	320
90 days or greater delinquent | Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	5,989	5,175
90 days or greater delinquent | Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	5,655	4,762
90 days or greater delinquent | Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	$ 334	$ 413

Loans Receivable and Allowanc72

Loans Receivable and Allowance for Loan Losses - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Credit quality indicators
Total loans	$ 7,793,409	$ 7,557,347
Pass
Credit quality indicators
Total loans	7,452,732	7,278,068
Special mention
Credit quality indicators
Total loans	102,834	60,916
Substandard
Credit quality indicators
Total loans	237,843	218,363
Doubtful
Credit quality indicators
Total loans	0	0
Loss
Credit quality indicators
Total loans	0	0
Special mention or substandard | Minimum
Credit quality indicators
Total loans	1,000
Personal Banking
Credit quality indicators
Total loans	4,757,947	4,686,497
Personal Banking | Residential mortgage loans
Credit quality indicators
Total loans	2,776,203	2,698,166
Personal Banking | Home equity loans
Credit quality indicators
Total loans	1,310,355	1,345,370
Personal Banking | Consumer Finance Loans
Credit quality indicators
Total loans	18,619	48,981
Personal Banking | Consumer loans
Credit quality indicators
Total loans	652,770	593,980
Commercial Banking
Credit quality indicators
Total loans	3,035,462	2,870,850
Commercial Banking | Commercial real estate loans
Credit quality indicators
Total loans	2,454,726	2,342,089
Commercial Banking | Commercial loans
Credit quality indicators
Total loans	580,736	528,761
Originated
Credit quality indicators
Total loans	6,968,333	6,512,071
Originated | Pass
Credit quality indicators
Total loans	6,682,937	6,281,250
Originated | Special mention
Credit quality indicators
Total loans	94,209	51,524
Originated | Substandard
Credit quality indicators
Total loans	191,187	179,297
Originated | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Loss
Credit quality indicators
Total loans	0	0
Originated | Personal Banking
Credit quality indicators
Total loans	4,285,923	4,084,613
Originated | Personal Banking | Pass
Credit quality indicators
Total loans	4,256,410	4,057,836
Originated | Personal Banking | Special mention
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Substandard
Credit quality indicators
Total loans	29,513	26,777
Originated | Personal Banking | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Loss
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Residential mortgage loans
Credit quality indicators
Total loans	2,662,380	2,564,655
Originated | Personal Banking | Residential mortgage loans | Pass
Credit quality indicators
Total loans	2,645,475	2,548,390
Originated | Personal Banking | Residential mortgage loans | Special mention
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Residential mortgage loans | Substandard
Credit quality indicators
Total loans	16,905	16,265
Originated | Personal Banking | Residential mortgage loans | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Residential mortgage loans | Loss
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Home equity loans
Credit quality indicators
Total loans	1,051,558	1,042,913
Originated | Personal Banking | Home equity loans | Pass
Credit quality indicators
Total loans	1,042,965	1,035,496
Originated | Personal Banking | Home equity loans | Special mention
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Home equity loans | Substandard
Credit quality indicators
Total loans	8,593	7,417
Originated | Personal Banking | Home equity loans | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Home equity loans | Loss
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Consumer Finance Loans
Credit quality indicators
Total loans	18,619	48,981
Originated | Personal Banking | Consumer Finance Loans | Pass
Credit quality indicators
Total loans	18,420	48,238
Originated | Personal Banking | Consumer Finance Loans | Special mention
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Consumer Finance Loans | Substandard
Credit quality indicators
Total loans	199	743
Originated | Personal Banking | Consumer Finance Loans | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Consumer Finance Loans | Loss
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Consumer loans
Credit quality indicators
Total loans	553,366	428,064
Originated | Personal Banking | Consumer loans | Pass
Credit quality indicators
Total loans	549,550	425,712
Originated | Personal Banking | Consumer loans | Special mention
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Consumer loans | Substandard
Credit quality indicators
Total loans	3,816	2,352
Originated | Personal Banking | Consumer loans | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Consumer loans | Loss
Credit quality indicators
Total loans	0	0
Originated | Commercial Banking
Credit quality indicators
Total loans	2,682,410	2,427,458
Originated | Commercial Banking | Pass
Credit quality indicators
Total loans	2,426,527	2,223,414
Originated | Commercial Banking | Special mention
Credit quality indicators
Total loans	94,209	51,524
Originated | Commercial Banking | Substandard
Credit quality indicators
Total loans	161,674	152,520
Originated | Commercial Banking | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Commercial Banking | Loss
Credit quality indicators
Total loans	0	0
Originated | Commercial Banking | Commercial real estate loans
Credit quality indicators
Total loans	2,161,212	1,972,083
Originated | Commercial Banking | Commercial real estate loans | Pass
Credit quality indicators
Total loans	1,964,565	1,821,548
Originated | Commercial Banking | Commercial real estate loans | Special mention
Credit quality indicators
Total loans	78,699	36,321
Originated | Commercial Banking | Commercial real estate loans | Substandard
Credit quality indicators
Total loans	117,948	114,214
Originated | Commercial Banking | Commercial real estate loans | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Commercial Banking | Commercial real estate loans | Loss
Credit quality indicators
Total loans	0	0
Originated | Commercial Banking | Commercial loans
Credit quality indicators
Total loans	521,198	455,375
Originated | Commercial Banking | Commercial loans | Pass
Credit quality indicators
Total loans	461,962	401,866
Originated | Commercial Banking | Commercial loans | Special mention
Credit quality indicators
Total loans	15,510	15,203
Originated | Commercial Banking | Commercial loans | Substandard
Credit quality indicators
Total loans	43,726	38,306
Originated | Commercial Banking | Commercial loans | Doubtful
Credit quality indicators
Total loans	0	0
Originated | Commercial Banking | Commercial loans | Loss
Credit quality indicators
Total loans	0	0
Acquired
Credit quality indicators
Total loans	825,076	1,045,276
Acquired | Pass
Credit quality indicators
Total loans	769,795	996,818
Acquired | Special mention
Credit quality indicators
Total loans	8,625	9,392
Acquired | Substandard
Credit quality indicators
Total loans	46,656	39,066
Acquired | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Loss
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking
Credit quality indicators
Total loans	472,024	601,884
Acquired | Personal Banking | Pass
Credit quality indicators
Total loans	468,961	596,911
Acquired | Personal Banking | Special mention
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Substandard
Credit quality indicators
Total loans	3,063	4,973
Acquired | Personal Banking | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Loss
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Residential mortgage loans
Credit quality indicators
Total loans	113,823	133,511
Acquired | Personal Banking | Residential mortgage loans | Pass
Credit quality indicators
Total loans	112,990	131,717
Acquired | Personal Banking | Residential mortgage loans | Special mention
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Residential mortgage loans | Substandard
Credit quality indicators
Total loans	833	1,794
Acquired | Personal Banking | Residential mortgage loans | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Residential mortgage loans | Loss
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Home equity loans
Credit quality indicators
Total loans	258,797	302,457
Acquired | Personal Banking | Home equity loans | Pass
Credit quality indicators
Total loans	257,312	300,100
Acquired | Personal Banking | Home equity loans | Special mention
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Home equity loans | Substandard
Credit quality indicators
Total loans	1,485	2,357
Acquired | Personal Banking | Home equity loans | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Home equity loans | Loss
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Consumer loans
Credit quality indicators
Total loans	99,404	165,916
Acquired | Personal Banking | Consumer loans | Pass
Credit quality indicators
Total loans	98,659	165,094
Acquired | Personal Banking | Consumer loans | Special mention
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Consumer loans | Substandard
Credit quality indicators
Total loans	745	822
Acquired | Personal Banking | Consumer loans | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Consumer loans | Loss
Credit quality indicators
Total loans	0	0
Acquired | Commercial Banking
Credit quality indicators
Total loans	353,052	443,392
Acquired | Commercial Banking | Pass
Credit quality indicators
Total loans	300,834	399,907
Acquired | Commercial Banking | Special mention
Credit quality indicators
Total loans	8,625	9,392
Acquired | Commercial Banking | Substandard
Credit quality indicators
Total loans	43,593	34,093
Acquired | Commercial Banking | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Commercial Banking | Loss
Credit quality indicators
Total loans	0	0
Acquired | Commercial Banking | Commercial real estate loans
Credit quality indicators
Total loans	293,514	370,006
Acquired | Commercial Banking | Commercial real estate loans | Pass
Credit quality indicators
Total loans	251,761	331,780
Acquired | Commercial Banking | Commercial real estate loans | Special mention
Credit quality indicators
Total loans	4,838	7,403
Acquired | Commercial Banking | Commercial real estate loans | Substandard
Credit quality indicators
Total loans	36,915	30,823
Acquired | Commercial Banking | Commercial real estate loans | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Commercial Banking | Commercial real estate loans | Loss
Credit quality indicators
Total loans	0	0
Acquired | Commercial Banking | Commercial loans
Credit quality indicators
Total loans	59,538	73,386
Acquired | Commercial Banking | Commercial loans | Pass
Credit quality indicators
Total loans	49,073	68,127
Acquired | Commercial Banking | Commercial loans | Special mention
Credit quality indicators
Total loans	3,787	1,989
Acquired | Commercial Banking | Commercial loans | Substandard
Credit quality indicators
Total loans	6,678	3,270
Acquired | Commercial Banking | Commercial loans | Doubtful
Credit quality indicators
Total loans	0	0
Acquired | Commercial Banking | Commercial loans | Loss
Credit quality indicators
Total loans	$ 0	$ 0

Loans Receivable and Allowanc73

Loans Receivable and Allowance for Loan Losses - Off-Balance Sheet Financial Instruments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	$ 1,079,476,000	$ 977,528,000
Recourse provisions for recovery of amounts from third parties	0	0
Loan commitments
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	181,058,000	109,032,000
Outstanding loan commitments for fixed rate loans	40,700,000
Outstanding loan commitments for adjustable rate loans	140,400,000
Undisbursed lines of credit
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	872,700,000	843,457,000
Standby letters of credit
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	25,718,000	25,039,000
Maximum potential amount of future payments	25,700,000
Maximum potential amount of future payments fully collateralized	17,200,000
Liability recognized for the obligations	$ 169,000	$ 178,000

Loans Receivable and Allowanc74

Loans Receivable and Allowance for Loan Losses - Mortgage Servicing Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Servicing Asset at Amortized Cost, Gross, Balance [Roll Forward]
Servicing rights, balance	$ 4,239	$ 1,666
Additions	833	3,523
Amortization	(1,549)	(950)
Servicing rights, balance	3,523	4,239
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Valuation allowance, balance	(4)	0
Additions	4	(4)
Valuation allowance, balance	0	(4)
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Net carrying and fair value, balance	4,235	1,666
Additions	837	3,519
Amortization	(1,549)	(950)
Net carrying and fair value, balance	$ 3,523	$ 4,235

Accrued Interest Receivable (De

Accrued Interest Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Interest Receivable and Other Assets [Abstract]
Investment securities	$ 1,260	$ 1,613
Mortgage-backed securities	1,107	910
Loans receivable	20,985	19,176
Accrued interest receivable	$ 23,352	$ 21,699

Federal Home Loan Bank Stock (D

Federal Home Loan Bank Stock (Details) - Federal Home Loan Bank of Pittsburgh $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)capital_stock	Dec. 31, 2016USD ($)
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Number of subclasses of capital stock required to invest in for membership | capital_stock	2
Dividend received on capital stock | $	$ 250	$ 1,400
Subclass B-1
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment in capital stock of FHLB, at cost, as a percent of member asset value, as defined by FHLB	0.10%
Subclass B-1 | Minimum
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment in capital stock of FHLB, at cost, as a percent of member asset value, as defined by FHLB	0.05%
Subclass B-1 | Maximum
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment in capital stock of FHLB, at cost, as a percent of member asset value, as defined by FHLB	1.00%
Subclass B-2
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment in capital stock of FHLB, at cost, as a percent of borrowings outstanding	4.00%
Investment in capital stock of FHLB, at cost, as a percent of acquired member assets	4.00%
Investment in capital stock of FHLB, at cost, as a percent of certain letters of credit	0.75%
Investment in capital stock of FHLB, at cost, as a percent of outstanding advance commitments settling more than 30 days after trade	0.00%
Subclass B-2 | Minimum
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment in capital stock of FHLB, at cost, as a percent of borrowings outstanding	2.00%
Investment in capital stock of FHLB, at cost, as a percent of acquired member assets	0.00%
Investment in capital stock of FHLB, at cost, as a percent of certain letters of credit	0.00%
Investment in capital stock of FHLB, at cost, as a percent of outstanding advance commitments settling more than 30 days after trade	0.00%
Subclass B-2 | Maximum
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Investment in capital stock of FHLB, at cost, as a percent of borrowings outstanding	6.00%
Investment in capital stock of FHLB, at cost, as a percent of acquired member assets	6.00%
Investment in capital stock of FHLB, at cost, as a percent of certain letters of credit	4.00%
Investment in capital stock of FHLB, at cost, as a percent of outstanding advance commitments settling more than 30 days after trade	6.00%

Premises and Equipment - By Maj

Premises and Equipment - By Major Classification (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Premises and Equipment
Total, at cost	$ 316,875	$ 317,641
Less accumulated depreciation and amortization	(164,931)	(156,456)
Premises and equipment, net	151,944	161,185
Depreciation and amortization expense	12,400	13,700	$ 13,300
Land and land improvements
Premises and Equipment
Total, at cost	21,563	21,229
Office buildings and improvements
Premises and Equipment
Total, at cost	150,056	156,162
Furniture, fixtures and equipment
Premises and Equipment
Total, at cost	125,347	120,391
Leasehold improvements
Premises and Equipment
Total, at cost	$ 19,909	$ 19,859

Premises and Equipment - Minimu

Premises and Equipment - Minimum Annual Rentals by Fiscal Year (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Minimum annual rentals
2,018	$ 4,395
2,019	3,300
2,020	2,726
2,021	2,232
2,022	1,620
Thereafter	7,413
Total	21,686
Rental expense	$ 5,600	$ 5,300	$ 4,600

Goodwill and Other Intangible79

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amortizable intangible assets:
Amortization expense	$ 6,764	$ 4,259	$ 1,688
Estimated amortization expense
For the year ended December 31, 2018	5,848
For the year ending December 31, 2019	4,933
For the year ending December 31, 2020	4,017
For the year ending December 31, 2021	3,188
For the year ending December 31, 2022	2,456
Core Deposits
Amortizable intangible assets:
Intangible asset - gross	63,685	37,953
Acquisitions	0	25,732
Less: accumulated amortization	(40,029)	(34,378)
Intangible asset - net	23,656	29,307
Customer and Contract
Amortizable intangible assets:
Intangible asset - gross	10,474	8,496
Acquisitions	0	1,978
Less: accumulated amortization	(8,461)	(7,348)
Intangible asset - net	$ 2,013	$ 3,126

Goodwill and Other Intangible80

Goodwill and Other Intangible Assets - Changes in the Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in the carrying amount of goodwill
Balance at the beginning of the period	$ 307,420,000	$ 261,736,000
Goodwill acquired	0	45,684,000
Balance at the end of the period	307,420,000	307,420,000
Goodwill impairment	$ 0	$ 0

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deposits [Abstract]
Savings deposits	$ 1,653,579	$ 1,622,879
Interest-bearing demand deposits	1,442,928	1,428,317
Noninterest-bearing demand deposits	1,610,409	1,448,972
Money market deposit accounts	1,707,450	1,841,567
Time deposits	1,412,623	1,540,586
Total deposits	7,826,989	7,882,321
Aggregate amount of certificates of deposit with a minimum denomination of $100,000	436,400	451,600
Deposits in accounts exceeding $250,000	1,639,000
Contractual maturity of the certificate accounts
Due within 12 months	666,348	836,525
Due between 12 and 24 months	226,171	311,976
Due between 24 and 36 months	201,654	153,708
Due between 36 and 48 months	131,530	90,777
Due between 48 and 60 months	174,704	134,687
After 60 months	12,216	12,913
Total time deposits	1,412,623	1,540,586
Interest expense incurred on deposits
Savings deposits	3,062	3,218	$ 3,387
Interest-bearing demand deposits	1,027	462	568
Money market deposit accounts	4,203	3,621	3,222
Time deposits	14,765	16,164	16,878
Total interest expense	$ 23,057	$ 23,465	$ 24,055

Borrowed Funds - Schedule of Bo

Borrowed Funds - Schedule of Borrowed Funds (Details) - Collateralized borrowings, due within one year - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Due within one year, amount	$ 108,238	$ 142,899
Due within one year, average rate	0.20%	0.17%

Borrowed Funds - Narrative (Det

Borrowed Funds - Narrative (Details)	Dec. 15, 2005USD ($)$ / sharesshares	Dec. 05, 2005USD ($)$ / sharesshares	Dec. 31, 2017USD ($)trust$ / sharesshares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Number of statutory business trusts owned | trust			3
Junior subordinated deferrable interest debentures held by trusts that issued guaranteed capital debt securities			$ 111,213,000	$ 111,213,000
FHLB of Pittsburgh
Debt Instrument [Line Items]
Maximum commitment			150,000,000
Collateralized borrowings, due within one year
Debt Instrument [Line Items]
Average amount of agreements outstanding			121,000,000	141,600,000	$ 144,700,000
Due within one year, amount			108,238,000	142,899,000
Maximum amount of outstanding security repurchase agreement			137,200,000	158,400,000	$ 166,400,000
Trust preferred investments
Debt Instrument [Line Items]
Total value of cumulative trust preferred securities issued			107,875,000
Junior subordinated deferrable interest debentures held by trusts that issued guaranteed capital debt securities			$ 111,213,000	111,213,000
Maximum period for which interest payment on the subordinated debentures can be deferred			5 years
Interest deferral			$ 0
Trust preferred investments | Northwest Bancorp Capital Trust III
Debt Instrument [Line Items]
Cumulative trust preferred securities issued (in shares) | shares		50,000
Cumulative trust preferred securities issued, liquidation value per preferred security (in dollars per security) | $ / shares		$ 1,000
Total value of cumulative trust preferred securities issued		$ 50,000,000	$ 50,000,000
Variable rate basis		three-month LIBOR
Spread on variable rate basis (as a percent)		1.38%	1.38%
Effective interest rate (as a percent)			3.07%
Junior subordinated deferrable interest debentures held by trusts that issued guaranteed capital debt securities			$ 51,547,000	51,547,000
Trust preferred investments | Northwest Bancorp Statutory Trust IV
Debt Instrument [Line Items]
Cumulative trust preferred securities issued (in shares) | shares	50,000
Cumulative trust preferred securities issued, liquidation value per preferred security (in dollars per security) | $ / shares	$ 1,000
Total value of cumulative trust preferred securities issued	$ 50,000,000		$ 50,000,000
Variable rate basis			three-month LIBOR
Spread on variable rate basis (as a percent)	1.38%		1.38%
Effective interest rate (as a percent)			2.97%
Junior subordinated deferrable interest debentures held by trusts that issued guaranteed capital debt securities			$ 51,547,000	51,547,000
Trust preferred investments | LNB Trust II
Debt Instrument [Line Items]
Total value of cumulative trust preferred securities issued			$ 7,875,000
Effective interest rate (as a percent)			3.07%
Junior subordinated deferrable interest debentures held by trusts that issued guaranteed capital debt securities			$ 8,119,000	$ 8,119,000
Cumulative Preferred Stock | Trust preferred investments | LNB Trust II
Debt Instrument [Line Items]
Securities outstanding (in shares) | shares			7,875
Liquidation value per preferred security (in dollars per security) | $ / shares			$ 1,000
Securities outstanding, liquidation value			$ 7,875,000
LIBOR | Trust preferred investments | LNB Trust II
Debt Instrument [Line Items]
Spread on variable rate basis (as a percent)			1.48%

Borrowed Funds - Schedule of Ca

Borrowed Funds - Schedule of Capital Debt Securities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 15, 2005	Dec. 05, 2005
Debt Instrument [Line Items]
Junior subordinated debentures	$ 111,213,000	$ 111,213,000
Trust preferred investments
Debt Instrument [Line Items]
Junior subordinated debentures	111,213,000	111,213,000
Total value of cumulative trust preferred securities issued	107,875,000
Trust preferred investments | Northwest Bancorp Capital Trust III
Debt Instrument [Line Items]
Junior subordinated debentures	51,547,000	51,547,000
Total value of cumulative trust preferred securities issued	50,000,000			$ 50,000,000
Trust preferred investments | Northwest Bancorp Statutory Trust IV
Debt Instrument [Line Items]
Junior subordinated debentures	51,547,000	51,547,000
Total value of cumulative trust preferred securities issued	50,000,000		$ 50,000,000
Trust preferred investments | LNB Trust II
Debt Instrument [Line Items]
Junior subordinated debentures	8,119,000	$ 8,119,000
Total value of cumulative trust preferred securities issued	$ 7,875,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allocation of total income tax
Income before income taxes	$ 6,576	$ 12,414	$ 14,402	$ 8,052	$ 12,361	$ 4,697	$ (3,491)	$ 8,081	$ 8,684	$ 5,238	$ 7,213	$ 6,825	$ 41,444	$ 21,648	$ 27,960
Shareholders’ equity for unrealized (loss)/ gain on securities available-for-sale													(3,403)	(1,871)	(85)
Shareholders’ equity for tax benefit for excess of fair value above cost of stock benefit plans													0	(1,425)	(332)
Shareholders’ equity for pension adjustment													(213)	(2,455)	(848)
Shareholders’ equity for swap fair value adjustment													585	539	699
Unallocated income tax													38,413	16,436	27,394
Income tax expense applicable to income before taxes
Current													30,127	18,914	21,670
Deferred													11,317	2,734	6,290
Total provision for income taxes	6,576	$ 12,414	$ 14,402	$ 8,052	12,361	$ 4,697	$ (3,491)	$ 8,081	$ 8,684	$ 5,238	$ 7,213	$ 6,825	$ 41,444	$ 21,648	$ 27,960
Reconciliation of the expected federal statutory income tax rate to the effective rate
Expected tax rate (as a percent)													35.00%	35.00%	35.00%
Tax-exempt interest income (as a percent)													(1.50%)	(3.30%)	(3.00%)
State income tax, net of federal benefit (as a percent)													3.20%	1.20%	2.90%
Bank-owned life insurance (as a percent)													(1.60%)	(2.60%)	(1.70%)
Stock-based compensation (as a percent)													(0.90%)	(0.00%)	(0.00%)
Dividends on stock plans (as a percent)													(1.10%)	(2.00%)	(0.80%)
Low income housing and historic tax credits (as a percent)													(0.50%)	(1.00%)	(1.40%)
Non-deductible acquisition expense (as a percent)													0.00%	0.00%	0.50%
ESOP termination (as a percent)													0.00%	3.40%	0.00%
Adjustment to net deferred tax liabilities for enacted changes in tax laws and rates (as a percent)													(2.30%)	0.00%	0.00%
Other (as a percent)													0.20%	(0.30%)	0.10%
Effective tax rate (as a percent)													30.50%	30.40%	31.60%
Deferred tax assets:
Deferred rent	87				187								$ 87	$ 187
Deferred compensation expense	1,040				2,893								1,040	2,893
Bad debts	10,277				18,823								10,277	18,823
Other reserves	953				1,823								953	1,823
Accrued postretirement benefit cost	413				641								413	641
Stock benefit plans	744				1,085								744	1,085
Writedown of investment securities	104				2,875								104	2,875
Accrued expenses	35				95								35	95
Pension and postretirement benefits	13,033				18,491								13,033	18,491
Unrealized loss on the fair value of derivatives	223				958								223	958
Unrealized loss on the fair value of securities available-for-sale	2,160				0								2,160	0
Purchase accounting	0				1,215								0	1,215
Deferred income	1,001				253								1,001	253
Other	141				153								141	153
Total deferred tax assets	30,211				49,492								30,211	49,492
Deferred tax liabilities:
Pension expense	5,542				8,689								5,542	8,689
Unrealized gain on the fair value of securities available-for-sale	0				252								0	252
Purchase accounting	303				0								303	0
Intangible assets	13,546				21,927								13,546	21,927
Mortgage servicing rights	777				1,559								777	1,559
Fixed assets	4,940				8,107								4,940	8,107
Net deferred loan fees	4,690				0								4,690	0
Other	274				635								274	635
Total deferred tax liabilities	30,072				41,169								30,072	41,169
Net deferred tax asset	$ 139				$ 8,323								$ 139	$ 8,323

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details)	12 Months Ended
	Dec. 31, 2017USD ($)
Income Tax Disclosure [Abstract]
Valuation allowance for deferred tax assets	$ 0
Operating loss carryforwards
Unrecognized tax benefits that would impact effective tax rate if recognized	0
Accrued interest on income taxes expense	0
Accrued amount of payment of interest or penalties	0
Income tax benefit, due to tax reform	3,100,000
State and Local Jurisdiction
Operating loss carryforwards
Income tax examination, additional tax liability	444,000
Domestic Tax Authority | LNB
Operating loss carryforwards
Income tax examination, additional tax liability	$ 0

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Bad debt deductions for which no deferred income taxes have been provided	$ 39.1	$ 39.1

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive securities excluded from the calculation of earnings per share
Options excluded from the calculation of earnings per share (in shares)			524,250
Stock options
Antidilutive securities excluded from the calculation of earnings per share
Average share price during the reporting period (in dollars per share)	$ 16.64	$ 14.79	$ 12.64
Weighted average share price during the reporting period (in dollars per share)			$ 13.15

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 24,494	$ 14,197	$ (7,008)	$ 17,984	$ 16,193	$ 12,872	$ 15,305	$ 16,170	$ 94,467	$ 49,667	$ 60,540
Weighted average common shares outstanding													101,015,083	99,439,174	94,314,420
Dilutive potential shares due to effect of stock options													1,549,822	1,225,514	515,369
Total weighted average common shares and dilutive potential shares													102,564,905	100,664,688	94,829,789
Basic earnings per share (in dollars per share)	$ 0.22	$ 0.23	$ 0.31	$ 0.18	$ 0.24	$ 0.14	$ (0.07)	$ 0.18	$ 0.16	$ 0.14	$ 0.17	$ 0.18	$ 0.94	$ 0.50	$ 0.64
Diluted earnings per share (in dollars per share)	$ 0.22	$ 0.23	$ 0.30	$ 0.17	$ 0.24	$ 0.14	$ (0.07)	$ 0.18	$ 0.16	$ 0.13	$ 0.17	$ 0.18	$ 0.92	$ 0.49	$ 0.64

Employee Benefit Plans - Pensio

Employee Benefit Plans - Pension Plans, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee benefit plans
Employer matching contribution	100.00%
Employee matching contribution	4.00%
Total expense for all retirement plans	$ 6.8	$ 5.8	$ 4.6
Pension Plans
Employee benefit plans
Estimated net loss that will be amortized from accumulated other comprehensive income into net periodic cost over the next year	3.3
Prior service credit that will be amortized from accumulated other comprehensive income into net periodic cost over the next year	(2.3)
Accumulated benefit obligation for funded defined benefit pension plan	186.9	165.9	155.9
Accumulated benefit obligation for unfunded defined benefit pension plan	$ 6.2	$ 6.3	$ 6.3
Target allocation of any one stock, maximum (as a percent)	10.00%
Maximum average maturity of bond portfolio	10 years
2,018	$ 5.9
2,019	6.4
2,020	6.6
2,021	7
2,022	7.5
2023 to 2027	42.6
Pension Plans | Minimum
Employee benefit plans
Contributions to defined benefit pension plan	4
Pension Plans | Maximum
Employee benefit plans
Contributions to defined benefit pension plan	$ 6
Pension Plans | Equity securities | Minimum
Employee benefit plans
Target allocation percentage	.3
Pension Plans | Equity securities | Maximum
Employee benefit plans
Target allocation percentage	0.6
Pension Plans | Debt securities | Minimum
Employee benefit plans
Target allocation percentage	.2
Pension Plans | Debt securities | Maximum
Employee benefit plans
Target allocation percentage	.5

Employee Benefit Plans - Pens91

Employee Benefit Plans - Pension Plans - Components of Net Periodic Pension Cost and Other Amounts Recognized In OCI (Details) - Pension Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of net periodic pension cost
Service cost	$ 6,149	$ 5,496	$ 5,721
Interest cost	6,879	6,781	6,125
Expected return on plan assets	(10,512)	(9,897)	(10,371)
Net amortization and deferral	1,388	1,388	1,375
Net periodic pension cost	3,904	3,768	2,850
Changes in the defined benefit pension plans’ plan assets and benefit obligations recognized in other comprehensive income
Net loss/ (gain)	(1,647)	1,550	(420)
Prior service cost/ (credit)	0	0	0
Amortization of prior service cost	2,323	2,323	2,323
Total recognized in other comprehensive income	676	3,873	1,903
Total recognized in net periodic benefit cost and other comprehensive income	$ 4,580	$ 7,641	$ 4,753

Employee Benefit Plans - Define

Employee Benefit Plans - Defined Benefit Pension Plans' Funded Status (Details) - Pension Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in benefit obligation:
Benefit obligation at beginning of year	$ 172,208	$ 162,133
Service cost	6,149	5,496	$ 5,721
Interest cost	6,879	6,781	6,125
Acquisition	0	0
Actuarial (gain)/ loss	14,807	4,267
Benefits paid	(6,901)	(6,469)
Benefit obligation at end of year	193,142	172,208	162,133
Change in plan assets:
Fair value of plan assets at beginning of year	152,625	143,655
Actual return on plan assets	23,255	8,903
Employer contributions	4,689	6,536
Acquisition	0	0
Benefits paid	(6,901)	(6,469)
Fair value of plan assets at end of period	173,668	152,625	$ 143,655
Funded status at end of year	$ (19,474)	$ (19,583)
Assumptions used to develop the net periodic pension cost
Discount rate	4.06%	4.25%	3.89%
Expected long-term rate of return on assets	7.00%	7.00%	7.50%
Rate of increase in compensation levels	3.00%	3.00%	3.00%
Assumptions used to determine benefit obligations
Discount rate	3.53%	4.06%	4.25%
Expected long-term rate of return on assets	7.00%	7.00%	7.00%
Rate of increase in compensation levels	3.00%	3.00%	3.00%

Employee Benefit Plans - Defi93

Employee Benefit Plans - Defined Benefit Plans Certain Information and Weighted Average Asset Allocation (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee benefit plans
Projected benefit obligation	$ 193,142	$ 172,208	$ 162,133
Accumulated benefit obligation	193,142	172,208
Fair value of plan assets	$ 173,668	$ 152,625	$ 143,655
Weighted average asset allocation of defined benefit plans
Total (as a percent)	100.00%	100.00%
Debt securities
Weighted average asset allocation of defined benefit plans
Total (as a percent)	23.00%	23.00%
Equity securities
Weighted average asset allocation of defined benefit plans
Total (as a percent)	73.00%	72.00%
Other
Weighted average asset allocation of defined benefit plans
Total (as a percent)	4.00%	5.00%
Minimum | Debt securities
Weighted average asset allocation of defined benefit plans
Target allocation, (as a percent)	20.00%	20.00%
Minimum | Equity securities
Weighted average asset allocation of defined benefit plans
Target allocation, (as a percent)	30.00%	30.00%
Minimum | Other
Weighted average asset allocation of defined benefit plans
Target allocation, (as a percent)	5.00%	5.00%
Maximum | Debt securities
Weighted average asset allocation of defined benefit plans
Target allocation, (as a percent)	50.00%	50.00%
Maximum | Equity securities
Weighted average asset allocation of defined benefit plans
Target allocation, (as a percent)	60.00%	60.00%
Maximum | Other
Weighted average asset allocation of defined benefit plans
Target allocation, (as a percent)	50.00%	50.00%

Employee Benefit Plans - Pens94

Employee Benefit Plans - Pension Plan Assets (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee benefit plans
Fair value of plan assets	$ 173,668	$ 152,625	$ 143,655
Level 1 | Mutual funds - debt
Employee benefit plans
Fair value of plan assets	40,010	35,224
Level 1 | Mutual funds - equity
Employee benefit plans
Fair value of plan assets	125,871	110,078
Level 1 | Cash and cash equivalents
Employee benefit plans
Fair value of plan assets	$ 7,787	$ 7,322

Employee Benefit Plans - Postre

Employee Benefit Plans - Postretirement Healthcare Plan, Narrative (Details) - Postretirement Healthcare Plan $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Requisite service age, minimum	55 years
Estimated net loss that will be amortized from accumulated other comprehensive income into net periodic cost over the next year	$ 98
Effect of one percentage point increase on healthcare cost (as a percent)	5.00%
Effect of 1-percent increase in assumed health care cost trend rates on interest cost in current period	$ 8
Effect of 1-percent increase in assumed health care cost trend rates on postretirement benefit obligation	$ 58

Employee Benefit Plans - Post96

Employee Benefit Plans - Postretirement Healthcare Plan - Components of Net Periodic Benefit Cost and Other Amounts Recognized in OCI (Details) - Postretirement Healthcare Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 0	$ 0	$ 0
Interest cost	68	70	58
Net amortization and deferral	108	90	60
Net periodic pension cost	176	160	118
Net loss/ (gain)	(156)	109	273
Total recognized in other comprehensive income	(156)	109	273
Total recognized in net periodic benefit cost and other comprehensive income	$ 20	$ 269	$ 391

Employee Benefit Plans - Post97

Employee Benefit Plans - Postretirement Healthcare Plan - Funded Status (Details) - Postretirement Healthcare Plan - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Change in benefit obligation:
Benefit obligation at beginning of year	$ 1,779,000	$ 1,737,000
Service cost	0	0	$ 0
Interest cost	68,000	70,000	58,000
Actuarial (gain)/ loss	(48,000)	200,000
Benefits paid	(162,000)	(228,000)
Benefit obligation at end of year	1,637,000	1,779,000	1,737,000
Change in plan assets:
Fair value of plan assets at beginning of year	0	0
Employer contributions	162,000	228,000
Benefits paid	(162,000)	(228,000)
Fair value of plan assets at end of period	$ 0	$ 0	$ 0
Funded status at end of year				$ (1,637,000)	$ (1,779,000)
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Discount rate	4.06%	4.25%	3.89%
Monthly cost of healthcare insurance per beneficiary	$ 548	$ 539	$ 470
Annual rate of increase in healthcare costs	4.00%	4.00%	4.00%
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Projected benefit obligation	$ 1,779,000	$ 1,737,000	$ 1,737,000	1,637,000	1,779,000
Accumulated benefit obligation				1,637,000	1,779,000
Fair value of plan assets	$ 0	$ 0	$ 0	$ 0	$ 0

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Stock Ownership Plan, Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Stock Ownership Plan
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Compensation expense	$ 0	$ 6,300,000	$ 335,000

Employee Benefit Plans - Common

Employee Benefit Plans - Common Stock Awards, Narrative (Details) - Restricted common shares - USD ($) $ / shares in Units, $ in Millions	May 17, 2017	May 18, 2016	May 20, 2015	Dec. 31, 2017	Apr. 20, 2011
Stock Related Compensation
Weighted average grant date fair value of shares issued (in dollars per share)	$ 15.24	$ 14.51	$ 12.31
Market value of shares issued	$ 5.8	$ 4.9	$ 3.8
Number of shares forfeited				105,600
Vesting period				10 years
2011 Equity Incentive Plan
Stock Related Compensation
Number of shares authorized					2,806,233
Number of shares forfeited				415,154
Employees
Stock Related Compensation
Number of shares awarded	378,050	310,160	282,050	353,750
Director
Stock Related Compensation
Number of shares awarded	24,300	24,300	24,300	24,300
2015 issuance
Stock Related Compensation
Percentage of granted awards which will vest				30.00%
2016 issuance
Stock Related Compensation
Percentage of granted awards which will vest				20.00%
2017 issuance
Stock Related Compensation
Percentage of granted awards which will vest				10.00%

Employee Benefit Plans - Stock

Employee Benefit Plans - Stock Option Plans, Narrative (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	May 17, 2017	May 18, 2016	May 20, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Outstanding and exercisable options
Granted (in shares)				819,010	725,400	665,370
Weighted average fair value of options at grant date (in dollars per share)			$ 12.37	$ 1.55	$ 1.52	$ 1.14
Granted (in dollars per share)	$ 15.57	$ 14.15		$ 15.57	$ 14.15	$ 12.37
Vesting period				10 years
Exercise period				10 years
Total intrinsic value of options exercised				$ 3.5	$ 5.1	$ 1.2
Aggregate intrinsic value of all options expected to vest				8.6
Aggregate intrinsic value of all options fully vested				$ 14.3
2011 Equity Incentive Plan
Outstanding and exercisable options
Number of shares authorized				7,015,583
Employees
Outstanding and exercisable options
Granted (in shares)	754,210	660,600	660,570	754,210
Director
Outstanding and exercisable options
Granted (in shares)	64,800	64,800	64,800	64,800

Employee Benefit Plans - Share-

Employee Benefit Plans - Share-Based Awards (Details) - Stock options - $ / shares	May 17, 2017	May 18, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number
Balance at beginning of year (in shares)			5,804,105	6,306,496	6,402,407
Granted (in shares)			819,010	725,400	665,370
Exercised (in shares)			(630,591)	(1,081,072)	(474,253)
Forfeited/ expired (in shares)			(296,954)	(146,719)	(287,028)
Balance at end of year (in shares)			5,695,570	5,804,105	6,306,496
Exercisable at end of year (in shares)			3,016,367	3,035,718	3,431,113
Weighted average exercise price
Balance at beginning of year (in dollars per share)			$ 12.25	$ 11.81	$ 11.65
Granted (in dollars per share)	$ 15.57	$ 14.15	15.57	14.15	12.37
Exercised (in dollars per share)			11.66	11.01	10.27
Forfeited (in dollars per share)			12.43	12.71	12.26
Balance at end of year (in dollars per share)			12.75	12.25	11.81
Exercisable at end of year (in dollars per share)			$ 11.99	$ 11.71	$ 11.42

Employee Benefit Plans - Number

Employee Benefit Plans - Number of Options Outstanding and Exercisable and Weighted Average Remaining Life of All Option Grants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Exercise price $7.48
Options outstanding:
Number of options (in shares)	164,289
Weighted average remaining contract life (years)	1 year 3 months
Options exercisable:
Number of options (in shares)	164,289
Weighted average remaining term - vested (years)	1 year 3 months
Exercise price $9.79
Options outstanding:
Number of options (in shares)	143,224
Weighted average remaining contract life (years)	1 year
Options exercisable:
Number of options (in shares)	143,224
Weighted average remaining term - vested (years)	1 year
Exercise price $11.12
Options outstanding:
Number of options (in shares)	48,027
Weighted average remaining contract life (years)	3 months
Options exercisable:
Number of options (in shares)	48,027
Weighted average remaining term - vested (years)	3 months
Exercise price $11.49
Options outstanding:
Number of options (in shares)	260,456
Weighted average remaining contract life (years)	2 years 3 months
Options exercisable:
Number of options (in shares)	260,456
Weighted average remaining term - vested (years)	2 years 3 months
Exercise price $11.70
Options outstanding:
Number of options (in shares)	384,380
Weighted average remaining contract life (years)	4 years 6 months
Options exercisable:
Number of options (in shares)	237,916
Weighted average remaining term - vested (years)	4 years 6 months
Exercise price $12.12
Options outstanding:
Number of options (in shares)	342,789
Weighted average remaining contract life (years)	3 years 3 months
Options exercisable:
Number of options (in shares)	299,253
Weighted average remaining term - vested (years)	3 years 3 months
Exercise price $12.17
Options outstanding:
Number of options (in shares)	14,500
Weighted average remaining contract life (years)	3 years 6 months
Options exercisable:
Number of options (in shares)	13,000
Weighted average remaining term - vested (years)	3 years 6 months
Exercise price $12.32
Options outstanding:
Number of options (in shares)	1,537,329
Weighted average remaining contract life (years)	3 years 6 months
Options exercisable:
Number of options (in shares)	1,079,159
Weighted average remaining term - vested (years)	3 years 6 months
Exercise price $12.37
Options outstanding:
Number of options (in shares)	522,750
Weighted average remaining contract life (years)	7 years 6 months
Options exercisable:
Number of options (in shares)	163,646
Weighted average remaining term - vested (years)	7 years 6 months
Exercise price $12.44
Options outstanding:
Number of options (in shares)	427,090
Weighted average remaining contract life (years)	5 years 6 months
Options exercisable:
Number of options (in shares)	226,292
Weighted average remaining term - vested (years)	5 years 6 months
Exercise price $13.15
Options outstanding:
Number of options (in shares)	440,653
Weighted average remaining contract life (years)	6 years 6 months
Options exercisable:
Number of options (in shares)	178,091
Weighted average remaining term - vested (years)	6 years 6 months
Exercise price $14.15
Options outstanding:
Number of options (in shares)	643,998
Weighted average remaining contract life (years)	8 years 6 months
Options exercisable:
Number of options (in shares)	126,374
Weighted average remaining term - vested (years)	8 years 6 months
Exercise price $15.57
Options outstanding:
Number of options (in shares)	766,085
Weighted average remaining contract life (years)	9 years 6 months
Options exercisable:
Number of options (in shares)	76,640
Weighted average remaining term - vested (years)	9 years 6 months
$12.75
Options outstanding:
Number of options (in shares)	5,695,570
Weighted average remaining contract life (years)	5 years 5 months 16 days
Options exercisable:
Number of options (in shares)	3,016,367
Weighted average remaining term - vested (years)	4 years 15 days
Stock options | Exercise price $7.48
Outstanding and exercisable options
Exercise price (in dollars per share)	$ 7.48
Stock options | Exercise price $9.79
Outstanding and exercisable options
Exercise price (in dollars per share)	9.79
Stock options | Exercise price $11.12
Outstanding and exercisable options
Exercise price (in dollars per share)	11.12
Stock options | Exercise price $11.49
Outstanding and exercisable options
Exercise price (in dollars per share)	11.49
Stock options | Exercise price $11.70
Outstanding and exercisable options
Exercise price (in dollars per share)	11.70
Stock options | Exercise price $12.12
Outstanding and exercisable options
Exercise price (in dollars per share)	12.12
Stock options | Exercise price $12.17
Outstanding and exercisable options
Exercise price (in dollars per share)	$ 12.17
Stock options | Exercise price $12.32
Outstanding and exercisable options
Exercise price (in dollars per share)		$ 12.32
Stock options | Exercise price $12.37
Outstanding and exercisable options
Exercise price (in dollars per share)		12.37
Stock options | Exercise price $12.44
Outstanding and exercisable options
Exercise price (in dollars per share)		12.44
Stock options | Exercise price $13.15
Outstanding and exercisable options
Exercise price (in dollars per share)		13.15
Stock options | Exercise price $14.15
Outstanding and exercisable options
Exercise price (in dollars per share)		14.15
Stock options | Exercise price $15.57
Outstanding and exercisable options
Exercise price (in dollars per share)		15.57
Stock options | Total $12.75
Outstanding and exercisable options
Exercise price (in dollars per share)		$ 12.75

Disclosures About Fair Value103

Disclosures About Fair Value of Financial Instruments - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Significant unrealized appreciation or depreciation in financial instruments	$ 0	$ 0
Financial assets:
Securities available-for-sale	792,535,000	826,200,000
Securities held-to-maturity	29,667,000	20,426,000
Accrued interest receivable	23,352,000	21,699,000
Derivative asset	214,000	238,000
Financial liabilities:
Borrowed funds	108,238,000	142,899,000
Junior subordinated debentures	111,213,000	111,213,000
Cash flow hedges - interest rate swaps	1,339,000	2,974,000
Assets transferred between Level 1 and Level 2	0	0
Level 1
Financial assets:
Cash and cash equivalents	77,710,000	389,867,000
Securities available-for-sale	574,000	4,440,000
Securities held-to-maturity	0	0
Loans receivable, net	3,128,000	9,625,000
Accrued interest receivable	23,352,000	21,699,000
Derivative asset	0	0
FHLB Stock	0	0
Total assets	104,764,000	425,631,000
Financial liabilities:
Savings and checking accounts	6,414,366,000	6,341,735,000
Time deposits	0	0
Borrowed funds	108,238,000	142,899,000
Junior subordinated debentures	0	0
Cash flow hedges - interest rate swaps		0
Accrued interest payable	460,000	643,000
Total financial liabilities	6,523,064,000	6,485,277,000
Level 2
Financial assets:
Cash and cash equivalents	0	0
Securities available-for-sale	791,961,000	812,394,000
Securities held-to-maturity	29,667,000	20,426,000
Loans receivable, net	0	0
Accrued interest receivable	0	0
Derivative asset	214,000	238,000
FHLB Stock	0	0
Total assets	821,842,000	833,058,000
Financial liabilities:
Savings and checking accounts	0	0
Time deposits	0	0
Borrowed funds	0	0
Junior subordinated debentures	0	0
Cash flow hedges - interest rate swaps		2,974,000
Accrued interest payable	0	0
Total financial liabilities	1,339,000	2,974,000
Level 3
Financial assets:
Cash and cash equivalents	0	0
Securities available-for-sale	0	9,366,000
Securities held-to-maturity	0	0
Loans receivable, net	7,759,434,000	7,869,190,000
Accrued interest receivable	0	0
Derivative asset	0	0
FHLB Stock	0	0
Total assets	7,759,434,000	7,878,556,000
Financial liabilities:
Savings and checking accounts	0	0
Time deposits	1,433,380,000	1,626,434,000
Borrowed funds	0	0
Junior subordinated debentures	110,954,000	113,313,000
Cash flow hedges - interest rate swaps		0
Accrued interest payable	0	0
Total financial liabilities	1,544,334,000	1,739,747,000
Carrying amount
Financial assets:
Cash and cash equivalents	77,710,000	389,867,000
Securities available-for-sale	792,535,000	826,200,000
Securities held-to-maturity	29,678,000	19,978,000
Loans receivable, net	7,736,614,000	7,496,408,000
Accrued interest receivable	23,352,000	21,699,000
Derivative asset	214,000	238,000
FHLB Stock	11,733,000	7,390,000
Total assets	8,671,836,000	8,761,780,000
Financial liabilities:
Savings and checking accounts	6,414,366,000	6,341,735,000
Time deposits	1,412,623,000	1,540,586,000
Borrowed funds	108,238,000	142,899,000
Junior subordinated debentures	111,213,000	111,213,000
Cash flow hedges - interest rate swaps		2,974,000
Accrued interest payable	460,000	643,000
Total financial liabilities	8,048,239,000	8,140,050,000
Estimated fair value
Financial assets:
Cash and cash equivalents	77,710,000	389,867,000
Securities available-for-sale	792,535,000	826,200,000
Securities held-to-maturity	29,667,000	20,426,000
Loans receivable, net	7,762,562,000	7,878,815,000
Accrued interest receivable	23,352,000	21,699,000
Derivative asset	214,000	238,000
FHLB Stock	11,733,000	7,390,000
Total assets	8,697,773,000	9,144,635,000
Financial liabilities:
Savings and checking accounts	6,414,366,000	6,341,735,000
Time deposits	1,433,380,000	1,626,434,000
Borrowed funds	108,238,000	142,899,000
Junior subordinated debentures	110,954,000	113,313,000
Cash flow hedges - interest rate swaps		2,974,000
Accrued interest payable	460,000	643,000
Total financial liabilities	8,068,737,000	$ 8,227,998,000
Interest rate swaps | Level 1
Financial liabilities:
Cash flow hedges - interest rate swaps	0
Interest rate swaps | Level 2
Financial liabilities:
Cash flow hedges - interest rate swaps	1,278,000
Interest rate swaps | Level 3
Financial liabilities:
Cash flow hedges - interest rate swaps	0
Interest rate swaps | Carrying amount
Financial liabilities:
Cash flow hedges - interest rate swaps	1,278,000
Interest rate swaps | Estimated fair value
Financial liabilities:
Cash flow hedges - interest rate swaps	1,278,000
Foreign exchange swaps | Level 1
Financial liabilities:
Cash flow hedges - interest rate swaps	0
Foreign exchange swaps | Level 2
Financial liabilities:
Cash flow hedges - interest rate swaps	61,000
Foreign exchange swaps | Level 3
Financial liabilities:
Cash flow hedges - interest rate swaps	0
Foreign exchange swaps | Carrying amount
Financial liabilities:
Cash flow hedges - interest rate swaps	61,000
Foreign exchange swaps | Estimated fair value
Financial liabilities:
Cash flow hedges - interest rate swaps	$ 61,000

Disclosures About Fair Value104

Disclosures About Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	$ 792,535	$ 826,200
Derivative asset	214	238
Cash flow hedges - swaps	1,339	2,974
Level 1
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	574	4,440
Derivative asset	0	0
Total assets	104,764	425,631
Cash flow hedges - swaps		0
Level 2
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	791,961	812,394
Derivative asset	214	238
Total assets	821,842	833,058
Cash flow hedges - swaps		2,974
Level 3
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	9,366
Derivative asset	0	0
Total assets	7,759,434	7,878,556
Cash flow hedges - swaps		0
Measured on recurring basis
Assets and liabilities measured at fair value on a recurring basis
Total assets	792,749	826,438
Total liabilities	1,339	2,974
Measured on recurring basis | Equity securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	574	4,440
Measured on recurring basis | Debt securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	261,235	374,226
Measured on recurring basis | Debt securities | U.S. Government and agencies
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	1	6
Measured on recurring basis | Debt securities | Government sponsored enterprises
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	209,269	294,170
Measured on recurring basis | Debt securities | States and political subdivisions
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	51,056	63,070
Measured on recurring basis | Debt securities | Corporate
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	909	16,980
Measured on recurring basis | Interest rate swaps
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	214	238
Cash flow hedges - swaps	1,278	2,974
Measured on recurring basis | Mortgage-backed securities
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	530,726	447,534
Measured on recurring basis | Residential mortgage-backed securities | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	29,695	30,883
Measured on recurring basis | Residential mortgage-backed securities | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	82,969	106,578
Measured on recurring basis | Residential mortgage-backed securities | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	64,021	82,115
Measured on recurring basis | Residential mortgage-backed securities | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	555	579
Measured on recurring basis | Collateralized mortgage obligations | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	4,769	6,287
Measured on recurring basis | Collateralized mortgage obligations | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	191,512	95,186
Measured on recurring basis | Collateralized mortgage obligations | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	157,190	119,197
Measured on recurring basis | Collateralized mortgage obligations | SBA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities		6,608
Measured on recurring basis | Collateralized mortgage obligations | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	15	101
Measured on recurring basis | Foreign exchange swaps
Assets and liabilities measured at fair value on a recurring basis
Cash flow hedges - swaps	61
Measured on recurring basis | Level 1
Assets and liabilities measured at fair value on a recurring basis
Total assets	574	4,440
Total liabilities	0	0
Measured on recurring basis | Level 1 | Equity securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	574	4,440
Measured on recurring basis | Level 1 | Debt securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 1 | Debt securities | U.S. Government and agencies
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 1 | Debt securities | Government sponsored enterprises
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 1 | Debt securities | States and political subdivisions
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 1 | Debt securities | Corporate
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 1 | Interest rate swaps
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	0	0
Cash flow hedges - swaps	0	0
Measured on recurring basis | Level 1 | Mortgage-backed securities
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Residential mortgage-backed securities | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Residential mortgage-backed securities | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Residential mortgage-backed securities | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Residential mortgage-backed securities | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Collateralized mortgage obligations | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Collateralized mortgage obligations | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Collateralized mortgage obligations | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Collateralized mortgage obligations | SBA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities		0
Measured on recurring basis | Level 1 | Collateralized mortgage obligations | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 1 | Foreign exchange swaps
Assets and liabilities measured at fair value on a recurring basis
Cash flow hedges - swaps	0
Measured on recurring basis | Level 2
Assets and liabilities measured at fair value on a recurring basis
Total assets	792,175	812,632
Total liabilities	1,339	2,974
Measured on recurring basis | Level 2 | Equity securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 2 | Debt securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	261,235	364,860
Measured on recurring basis | Level 2 | Debt securities | U.S. Government and agencies
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	1	6
Measured on recurring basis | Level 2 | Debt securities | Government sponsored enterprises
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	209,269	294,170
Measured on recurring basis | Level 2 | Debt securities | States and political subdivisions
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	51,056	63,070
Measured on recurring basis | Level 2 | Debt securities | Corporate
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	909	7,614
Measured on recurring basis | Level 2 | Interest rate swaps
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	214	238
Cash flow hedges - swaps	1,278	2,974
Measured on recurring basis | Level 2 | Mortgage-backed securities
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	530,726	447,534
Measured on recurring basis | Level 2 | Residential mortgage-backed securities | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	29,695	30,883
Measured on recurring basis | Level 2 | Residential mortgage-backed securities | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	82,969	106,578
Measured on recurring basis | Level 2 | Residential mortgage-backed securities | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	64,021	82,115
Measured on recurring basis | Level 2 | Residential mortgage-backed securities | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	555	579
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	4,769	6,287
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	191,512	95,186
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	157,190	119,197
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | SBA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities		6,608
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	15	101
Measured on recurring basis | Level 2 | Foreign exchange swaps
Assets and liabilities measured at fair value on a recurring basis
Cash flow hedges - swaps	61
Measured on recurring basis | Level 3
Assets and liabilities measured at fair value on a recurring basis
Total assets	0	9,366
Total liabilities	0	0
Measured on recurring basis | Level 3 | Equity securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 3 | Debt securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	9,366
Measured on recurring basis | Level 3 | Debt securities | U.S. Government and agencies
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 3 | Debt securities | Government sponsored enterprises
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 3 | Debt securities | States and political subdivisions
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Measured on recurring basis | Level 3 | Debt securities | Corporate
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	9,366
Measured on recurring basis | Level 3 | Interest rate swaps
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	0	0
Cash flow hedges - swaps	0	0
Measured on recurring basis | Level 3 | Mortgage-backed securities
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Residential mortgage-backed securities | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Residential mortgage-backed securities | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Residential mortgage-backed securities | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Residential mortgage-backed securities | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Collateralized mortgage obligations | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Collateralized mortgage obligations | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Collateralized mortgage obligations | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	0
Measured on recurring basis | Level 3 | Collateralized mortgage obligations | SBA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities		0
Measured on recurring basis | Level 3 | Collateralized mortgage obligations | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	0	$ 0
Measured on recurring basis | Level 3 | Foreign exchange swaps
Assets and liabilities measured at fair value on a recurring basis
Cash flow hedges - swaps	$ 0

Disclosures About Fair Value105

Disclosures About Fair Value of Financial Instruments - Reconciliation of all Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) - Level 3 - Debt securities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance at the beginning of the period	$ 9,366	$ 8,955
Total net realized investment gains/ (losses) and net change in unrealized appreciation/ (depreciation):
Included in net income as OTTI	0	0
Included in other comprehensive income	1,282	411
Purchases	0	0
Sales	(10,648)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at the end of the period	$ 0	$ 9,366

Disclosures About Fair Value106

Disclosures About Fair Value of Financial Instruments - Nonrecurring Assets that had Fair Market Values Below the Carrying Amount (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	$ 39,087	$ 47,068
Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	0	0
Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	0	0
Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	39,087	47,068
Loans evaluated for impairment
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	33,421	41,933
Loans evaluated for impairment | Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	0	0
Loans evaluated for impairment | Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	0	0
Loans evaluated for impairment | Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	33,421	41,933
Mortgage servicing rights
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets		246
Mortgage servicing rights | Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets		0
Mortgage servicing rights | Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets		0
Mortgage servicing rights | Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets		246
Real estate owned
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	5,666	4,889
Real estate owned | Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	0	0
Real estate owned | Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	0	0
Real estate owned | Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Total assets	$ 5,666	$ 4,889

Disclosures About Fair Value107

Disclosures About Fair Value of Financial Instruments - Additional Quantitative Information, Assets Measured at Fair Value, Recurring and Nonrecurring Basis, Level 3 Input (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Loans evaluated for impairment
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value	$ 33,421
Loans evaluated for impairment | Discounted cash flow | Minimum
Quantitative information for Level 3 Fair Value Measurements Assets
Discount rate	4.25%
Loans evaluated for impairment | Discounted cash flow | Maximum
Quantitative information for Level 3 Fair Value Measurements Assets
Discount rate	10.00%
Loans evaluated for impairment | Discounted cash flow | Weighted Average
Quantitative information for Level 3 Fair Value Measurements Assets
Discount rate	7.50%
Loans evaluated for impairment | Appraisal Value
Quantitative information for Level 3 Fair Value Measurements Assets
Estimated costs to sell	10.00%
Real estate owned
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value	$ 5,666

Regulatory Capital Requireme108

Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Tier 1 capital (leverage) (to average assets)
Minimum capital requirements (as a percent)	1.25%	0.625%
Northwest Bank
Total capital (to risk weighted assets)
Actual amount	$ 1,017,251	$ 961,279
Actual ratio (as a percent)	14.189%	13.609%
Capital required for capital adequacy	$ 663,179	$ 609,248
Minimum capital requirements ratio (as a percent)	9.25%	8.625%
Well capitalized requirements amount	$ 716,951	$ 706,375
Well capitalized requirements ratio (as a percent)	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Actual amount	$ 960,443	$ 900,328
Actual ratio (as a percent)	13.396%	12.746%
Minimum capital requirements amount	$ 519,789	$ 467,973
Minimum capital requirements ratio (as a percent)	7.25%	6.625%
Well capitalized requirements amount	$ 573,560	$ 565,100
Well capitalized requirements ratio (as a percent)	8.00%	8.00%
CET 1 capital (to risk weighted assets)
Actual amount	$ 960,443	$ 900,328
Actual ratio (as a percent)	13.396%	12.746%
Minimum capital requirements amount	$ 412,247	$ 362,017
Minimum capital requirements ratio (as a percent)	5.75%	5.125%
Well capitalized requirements amount	$ 430,170	$ 459,144
Well capitalized requirements ratio (as a percent)	6.00%	6.50%
Tier 1 capital (leverage) (to average assets)
Actual amount	$ 960,443	$ 900,328
Actual ratio (as a percent)	10.40%	9.585%
Minimum capital requirements amount	$ 369,482	$ 375,735
Minimum capital requirements ratio (as a percent)	4.00%	4.00%
Well capitalized requirements amount	$ 461,853	$ 469,669
Well capitalized requirements ratio (as a percent)	5.00%	5.00%
Northwest Bancshares, Inc.
Total capital (to risk weighted assets)
Actual amount	$ 1,136,076	$ 1,051,582
Actual ratio (as a percent)	15.831%	14.873%
Capital required for capital adequacy	$ 663,823	$ 609,835
Minimum capital requirements ratio (as a percent)	9.25%	8.625%
Well capitalized requirements amount	$ 717,647	$ 707,056
Well capitalized requirements ratio (as a percent)	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Actual amount	$ 1,079,270	$ 990,153
Actual ratio (as a percent)	15.039%	14.004%
Minimum capital requirements amount	$ 520,294	$ 468,424
Minimum capital requirements ratio (as a percent)	7.25%	6.625%
Well capitalized requirements amount	$ 574,117	$ 565,644
Well capitalized requirements ratio (as a percent)	8.00%	8.00%
CET 1 capital (to risk weighted assets)
Actual amount	$ 971,395	$ 882,278
Actual ratio (as a percent)	13.536%	12.478%
Minimum capital requirements amount	$ 412,647	$ 362,366
Minimum capital requirements ratio (as a percent)	5.75%	5.125%
Well capitalized requirements amount	$ 466,470	$ 459,586
Well capitalized requirements ratio (as a percent)	6.50%	6.50%
Tier 1 capital (leverage) (to average assets)
Actual amount	$ 1,079,270	$ 990,153
Actual ratio (as a percent)	11.676%	10.53%
Minimum capital requirements amount	$ 369,735	$ 376,116
Minimum capital requirements ratio (as a percent)	4.00%	4.00%
Well capitalized requirements amount	$ 462,169	$ 470,145
Well capitalized requirements ratio (as a percent)	5.00%	5.00%

Components of Accumulated Ot109

Components of Accumulated Other Comprehensive Income - (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	$ 1,207,724	$ 1,170,663	$ 1,163,163	$ 1,062,647
Unrealized gain on marketable securities available-for-sale
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	(4,409)	395	3,325	3,461
Fair value of interest rate swaps
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	(691)	(1,778)	(2,779)	(4,078)
Defined benefit pension plans
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	(26,980)	(26,608)	(25,081)	(23,753)
Accumulated other comprehensive income
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	$ (32,080)	$ (27,991)	$ (24,535)	$ (24,370)

Components of Accumulated Ot110

Components of Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	$ 1,170,663	$ 1,163,163	$ 1,062,647
Other comprehensive income/ (loss) before reclassification adjustments	(2,645)
Amounts reclassified from accumulated other comprehensive income	(1,444)
Other comprehensive loss	(4,089)	(3,456)	(165)
Balance at end of the period	1,207,724	1,170,663	1,163,163
Reclassification adjustment for gains (losses) on securities, net of tax	2,326	202	451
Income tax (expense) benefit related to (gain) loss on securities	(1,488)	(129)	(289)
Amortization of prior service cost (compensation and employee benefits)	882	872	875
Income tax expense (benefit) related to compensation and employee benefits	613	606	560
Unrealized gain on marketable securities available-for-sale
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	395	3,325	3,461
Other comprehensive income/ (loss) before reclassification adjustments	(2,478)	(2,728)	315
Amounts reclassified from accumulated other comprehensive income	(2,326)	(202)	(451)
Other comprehensive loss	(4,804)	(2,930)	(136)
Balance at end of the period	(4,409)	395	3,325
Reclassification adjustment for gains (losses) on securities, net of tax	3,814	331	(740)
Income tax (expense) benefit related to (gain) loss on securities	(1,488)	(129)	(289)
Fair value of interest rate swaps
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	(1,778)	(2,779)	(4,078)
Other comprehensive income/ (loss) before reclassification adjustments	1,087	1,001	1,299
Amounts reclassified from accumulated other comprehensive income	0	0	0
Other comprehensive loss	1,087	1,001	1,299
Balance at end of the period	(691)	(1,778)	(2,779)
Defined benefit pension plans
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	(26,608)	(25,081)	(23,753)
Other comprehensive income/ (loss) before reclassification adjustments	(1,254)	(2,399)	(2,203)
Amounts reclassified from accumulated other comprehensive income	882	872	875
Other comprehensive loss	(372)	(1,527)	(1,328)
Balance at end of the period	(26,980)	(26,608)	(25,081)
Amortization of prior service cost (compensation and employee benefits)	2,323	2,323	2,323
Amortization of net loss (compensation and employee benefits)	(3,818)	(3,801)	(3,758)
Income tax expense (benefit) related to compensation and employee benefits	613	606	560
Accumulated other comprehensive income
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	(27,991)	(24,535)	(24,370)
Other comprehensive income/ (loss) before reclassification adjustments		(4,126)	(589)
Amounts reclassified from accumulated other comprehensive income		670	424
Other comprehensive loss	(4,089)	(3,456)	(165)
Balance at end of the period	$ (32,080)	$ (27,991)	$ (24,535)

Parent Company Only Financia111

Parent Company Only Financial Statements - Condensed - Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Total cash and cash equivalents	$ 77,710	$ 389,867	$ 167,408	$ 240,706
Marketable securities available-for-sale (amortized cost of $800,094 and $825,552)	792,535	826,200
Other assets	30,066	32,194
Total assets	9,363,934	9,623,640
Liabilities:
Debentures payable	111,213	111,213
Other liabilities	68,485	63,373
Total liabilities	8,156,210	8,452,977
Shareholders’ equity	1,207,724	1,170,663	1,163,163	1,062,647
Total liabilities and shareholders’ equity	9,363,934	9,623,640
Parent Company
Assets
Total cash and cash equivalents	26,088	34,521	$ 91,056	$ 110,699
Marketable securities available-for-sale (amortized cost of $800,094 and $825,552)	545	4,413
Investment in bank subsidiary	1,200,799	1,193,175
Other assets	92,712	52,645
Total assets	1,320,144	1,284,754
Liabilities:
Debentures payable	111,213	111,213
Other liabilities	1,207	2,878
Total liabilities	112,420	114,091
Shareholders’ equity	1,207,724	1,170,663
Total liabilities and shareholders’ equity	$ 1,320,144	$ 1,284,754

Parent Company Only Financia112

Parent Company Only Financial Statements - Condensed - Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income:
Interest income	$ 91,561	$ 90,231	$ 89,797	$ 87,267	$ 90,033	$ 84,748	$ 85,555	$ 85,298	$ 85,639	$ 81,091	$ 75,970	$ 76,880	$ 358,856	$ 345,634	$ 319,580
Expense:
Other expense													12,630	13,014	9,031
Interest expense	7,321	6,994	7,066	6,690	7,091	7,454	10,008	13,746	14,486	14,150	13,792	13,899	28,071	38,299	56,327
Income before income taxes	28,724	36,005	45,384	25,798	36,855	18,894	(10,499)	26,065	24,877	18,110	22,518	22,995	135,911	71,315	88,500
Federal and state income taxes	6,576	12,414	14,402	8,052	12,361	4,697	(3,491)	8,081	8,684	5,238	7,213	6,825	41,444	21,648	27,960
Net income	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 24,494	$ 14,197	$ (7,008)	$ 17,984	$ 16,193	$ 12,872	$ 15,305	$ 16,170	94,467	49,667	60,540
Parent Company
Income:
Interest income													137	737	1,258
Other income													2,297	709	659
Dividends from bank subsidiary													90,000	50,000	135,000
Undistributed earnings from equity investment in bank subsidiary													7,255	2,760	(70,854)
Total income													99,689	54,206	66,063
Expense:
Compensation and benefits													1,282	1,129	1,061
Other expense													553	561	1,356
Interest expense													4,666	4,560	4,926
Total expense													6,501	6,250	7,343
Income before income taxes													93,188	47,956	58,720
Federal and state income taxes													(1,279)	(1,711)	(1,820)
Net income													$ 94,467	$ 49,667	$ 60,540

Parent Company Only Financia113

Parent Company Only Financial Statements - Condensed - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net Income	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 24,494	$ 14,197	$ (7,008)	$ 17,984	$ 16,193	$ 12,872	$ 15,305	$ 16,170	$ 94,467	$ 49,667	$ 60,540
Adjustments to reconcile net income to net cash provided by operating activities:
Noncash stock benefit plan compensation expense													4,894	10,916	5,570
Gain on sale of marketable securities													(1,148)	(625)	(1,037)
Net cash provided by operating activities													156,057	136,902	113,202
Investing activities:
Net sale of marketable securities													36,811	1,951	1,246
Acquisition, net of cash received													0	1,102,237	(61,108)
Net cash provided by/ (used in) investing activities													(108,299)	1,149,408	(88,812)
Financing activities:
Cash dividends paid													(65,212)	(60,156)	(52,825)
Share repurchases													0	(1,752)	(7,847)
Redemption of junior subordinated debt													0	0	(8,119)
Excess tax benefit from stock-based compensation													0	1,425	332
Proceeds from options exercised													7,001	10,856	4,303
Net cash used in financing activities													(359,915)	(1,063,851)	(97,688)
Net increase/ (decrease) in cash and cash equivalents													(312,157)	222,459	(73,298)
Cash and cash equivalents at beginning of period				389,867				167,408				240,706	389,867	167,408	240,706
Cash and cash equivalents at end of period	77,710				389,867				167,408				77,710	389,867	167,408
Parent Company
Operating activities:
Net Income													94,467	49,667	60,540
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiary													(7,255)	(2,760)	70,854
Noncash stock benefit plan compensation expense													4,894	10,916	5,654
Gain on sale of marketable securities													(1,615)	(43)	(54)
Net change in other assets and liabilities													(43,513)	(63,533)	(5,824)
Net cash provided by operating activities													46,978	(5,753)	131,170
Investing activities:
Net sale of marketable securities													2,800	(1,952)	1,192
Acquisition, net of cash received													0	0	(89,398)
Net cash provided by/ (used in) investing activities													2,800	(1,952)	(88,206)
Financing activities:
Cash dividends paid													(65,212)	(60,156)	(52,825)
Share repurchases													0	(1,752)	(7,847)
Repayment of loan to ESOP													0	797	1,549
Redemption of junior subordinated debt													0	0	(8,119)
Excess tax benefit from stock-based compensation													0	1,425	332
Proceeds from options exercised													7,001	10,856	4,303
Net cash used in financing activities													(58,211)	(48,830)	(62,607)
Net increase/ (decrease) in cash and cash equivalents													(8,433)	(56,535)	(19,643)
Cash and cash equivalents at beginning of period				$ 34,521				$ 91,056				$ 110,699	34,521	91,056	110,699
Cash and cash equivalents at end of period	$ 26,088				$ 34,521				$ 91,056				$ 26,088	$ 34,521	$ 91,056

Derivative Financial Instrum114

Derivative Financial Instruments - Narrative (Details)	12 Months Ended
	Dec. 31, 2017USD ($)derivative	Dec. 31, 2016USD ($)
Derivative [Line Items]
Fair value of swap agreements	$ 1,339,000	$ 2,974,000
Interest rate swaps
Derivative [Line Items]
Number of interest rate swap agreements held | derivative	2
Derivative liability, notional amount	$ 1,600,000
Amount of ineffectiveness on net investment hedges	0
Gain (loss) reclassified within twelve months	$ 700,000
Northwest Bancorp Capital Trust III | Interest rate swaps
Derivative [Line Items]
Derivative expiration period	10 years
Fixed rate	4.61%
Northwest Bancorp Statutory Trust IV | Interest rate swaps
Derivative [Line Items]
Derivative expiration period	10 years
Cash flow hedges | Northwest Bancorp Capital Trust III | Interest rate swaps
Derivative [Line Items]
Notional amount	$ 25,000,000
Trust preferred investments | Northwest Bancorp Statutory Trust IV | Derivative Instrument
Derivative [Line Items]
Fixed rate	4.09%
Trust preferred investments | Cash flow hedges | Northwest Bancorp Statutory Trust IV | Derivative Instrument
Derivative [Line Items]
Notional amount	$ 25,000,000
Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Fair value of swap agreements	$ 1,064,000	$ 2,736,000

Derivative Financial Instrum115

Derivative Financial Instruments - Schedule of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative asset, notional amount	$ 92,631	$ 10,559
Derivative asset	214	238
Derivative liability, notional amount	154,975	60,559
Cash flow hedges - interest rate swaps	1,339	2,974
Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Derivative asset, notional amount	0	0
Derivative asset	0	0
Derivative liability, notional amount	50,000	50,000
Cash flow hedges - interest rate swaps	1,064	2,736
Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Derivative asset, notional amount	92,631	10,559
Derivative asset	214	238
Derivative liability, notional amount	92,631	10,559
Cash flow hedges - interest rate swaps	214	238
Derivatives not designated as hedging instruments: | Foreign exchange swaps
Derivative [Line Items]
Derivative asset, notional amount	0	0
Derivative asset	0	0
Derivative liability, notional amount	12,344	0
Cash flow hedges - interest rate swaps	$ 61	$ 0

Derivative Financial Instrum116

Derivative Financial Instruments - Gain (Loss) on Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Gain (loss) on non-hedging swap derivatives	$ (373)	$ 0	$ 0
Gain (loss) on hedging interest rate derivatives	$ 1,599	$ 1,866	$ 2,922

Selected Quarterly Financial117

Selected Quarterly Financial Data - Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 91,561	$ 90,231	$ 89,797	$ 87,267	$ 90,033	$ 84,748	$ 85,555	$ 85,298	$ 85,639	$ 81,091	$ 75,970	$ 76,880	$ 358,856	$ 345,634	$ 319,580
Interest expense	7,321	6,994	7,066	6,690	7,091	7,454	10,008	13,746	14,486	14,150	13,792	13,899	28,071	38,299	56,327
Net interest income	84,240	83,237	82,731	80,577	82,942	77,294	75,547	71,552	71,153	66,941	62,178	62,981	330,785	307,335	263,253
Provision for loan losses	6,525	3,027	5,562	4,637	2,145	5,538	4,199	1,660	4,595	3,167	1,050	900	19,751	13,542	9,712
Noninterest income	22,905	24,594	41,477	21,504	24,819	20,818	20,275	19,448	19,546	18,140	16,525	14,625	110,480	85,360	68,836
Noninterest expenses	71,896	68,799	73,262	71,646	68,761	73,680	102,122	63,275	61,227	63,804	55,135	53,711	285,603	307,838	233,877
Income before income taxes	28,724	36,005	45,384	25,798	36,855	18,894	(10,499)	26,065	24,877	18,110	22,518	22,995	135,911	71,315	88,500
Income tax expense/ (benefit)	6,576	12,414	14,402	8,052	12,361	4,697	(3,491)	8,081	8,684	5,238	7,213	6,825	41,444	21,648	27,960
Net income	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 24,494	$ 14,197	$ (7,008)	$ 17,984	$ 16,193	$ 12,872	$ 15,305	$ 16,170	$ 94,467	$ 49,667	$ 60,540
Basic earnings per share (in dollars per share)	$ 0.22	$ 0.23	$ 0.31	$ 0.18	$ 0.24	$ 0.14	$ (0.07)	$ 0.18	$ 0.16	$ 0.14	$ 0.17	$ 0.18	$ 0.94	$ 0.50	$ 0.64
Diluted earnings per share (in dollars per share)	$ 0.22	$ 0.23	$ 0.30	$ 0.17	$ 0.24	$ 0.14	$ (0.07)	$ 0.18	$ 0.16	$ 0.13	$ 0.17	$ 0.18	$ 0.92	$ 0.49	$ 0.64