Northwest Bancshares (NWBI) 10-K 2 Mar 20 2019 FY Annual report Financial data

Cover Document and Entity Infor

Cover Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-34582
Entity Registrant Name	NORTHWEST BANCSHARES, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	27-0950358
Entity Address, Address Line One	100 Liberty Street,
Entity Address, City or Town	Warren,
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	16365
City Area Code	814
Local Phone Number	726-2140
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	NWBI
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		106,934,228
Entity Public Float			$ 1,877
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Proxy Statement for the 2020 Annual Meeting of Stockholders of the Registrant (Part III).
Entity Central Index Key	0001471265
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED STATEMENTS OF FINA

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	$ 60,846	$ 68,789
Marketable securities available-for-sale (amortized cost of $815,495 and $811,015, respectively)	819,901	801,450
Marketable securities held-to-maturity (fair value of $18,223 and $22,446, respectively)	18,036	22,765
Loans receivable, net of allowance for loan losses of $57,941 and $55,214	8,750,733	7,996,225
Federal Home Loan Bank stock, at cost	14,740	15,635
Accrued interest receivable	25,755	24,490
Real estate owned, net	950	2,498
Premises and equipment, net	147,409	143,390
Bank-owned life insurance	189,091	171,079
Goodwill	346,103	307,420
Other intangible assets	23,076	19,821
Other assets	97,268	34,211
Total assets	10,493,908	9,607,773
Liabilities:
Deposits	8,592,007	7,894,179
Borrowed funds	246,336	234,389
Junior subordinated debentures	121,800	111,213
Advances by borrowers for taxes and insurance	44,556	43,298
Accrued interest payable	1,142	744
Other liabilities	134,782	66,312
Total liabilities	9,140,623	8,350,135
Shareholders’ equity:
Preferred stock, $0.01 par value: 50,000,000 shares authorized, no shares issued	0	0
Common stock, $0.01 par value: 500,000,000 shares authorized, 106,859,088 and 103,354,030 shares issued and outstanding, respectively	1,069	1,034
Paid-in capital	805,750	745,926
Retained earnings	583,407	550,374
Accumulated other comprehensive loss	(36,941)	(39,696)
Total shareholders’ equity	1,353,285	1,257,638
Total liabilities and shareholders’ equity	$ 10,493,908	$ 9,607,773

CONSOLIDATED STATEMENTS OF FI_2

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Marketable securities available-for-sale, amortized cost	$ 815,495	$ 811,015
Investment securities held-to-maturity, fair value	18,223	22,446
Allowance for loan losses	$ 57,941	$ 55,214
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	106,859,088	103,354,030
Common stock, shares outstanding (in shares)	106,859,088	103,354,030

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income:
Loans receivable	$ 394,809	$ 356,571	$ 339,992
Mortgage-backed securities	16,670	13,781	11,343
Taxable investment securities	3,401	3,064	3,749
Tax-free investment securities	844	1,078	2,023
Federal Home Loan Bank stock dividends	1,056	452	250
Interest-earning deposits	600	835	1,499
Total interest income	417,380	375,781	358,856
Interest expense:
Deposits	49,216	30,985	23,057
Borrowed funds	7,698	6,155	5,014
Total interest expense	56,914	37,140	28,071
Net interest income	360,466	338,641	330,785
Provision for loan losses	22,659	20,332	19,751
Net interest income after provision for loan losses	337,807	318,309	311,034
Noninterest income:
Gain on sale of investments	50	157	1,148
Gain on sale of loans	1,734	0	0
Service charges and fees	53,065	50,792	49,717
Trust and other financial services income	17,765	16,581	17,987
Insurance commission income	8,068	8,791	9,013
Loss on real estate owned, net	(53)	(631)	(797)
Income from bank-owned life insurance	4,418	5,821	6,093
Mortgage banking income	3,819	596	1,418
Gain on sale of offices	0	0	17,186
Other operating income	10,541	9,595	8,715
Total noninterest income	99,407	91,702	110,480
Noninterest expense:
Compensation and employee benefits	163,086	152,395	152,296
Premises and occupancy costs	28,717	27,519	28,863
Office operations	14,133	14,139	16,342
Collections expense	2,560	2,209	2,849
Processing expenses	42,453	39,046	39,086
Marketing expenses	6,998	8,434	9,607
Federal deposit insurance premiums	685	2,746	3,518
Professional services	12,287	10,598	10,293
Amortization of intangible assets	6,543	5,848	6,764
Real estate owned expense	478	817	1,004
Restructuring/acquisition expense	4,168	1,014	4,419
Other expenses	13,995	11,333	10,562
Total noninterest expense	296,103	276,098	285,603
Income before income taxes	141,111	133,913	135,911
Provision for income taxes:
Federal	24,069	21,948	34,801
State	6,610	6,474	6,643
Total provision for income taxes	30,679	28,422	41,444
Net income	$ 110,432	$ 105,491	$ 94,467
Basic earnings per share (in dollars per share)	$ 1.05	$ 1.03	$ 0.94
Diluted earnings per share (in dollars per share)	$ 1.04	$ 1.02	$ 0.92

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 110,432	$ 105,491	$ 94,467
Net unrealized holding gains/losses on marketable securities:
Unrealized holding gain/(loss) net of tax of ($3,990), $513, and $1,915, respectively	9,984	(1,277)	(2,478)
Reclassification adjustment for gains included in net income, net of tax of $2, $60, and $1,488, respectively	(5)	(155)	(2,326)
Net unrealized holding gain/(loss) on marketable securities	9,979	(1,432)	(4,804)
Change in fair value of interest rate swaps, net of tax of $0, ($223), and ($585), respectively	0
Change in fair value of interest rate swaps, net of tax of $0, ($223), and ($585), respectively		840	1,087
Defined benefit plans:
Net loss, net of tax $3,193, $770, $826, respectively	(8,059)	(1,181)	(1,254)
Reclassification adjustments for prior period service costs and net losses included in net income, net of tax of ($334), ($746), and ($613), respectively	835	903	882
Net loss on defined benefit plans	(7,224)	(278)	(372)
Other comprehensive income/(loss)	2,755	(870)	(4,089)
Total comprehensive income	$ 113,187	$ 104,621	$ 90,378

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Income tax (expense) benefit related to unrealized holding gains/ losses on securities	$ (3,990)	$ 513	$ 1,915
Income tax (expense) benefit related to (gain) loss on securities	2	60	1,488
Change in fair value of interest rate swaps, tax	0
Change in fair value of interest rate swaps, tax		(223)	(585)
Net loss, tax	3,193	770	826
Reclassification adjustments for prior period service costs and net losses included in net income, tax	$ (334)	$ (746)	$ (613)

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)
Balance at beginning of the period at Dec. 31, 2016	$ 1,170,663	$ 1,017	$ 718,834	$ 478,803	$ (27,991)
Comprehensive income:
Net income	94,467			94,467
Other comprehensive (loss) income 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	4,894	4	4,890
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)
Increase (Decrease) in Stockholders' Equity
Reclassification due to adoption of ASU No. 2018-02	(6,746)			6,746	(6,746)
Comprehensive income:
Net income	105,491			105,491
Other comprehensive (loss) income net of tax	(870)				(870)
Total comprehensive income	104,621			112,237	(7,616)
Exercise of stock options	8,191	8	8,183
Stock-based compensation expense	7,023	4	7,019
Stock-based compensation forfeited	0	(5)	5
Dividends paid	(69,921)			(69,921)
Balance at end of the period at Dec. 31, 2018	1,257,638	1,034	745,926	550,374	(39,696)
Comprehensive income:
Net income	110,432			110,432
Other comprehensive (loss) income net of tax	2,755				2,755
Total comprehensive income	113,187			110,432	2,755
Acquisition of Union Community Bank	43,288	24	43,264
Exercise of stock options	9,727	9	9,718
Stock-based compensation expense	6,845	3	6,842
Stock-based compensation forfeited	(1)	(1)
Dividends paid	(76,173)			(76,173)
Balance at end of the period at Dec. 31, 2019	$ 1,353,285	$ 1,069	$ 805,750	$ 583,407	$ (36,941)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Other comprehensive income, tax	$ (1,129)	$ 374	$ 3,031
Dividends paid, per share (in dollars per share)	$ 0.72	$ 0.68	$ 0.64

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net income	$ 110,432	$ 105,491	$ 94,467
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	22,659	20,332	19,751
Net (gain)/loss on sale of assets	(2,472)	1,677	(627)
Net gain on sale of offices	0	0	(17,186)
Net depreciation, amortization and accretion	3,824	8,120	14,293
(Increase)/decrease in other assets	(66,080)	(6,428)	2,902
Increase/(decrease) in other liabilities	53,998	(1,129)	11,694
Net amortization on marketable securities	922	1,871	2,017
Noncash compensation expense related to stock benefit plans	6,845	7,023	4,894
Noncash write-down of real estate owned	607	1,518	1,231
Deferred income tax (benefit)/expense	2,776	(2,770)	11,317
Origination of loans held-for-sale	(68,400)	(1,297)	(66,058)
Proceeds from sale of loans held-for-sale	62,351	4,501	73,103
Net cash provided by operating activities	127,462	138,909	151,798
Investing activities:
Purchase of marketable securities held-to-maturity	0	0	(23,621)
Purchase of marketable securities available-for-sale	(200,204)	(228,180)	(218,292)
Proceeds from maturities and principal reductions of marketable securities held-to-maturity	4,707	6,892	13,902
Proceeds from maturities and principal reductions of marketable securities available-for-sale	241,079	210,362	206,089
Proceeds from sale of marketable securities available-for-sale	32,389	5,206	36,811
Proceeds of bank-owned life insurance	2,638	2,730	4,259
Loan originations	(3,721,001)	(3,002,810)	(2,777,573)
Proceeds from loan maturities and principal reductions	3,275,400	2,726,103	2,657,497
Proceeds from sale of loans held for investment	97,923	0	0
Net (proceeds)/redemptions of Federal Home Loan Bank stock	1,348
Net (proceeds)/redemptions of Federal Home Loan Bank stock		(3,902)	(4,343)
Proceeds from sale of real estate owned	4,198	6,312	4,342
Sale of real estate owned for investment, net	608	607	608
Purchases of premises and equipment	(10,899)	(5,233)	(3,719)
Acquisitions, net of cash received	(28,779)	0	0
Net cash provided used in investing activities	(300,593)	(281,913)	(104,040)
Financing activities:
Net increase/(decrease) in deposits	218,449	67,190	(270,989)
Net increase/(decrease) in short-term borrowings	11,947	126,151
Net increase/(decrease) in short-term borrowings			(34,661)
Increase in advances by borrowers for taxes and insurance	1,238	2,473	3,946
Cash dividends paid on common stock	(76,173)	(69,921)	(65,212)
Proceeds from stock options exercised	9,727	8,190	7,001
Net cash provided by/(used) in financing activities	165,188	134,083	(359,915)
Net decrease in cash and cash equivalents	(7,943)	(8,921)	(312,157)
Cash and cash equivalents at beginning of period	68,789	77,710	389,867
Cash and cash equivalents at end of period	60,846	68,789	77,710
Cash paid during the period for:
Interest on deposits and borrowings (including interest credited to deposit accounts of $44,928, $29,330, and $22,385, respectively)	54,277	36,856	28,254
Income taxes	29,283	25,849	32,270
Business acquisitions:
Fair value of assets acquired	584,253	0	0
Northwest Bancshares, Inc. common stock issued	(43,288)	0	0
Net cash paid	45,600	0	0
Liabilities assumed	495,365	0	0
Noncash activities:
Loan foreclosures and repossessions	5,815	7,181	8,130
Sale of real estate owned financed by the Company	$ 44	$ 296	$ 168

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Interest on deposits and borrowings, interest credited to deposit accounts	$ 44,928	$ 29,330	$ 22,385

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
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 181 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, 2019 and 2018 . 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 restructuring 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, 2019 and 2018 , there were $7.7 million and no 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 costs 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 for 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, 2019 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 2019 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 2019. 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, 2019 and 2018. Accordingly, we have determined that goodwill is not impaired as of December 31, 2019 and 2018. (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) Revenue recognition Revenue that is not associated with our financial assets and financial liabilities is recognized when performance obligations under the terms of a contract with our customers are satisfied. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or providing services. The majority of our revenue continues to be recognized at the point in time when the services are provided to our customers. (o) 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. The other components of the net periodic benefit cost are included in other expense on the Consolidated Statement of Income and are reported separately from the service costs. (p) 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. (q) 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, 2019 , the following assumptions were used to determine the option's fair value: (1) annual rate of quarterly dividends ranging from 3.2% to 4.7% based on historical dividends and market prices; (2) expected volatility of 13.0% 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 ten years based on previous grants. During the year ended December 31, 2019 , we awarded 547,410 stock options to employees and 64,800 stock options to directors. During the year ended December 31, 2018 , we awarded 831,160 stock options to employees and 64,800 stock options to directors.The options granted in 2019 and 2018 vest over a seven -year period, with the first vesting occurring on the grant date. New shares are issued when options are exercised. 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. 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. During the year ended December 31, 2019 , we awarded 256,800 restricted shares to employees and 24,300 restricted shares to directors. During the year ended December 31, 2018 we awarded 390,030 restricted shares to employees and 24,300 restricted shares to directors.These common share awards vest over a seven -year period, with the first vesting occurring on the grant date. For additional information regarding grants of stock options and common shares, see note 16. Stock-based employee compensation expense related to common share awards of $5.7 million , $5.8 million and $3.8 million was included in income before income taxes during the years ended December 31, 2019 , 2018 and 2017 , respectively. The effect on net income for the years ended December 31, 2019 , 2018 and 2017 was a reduction of $4.1 million , $4.2 million and $2.3 million , respectively. Total compensation expense for unvested stock options of $3.5 million has yet to be recognized as of December 31, 2019 . The weighted average period over which this remaining stock option expense will be recognized is approximately 3.79 years. (r) 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. (s) 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. At times, 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. (t) 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. (u) 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. (v) 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, 2019
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02, Leases (Topic 842) , which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Accounting Standards Codification ("ASC") Topic 842 establishes a right of use ("ROU") model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The Company has elected not to recognize ROU assets and lease liabilities for short-term leases of all classes of underlying assets that have a lease term of 12 months or less and recognizes lease expense for these leases on a straight-line basis over the term of the lease. On January 1, 2019, the Company adopted ASU 2016-02 using a modified retrospective transition approach as of the effective date, January 1, 2019. As a result, the Company was not required to adjust its comparative period financial information for effects of the standard or make the new required lease disclosures for periods before the date of adoption (i.e. January 1, 2017). The Company has elected to adopt the package of transition practical expedients and, therefore, has not reassessed (1) whether existing or expired contracts contain a lease, (2) lease classification for existing or expired leases or (3) the accounting for initial direct costs that were previously capitalized. The Company also elected the practical expedient to use hindsight for leases existing at the adoption date. As a result of the adoption of ASU 2016-02, we recognized an operating lease ROU asset of approximately $40.2 million , an operating lease liability of approximately $42.2 million and a cumulative-effect adjustment on retained earnings of $1.2 million on the Consolidated Statements of Financial Condition as of January 1, 2019, with no impact on our Consolidated Statement of Income or Consolidated Statement of Cash Flows compared to the prior lease accounting model.

Acquisition

Acquisition	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisition	Acquisition On March 8, 2019, the Company completed the merger with Donegal Financial Services Corporation ("DFSC"), the holding company for UCB, for total consideration of $85.8 million . The transaction expanded Northwest’s franchise by 12 offices in Lancaster County in eastern Pennsylvania. The result of UCB's operations are included in the Consolidated Statements of Income from the date of acquisition. Under the terms of the merger agreement, the two shareholders of DFSC, Donegal Mutual Insurance Company and Donegal Group Inc., received payment in the form of 50% cash and 50% stock, or a total of $42.5 million and 2,462,373 shares of common stock of the Company, valued at $43.3 million , based on the $17.58 closing price of the Company's stock on March 8, 2019. The following table shows the assets acquired and the liabilities assumed that were recorded at fair value on the date of acquisition: Consideration paid: Northwest Bancshares, Inc. common stock issued $ 43,288 Cash paid to DFSC 42,500 Total consideration paid 85,788 Recognized amounts of identifiable assets acquired and (liabilities assumed), at fair value (1) Cash and cash equivalents $ 16,667 Investment securities available-for-sale 78,594 Loans 407,840 Federal Home Loan Bank stock 453 Premises and equipment 6,520 Core deposit intangible 7,498 Other assets 25,535 Deposits (479,379 ) Other liabilities (15,240 ) Total identifiable net assets $ 48,488 Goodwill $ 37,300 (1) Amounts are estimates and subject to adjustment. Actual amounts are not expected to differ materially from the amounts shown. We estimated the fair value of loans acquired from UCB by utilizing a methodology wherein similar loans were aggregated into pools. Cash flows for each pool were determined by estimating future credit losses and the rate of prepayments. Projected monthly cash flows were then discounted to present value based on a market rate for similar loans. There was no carryover of UCB’s allowance for loan losses associated with the loans we acquired as the loans were initially recorded at fair value. Loans acquired with evidence of credit quality deterioration were evaluated and not considered to be significant. The core deposit intangible asset recognized as part of the UCB merger is being amortized over its estimated useful life of seven years utilizing an accelerated method. The goodwill, which is not amortized for book purposes, was assigned to our Community Banking segment and is not deductible for tax purposes. The fair values of savings and transaction deposit accounts acquired from UCB were assumed to approximate the carrying value as these accounts have no stated maturity and are payable on demand. Certificates of deposit were valued by projecting out the expected cash flows based on the contractual terms of the certificates of deposit. These cash flows were discounted based on a market rate for a certificate of deposit with a corresponding maturity. Direct costs related to the UCB merger were expensed as incurred and were $3.1 million during the year ended December 31, 2019 , which includes technology and communications costs, professional services, marketing and advertising, and other noninterest expenses.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases At inception, the Company determines if an arrangement contains a lease and whether that lease meets the classification of a finance or operating lease. Operating lease ROU assets represent our right to use an underlying asset during the lease term and operating lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and operating lease liabilities are recognized at lease commencement based on the present value of the remaining lease payments. ROU assets are further adjusted for lease incentives and initial direct costs. The Company has operating leases for certain branch and office facilities or land with lease terms up to 35 years . These leases generally contain renewal options for periods ranging from one to ten years . These options are included in the lease term when it is reasonably certain that the options will be exercised. Some of the Company’s lease arrangements contain lease components (e.g., minimum rent payments) and non-lease components (e.g., common area maintenance, taxes, etc.). The Company elected the option of not separating lease and non-lease components and instead we account for them as a single lease component. Certain lease agreements include rental payments that are adjusted periodically for an index or rate. The leases are initially measured using the projected adjustment for the index or rate in effect at the commencement date. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. Generally, the Company cannot practically determine the interest rate implicit in the lease. Therefore, the Company uses its incremental borrowing rate as the discount rate for the lease. The Company’s incremental borrowing rate for a lease is the rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. Lease expense for these leases is recognized on a straight-line basis over the lease term, with variable lease payments recognized in the period those payments are incurred. The components of lease cost recognized within our consolidated statements of income were as follows: For the year ended December 31, 2019 Operating lease costs (office operations) $ 5,603 Variable lease costs (office operations) 596 Total operating lease costs $ 6,199 Amounts reported in the Consolidated Statements of Financial Condition were as follows: Operating leases: As of December 31, 2019 Operating lease ROU assets (other assets) $ 49,380 Operating lease liabilities (other liabilities) 52,092 Other information related to leases as of December 31, 2019 were as follows: Supplemental cash flow information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flow from operating leases $ 5,564 ROU assets obtained in exchange for lease obligations $ 13,268 Weighted average remaining lease term 15.7 years Weighted average discount rate 3.7 % Amounts disclosed for ROU assets obtained in exchange for lease obligations include amounts added to the carrying amount of ROU assets resulting from lease modifications and reassessments. Maturities of lease liabilities by fiscal year for our operating leases are as follows: As of December 31, 2019 2020 $ 5,692 2021 5,362 2022 5,042 2023 4,734 2024 4,408 Thereafter 44,758 Total lease payments 69,996 Less amount of lease payments representing interest 17,904 Total present value of lease payments $ 52,092 As of December 31, 2018 2019 $ 4,677 2020 3,884 2021 3,179 2022 2,465 2023 2,040 Thereafter 7,784 Total lease payments $ 24,029 Rental expense for the years ended December 31, 2019 , 2018 and 2017 was $6.2 million , $5.4 million and $5.6 million , respectively.

Loans Receivable and Allowance

Loans Receivable and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Loans Receivable and Allowance for Loan Losses	Loans Receivable and Allowance for Loan Losses Loans receivable at December 31, 2019 and 2018 are summarized in the table below: December 31, 2019 December 31, 2018 Originated Acquired Total Originated Acquired Total Personal Banking: Residential mortgage loans (1) $ 2,779,764 82,938 2,862,702 2,766,430 93,782 2,860,212 Home equity loans 1,099,514 243,404 1,342,918 1,043,878 214,544 1,258,422 Consumer finance loans (2) 509 — 509 3,817 — 3,817 Consumer loans 1,057,384 35,502 1,092,886 775,378 58,671 834,049 Total Personal Banking 4,937,171 361,844 5,299,015 4,589,503 366,997 4,956,500 Commercial Banking: Commercial real estate loans 2,557,904 407,003 2,964,907 2,416,047 223,327 2,639,374 Commercial loans 719,477 55,094 774,571 612,962 48,816 661,778 Total Commercial Banking 3,277,381 462,097 3,739,478 3,029,009 272,143 3,301,152 Total loans receivable, gross 8,214,552 823,941 9,038,493 7,618,512 639,140 8,257,652 Deferred loan costs 51,616 483 52,099 36,820 798 37,618 Allowance for loan losses (51,439 ) (6,502 ) (57,941 ) (51,751 ) (3,463 ) (55,214 ) Undisbursed loan proceeds: Residential mortgage loans (14,937 ) — (14,937 ) (11,513 ) — (11,513 ) Commercial real estate loans (208,857 ) (1,661 ) (210,518 ) (167,029 ) (524 ) (167,553 ) Commercial loans (55,317 ) (1,146 ) (56,463 ) (63,605 ) (1,160 ) (64,765 ) Total loans receivable, net $ 7,935,618 815,115 8,750,733 7,361,434 634,791 7,996,225 (1) Includes $7.7 million and no loans held for sale at December 31, 2019 and 2018 , respectively. (2) Represents loans from our consumer finance subsidiary that was closed in 2017 which are no longer being originated. As of December 31, 2019 , 2018 and 2017 , we serviced loans for others approximating $793.1 million , $794.2 million and $887.3 million , respectively. These loans serviced for others are not our assets and are not included in our financial statements. As of December 31, 2019 and 2018 , approximately 50% and 58% , 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, 2019 and 2018 include $3.090 billion and $2.810 billion , respectively, of adjustable rate loans and $5.948 billion and $5.448 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, 2019 2018 Acquired loans evaluated individually for future credit losses: Outstanding principal balance $ 7,187 8,189 Carrying value 4,975 5,690 Acquired loans evaluated collectively for future credit losses: Outstanding principal balance 826,412 637,170 Carrying value 816,642 632,564 Total acquired loans: Outstanding principal balance 833,599 645,359 Carrying value 821,617 638,254 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, 2017 $ 1,540 Accretion (785 ) Net reclassification from nonaccretable yield — Balance at December 31, 2018 755 Accretion (551 ) Net reclassification from nonaccretable yield 966 Balance at December 31, 2019 $ 1,170 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, 2019 : Carrying value Outstanding principal balance Related impairment reserve Average recorded investment in impaired loans Interest income/accretion recognized Personal Banking: Residential mortgage loans $ 742 1,232 7 866 147 Home equity loans 715 1,569 25 861 114 Consumer loans 7 34 1 18 12 Total Personal Banking 1,464 2,835 33 1,745 273 Commercial Banking: Commercial real estate loans 3,433 4,268 6 3,509 273 Commercial loans 78 84 1 78 5 Total Commercial Banking 3,511 4,352 7 3,587 278 Total $ 4,975 7,187 40 5,332 551 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, 2018 : Carrying Outstanding Related Average Interest Personal Banking: Residential mortgage loans $ 990 1,598 6 1,294 226 Home equity loans 1,008 1,959 7 1,483 157 Consumer loans 29 76 4 53 35 Total Personal Banking 2,027 3,633 17 2,830 418 Commercial Banking: Commercial real estate loans 3,584 4,471 1 4,028 358 Commercial loans 79 85 — 82 9 Total Commercial Banking 3,663 4,556 1 4,110 367 Total $ 5,690 8,189 18 6,940 785 The following table provides information related to changes in the allowance for loan losses for the year ended December 31, 2019 : Balance as of December 31, 2019 Provision Charge-offs Recoveries Balance as of December 31, 2018 Originated loans Personal Banking: Residential mortgage loans $ 2,463 (1,089 ) (935 ) 433 4,054 Home equity loans 2,830 46 (619 ) 219 3,184 Consumer finance loans 76 (671 ) (320 ) 391 676 Consumer loans 11,979 10,696 (11,217 ) 2,096 10,404 Total Personal Banking 17,348 8,982 (13,091 ) 3,139 18,318 Commercial Banking: Commercial real estate loans 17,292 (5,241 ) (5,078 ) 1,232 26,379 Commercial loans 16,799 12,449 (3,237 ) 533 7,054 Total Commercial Banking 34,091 7,208 (8,315 ) 1,765 33,433 Total originated loans 51,439 16,190 (21,406 ) 4,904 51,751 Acquired loans Personal Banking: Residential mortgage loans 111 184 (231 ) 75 83 Home equity loans 359 322 (502 ) 191 348 Consumer loans 538 156 (270 ) 233 419 Total Personal Banking 1,008 662 (1,003 ) 499 850 Commercial Banking: Commercial real estate loans 4,296 2,092 (389 ) 597 1,996 Commercial loans 1,198 3,715 (3,414 ) 280 617 Total Commercial Banking 5,494 5,807 (3,803 ) 877 2,613 Total acquired loans 6,502 6,469 (4,806 ) 1,376 3,463 Total $ 57,941 22,659 (26,212 ) 6,280 55,214 The following table provides information related to changes in the allowance for loan losses for the year ended December 31, 2018 : Balance as of December 31, 2018 Provision Charge-offs Recoveries Balance as of December 31, 2017 Originated loans Personal Banking: Residential mortgage loans $ 4,054 808 (1,067 ) 489 3,824 Home equity loans 3,184 (25 ) (1,183 ) 320 4,072 Consumer finance loans 676 (1,282 ) (2,813 ) 803 3,968 Consumer loans 10,404 12,151 (12,861 ) 2,639 8,475 Total Personal Banking 18,318 11,652 (17,924 ) 4,251 20,339 Commercial Banking: Commercial real estate loans 26,379 11,349 (6,096 ) 1,215 19,911 Commercial loans 7,054 (2,062 ) (2,675 ) 1,469 10,322 Total Commercial Banking 33,433 9,287 (8,771 ) 2,684 30,233 Total originated loans 51,751 20,939 (26,695 ) 6,935 50,572 Acquired loans Personal Banking: Residential mortgage loans 83 (61 ) (112 ) 125 131 Home equity loans 348 (23 ) (602 ) 211 762 Consumer loans 419 (335 ) (291 ) 155 890 Total Personal Banking 850 (419 ) (1,005 ) 491 1,783 Commercial Banking: Commercial real estate loans 1,996 (467 ) (1,291 ) 205 3,549 Commercial loans 617 279 (650 ) 97 891 Total Commercial Banking 2,613 (188 ) (1,941 ) 302 4,440 Total acquired loans 3,463 (607 ) (2,946 ) 793 6,223 Total $ 55,214 20,332 (29,641 ) 7,728 56,795 The following table provides information related to changes in the allowance for loan losses for the year ended December 31, 2017 : Balance as of December 31, 2017 Provision Charge-offs Recoveries Balance as of December 31, 2016 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 Other 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 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, 2019 : Total loans receivable Allowance for loan losses Nonaccrual loans (1) Loans 90 days past maturity and accruing TDRs Allowance related to TDRs Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,868,127 2,574 14,476 — 7,550 560 — Home equity loans 1,342,918 3,189 6,745 32 1,973 393 26 Consumer finance loans 509 76 1 — — — — Consumer loans 1,124,623 12,517 4,225 — — — — Total Personal Banking 5,336,177 18,356 25,447 32 9,523 953 26 Commercial Banking: Commercial real estate loans 2,754,390 21,588 34,864 — 19,358 1,384 476 Commercial loans 718,107 17,997 8,559 — 3,118 665 64 Total Commercial Banking 3,472,497 39,585 43,423 — 22,476 2,049 540 Total $ 8,808,674 57,941 68,870 32 31,999 3,002 566 (1) Includes $9.0 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, 2018 : Total loans receivable Allowance for loan losses Nonaccrual loans (1) Loans 90 days past maturity and accruing TDRs Allowance related to TDRs Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,864,470 4,137 15,848 — 5,382 993 — Home equity loans 1,258,422 3,532 7,075 136 4,502 1,520 4 Consumer finance loans 3,817 676 22 3 — — — Consumer loans 855,896 10,823 4,300 27 — — — Total Personal Banking 4,982,605 19,168 27,245 166 9,884 2,513 4 Commercial Banking: Commercial real estate loans 2,471,821 28,375 36,935 — 19,859 313 310 Commercial loans 597,013 7,671 8,101 — 3,865 263 74 Total Commercial Banking 3,068,834 36,046 45,036 — 23,724 576 384 Total $ 8,051,439 55,214 72,281 166 33,608 3,089 388 (1) Includes $15.3 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, 2019 : 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 $ 12,682 1,794 — 6,817 21,293 19,767 688 Home equity loans 5,635 1,110 — 1,654 8,399 8,571 368 Consumer finance loans 1 — — — 1 — — Consumer loans 3,609 616 — — 4,225 3,842 179 Total Personal Banking 21,927 3,520 — 8,471 33,918 32,180 1,235 Commercial Banking: Commercial real estate loans 25,014 9,850 933 10,329 46,126 46,284 1,490 Commercial loans 4,739 3,820 15,916 1,474 25,949 10,179 345 Total Commercial Banking 29,753 13,670 16,849 11,803 72,075 56,463 1,835 Total $ 51,680 17,190 16,849 20,274 105,993 88,643 3,070 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, 2018 : 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 $ 12,965 2,883 — 6,660 22,508 20,733 910 Home equity loans 5,996 1,079 — 1,818 8,893 9,075 511 Consumer finance loans 22 — — — 22 24 — Consumer loans 3,228 1,072 — — 4,300 3,992 235 Total Personal Banking 22,211 5,034 — 8,478 35,723 33,824 1,656 Commercial Banking: Commercial real estate loans 25,509 11,426 8,549 4,435 49,919 41,328 1,599 Commercial loans 3,010 5,091 2,453 2,087 12,641 9,186 507 Total Commercial Banking 28,519 16,517 11,002 6,522 62,560 50,514 2,106 Total $ 50,730 21,551 11,002 15,000 98,283 84,338 3,762 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 evaluation of impaired loans by portfolio segment and by class of financing receivable as of and for the year ended December 31, 2019 : 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 $ 2,860,026 8,101 8,101 560 — Home equity loans 1,340,944 1,974 1,974 393 — Consumer finance loans 509 — — — — Consumer loans 1,124,614 9 9 3 — Total Personal Banking 5,326,093 10,084 10,084 956 — Commercial Banking: Commercial real estate loans 2,718,855 35,535 29,578 2,679 5,957 Commercial loans 694,424 23,683 18,337 8,127 5,346 Total Commercial Banking 3,413,279 59,218 47,915 10,806 11,303 Total $ 8,739,372 69,302 57,999 11,762 11,303 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, 2018 : 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 $ 2,856,359 8,111 8,111 747 — Home equity loans 1,256,255 2,167 2,167 523 — Consumer finance loans 3,817 — — — — Consumer loans 855,867 29 29 6 — Total Personal Banking 4,972,298 10,307 10,307 1,276 — Commercial Banking: Commercial real estate loans 2,436,605 35,216 31,830 6,499 3,386 Commercial loans 588,932 8,081 6,738 767 1,343 Total Commercial Banking 3,025,537 43,297 38,568 7,266 4,729 Total $ 7,997,835 53,604 48,875 8,542 4,729 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, in accordance with 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, 2019 2018 Number of Amount Number of Amount Beginning TDR balance: 195 $ 33,608 205 $ 32,104 New TDRs 14 3,344 29 1,800 Re-modified TDRs 8 5,678 6 3,086 Net paydowns (7,806 ) (6,606 ) Charge-offs: Residential mortgage loans — — 1 (135 ) Home equity loans — — — — Commercial real estate loans — — 2 (294 ) Commercial loans 2 (235 ) 7 (1,345 ) Paid-off loans: Residential mortgage loans 5 (225 ) 5 258 Home equity loans 9 (196 ) 5 83 Commercial real estate loans 12 (2,122 ) 10 2,254 Commercial loans 5 (47 ) 9 2,403 Ending TDR balance: 176 $ 31,999 195 $ 33,608 Accruing TDRs $ 22,956 $ 18,302 Non-accrual TDRs 9,043 15,306 The following table provides information related to troubled debt restructurings (including re-modified TDRs) by portfolio segment and by class of financing receivable occurring during the year ended December 31, 2019 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 3 $ 297 297 19 Home equity loans 5 171 165 12 Total Personal Banking 8 468 462 31 Commercial Banking: Commercial real estate loans 10 8,333 7,369 613 Commercial loans 4 221 192 21 Total Commercial Banking 14 8,554 7,561 634 Total 22 $ 9,022 8,023 665 There were no troubled debt restructurings modified within the previous twelve months that have subsequently defaulted. 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, 2018 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 9 $ 754 749 72 Home equity loans 17 636 610 150 Total Personal Banking 26 1,390 1,359 222 Commercial Banking: Commercial real estate loans 5 3,157 3,114 169 Commercial loans 4 339 342 69 Total Commercial Banking 9 3,496 3,456 238 Total 35 $ 4,886 4,815 460 There are no troubled debt restructurings modified within the previous twelve months that have subsequently defaulted. 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 The following table provides information related to troubled debt restructurings modified within the previous twelve months that have subsequently defaulted during the year ended December 31, 2017 : Number of contracts Recorded investment at the time of modification Current recorded investment Current allowance 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 3 $ 774 760 69 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 occurring the year ended December 31, 2019 : Number of contracts Type of modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 3 $ — — 297 — 297 Home equity loans 5 109 — 56 — 165 Total Personal Banking 8 109 — 353 — 462 Commercial Banking: Commercial real estate loans 10 — 2,541 4,828 — 7,369 Commercial loans 4 37 — 155 — 192 Total Commercial Banking 14 37 2,541 4,983 — 7,561 Total 22 $ 146 2,541 5,336 — 8,023 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, 2018 : Number of contracts Type of modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 9 $ 7 326 330 86 749 Home equity loans 17 64 264 90 192 610 Total Personal Banking 26 71 590 420 278 1,359 Commercial Banking: Commercial real estate loans 5 — — 3,114 — 3,114 Commercial loans 4 — — 342 — 342 Total Commercial Banking 9 — — 3,456 — 3,456 Total 35 $ 71 590 3,876 278 4,815 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, 2019 : Number of re-modified TDRs Type of re-modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans — $ — — — — — Home equity loans — — — — — — Total Personal Banking — — — — — — Commercial Banking: Commercial real estate loans 7 — 219 4,448 — 4,667 Commercial loans 1 — — 38 — 38 Total Commercial Banking 8 — 219 4,486 — 4,705 Total 8 $ — 219 4,486 — 4,705 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, 2018 : Number of re-modified TDRs Type of re-modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans — $ — — — — — Home equity loans — — — — — — Total Personal Banking — — — — — — Commercial Banking: Commercial real estate loans 3 — — 2,854 — 2,854 Commercial loans 3 — — 192 — 192 Total Commercial Banking 6 — — 3,046 — 3,046 Total 6 $ — — 3,046 — 3,046 The following table provides information related to loan payment delinquencies as of December 31, 2019 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans receivable 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 20,447 5,572 11,080 37,099 2,748,090 2,785,189 — Home equity loans 5,119 2,096 4,573 11,788 1,087,726 1,099,514 — Consumer finance loans 63 35 1 99 410 509 — Consumer loans 8,906 3,163 3,466 15,535 1,073,103 1,088,638 — Total Personal Banking 34,535 10,866 19,120 64,521 4,909,329 4,973,850 — Commercial Banking: Commercial real estate loans 5,598 1,387 17,959 24,944 2,324,104 2,349,048 — Commercial loans 987 6,360 4,296 11,643 652,516 664,159 — Total Commercial Banking 6,585 7,747 22,255 36,587 2,976,620 3,013,207 — Total originated loans 41,120 18,613 41,375 101,108 7,885,949 7,987,057 — Acquired loans Personal Banking: Residential mortgage loans 2,849 121 1,695 4,665 78,273 82,938 93 Home equity loans 1,350 309 1,115 2,774 240,630 243,404 53 Consumer loans 239 104 144 487 35,498 35,985 1 Total Personal Banking 4,438 534 2,954 7,926 354,401 362,327 147 Commercial Banking: Commercial real estate loans 2,323 303 7,055 9,681 395,661 405,342 — Commercial loans 200 43 443 686 53,262 53,948 — Total Commercial Banking 2,523 346 7,498 10,367 448,923 459,290 — Total acquired loans 6,961 880 10,452 18,293 803,324 821,617 147 Total loans $ 48,081 19,493 51,827 119,401 8,689,273 8,808,674 147 (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, 2018 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans receivable 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 27,245 5,732 11,668 44,645 2,714,474 2,759,119 — Home equity loans 6,810 1,771 4,825 13,406 1,030,472 1,043,878 — Consumer finance loans 661 172 21 854 2,963 3,817 — Consumer loans 9,000 2,867 3,037 14,904 793,092 807,996 — Total Personal Banking 43,716 10,542 19,551 73,809 4,541,001 4,614,810 — Commercial Banking: Commercial real estate loans 5,391 4,801 21,721 31,913 2,217,105 2,249,018 — Commercial loans 609 560 2,714 3,883 545,474 549,357 — Total Commercial Banking 6,000 5,361 24,435 35,796 2,762,579 2,798,375 — Total originated loans 49,716 15,903 43,986 109,605 7,303,580 7,413,185 — Acquired loans Personal Banking: Residential mortgage loans 532 693 1,317 2,542 91,240 93,782 19 Home equity loans 1,839 294 1,212 3,345 211,199 214,544 40 Consumer loans 447 175 196 818 58,651 59,469 6 Total Personal Banking 2,818 1,162 2,725 6,705 361,090 367,795 65 Commercial Banking: Commercial real estate loans 112 586 3,866 4,564 218,239 222,803 78 Commercial loans 364 — 296 660 46,996 47,656 — Total Commercial Banking 476 586 4,162 5,224 265,235 270,459 78 Total acquired loans 3,294 1,748 6,887 11,929 626,325 638,254 143 Total loans $ 53,010 17,651 50,873 121,534 7,929,905 8,051,439 143 (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, 2019 : Pass Special mention Substandard Doubtful Loss Total loans receivable Originated loans Personal Banking: Residential mortgage loans $ 2,776,971 — 8,218 — — 2,785,189 Home equity loans 1,093,874 — 5,640 — — 1,099,514 Consumer loans 1,084,986 — 4,161 — — 1,089,147 Total Personal Banking 4,955,831 — 18,019 — — 4,973,850 Commercial Banking: Commercial real estate loans 2,188,823 70,327 89,898 — — 2,349,048 Commercial loans 571,011 42,352 50,796 — — 664,159 Total Commercial Banking 2,759,834 112,679 140,694 — — 3,013,207 Total originated loans 7,715,665 112,679 158,713 — — 7,987,057 Acquired loans Personal Banking: Residential mortgage loans 81,611 — 1,327 — — 82,938 Home equity loans 242,237 — 1,167 — — 243,404 Consumer loans

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable securities Marketable securities available-for-sale at December 31, 2019 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 less than one year $ 14,951 40 — 14,991 Debt issued by government sponsored enterprises: Due in less than one year 50,777 345 — 51,122 Due in one year through five years 50,229 — (227 ) 50,002 Due after five years through ten years 3,716 53 (109 ) 3,660 Municipal securities: Due in less than one year 809 4 — 813 Due in one year through five years 2,891 79 — 2,970 Due in five years through ten years 10,155 148 — 10,303 Due after ten years 11,695 267 — 11,962 Corporate debt issues: Due in five years through ten years 919 — — 919 Residential mortgage-backed securities: Fixed rate pass-through 142,421 1,941 (881 ) 143,481 Variable rate pass-through 18,933 749 (4 ) 19,678 Fixed rate agency CMOs 452,256 3,518 (1,606 ) 454,168 Variable rate agency CMOs 55,743 207 (118 ) 55,832 Total residential mortgage-backed securities 669,353 6,415 (2,609 ) 673,159 Total marketable securities available-for-sale $ 815,495 7,351 (2,945 ) 819,901 Marketable securities held-to-maturity at December 31, 2019 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Residential mortgage-backed securities: Fixed rate pass-through $ 2,197 83 — 2,280 Variable rate pass-through 1,210 28 — 1,238 Fixed rate agency CMOs 14,016 68 — 14,084 Variable rate agency CMOs 613 8 — 621 Total residential mortgage-backed securities 18,036 187 — 18,223 Total marketable securities held-to-maturity $ 18,036 187 — 18,223 Marketable securities available-for-sale at December 31, 2018 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 less than one year $ 14,756 24 — 14,780 Debt issued by government sponsored enterprises: Due in less than one year 85,089 — (795 ) 84,294 Due in one year through five years 101,078 71 (1,512 ) 99,637 Due after ten years 3,546 — (142 ) 3,404 Municipal securities: Due in less than one year 1,333 2 (6 ) 1,329 Due after one year through five years 3,985 54 (4 ) 4,035 Due after five years through ten years 10,603 60 — 10,663 Due after ten years 5,105 31 — 5,136 Corporate debt issues: Due in five years through ten years 914 — — 914 Residential mortgage-backed securities: Fixed rate pass-through 130,172 568 (4,113 ) 126,627 Variable rate pass-through 24,761 1,003 (5 ) 25,759 Fixed rate agency CMOs 365,427 865 (5,921 ) 360,371 Variable rate agency CMOs 64,246 280 (25 ) 64,501 Total residential mortgage-backed securities 584,606 2,716 (10,064 ) 577,258 Total marketable securities available-for-sale $ 811,015 2,958 (12,523 ) 801,450 Marketable securities held-to-maturity at December 31, 2018 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Residential mortgage-backed securities: Fixed rate pass-through $ 2,896 53 — 2,949 Variable rate pass-through 1,666 39 — 1,705 Fixed rate agency CMOs 17,552 — (422 ) 17,130 Variable rate agency CMOs 651 11 — 662 Total residential mortgage-backed securities 22,765 103 (422 ) 22,446 Total marketable securities held-to-maturity $ 22,765 103 (422 ) 22,446 The following table presents information regarding the issuers and the carrying values of our mortgage-backed securities at December 31, 2019 and 2018 : December 31, 2019 2018 Residential mortgage backed securities: FNMA $ 280,832 288,825 GNMA 231,491 81,444 FHLMC 178,375 229,226 Other (including non-agency) 497 528 Total residential mortgage-backed securities $ 691,195 600,023 Marketable securities having a carrying value of $121.8 million at December 31, 2019 were pledged under collateral agreements. During the year ended December 31, 2019 , we sold marketable securities classified as available-for-sale for $ 32.4 million , with gross realized gains of $ 29,000 and no gross realized losses. During the year ended December 31, 2018 , we sold marketable securities classified as available-for-sale for $5.2 million , with gross realized gains of $189,000 and gross realized losses of $37,000 . 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 years ended December 31, 2019 , 2018 and 2017 , we did no t 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, 2019 : Less than 12 months 12 months or more Total Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss U.S. government sponsored enterprises $ — — 52,620 (336 ) 52,620 (336 ) Residential mortgage-backed securities - agency 173,112 (858 ) 109,324 (1,751 ) 282,436 (2,609 ) Total temporarily impaired securities $ 173,112 (858 ) 161,944 (2,087 ) 335,056 (2,945 ) 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, 2018 : Less than 12 months 12 months or more Total Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss U.S. government sponsored enterprises $ — — 136,425 (2,449 ) 136,425 (2,449 ) Municipal securities 929 (1 ) 1,709 (10 ) 2,638 (11 ) Residential mortgage-backed securities - agency 34,031 (30 ) 346,675 (10,456 ) 380,706 (10,486 ) Total temporarily impaired securities $ 34,960 (31 ) 484,809 (12,915 ) 519,769 (12,946 ) 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 enhancements 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 119 positions that are temporarily impaired at December 31, 2019 . The aggregate carrying amount of cost-method investments, including both held-to-maturity and available-for-sale, at December 31, 2019 was $837.9 million , of which all were evaluated for impairment. As of December 31, 2019 , there were no investment securities for which other-than-temporary impairment charges were recorded in earnings. 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, 2019 2018 Beginning balance at January 1, (1) $ — 352 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 — — Reduction for securities sold/called realized during the year — (352 ) Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized — — Ending balance at December 31, $ — — (1) The beginning balance represents credit losses included in other-than-temporary impairment charges recognized on debt securities in prior periods.

Accrued Interest Receivable

Accrued Interest Receivable	12 Months Ended
	Dec. 31, 2019
Interest Receivable and Other Assets [Abstract]
Accrued Interest Receivable	Accrued Interest Receivable Accrued interest receivable as of December 31, 2019 and 2018 is presented in the following table: December 31, 2019 2018 Investment securities $ 941 1,035 Mortgage-backed securities 1,508 1,333 Loans receivable 23,306 22,122 $ 25,755 24,490

Federal Home Loan Bank Stock

Federal Home Loan Bank Stock	12 Months Ended
	Dec. 31, 2019
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 ("FHLB") 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 %. Our investment in the capital stock of the FHLB of Pittsburgh at December 31, 2019 and December 31, 2018 was $ 14.7 million and $ 15.6 million , respectively. We received dividends on capital stock during the years ended December 31, 2019 and 2018 of $1.1 million and $452,000 , 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, 2019
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment Premises and equipment at December 31, 2019 and 2018 are summarized by major classification in the following table: December 31, 2019 2018 Land and land improvements $ 22,194 21,042 Office buildings and improvements 154,535 150,328 Furniture, fixtures and equipment 124,216 119,829 Leasehold improvements 20,770 17,419 Total, at cost 321,715 308,618 Less accumulated depreciation and amortization (174,306 ) (165,228 ) Premises and equipment, net $ 147,409 143,390 Depreciation and amortization expense for the years ended December 31, 2019 , 2018 and 2017 was $11.7 million , $12.1 million and $12.4 million , respectively.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2019
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, 2019 and 2018 : December 31, 2019 2018 Amortizable intangible assets: Core deposit intangibles - gross $ 71,183 63,685 Less: accumulated amortization (50,934 ) (45,027 ) Core deposit intangibles - net $ 20,249 18,658 Customer and Contract intangible assets - gross $ 12,775 10,474 Less: accumulated amortization (9,948 ) (9,311 ) Customer and Contract intangible assets - net $ 2,827 1,163 Total intangible assets - net $ 23,076 19,821 The following information shows the actual aggregate amortization expense for the years ended December 31, 2019 , 2018 and 2017 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, 2017 $ 6,764 For the year ended December 31, 2018 5,848 For the year ended December 31, 2019 6,543 For the year ending December 31, 2020 6,237 For the year ending December 31, 2021 5,058 For the year ending December 31, 2022 3,976 For the year ending December 31, 2023 3,016 For the year ending December 31, 2024 2,249 The following table provides information for the changes in the carrying amount of goodwill: Total Balance at December 31, 2017 $ 307,420 Goodwill acquired — Balance at December 31, 2018 307,420 Goodwill acquired 38,683 Balance at December 31, 2019 $ 346,103 We have determined that goodwill is not impaired as of December 31, 2019 and 2018 . There were no changes in our operations that would cause us to update the goodwill impairment test performed as of June 30, 2019 .

Deposits

Deposits	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Deposits	Deposits Deposit balances at December 31, 2019 and 2018 are shown in the table below: December 31, 2019 2018 Noninterest-bearing demand deposits $ 1,609,653 1,736,156 Interest-bearing demand deposits 1,944,108 1,455,460 Money market deposit accounts 1,863,998 1,661,623 Savings deposits 1,604,838 1,636,099 Time deposits 1,569,410 1,404,841 Total deposits $ 8,592,007 7,894,179 The aggregate amount of time deposits with a minimum denomination of $100,000 at December 31, 2019 and 2018 was $521.1 million and $460.8 million , respectively. Generally, deposits in excess of $250,000 are not federally insured. At December 31, 2019 we had $2.211 billion of deposits in accounts exceeding $250,000 . The following table summarizes the contractual maturity of time deposits at December 31, 2019 and 2018 : December 31, 2019 2018 Due within 12 months $ 909,509 553,173 Due between 12 and 24 months 300,656 352,074 Due between 24 and 36 months 214,301 213,591 Due between 36 and 48 months 106,065 171,866 Due between 48 and 60 months 35,358 108,068 After 60 months 3,521 6,069 Total time deposits $ 1,569,410 1,404,841 The following table summarizes the interest expense incurred on the respective deposits for the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Interest-bearing demand deposits $ 6,012 3,607 1,027 Money market deposit accounts 13,010 5,740 4,203 Savings deposits 3,115 3,064 3,062 Time deposits 27,079 18,574 14,765 Total interest expense on deposits $ 49,216 30,985 23,057

Borrowed Funds

Borrowed Funds	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Borrowed Funds	Borrowed Funds (a) Borrowings Borrowed funds at December 31, 2019 and 2018 are presented in the following table: December 31, 2019 2018 Amount Average rate Amount Average rate Term notes payable to the FHLB of Pittsburgh: Due within one year $ 153,600 2.38 % $ 128,600 2.60 % Total term notes payable to FHLB of Pittsburgh 153,600 128,600 Collateralized borrowings, due within one year 92,736 0.25 % 105,789 0.20 % Total borrowed funds $ 246,336 $ 234,389 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 $250.0 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, 2019 and December 31, 2018 , collateralized borrowings due within one year were $ 92.7 million and $ 105.8 million , respectively. 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, 2019 , 2018 and 2017 was $91.1 million , $102.3 million and $121.0 million , respectively. The maximum amount of collateralized borrowings outstanding during the years ended December 31, 2019 , 2018 and 2017 was $101.1 million , $110.3 million and $137.2 million , respectively. (b) Trust Preferred Securities Prior to our merger with DFSC, we owned 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 and 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, 2019 was 3.34% . 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, 2019 was 3.27% . 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, 2019 was 3.37% . As a result of the merger with DFSC, we acquired two additional statutory business trusts: Union National Capital Trust I ("UNCT I") and Union National Capital Trust II ("UNCT II"); both are Delaware statutory business trusts. At December 31, 2019 , UNCT I had 8,000 cumulative trust preferred securities outstanding (liquidation value of $1,000 per preferred security or $8,000,000 ) with a stated maturity of January 23, 2034. These securities carry a floating interest rate, which is reset quarterly, equal to three-month LIBOR plus 2.85% . The rate in effect at December 31, 2019 was 4.79% . At December 31, 2019 , UNCT II had 3,000 cumulative trust preferred securities outstanding (liquidation value of $1,000 per preferred security or $3,000,000 ) with a stated maturity of November 23, 2034. These securities carry a floating interest rate, which is reset quarterly, equal to three-month LIBOR plus 2.00% . The rate in effect at December 31, 2019 was 3.91% . The Trusts have invested the proceeds of the offerings in junior subordinated deferrable interest debentures held by the Company. The structure of these debentures mirrors the structure of the trust-preferred securities. UNCT I holds $8,248,000 of junior subordinated debentures and UNCT II holds $3,093,000 of junior subordinated debentures. These subordinated debentures are the sole assets of the Trusts. As the shareholders of the trust preferred securities are the primary beneficiaries of the Trusts, the Trusts are not consolidated in our financial statements. 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 five 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 debentures held by the trusts as of December 31, 2019 and 2018 : Capital debt securities December 31, 2019 2018 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 Union National Capital Trust I (1) 8,000 7,900 — Union National Capital Trust II (1) 3,000 2,687 — Total $ 118,875 121,800 111,213 (1) Net of discounts due to the fair value adjustment made at the time of acquisition.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Total income tax was allocated for the years ended December 31, 2019 , 2018 and 2017 as follows: Years ended December 31, 2019 2018 2017 Income tax expense $ 30,679 28,422 41,444 Shareholders’ equity for unrealized gain/(loss) on securities available-for-sale 3,992 (573 ) (3,403 ) Shareholders’ equity for pension adjustment (2,859 ) (24 ) (213 ) Shareholders’ equity for swap fair value adjustment — 223 585 Unallocated income tax $ 31,812 28,048 38,413 Income tax expense applicable to income before taxes consists of: Years ended December 31, 2019 2018 2017 Current $ 27,903 31,192 30,127 Deferred 2,776 (2,770 ) 11,317 Total income tax expense $ 30,679 28,422 41,444 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, 2019 , 2018 and 2017 , is as follows: Years ended December 31, 2019 2018 2017 Expected tax rate 21.0 % 21.0 % 35.0 % Tax-exempt interest income (0.8 )% (0.9 )% (1.5 )% State income tax, net of federal benefit 3.7 % 3.8 % 3.2 % Bank-owned life insurance (0.6 )% (0.9 )% (1.6 )% Stock-based compensation (0.6 )% (0.8 )% (0.9 )% Dividends on stock plans (0.6 )% (0.6 )% (1.1 )% Low income housing and historic tax credits (0.5 )% (0.6 )% (0.5 )% Adjustment to net deferred tax liabilities for enacted changes in tax laws and rates — % — % (2.3 )% Other 0.1 % 0.2 % 0.2 % Effective tax rate 21.7 % 21.2 % 30.5 % The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities at December 31, 2019 and 2018 are presented below: December 31, 2019 2018 Deferred tax assets: Deferred rent $ — 115 Deferred compensation expense 1,974 2,357 Bad debts 12,609 11,257 Other reserves 961 1,065 Accrued post-retirement benefit cost 436 410 Stock benefit plans 994 904 Pension and post-retirement benefits 15,916 13,057 Unrealized loss on the fair value of securities available-for-sale — 2,733 Deferred income 728 822 Lease liability 11,493 — Net operating loss 504 — Other 626 219 Total deferred tax assets 46,241 32,939 Deferred tax liabilities: Pension expense 5,864 5,686 Purchase accounting 291 180 Intangible assets 14,464 13,839 Mortgage servicing rights 407 460 Fixed assets 5,755 4,602 Net deferred loan costs 5,042 4,558 Right of use asset 10,895 — Unrealized gain on fair value of securities available-for-sale 1,259 — Other 314 331 Total deferred tax liabilities 44,291 29,656 Net deferred tax asset $ 1,950 3,283 We have $2.4 million of federal net operating loss carryovers subject to the annual limitation under Internal Revenue Code Section 382 at December 31, 2019. The majority of net operating loss carryovers do not have an expiration date since it was generated after 2018 and is expected to be fully realized. 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, 2019 , 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, 2019 , we did no t accrue any interest. At December 31, 2019 , 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 after December 31, 2016 and subject to audit by any state in which we conduct business for the tax periods ended after December 31, 2016 . The New York State audit of the Company's 2011 to 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. Effective January 1, 2018, the Tax Cuts and Jobs Act of 2017 reduced our corporate federal tax rate from 35.0% to 21.0% . As a result, on the enactment date of December 22, 2017, we were 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. This re-measurement of our net deferred tax liability resulted in prior year 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 three areas where information necessary to complete the accounting was not available, prepared, or analyzed: (i) our deferred tax asset for temporary differences associated with accrued compensation was awaiting final determinations of amounts that will be paid on or before March 15, 2019 and deducted on the 2018 income tax returns;(ii) our deferred tax liability for temporary differences associated with equity investments in partnerships was awaiting receipt of Schedules K-1 from outside preparers, which was necessary to determine our 2018 tax impact from these investments; (iii) we made no adjustments until further analysis can be completed 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.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2019
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, 2019 and 2018 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, 2019
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, 2019 , 2018 and 2017 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 $17.07 , $17.20 , and $ 16.64 , respectively. The computation of basic and diluted earnings per share for the years ended December 31, 2019 , 2018 and 2017 follows: Years ended December 31, 2019 2018 2017 Net income available to common shareholders $ 110,432 105,491 94,467 Weighted average common shares outstanding (1) 104,878,774 102,073,888 101,015,083 Dilutive potential shares due to effect of stock options (1) 960,375 1,492,013 1,549,822 Total weighted average common shares and dilutive potential shares (1) 105,839,149 103,565,901 102,564,905 Basic earnings per share (1) $ 1.05 1.03 0.94 Diluted earnings per share (1) $ 1.04 1.02 0.92 (1) Not in thousands.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2019
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 $6.7 million , $5.8 million and $6.8 million , for the years ended December 31, 2019 , 2018 and 2017 , 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, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Service cost $ 5,949 6,864 6,149 Interest cost 7,353 6,712 6,879 Expected return on plan assets (11,037 ) (11,968 ) (10,512 ) Net amortization and deferral 1,101 1,167 1,388 Net periodic pension cost $ 3,366 2,775 3,904 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, 2019 2018 2017 Net (gain)/loss $ 8,235 (1,716 ) (1,647 ) Amortization of prior service cost 2,323 2,323 2,323 Total recognized in other comprehensive income $ 10,558 607 676 Total recognized in net periodic pension cost and other comprehensive income $ 13,924 3,382 4,580 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 $3.6 million and $(2.3) million , respectively. The following table sets forth information for the defined benefit pension plans’ funded status at December 31, 2019 and 2018 : December 31, 2019 2018 Change in benefit obligation: Benefit obligation at beginning of year $ 181,121 193,142 Service cost 5,949 6,864 Interest cost 7,353 6,712 Actuarial (gain)/loss 35,203 (19,015 ) Benefits paid (7,129 ) (6,582 ) Benefit obligation at end of year $ 222,497 181,121 Change in plan assets: Fair value of plan assets at beginning of year $ 160,766 173,668 Actual return on plan assets 34,582 (8,820 ) Employer contributions 5,322 2,500 Benefits paid (7,129 ) (6,582 ) Fair value of plan assets at end of period $ 193,541 160,766 Funded status at end of year $ (28,956 ) (20,355 ) The following table sets forth the assumptions used to develop the net periodic pension cost: Years ended December 31, 2019 2018 2017 Discount rate 4.15 % 3.53 % 4.06 % 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 following table sets forth the assumptions used to determine benefit obligations at the end of each period: Years ended December 31, 2019 2018 2017 Discount rate 3.14 % 4.15 % 3.53 % Expected long-term rate of return on assets 6.50 % 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 $217.3 million , $175.1 million and $186.9 million at December 31, 2019 , 2018 and 2017 , respectively. The accumulated benefit obligation for all unfunded defined benefit plans was $5.2 million , $4.8 million and $6.2 million at December 31, 2019 , 2018 and 2017 , respectively. The following table sets forth certain information related to our pension plans: December 31, 2019 2018 Projected benefit obligation $ 222,497 181,121 Accumulated benefit obligation 222,497 181,121 Fair value of plan assets 193,541 160,766 We anticipate making a contribution to our defined benefit pension plan of $2.0 million to $4.0 million during the year ending December 31, 2020 . 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 20% to 50% bonds and 30% to 60% equities. 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 ten years . The following table sets forth the weighted average asset allocation of defined benefit plans: Target December 31, allocation 2019 2018 Debt securities 20 – 50% 24 % 27 % Equity securities 30 – 60% 70 % 70 % Other 5 – 50% 6 % 3 % 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 and Level 2 assets, as defined by the fair value hierarchy defined in note 17. The following table sets forth the pension plan assets as of December 31, 2019 and 2018 : December 31, 2019 2018 Mutual funds - debt $ 46,563 43,549 Mutual funds - equity 134,773 112,580 Cash and cash equivalents 12,204 4,637 The benefits expected to be paid in each year from 2020 to 2024 are $7.7 million , $8.0 million , $8.1 million , $8.0 million and $8.4 million , respectively. The aggregate benefits expected to be paid in the five years from 2025 to 2029 are $46.3 million . The expected benefits to be paid are based on the same assumptions used to measure our benefit obligations at December 31, 2019 and include estimated future employee service. (b) Post-retirement Healthcare Plan In addition to pension benefits, we provide post-retirement 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 post-retirement 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 post-retirement healthcare benefits plan for the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Interest cost $ 52 54 68 Amortization of net loss 68 98 108 Net period benefit cost $ 120 152 176 The following table sets forth other changes in the post-retirement healthcare plan’s plan assets and benefit obligations recognized in other comprehensive income: Years ended December 31, 2019 2018 2017 Net gain $ (475 ) (305 ) (156 ) Total recognized in other comprehensive income $ (475 ) (305 ) (156 ) Total recognized in net periodic benefit cost and other comprehensive income/(loss) $ (355 ) (153 ) 20 The estimated net loss for the post-retirement healthcare benefit plan that will be amortized from accumulated other comprehensive income into net periodic benefit cost over the year ending December 31, 2020 is $18,000 . The following table sets forth the funded status of the post-retirement healthcare benefit plan at December 31, 2019 and 2018 : December 31, 2019 2018 Change in benefit obligation: Benefit obligation at beginning of year $ 1,332 1,637 Interest cost 52 54 Actuarial gain (405 ) (207 ) Benefits paid (90 ) (152 ) Benefit obligation at end of year $ 889 1,332 Change in plan assets: Employer contributions 90 152 Benefits paid (90 ) (152 ) Funded status at year end $ (889 ) (1,332 ) The assumptions used to develop the preceding information for post-retirement healthcare benefits are as follows: Years ended December 31, 2019 2018 2017 Discount rate 4.15 % 3.53 % 4.06 % Monthly cost of healthcare insurance per beneficiary (1) $ 391 507 548 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 post-retirement healthcare benefit cost would increase by $4,000 and the accumulated post-retirement benefit obligation for healthcare benefits would increase by $24,000 . The following table sets forth information for plans with an accumulated benefit obligation in excess of plan assets: December 31, 2019 2018 Projected benefit obligation $ 889 1,332 Accumulated benefit obligation 889 1,332 (c) Common stock awards On April 20, 2011, we established the Northwest Bancshares, Inc. 2011 Equity Incentive Plan with 2,806,233 common shares authorized. From this plan, we awarded employees 353,750 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). These common shares vest over a ten-year period with the first vesting occurring on the grant date. Total common shares forfeited from the 2011 plan were 539,853 , of which, 58,199 shares were forfeited during the year ended December 31, 2019 . Forfeited shares may be awarded to other eligible recipients in future grants until the plan termination date in 2021. On April 18, 2018, we established the Northwest Bancshares, Inc. 2018 Equity Incentive Plan with 1,500,000 common shares. From this plan, we awarded employees 390,030 common shares and outside directors 24,300 common shares with a grant date fair value of $16.59 per share (total market value of $6.9 million at issuance) on May 14, 2018. We also awarded employees 256,800 common shares and outside directors 24,300 common shares with a grant date fair value of $17.27 per share (total market value of $4.9 million at issuance) on May 22, 2019. These common shares vest over a seven -year period with the first vesting occurring on the grant date. Total common shares forfeited from the 2018 plan were 42,610 , of which, 32,898 shares were forfeited during the year ended December 31, 2019 . Forfeited shares may be awarded to other eligible recipients in future grants until the plan termination date in 2028. (d) Stock option plans The Northwest Bancshares, Inc. 2011 Equity Incentive Plan also authorized the granting of 7,015,583 stock options. 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. These 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 Northwest Bancshares, Inc. 2018 Equity Incentive Plan also authorized the granting of 3,500,000 stock options. On May 14, 2018, we granted employees 831,160 stock options and outside directors 64,800 stock options with an exercise price of $16.59 per share. On May 22, 2019, we granted employees 547,410 stock options and outside directors 64,800 stock options with an exercise price of $17.27 per share. These awarded stock options vest over a seven -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, 2019 , 2018 and 2017 (amounts in this table are not in thousands): Years ended December 31, 2019 2018 2017 Number Weighted average exercise price Number Weighted average exercise price Number Weighted average exercise price Balance at beginning of year 5,612,812 $ 13.49 5,695,570 $ 12.75 5,804,105 $ 12.25 Granted (1) 612,210 17.27 895,960 16.59 819,010 15.57 Exercised (2) (917,845 ) 11.77 (830,712 ) 10.38 (630,591 ) 11.66 Forfeited/expired (205,826 ) 14.28 (148,006 ) 12.52 (296,954 ) 12.43 Balance at end of year 5,101,351 14.28 5,612,812 13.49 5,695,570 12.75 Exercisable at end of year 2,803,918 13.36 3,016,175 12.61 3,016,367 11.99 (1) Weighted average fair value of options at grant date: $1.14 , $1.49 and $1.55 , respectively. (2) The total intrinsic value of options exercised was $5.2 million , $4.8 million and $3.5 million , respectively. The aggregate intrinsic value of all options expected to vest and fully vested options at December 31, 2019 is $3.2 million and $20.7 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, 2019 : Exercise Exercise Exercise Exercise Exercise Exercise Options outstanding: Number of options 67,501 280,681 136,425 3,200 917,438 420,660 Weighted average remaining contract life (years) 0.25 2.50 1.00 1.25 1.50 5.50 Options exercisable: Number of options 67,501 229,262 136,425 3,200 812,791 225,735 Weighted average remaining term - vested (years) 0.25 2.50 1.00 1.25 1.50 5.50 Exercise Exercise Exercise Exercise Exercise Exercise Total Options outstanding: Number of options 326,824 351,842 536,889 660,074 813,975 585,842 5,101,351 Weighted average remaining contract life (years) 3.50 4.50 6.50 7.50 5.50 6.50 4.71 Options exercisable: Number of options 238,918 222,818 243,507 242,244 284,495 97,022 2,803,918 Weighted average remaining term - vested (years) 3.50 4.50 6.50 7.50 5.50 6.50 3.79

Disclosures About Fair Value of

Disclosures About Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2019
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 and cash equivalents, marketable securities available-for-sale, accrued interest receivable, interest rate lock commitments, forward commitments, interest rate swaps, savings and checking deposits and accrued interest payable. 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 U.S. 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. 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. Loans held-for-sale The estimated fair value of loans held-for-sale is based on market bids obtained from potential buyers. Loans held for investment The fair value of the loans held for investment is estimated using a discounted cash flow analysis that utilizes interest rates currently being offered for similar loans adjusted for liquidity and credit risk. 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 lock commitments and forward commitments The fair value of interest rate lock commitments is based on the value of underlying loans held-for-sale which is based on quoted prices for similar loans in the secondary market. This value is then adjusted based on the probability of the loan closing (i.e. the “pullthrough”amount, a significant unobservable input). The fair value of forward sale commitments is based on quoted prices from the secondary market based on the settlement date of the contracts. Cash flow hedges, interest rate and foreign exchange swap agreements The fair value of 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, 2019 and 2018 , 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, 2019 and 2018 : December 31, 2019 Carrying amount Estimated fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 60,846 60,846 60,846 — — Securities available-for-sale 819,901 819,901 — 819,901 — Securities held-to-maturity 18,036 18,223 — 18,223 — Loans receivable, net 8,743,024 8,666,149 — — 8,666,149 Residential mortgage loans held-for-sale 7,709 7,709 — — 7,709 Accrued interest receivable 25,755 25,755 25,755 — — Interest rate lock commitments 559 559 — — 559 Forward commitments 145 145 — 145 — Interest rate swaps 20,889 20,889 — 20,889 — FHLB stock 14,740 14,740 — — — Total financial assets $ 9,711,604 9,634,916 86,601 859,158 8,674,417 Financial liabilities: Savings and checking accounts $ 7,022,597 7,022,597 7,022,597 — — Time deposits 1,569,410 1,574,063 — — 1,574,063 Borrowed funds 246,336 246,341 246,341 — — Junior subordinated debentures 121,800 115,518 — — 115,518 Interest rate swaps 20,952 20,952 — 20,952 — Risk participation agreements 39 39 — 39 — Accrued interest payable 1,142 1,142 1,142 — — Total financial liabilities $ 8,982,276 8,980,652 7,270,080 20,991 1,689,581 December 31, 2018 Carrying amount Estimated fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 68,789 68,789 68,789 — — Securities available-for-sale 801,450 801,450 — 801,450 — Securities held-to-maturity 22,765 22,446 — 22,446 — Loans receivable, net 7,996,225 7,845,313 — — 7,845,313 Accrued interest receivable 24,490 24,490 24,490 — — Interest rate swaps 6,445 6,445 — 6,445 — FHLB stock 15,635 15,635 — — — Total financial assets $ 8,935,799 8,784,568 93,279 830,341 7,845,313 Financial liabilities: Savings and checking deposits $ 6,489,338 6,489,338 6,489,338 — — Time deposits 1,404,841 1,434,410 — — 1,434,410 Borrowed funds 234,389 234,389 234,389 — — Junior subordinated debentures 111,213 102,572 — — 102,572 Interest rate swaps 6,445 6,445 — 6,445 — Accrued interest payable 744 744 744 — — Total financial liabilities $ 8,246,970 8,267,898 6,724,471 6,445 1,536,982 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, 2019 and 2018 . There were no transfers of financial instruments between Level 1 and Level 2 during the years ended December 31, 2019 and 2018 . The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2019 : Level 1 Level 2 Level 3 Total at fair value Debt securities: U.S. government and agencies $ — 14,991 — 14,991 Government sponsored enterprises — 104,784 — 104,784 States and political subdivisions — 26,048 — 26,048 Corporate — 919 — 919 Total debt securities — 146,742 — 146,742 Residential mortgage-backed securities: GNMA — 23,264 — 23,264 FNMA — 89,259 — 89,259 FHLMC — 50,139 — 50,139 Non-agency — 497 — 497 Collateralized mortgage obligations: GNMA — 207,016 — 207,016 FNMA — 184,682 — 184,682 FHLMC — 118,302 — 118,302 Total mortgage-backed securities — 673,159 — 673,159 Interest rate lock commitments — — 559 559 Forward commitments — 145 — 145 Interest rate swaps — 20,889 — 20,889 Total assets $ — 840,935 559 841,494 Interest rate swaps $ — 20,952 — 20,952 Total liabilities $ — 20,952 — 20,952 The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2018 : Level 1 Level 2 Level 3 Total at fair value Debt securities: U.S. government and agencies $ — 14,780 — 14,780 Government sponsored enterprises — 187,335 — 187,335 States and political subdivisions — 21,163 — 21,163 Corporate — 914 — 914 Total debt securities — 224,192 — 224,192 Residential mortgage-backed securities: GNMA — 27,041 — 27,041 FNMA — 73,196 — 73,196 FHLMC — 51,621 — 51,621 Non-agency — 528 — 528 Collateralized mortgage obligations: GNMA — 52,331 — 52,331 FNMA — 207,033 — 207,033 FHLMC — 165,508 — 165,508 Total mortgage-backed securities — 577,258 — 577,258 Interest rate swaps — 6,445 — 6,445 Total assets $ — 807,895 — 807,895 Interest rate swaps $ — 6,445 — 6,445 Total liabilities $ — 6,445 — 6,445 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, 2019 and 2018 : December 31, 2019 2018 Beginning balance January 1, $ — — Total gains or losses: Included in net income — — Purchases 559 — Sales — — Transfers into Level 3 — — Transfers out of Level 3 — — Ending balance December 31, $ 559 — 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, 2019 : Level 1 Level 2 Level 3 Total assets at fair value Loans measured for impairment $ — — 46,238 46,238 Real estate owned, net — — 950 950 Total assets $ — — 47,188 47,188 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, 2018 : Level 1 Level 2 Level 3 Total assets at fair value Loans measured for impairment $ — — 40,333 40,333 Real estate owned, net — — 2,498 2,498 Total assets $ — — 42,831 42,831 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. 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, 2019 : Fair value Valuation techniques Significant unobservable inputs Range (weighted average) Loans measured for impairment $ 46,238 Appraisal value (1) Estimated costs to sell 10% Discounted cash flow Discount rate 4.25% to 11.0% (7.50%) Real estate owned, net $ 950 Appraisal value (1) Estimated costs to sell 10% (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, 2019
Broker-Dealer, Net Capital Requirement, SEC Regulation [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, 2019 and 2018 , we and our banking subsidiary exceeded all capital adequacy requirements to which we were subject. As of December 15, 2019 , 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, 2019 and 2018 were as follows: At December 31, 2019 Actual Minimum capital requirements (1) Well capitalized requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,300,321 15.701 % $ 869,585 10.500 % $ 828,176 10.000 % Northwest Bank 1,146,641 13.858 % 868,768 10.500 % 827,398 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,242,380 15.001 % 703,950 8.500 % 662,541 8.000 % Northwest Bank 1,087,727 13.146 % 703,288 8.500 % 661,918 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,124,259 13.575 % 579,723 7.000 % 538,314 6.500 % Northwest Bank 1,087,727 13.146 % 579,178 7.000 % 537,809 6.500 % Tier 1 capital (leverage) (to average assets) Northwest Bancshares, Inc. 1,242,380 11.913 % 417,143 4.000 % 521,428 5.000 % Northwest Bank 1,087,727 10.515 % 413,772 4.000 % 517,216 5.000 % (1) Amounts and ratios include the 2019 capital conservation buffer of 2.5% 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, 2018 Actual Minimum capital requirements (1) Well capitalized requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,183,619 15.833 % $ 738,212 9.875 % $ 747,557 10.000 % Northwest Bank 1,026,027 13.736 % 737,647 9.875 % 746,984 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,128,405 15.095 % 588,701 7.875 % 598,045 8.000 % Northwest Bank 970,813 12.996 % 588,250 7.875 % 597,587 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,020,530 13.652 % 476,567 6.375 % 485,912 6.500 % Northwest Bank 970,813 12.996 % 476,202 6.375 % 448,190 6.500 % Tier I capital (leverage) (to average assets) Northwest Bancshares, Inc. 1,128,405 11.899 % 379,342 4.000 % 474,177 5.000 % Northwest Bank 970,813 10.240 % 379,236 4.000 % 474,045 5.000 % (1) Amounts and ratios include the 2018 capital conservation buffer of 1.875% 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, 2019
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, 2019
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, 2019 , we do not anticipate that the aggregate ultimate liability arising out of any pending or threatened legal proceedings will be material to our Consolidated Financial Statements. 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. During the year-ended December 31, 2018, Northwest and our subsidiary, Northwest Insurance Services (“NWIS”), were involved in a lawsuit against, among others, First National Bank of Pennsylvania (“FNB”) and their insurance subsidiary, First National Insurance Agency, LLC (“FNIA”). All counterclaims against Northwest were discontinued and, in December 2018, a verdict was rendered in favor of NWIS on several of its claims. Post-trial proceedings have continued throughout the current year and, due to the inherent uncertainties with respect to these proceedings, we have not accrued any awards associated with this verdict within our consolidated financial statements as of December 31, 2019.

Components of Accumulated Other

Components of Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2019
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 loss as of December 31, 2019 and 2018 : December 31, 2019 2018 Unrealized gain/(loss) on marketable securities available-for-sale $ 3,147 (6,832 ) Defined benefit pension plans (40,088 ) (32,864 ) Accumulated other comprehensive loss $ (36,941 ) (39,696 ) The following table shows the changes in accumulated other comprehensive loss by component for the year ended December 31, 2019 : Unrealized gains and losses on securities available-for- sale Change in defined benefit pension plans Total Balance as of January 1, $ (6,832 ) (32,864 ) (39,696 ) Other comprehensive income/(loss) before reclassification adjustments 9,984 (8,059 ) 1,925 Amounts reclassified from accumulated other comprehensive income (1), (2) (5 ) 835 830 Net other comprehensive income/(loss) 9,979 (7,224 ) 2,755 Balance as of December 31, $ 3,147 (40,088 ) (36,941 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $7 , net of tax (income tax expense) of $2 . (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 $(3,492) , net of tax (income tax expense) of $334 . The following table shows the changes in accumulated other comprehensive loss by component for the year ended December 31, 2018 : 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, $ (4,409 ) (691 ) (26,980 ) (32,080 ) Reclassification due to adoption of ASU No. 2018-02 (991 ) (149 ) (5,606 ) (6,746 ) Other comprehensive income/(loss) before reclassification adjustments (1,277 ) 840 (1,181 ) (1,618 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (155 ) — 903 748 Net other comprehensive income/(loss) (2,423 ) 691 (5,884 ) (7,616 ) Balance as of December 31, $ (6,832 ) — (32,864 ) (39,696 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $215 , net of tax (income tax expense) of $60 . (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 $(3,587) , net of tax (income tax expense) of $361 . The following table shows the changes in accumulated other comprehensive loss 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 losses 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

Parent Company Only Financial S

Parent Company Only Financial Statements - Condensed	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Parent Company Only Financial Statements - Condensed	Parent Company Only Financial Statements - Condensed Statements of Financial Condition December 31, 2019 2018 Assets Cash and cash equivalents $ 150,926 155,524 Investment in bank subsidiary 1,314,724 1,211,258 Other assets 9,817 2,298 Total assets $ 1,475,467 1,369,080 Liabilities and shareholders’ equity Liabilities: Debentures payable $ 121,801 111,213 Other liabilities 381 230 Total liabilities 122,182 111,443 Shareholders’ equity 1,353,285 1,257,637 Total liabilities and shareholders’ equity $ 1,475,467 1,369,080 Statements of Income Years ended December 31, 2019 2018 2017 Income: Interest income $ 209 198 137 Other income 628 752 2,297 Dividends from bank subsidiary 110,000 105,000 90,000 Undistributed earnings from equity investment in bank subsidiary 5,102 5,149 7,255 Total income 115,939 111,099 99,689 Expense: Compensation and benefits 1,124 1,225 1,282 Other expense 791 660 553 Interest expense 4,833 4,961 4,666 Total expense 6,748 6,846 6,501 Income before income taxes 109,191 104,253 93,188 Federal and state income taxes (1,241 ) (1,238 ) (1,279 ) Net income $ 110,432 105,491 94,467 Statements of Cash Flows Years ended December 31, 2019 2018 2017 Operating activities: Net income $ 110,432 105,491 94,467 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed earnings of subsidiary (5,102 ) (5,149 ) (7,255 ) Noncash stock benefit plan compensation expense — — 4,894 Gain on sale of marketable securities (29 ) (146 ) (1,615 ) Net change in other assets and liabilities (43,453 ) 91,520 (43,513 ) Net cash provided by/(used in) operating activities 61,848 191,716 46,978 Investing activities: Net (purchase)/sale of marketable securities — (550 ) 2,800 Net cash provided by/(used in) investing activities — (550 ) 2,800 Financing activities: Cash dividends paid on common stock (76,173 ) (69,921 ) (65,212 ) Proceeds from stock options exercised 9,727 8,191 7,001 Net cash used in financing activities (66,446 ) (61,730 ) (58,211 ) Net increase/(decrease) in cash and cash equivalents $ (4,598 ) 129,436 (8,433 ) Cash and cash equivalents at beginning of year $ 155,524 26,088 34,521 Net increase/(decrease) in cash and cash equivalents (4,598 ) 129,436 (8,433 ) Cash and cash equivalents at end of year $ 150,926 155,524 26,088

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2019
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 With the expiration of the $50.0 million in notional of interest rate swap agreements ("swaps") previously designated in hedging relationships, we are no longer a counterparty to any interest rate swap agreements designated as cash flow hedges. Previously, the swaps were intended to protect against the variability of cash flows associated with Northwest Bancorp Capital Trust III and Northwest Bancorp Capital Trust IV. In 2018, the swaps matured without replacement. (b) Derivatives not designated in hedging 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 the 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. We enter into interest rate lock commitments for residential mortgage loans which commit us to lend funds to a potential borrower at a specific interest rate within a specified period of time. Interest rate lock commitments that relate to the origination of mortgage loans that will be held-for-sale are considered derivative financial instruments under applicable accounting guidance. Interest rate lock commitments on loans held-for-sale are carried at fair value in other assets on the Consolidated Statement of Financial Condition. Northwest sells loans to the secondary market on a mandatory or best efforts basis. The loans sold on a mandatory basis commit us to deliver a specific principal amount of mortgage loans to an investor at a specified price, by a specified date, or the commitment must be paired off. These forward commitments entered into on a mandatory delivery basis meet the definition of a derivative financial instrument. All closed loans to be sold on a mandatory delivery basis are classified as held-for-sale on the Consolidated Statement of Financial Condition. Changes to the fair value of the interest rate lock commitments and the forward commitments are recorded in mortgage banking income in the Consolidated Statements of Income. We enter into risk participation agreements with financial institution counterparties for interest rate swaps related to loans in which we are a participant. The risk participation agreements provide credit protection to the financial institution should the borrower fail to perform on its interest rate derivative contract with the financial institution. 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 At December 31, 2019 Derivatives not designated as hedging instruments: Interest rate swap agreements $ 391,502 20,889 391,502 20,952 Interest rate lock commitments 24,373 559 — — Forward commitments 5,151 145 — — Risk participation agreements — — 41,164 39 Total derivatives $ 421,026 21,593 432,666 20,991 At December 31, 2018 Derivatives not designated as hedging instruments: Interest rate swap agreements $ 221,919 6,445 221,919 6,445 Total derivatives $ 221,919 6,445 221,919 6,445 The following table indicates the gain or loss recognized in income on derivatives for the periods indicated: For the years ended December 31, 2019 2018 2017 Non-hedging swap derivatives: Decrease in other income $ (63 ) (288 ) (373 ) Hedging interest rate derivatives: Increase in interest expense — 949 1,599

Selected Quarterly Financial Da

Selected Quarterly Financial Data - Unaudited	12 Months Ended
	Dec. 31, 2019
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) 2019 Interest income $ 100,289 106,807 106,866 103,418 Interest expense 12,307 14,204 15,930 14,473 Net interest income 87,982 92,603 90,936 88,945 Provision for loan losses 6,467 4,667 3,302 8,223 Noninterest income 21,662 23,363 26,169 28,213 Noninterest expense 71,424 77,512 70,596 76,571 Income before income taxes 31,753 33,787 43,207 32,364 Income tax expense 6,709 7,404 9,793 6,773 Net income $ 25,044 26,383 33,414 25,591 Basic earnings per share $ 0.24 0.25 0.32 0.24 Diluted earnings per share $ 0.24 0.25 0.31 0.24 Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2018 Interest income $ 89,533 92,875 95,605 97,768 Interest expense 7,766 8,649 9,788 10,937 Net interest income 81,767 84,226 85,817 86,831 Provision for loan losses 4,209 5,349 6,982 3,792 Noninterest income 21,788 24,109 22,557 23,248 Noninterest expense 67,421 69,787 66,617 72,273 Income before income taxes 31,925 33,199 34,775 34,014 Income tax expense 6,940 6,900 7,035 7,547 Net income $ 24,985 26,299 27,740 26,467 Basic earnings per share $ 0.25 0.26 0.27 0.26 Diluted earnings per share $ 0.24 0.25 0.27 0.26 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

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent events The Company previously announced that it has entered into an Agreement and Plan of Merger (the “Merger Agreement”) by and between the Company and MutualFirst Financial, Inc. (“MutualFirst Financial”). Pursuant to the Merger Agreement, MutualFirst Financial will merge with and into the Company, with the Company as the surviving entity. Immediately thereafter, MutualBank, the wholly owned subsidiary of MutualFirst Financial, will merge with and into Northwest Bank, the wholly owned subsidiary of the Company, with Northwest Bank as the surviving entity. Under the terms of the Merger Agreement, each share of common stock of MutualFirst Financial will be converted into the right to receive 2.4 shares of the Company’s common stock, for total consideration valued at approximately $346 million , or $39.89 per share based on the Company's 15-day volume weighted average closing stock pricing ending on October 23, 2019. The transaction has been approved by the Boards of Directors of the Company and MutualFirst Financial. Completion of the transaction is subject to customary closing conditions, including the receipt of required regulatory approvals and the approval of stockholders of MutualFirst Financial.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
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 181 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, 2019 and 2018 . 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 restructuring 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, 2019 and 2018 , there were $7.7 million and no 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 costs 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 for 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, 2019 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 2019 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 2019. 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, 2019 and 2018. Accordingly, we have determined that goodwill is not impaired as of December 31, 2019 and 2018.
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.
Revenue Recognition	Revenue recognition Revenue that is not associated with our financial assets and financial liabilities is recognized when performance obligations under the terms of a contract with our customers are satisfied. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or providing services. The majority of our revenue continues to be recognized at the point in time when the services are provided to our customers.
Pension Plans	Pension plans
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
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. At times, 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	Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02, Leases (Topic 842) , which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Accounting Standards Codification ("ASC") Topic 842 establishes a right of use ("ROU") model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The Company has elected not to recognize ROU assets and lease liabilities for short-term leases of all classes of underlying assets that have a lease term of 12 months or less and recognizes lease expense for these leases on a straight-line basis over the term of the lease. On January 1, 2019, the Company adopted ASU 2016-02 using a modified retrospective transition approach as of the effective date, January 1, 2019. As a result, the Company was not required to adjust its comparative period financial information for effects of the standard or make the new required lease disclosures for periods before the date of adoption (i.e. January 1, 2017). The Company has elected to adopt the package of transition practical expedients and, therefore, has not reassessed (1) whether existing or expired contracts contain a lease, (2) lease classification for existing or expired leases or (3) the accounting for initial direct costs that were previously capitalized. The Company also elected the practical expedient to use hindsight for leases existing at the adoption date. As a result of the adoption of ASU 2016-02, we recognized an operating lease ROU asset of approximately $40.2 million , an operating lease liability of approximately $42.2 million and a cumulative-effect adjustment on retained earnings of $1.2 million on the Consolidated Statements of Financial Condition as of January 1, 2019, with no impact on our Consolidated Statement of Income or Consolidated Statement of Cash Flows compared to the prior lease accounting model.

Acquisition (Tables)

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table shows the assets acquired and the liabilities assumed that were recorded at fair value on the date of acquisition: Consideration paid: Northwest Bancshares, Inc. common stock issued $ 43,288 Cash paid to DFSC 42,500 Total consideration paid 85,788 Recognized amounts of identifiable assets acquired and (liabilities assumed), at fair value (1) Cash and cash equivalents $ 16,667 Investment securities available-for-sale 78,594 Loans 407,840 Federal Home Loan Bank stock 453 Premises and equipment 6,520 Core deposit intangible 7,498 Other assets 25,535 Deposits (479,379 ) Other liabilities (15,240 ) Total identifiable net assets $ 48,488 Goodwill $ 37,300 (1) Amounts are estimates and subject to adjustment. Actual amounts are not expected to differ materially from the amounts shown.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease, Cost	Other information related to leases as of December 31, 2019 were as follows: Supplemental cash flow information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flow from operating leases $ 5,564 ROU assets obtained in exchange for lease obligations $ 13,268 Weighted average remaining lease term 15.7 years Weighted average discount rate 3.7 % For the year ended December 31, 2019 Operating lease costs (office operations) $ 5,603 Variable lease costs (office operations) 596 Total operating lease costs $ 6,199
Assets And Liabilities, Lessee	Amounts reported in the Consolidated Statements of Financial Condition were as follows: Operating leases: As of December 31, 2019 Operating lease ROU assets (other assets) $ 49,380 Operating lease liabilities (other liabilities) 52,092
Lessee, Operating Lease, Liability, Maturity	Maturities of lease liabilities by fiscal year for our operating leases are as follows: As of December 31, 2019 2020 $ 5,692 2021 5,362 2022 5,042 2023 4,734 2024 4,408 Thereafter 44,758 Total lease payments 69,996 Less amount of lease payments representing interest 17,904 Total present value of lease payments $ 52,092
Schedule of minimum annual rentals	As of December 31, 2018 2019 $ 4,677 2020 3,884 2021 3,179 2022 2,465 2023 2,040 Thereafter 7,784 Total lease payments $ 24,029

Loans Receivable and Allowanc_2

Loans Receivable and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Summary of loans receivable	Loans receivable at December 31, 2019 and 2018 are summarized in the table below: December 31, 2019 December 31, 2018 Originated Acquired Total Originated Acquired Total Personal Banking: Residential mortgage loans (1) $ 2,779,764 82,938 2,862,702 2,766,430 93,782 2,860,212 Home equity loans 1,099,514 243,404 1,342,918 1,043,878 214,544 1,258,422 Consumer finance loans (2) 509 — 509 3,817 — 3,817 Consumer loans 1,057,384 35,502 1,092,886 775,378 58,671 834,049 Total Personal Banking 4,937,171 361,844 5,299,015 4,589,503 366,997 4,956,500 Commercial Banking: Commercial real estate loans 2,557,904 407,003 2,964,907 2,416,047 223,327 2,639,374 Commercial loans 719,477 55,094 774,571 612,962 48,816 661,778 Total Commercial Banking 3,277,381 462,097 3,739,478 3,029,009 272,143 3,301,152 Total loans receivable, gross 8,214,552 823,941 9,038,493 7,618,512 639,140 8,257,652 Deferred loan costs 51,616 483 52,099 36,820 798 37,618 Allowance for loan losses (51,439 ) (6,502 ) (57,941 ) (51,751 ) (3,463 ) (55,214 ) Undisbursed loan proceeds: Residential mortgage loans (14,937 ) — (14,937 ) (11,513 ) — (11,513 ) Commercial real estate loans (208,857 ) (1,661 ) (210,518 ) (167,029 ) (524 ) (167,553 ) Commercial loans (55,317 ) (1,146 ) (56,463 ) (63,605 ) (1,160 ) (64,765 ) Total loans receivable, net $ 7,935,618 815,115 8,750,733 7,361,434 634,791 7,996,225 (1) Includes $7.7 million and no loans held for sale at December 31, 2019 and 2018 , 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, 2019 2018 Acquired loans evaluated individually for future credit losses: Outstanding principal balance $ 7,187 8,189 Carrying value 4,975 5,690 Acquired loans evaluated collectively for future credit losses: Outstanding principal balance 826,412 637,170 Carrying value 816,642 632,564 Total acquired loans: Outstanding principal balance 833,599 645,359 Carrying value 821,617 638,254
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, 2017 $ 1,540 Accretion (785 ) Net reclassification from nonaccretable yield — Balance at December 31, 2018 755 Accretion (551 ) Net reclassification from nonaccretable yield 966 Balance at December 31, 2019 $ 1,170
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, 2019 : 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 $ 12,682 1,794 — 6,817 21,293 19,767 688 Home equity loans 5,635 1,110 — 1,654 8,399 8,571 368 Consumer finance loans 1 — — — 1 — — Consumer loans 3,609 616 — — 4,225 3,842 179 Total Personal Banking 21,927 3,520 — 8,471 33,918 32,180 1,235 Commercial Banking: Commercial real estate loans 25,014 9,850 933 10,329 46,126 46,284 1,490 Commercial loans 4,739 3,820 15,916 1,474 25,949 10,179 345 Total Commercial Banking 29,753 13,670 16,849 11,803 72,075 56,463 1,835 Total $ 51,680 17,190 16,849 20,274 105,993 88,643 3,070 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, 2018 : 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 $ 12,965 2,883 — 6,660 22,508 20,733 910 Home equity loans 5,996 1,079 — 1,818 8,893 9,075 511 Consumer finance loans 22 — — — 22 24 — Consumer loans 3,228 1,072 — — 4,300 3,992 235 Total Personal Banking 22,211 5,034 — 8,478 35,723 33,824 1,656 Commercial Banking: Commercial real estate loans 25,509 11,426 8,549 4,435 49,919 41,328 1,599 Commercial loans 3,010 5,091 2,453 2,087 12,641 9,186 507 Total Commercial Banking 28,519 16,517 11,002 6,522 62,560 50,514 2,106 Total $ 50,730 21,551 11,002 15,000 98,283 84,338 3,762 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 purchased credit impaired loans by portfolio segment and by class of financing receivable at and for the year ended December 31, 2019 : Carrying value Outstanding principal balance Related impairment reserve Average recorded investment in impaired loans Interest income/accretion recognized Personal Banking: Residential mortgage loans $ 742 1,232 7 866 147 Home equity loans 715 1,569 25 861 114 Consumer loans 7 34 1 18 12 Total Personal Banking 1,464 2,835 33 1,745 273 Commercial Banking: Commercial real estate loans 3,433 4,268 6 3,509 273 Commercial loans 78 84 1 78 5 Total Commercial Banking 3,511 4,352 7 3,587 278 Total $ 4,975 7,187 40 5,332 551 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, 2018 : Carrying Outstanding Related Average Interest Personal Banking: Residential mortgage loans $ 990 1,598 6 1,294 226 Home equity loans 1,008 1,959 7 1,483 157 Consumer loans 29 76 4 53 35 Total Personal Banking 2,027 3,633 17 2,830 418 Commercial Banking: Commercial real estate loans 3,584 4,471 1 4,028 358 Commercial loans 79 85 — 82 9 Total Commercial Banking 3,663 4,556 1 4,110 367 Total $ 5,690 8,189 18 6,940 785
Schedule of the changes in the allowance for losses on loans receivable	The following table provides information related to changes in the allowance for loan losses for the year ended December 31, 2019 : Balance as of December 31, 2019 Provision Charge-offs Recoveries Balance as of December 31, 2018 Originated loans Personal Banking: Residential mortgage loans $ 2,463 (1,089 ) (935 ) 433 4,054 Home equity loans 2,830 46 (619 ) 219 3,184 Consumer finance loans 76 (671 ) (320 ) 391 676 Consumer loans 11,979 10,696 (11,217 ) 2,096 10,404 Total Personal Banking 17,348 8,982 (13,091 ) 3,139 18,318 Commercial Banking: Commercial real estate loans 17,292 (5,241 ) (5,078 ) 1,232 26,379 Commercial loans 16,799 12,449 (3,237 ) 533 7,054 Total Commercial Banking 34,091 7,208 (8,315 ) 1,765 33,433 Total originated loans 51,439 16,190 (21,406 ) 4,904 51,751 Acquired loans Personal Banking: Residential mortgage loans 111 184 (231 ) 75 83 Home equity loans 359 322 (502 ) 191 348 Consumer loans 538 156 (270 ) 233 419 Total Personal Banking 1,008 662 (1,003 ) 499 850 Commercial Banking: Commercial real estate loans 4,296 2,092 (389 ) 597 1,996 Commercial loans 1,198 3,715 (3,414 ) 280 617 Total Commercial Banking 5,494 5,807 (3,803 ) 877 2,613 Total acquired loans 6,502 6,469 (4,806 ) 1,376 3,463 Total $ 57,941 22,659 (26,212 ) 6,280 55,214 The following table provides information related to changes in the allowance for loan losses for the year ended December 31, 2018 : Balance as of December 31, 2018 Provision Charge-offs Recoveries Balance as of December 31, 2017 Originated loans Personal Banking: Residential mortgage loans $ 4,054 808 (1,067 ) 489 3,824 Home equity loans 3,184 (25 ) (1,183 ) 320 4,072 Consumer finance loans 676 (1,282 ) (2,813 ) 803 3,968 Consumer loans 10,404 12,151 (12,861 ) 2,639 8,475 Total Personal Banking 18,318 11,652 (17,924 ) 4,251 20,339 Commercial Banking: Commercial real estate loans 26,379 11,349 (6,096 ) 1,215 19,911 Commercial loans 7,054 (2,062 ) (2,675 ) 1,469 10,322 Total Commercial Banking 33,433 9,287 (8,771 ) 2,684 30,233 Total originated loans 51,751 20,939 (26,695 ) 6,935 50,572 Acquired loans Personal Banking: Residential mortgage loans 83 (61 ) (112 ) 125 131 Home equity loans 348 (23 ) (602 ) 211 762 Consumer loans 419 (335 ) (291 ) 155 890 Total Personal Banking 850 (419 ) (1,005 ) 491 1,783 Commercial Banking: Commercial real estate loans 1,996 (467 ) (1,291 ) 205 3,549 Commercial loans 617 279 (650 ) 97 891 Total Commercial Banking 2,613 (188 ) (1,941 ) 302 4,440 Total acquired loans 3,463 (607 ) (2,946 ) 793 6,223 Total $ 55,214 20,332 (29,641 ) 7,728 56,795 The following table provides information related to changes in the allowance for loan losses for the year ended December 31, 2017 : Balance as of December 31, 2017 Provision Charge-offs Recoveries Balance as of December 31, 2016 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 Other 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
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, 2019 : Total loans receivable Allowance for loan losses Nonaccrual loans (1) Loans 90 days past maturity and accruing TDRs Allowance related to TDRs Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,868,127 2,574 14,476 — 7,550 560 — Home equity loans 1,342,918 3,189 6,745 32 1,973 393 26 Consumer finance loans 509 76 1 — — — — Consumer loans 1,124,623 12,517 4,225 — — — — Total Personal Banking 5,336,177 18,356 25,447 32 9,523 953 26 Commercial Banking: Commercial real estate loans 2,754,390 21,588 34,864 — 19,358 1,384 476 Commercial loans 718,107 17,997 8,559 — 3,118 665 64 Total Commercial Banking 3,472,497 39,585 43,423 — 22,476 2,049 540 Total $ 8,808,674 57,941 68,870 32 31,999 3,002 566 (1) Includes $9.0 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, 2018 : Total loans receivable Allowance for loan losses Nonaccrual loans (1) Loans 90 days past maturity and accruing TDRs Allowance related to TDRs Additional commitments to customers with loans classified as TDRs Personal Banking: Residential mortgage loans $ 2,864,470 4,137 15,848 — 5,382 993 — Home equity loans 1,258,422 3,532 7,075 136 4,502 1,520 4 Consumer finance loans 3,817 676 22 3 — — — Consumer loans 855,896 10,823 4,300 27 — — — Total Personal Banking 4,982,605 19,168 27,245 166 9,884 2,513 4 Commercial Banking: Commercial real estate loans 2,471,821 28,375 36,935 — 19,859 313 310 Commercial loans 597,013 7,671 8,101 — 3,865 263 74 Total Commercial Banking 3,068,834 36,046 45,036 — 23,724 576 384 Total $ 8,051,439 55,214 72,281 166 33,608 3,089 388 (1) Includes $15.3 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, 2019 : 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 $ 2,860,026 8,101 8,101 560 — Home equity loans 1,340,944 1,974 1,974 393 — Consumer finance loans 509 — — — — Consumer loans 1,124,614 9 9 3 — Total Personal Banking 5,326,093 10,084 10,084 956 — Commercial Banking: Commercial real estate loans 2,718,855 35,535 29,578 2,679 5,957 Commercial loans 694,424 23,683 18,337 8,127 5,346 Total Commercial Banking 3,413,279 59,218 47,915 10,806 11,303 Total $ 8,739,372 69,302 57,999 11,762 11,303 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, 2018 : 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 $ 2,856,359 8,111 8,111 747 — Home equity loans 1,256,255 2,167 2,167 523 — Consumer finance loans 3,817 — — — — Consumer loans 855,867 29 29 6 — Total Personal Banking 4,972,298 10,307 10,307 1,276 — Commercial Banking: Commercial real estate loans 2,436,605 35,216 31,830 6,499 3,386 Commercial loans 588,932 8,081 6,738 767 1,343 Total Commercial Banking 3,025,537 43,297 38,568 7,266 4,729 Total $ 7,997,835 53,604 48,875 8,542 4,729
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, 2019 2018 Number of Amount Number of Amount Beginning TDR balance: 195 $ 33,608 205 $ 32,104 New TDRs 14 3,344 29 1,800 Re-modified TDRs 8 5,678 6 3,086 Net paydowns (7,806 ) (6,606 ) Charge-offs: Residential mortgage loans — — 1 (135 ) Home equity loans — — — — Commercial real estate loans — — 2 (294 ) Commercial loans 2 (235 ) 7 (1,345 ) Paid-off loans: Residential mortgage loans 5 (225 ) 5 258 Home equity loans 9 (196 ) 5 83 Commercial real estate loans 12 (2,122 ) 10 2,254 Commercial loans 5 (47 ) 9 2,403 Ending TDR balance: 176 $ 31,999 195 $ 33,608 Accruing TDRs $ 22,956 $ 18,302 Non-accrual TDRs 9,043 15,306
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 occurring during the year ended December 31, 2019 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 3 $ 297 297 19 Home equity loans 5 171 165 12 Total Personal Banking 8 468 462 31 Commercial Banking: Commercial real estate loans 10 8,333 7,369 613 Commercial loans 4 221 192 21 Total Commercial Banking 14 8,554 7,561 634 Total 22 $ 9,022 8,023 665 There were no troubled debt restructurings modified within the previous twelve months that have subsequently defaulted. 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, 2018 : Number of Recorded investment at the time of modification Current recorded investment Current allowance Troubled debt restructurings: Personal Banking: Residential mortgage loans 9 $ 754 749 72 Home equity loans 17 636 610 150 Total Personal Banking 26 1,390 1,359 222 Commercial Banking: Commercial real estate loans 5 3,157 3,114 169 Commercial loans 4 339 342 69 Total Commercial Banking 9 3,496 3,456 238 Total 35 $ 4,886 4,815 460 There are no troubled debt restructurings modified within the previous twelve months that have subsequently defaulted. 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 The following table provides information related to troubled debt restructurings modified within the previous twelve months that have subsequently defaulted during the year ended December 31, 2017 : Number of contracts Recorded investment at the time of modification Current recorded investment Current allowance 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 3 $ 774 760 69
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 occurring the year ended December 31, 2019 : Number of contracts Type of modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 3 $ — — 297 — 297 Home equity loans 5 109 — 56 — 165 Total Personal Banking 8 109 — 353 — 462 Commercial Banking: Commercial real estate loans 10 — 2,541 4,828 — 7,369 Commercial loans 4 37 — 155 — 192 Total Commercial Banking 14 37 2,541 4,983 — 7,561 Total 22 $ 146 2,541 5,336 — 8,023 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, 2018 : Number of contracts Type of modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans 9 $ 7 326 330 86 749 Home equity loans 17 64 264 90 192 610 Total Personal Banking 26 71 590 420 278 1,359 Commercial Banking: Commercial real estate loans 5 — — 3,114 — 3,114 Commercial loans 4 — — 342 — 342 Total Commercial Banking 9 — — 3,456 — 3,456 Total 35 $ 71 590 3,876 278 4,815
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, 2019 : Number of re-modified TDRs Type of re-modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans — $ — — — — — Home equity loans — — — — — — Total Personal Banking — — — — — — Commercial Banking: Commercial real estate loans 7 — 219 4,448 — 4,667 Commercial loans 1 — — 38 — 38 Total Commercial Banking 8 — 219 4,486 — 4,705 Total 8 $ — 219 4,486 — 4,705 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, 2018 : Number of re-modified TDRs Type of re-modification Rate Payment Maturity date Other Total Personal Banking: Residential mortgage loans — $ — — — — — Home equity loans — — — — — — Total Personal Banking — — — — — — Commercial Banking: Commercial real estate loans 3 — — 2,854 — 2,854 Commercial loans 3 — — 192 — 192 Total Commercial Banking 6 — — 3,046 — 3,046 Total 6 $ — — 3,046 — 3,046
Schedule of loan delinquencies	The following table provides information related to loan payment delinquencies as of December 31, 2019 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans receivable 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 20,447 5,572 11,080 37,099 2,748,090 2,785,189 — Home equity loans 5,119 2,096 4,573 11,788 1,087,726 1,099,514 — Consumer finance loans 63 35 1 99 410 509 — Consumer loans 8,906 3,163 3,466 15,535 1,073,103 1,088,638 — Total Personal Banking 34,535 10,866 19,120 64,521 4,909,329 4,973,850 — Commercial Banking: Commercial real estate loans 5,598 1,387 17,959 24,944 2,324,104 2,349,048 — Commercial loans 987 6,360 4,296 11,643 652,516 664,159 — Total Commercial Banking 6,585 7,747 22,255 36,587 2,976,620 3,013,207 — Total originated loans 41,120 18,613 41,375 101,108 7,885,949 7,987,057 — Acquired loans Personal Banking: Residential mortgage loans 2,849 121 1,695 4,665 78,273 82,938 93 Home equity loans 1,350 309 1,115 2,774 240,630 243,404 53 Consumer loans 239 104 144 487 35,498 35,985 1 Total Personal Banking 4,438 534 2,954 7,926 354,401 362,327 147 Commercial Banking: Commercial real estate loans 2,323 303 7,055 9,681 395,661 405,342 — Commercial loans 200 43 443 686 53,262 53,948 — Total Commercial Banking 2,523 346 7,498 10,367 448,923 459,290 — Total acquired loans 6,961 880 10,452 18,293 803,324 821,617 147 Total loans $ 48,081 19,493 51,827 119,401 8,689,273 8,808,674 147 (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, 2018 : 30-59 days delinquent 60-89 days delinquent 90 days or greater delinquent Total delinquency Current Total loans receivable 90 days or greater delinquent and accruing (1) Originated loans Personal Banking: Residential mortgage loans $ 27,245 5,732 11,668 44,645 2,714,474 2,759,119 — Home equity loans 6,810 1,771 4,825 13,406 1,030,472 1,043,878 — Consumer finance loans 661 172 21 854 2,963 3,817 — Consumer loans 9,000 2,867 3,037 14,904 793,092 807,996 — Total Personal Banking 43,716 10,542 19,551 73,809 4,541,001 4,614,810 — Commercial Banking: Commercial real estate loans 5,391 4,801 21,721 31,913 2,217,105 2,249,018 — Commercial loans 609 560 2,714 3,883 545,474 549,357 — Total Commercial Banking 6,000 5,361 24,435 35,796 2,762,579 2,798,375 — Total originated loans 49,716 15,903 43,986 109,605 7,303,580 7,413,185 — Acquired loans Personal Banking: Residential mortgage loans 532 693 1,317 2,542 91,240 93,782 19 Home equity loans 1,839 294 1,212 3,345 211,199 214,544 40 Consumer loans 447 175 196 818 58,651 59,469 6 Total Personal Banking 2,818 1,162 2,725 6,705 361,090 367,795 65 Commercial Banking: Commercial real estate loans 112 586 3,866 4,564 218,239 222,803 78 Commercial loans 364 — 296 660 46,996 47,656 — Total Commercial Banking 476 586 4,162 5,224 265,235 270,459 78 Total acquired loans 3,294 1,748 6,887 11,929 626,325 638,254 143 Total loans $ 53,010 17,651 50,873 121,534 7,929,905 8,051,439 143 (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, 2019 : Pass Special mention Substandard Doubtful Loss Total loans receivable Originated loans Personal Banking: Residential mortgage loans $ 2,776,971 — 8,218 — — 2,785,189 Home equity loans 1,093,874 — 5,640 — — 1,099,514 Consumer loans 1,084,986 — 4,161 — — 1,089,147 Total Personal Banking 4,955,831 — 18,019 — — 4,973,850 Commercial Banking: Commercial real estate loans 2,188,823 70,327 89,898 — — 2,349,048 Commercial loans 571,011 42,352 50,796 — — 664,159 Total Commercial Banking 2,759,834 112,679 140,694 — — 3,013,207 Total originated loans 7,715,665 112,679 158,713 — — 7,987,057 Acquired loans Personal Banking: Residential mortgage loans 81,611 — 1,327 — — 82,938 Home equity loans 242,237 — 1,167 — — 243,404 Consumer loans 35,746 — 239 — — 35,985 Total Personal Banking 359,594 — 2,733 — — 362,327 Commercial Banking: Commercial real estate loans 349,993 10,243 45,106 — — 405,342 Commercial loans 45,972 28 7,948 — — 53,948 Total Commercial Banking 395,965 10,271 53,054 — — 459,290 Total acquired loans 755,559 10,271 55,787 — — 821,617 Total loans $ 8,471,224 122,950 214,500 — — 8,808,674 The following table sets forth information about credit quality indicators as of December 31, 2018 : Pass Special mention Substandard Doubtful Loss Total loans receivable Originated loans Personal Banking: Residential mortgage loans $ 2,749,266 — 9,853 — — 2,759,119 Home equity loans 1,038,245 — 5,633 — — 1,043,878 Consumer finance loans 3,817 — — — — 3,817 Consumer loans 804,075 — 3,921 — — 807,996 Total Personal Banking 4,595,403 — 19,407 — — 4,614,810 Commercial Banking: Commercial real estate loans 2,062,728 91,142 95,148 — — 2,249,018 Commercial loans 503,665 15,760 29,932 — — 549,357 Total Commercial Banking 2,566,393 106,902 125,080 — — 2,798,375 Total originated loans 7,161,796 106,902 144,487 — — 7,413,185 Acquired loans Personal Banking: Residential mortgage loans 92,625 — 1,157 — — 93,782 Home equity loans 213,273 — 1,271 — — 214,544 Consumer loans 58,954 — 515 — — 59,469 Total Personal Banking 364,852 — 2,943 — — 367,795 Commercial Banking: Commercial real estate loans 191,622 3,546 27,635 — — 222,803 Commercial loans 35,397 3,521 8,738 — — 47,656 Total Commercial Banking 227,019 7,067 36,373 — — 270,459 Total acquired loans 591,871 7,067 39,316 — — 638,254 Total loans $ 7,753,667 113,969 183,803 — — 8,051,439
Schedule of financial instruments with off-balance-sheet risk	Financial instruments with off-balance-sheet risk as of December 31, 2019 and 2018 are presented in the following table: December 31, 2019 2018 Loan commitments $ 234,137 136,760 Undisbursed lines of credit 917,161 788,262 Standby letters of credit 40,303 32,581 Total $ 1,191,601 957,603
Schedule of changes in mortgage servicing rights	The following table shows changes in MSRs as of and for the years ended December 31, 2019 and 2018 : Servicing rights Valuation allowance Net carrying value and fair value Balance at December 31, 2017 $ 3,523 — 3,523 Additions 50 — 50 Amortization (1,470 ) — (1,470 ) Balance at December 31, 2018 2,103 — 2,103 Additions 862 (1 ) 861 Amortization (1,117 ) — (1,117 ) Balance at December 31, 2019 $ 1,848 (1 ) 1,847

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Schedule of the portfolio of investment securities available-for-sale	Marketable securities available-for-sale at December 31, 2019 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 less than one year $ 14,951 40 — 14,991 Debt issued by government sponsored enterprises: Due in less than one year 50,777 345 — 51,122 Due in one year through five years 50,229 — (227 ) 50,002 Due after five years through ten years 3,716 53 (109 ) 3,660 Municipal securities: Due in less than one year 809 4 — 813 Due in one year through five years 2,891 79 — 2,970 Due in five years through ten years 10,155 148 — 10,303 Due after ten years 11,695 267 — 11,962 Corporate debt issues: Due in five years through ten years 919 — — 919 Residential mortgage-backed securities: Fixed rate pass-through 142,421 1,941 (881 ) 143,481 Variable rate pass-through 18,933 749 (4 ) 19,678 Fixed rate agency CMOs 452,256 3,518 (1,606 ) 454,168 Variable rate agency CMOs 55,743 207 (118 ) 55,832 Total residential mortgage-backed securities 669,353 6,415 (2,609 ) 673,159 Total marketable securities available-for-sale $ 815,495 7,351 (2,945 ) 819,901 Marketable securities available-for-sale at December 31, 2018 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 less than one year $ 14,756 24 — 14,780 Debt issued by government sponsored enterprises: Due in less than one year 85,089 — (795 ) 84,294 Due in one year through five years 101,078 71 (1,512 ) 99,637 Due after ten years 3,546 — (142 ) 3,404 Municipal securities: Due in less than one year 1,333 2 (6 ) 1,329 Due after one year through five years 3,985 54 (4 ) 4,035 Due after five years through ten years 10,603 60 — 10,663 Due after ten years 5,105 31 — 5,136 Corporate debt issues: Due in five years through ten years 914 — — 914 Residential mortgage-backed securities: Fixed rate pass-through 130,172 568 (4,113 ) 126,627 Variable rate pass-through 24,761 1,003 (5 ) 25,759 Fixed rate agency CMOs 365,427 865 (5,921 ) 360,371 Variable rate agency CMOs 64,246 280 (25 ) 64,501 Total residential mortgage-backed securities 584,606 2,716 (10,064 ) 577,258 Total marketable securities available-for-sale $ 811,015 2,958 (12,523 ) 801,450
Schedule of the portfolio of investment securities held-to-maturity	Marketable securities held-to-maturity at December 31, 2018 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Residential mortgage-backed securities: Fixed rate pass-through $ 2,896 53 — 2,949 Variable rate pass-through 1,666 39 — 1,705 Fixed rate agency CMOs 17,552 — (422 ) 17,130 Variable rate agency CMOs 651 11 — 662 Total residential mortgage-backed securities 22,765 103 (422 ) 22,446 Total marketable securities held-to-maturity $ 22,765 103 (422 ) 22,446 Marketable securities held-to-maturity at December 31, 2019 are as follows: Amortized cost Gross unrealized holding gains Gross unrealized holding losses Fair value Residential mortgage-backed securities: Fixed rate pass-through $ 2,197 83 — 2,280 Variable rate pass-through 1,210 28 — 1,238 Fixed rate agency CMOs 14,016 68 — 14,084 Variable rate agency CMOs 613 8 — 621 Total residential mortgage-backed securities 18,036 187 — 18,223 Total marketable securities held-to-maturity $ 18,036 187 — 18,223
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, 2019 and 2018 : December 31, 2019 2018 Residential mortgage backed securities: FNMA $ 280,832 288,825 GNMA 231,491 81,444 FHLMC 178,375 229,226 Other (including non-agency) 497 528 Total residential mortgage-backed securities $ 691,195 600,023
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, 2019 : Less than 12 months 12 months or more Total Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss U.S. government sponsored enterprises $ — — 52,620 (336 ) 52,620 (336 ) Residential mortgage-backed securities - agency 173,112 (858 ) 109,324 (1,751 ) 282,436 (2,609 ) Total temporarily impaired securities $ 173,112 (858 ) 161,944 (2,087 ) 335,056 (2,945 ) 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, 2018 : Less than 12 months 12 months or more Total Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss U.S. government sponsored enterprises $ — — 136,425 (2,449 ) 136,425 (2,449 ) Municipal securities 929 (1 ) 1,709 (10 ) 2,638 (11 ) Residential mortgage-backed securities - agency 34,031 (30 ) 346,675 (10,456 ) 380,706 (10,486 ) Total temporarily impaired securities $ 34,960 (31 ) 484,809 (12,915 ) 519,769 (12,946 )
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, 2019 2018 Beginning balance at January 1, (1) $ — 352 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 — — Reduction for securities sold/called realized during the year — (352 ) Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized — — Ending balance at December 31, $ — — (1) The beginning balance represents credit losses included in other-than-temporary impairment charges recognized on debt securities in prior periods.

Accrued Interest Receivable (Ta

Accrued Interest Receivable (Tables)	12 Months Ended
	Dec. 31, 2019
Interest Receivable and Other Assets [Abstract]
Schedule of accrued interest receivable	Accrued interest receivable as of December 31, 2019 and 2018 is presented in the following table: December 31, 2019 2018 Investment securities $ 941 1,035 Mortgage-backed securities 1,508 1,333 Loans receivable 23,306 22,122 $ 25,755 24,490

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Schedule of premises and equipment	Premises and equipment at December 31, 2019 and 2018 are summarized by major classification in the following table: December 31, 2019 2018 Land and land improvements $ 22,194 21,042 Office buildings and improvements 154,535 150,328 Furniture, fixtures and equipment 124,216 119,829 Leasehold improvements 20,770 17,419 Total, at cost 321,715 308,618 Less accumulated depreciation and amortization (174,306 ) (165,228 ) Premises and equipment, net $ 147,409 143,390

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 and 2018 : December 31, 2019 2018 Amortizable intangible assets: Core deposit intangibles - gross $ 71,183 63,685 Less: accumulated amortization (50,934 ) (45,027 ) Core deposit intangibles - net $ 20,249 18,658 Customer and Contract intangible assets - gross $ 12,775 10,474 Less: accumulated amortization (9,948 ) (9,311 ) Customer and Contract intangible assets - net $ 2,827 1,163 Total intangible assets - net $ 23,076 19,821
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, 2019 , 2018 and 2017 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, 2017 $ 6,764 For the year ended December 31, 2018 5,848 For the year ended December 31, 2019 6,543 For the year ending December 31, 2020 6,237 For the year ending December 31, 2021 5,058 For the year ending December 31, 2022 3,976 For the year ending December 31, 2023 3,016 For the year ending December 31, 2024 2,249
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, 2017 $ 307,420 Goodwill acquired — Balance at December 31, 2018 307,420 Goodwill acquired 38,683 Balance at December 31, 2019 $ 346,103

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Schedule of deposit balances	Deposit balances at December 31, 2019 and 2018 are shown in the table below: December 31, 2019 2018 Noninterest-bearing demand deposits $ 1,609,653 1,736,156 Interest-bearing demand deposits 1,944,108 1,455,460 Money market deposit accounts 1,863,998 1,661,623 Savings deposits 1,604,838 1,636,099 Time deposits 1,569,410 1,404,841 Total deposits $ 8,592,007 7,894,179
Summarizes the contractual maturity of the certificate accounts	The following table summarizes the contractual maturity of time deposits at December 31, 2019 and 2018 : December 31, 2019 2018 Due within 12 months $ 909,509 553,173 Due between 12 and 24 months 300,656 352,074 Due between 24 and 36 months 214,301 213,591 Due between 36 and 48 months 106,065 171,866 Due between 48 and 60 months 35,358 108,068 After 60 months 3,521 6,069 Total time deposits $ 1,569,410 1,404,841
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, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Interest-bearing demand deposits $ 6,012 3,607 1,027 Money market deposit accounts 13,010 5,740 4,203 Savings deposits 3,115 3,064 3,062 Time deposits 27,079 18,574 14,765 Total interest expense on deposits $ 49,216 30,985 23,057

Borrowed Funds (Tables)

Borrowed Funds (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of borrowed funds	Borrowed funds at December 31, 2019 and 2018 are presented in the following table: December 31, 2019 2018 Amount Average rate Amount Average rate Term notes payable to the FHLB of Pittsburgh: Due within one year $ 153,600 2.38 % $ 128,600 2.60 % Total term notes payable to FHLB of Pittsburgh 153,600 128,600 Collateralized borrowings, due within one year 92,736 0.25 % 105,789 0.20 % Total borrowed funds $ 246,336 $ 234,389
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 debentures held by the trusts as of December 31, 2019 and 2018 : Capital debt securities December 31, 2019 2018 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 Union National Capital Trust I (1) 8,000 7,900 — Union National Capital Trust II (1) 3,000 2,687 — Total $ 118,875 121,800 111,213 (1) Net of discounts due to the fair value adjustment made at the time of acquisition.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of allocation of income tax	Total income tax was allocated for the years ended December 31, 2019 , 2018 and 2017 as follows: Years ended December 31, 2019 2018 2017 Income tax expense $ 30,679 28,422 41,444 Shareholders’ equity for unrealized gain/(loss) on securities available-for-sale 3,992 (573 ) (3,403 ) Shareholders’ equity for pension adjustment (2,859 ) (24 ) (213 ) Shareholders’ equity for swap fair value adjustment — 223 585 Unallocated income tax $ 31,812 28,048 38,413
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, 2019 2018 2017 Current $ 27,903 31,192 30,127 Deferred 2,776 (2,770 ) 11,317 Total income tax expense $ 30,679 28,422 41,444
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, 2019 , 2018 and 2017 , is as follows: Years ended December 31, 2019 2018 2017 Expected tax rate 21.0 % 21.0 % 35.0 % Tax-exempt interest income (0.8 )% (0.9 )% (1.5 )% State income tax, net of federal benefit 3.7 % 3.8 % 3.2 % Bank-owned life insurance (0.6 )% (0.9 )% (1.6 )% Stock-based compensation (0.6 )% (0.8 )% (0.9 )% Dividends on stock plans (0.6 )% (0.6 )% (1.1 )% Low income housing and historic tax credits (0.5 )% (0.6 )% (0.5 )% Adjustment to net deferred tax liabilities for enacted changes in tax laws and rates — % — % (2.3 )% Other 0.1 % 0.2 % 0.2 % Effective tax rate 21.7 % 21.2 % 30.5 %
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, 2019 and 2018 are presented below: December 31, 2019 2018 Deferred tax assets: Deferred rent $ — 115 Deferred compensation expense 1,974 2,357 Bad debts 12,609 11,257 Other reserves 961 1,065 Accrued post-retirement benefit cost 436 410 Stock benefit plans 994 904 Pension and post-retirement benefits 15,916 13,057 Unrealized loss on the fair value of securities available-for-sale — 2,733 Deferred income 728 822 Lease liability 11,493 — Net operating loss 504 — Other 626 219 Total deferred tax assets 46,241 32,939 Deferred tax liabilities: Pension expense 5,864 5,686 Purchase accounting 291 180 Intangible assets 14,464 13,839 Mortgage servicing rights 407 460 Fixed assets 5,755 4,602 Net deferred loan costs 5,042 4,558 Right of use asset 10,895 — Unrealized gain on fair value of securities available-for-sale 1,259 — Other 314 331 Total deferred tax liabilities 44,291 29,656 Net deferred tax asset $ 1,950 3,283

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 , 2018 and 2017 follows: Years ended December 31, 2019 2018 2017 Net income available to common shareholders $ 110,432 105,491 94,467 Weighted average common shares outstanding (1) 104,878,774 102,073,888 101,015,083 Dilutive potential shares due to effect of stock options (1) 960,375 1,492,013 1,549,822 Total weighted average common shares and dilutive potential shares (1) 105,839,149 103,565,901 102,564,905 Basic earnings per share (1) $ 1.05 1.03 0.94 Diluted earnings per share (1) $ 1.04 1.02 0.92 (1) Not in thousands.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
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 benefit cost for the post-retirement healthcare benefits plan for the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Interest cost $ 52 54 68 Amortization of net loss 68 98 108 Net period benefit cost $ 120 152 176 The following table sets forth the net periodic pension cost for the defined benefit pension plans for the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Service cost $ 5,949 6,864 6,149 Interest cost 7,353 6,712 6,879 Expected return on plan assets (11,037 ) (11,968 ) (10,512 ) Net amortization and deferral 1,101 1,167 1,388 Net periodic pension cost $ 3,366 2,775 3,904
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 post-retirement healthcare plan’s plan assets and benefit obligations recognized in other comprehensive income: Years ended December 31, 2019 2018 2017 Net gain $ (475 ) (305 ) (156 ) Total recognized in other comprehensive income $ (475 ) (305 ) (156 ) Total recognized in net periodic benefit cost and other comprehensive income/(loss) $ (355 ) (153 ) 20 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, 2019 2018 2017 Net (gain)/loss $ 8,235 (1,716 ) (1,647 ) Amortization of prior service cost 2,323 2,323 2,323 Total recognized in other comprehensive income $ 10,558 607 676 Total recognized in net periodic pension cost and other comprehensive income $ 13,924 3,382 4,580
Schedule of defined benefit pension plans' funded status	The following table sets forth the funded status of the post-retirement healthcare benefit plan at December 31, 2019 and 2018 : December 31, 2019 2018 Change in benefit obligation: Benefit obligation at beginning of year $ 1,332 1,637 Interest cost 52 54 Actuarial gain (405 ) (207 ) Benefits paid (90 ) (152 ) Benefit obligation at end of year $ 889 1,332 Change in plan assets: Employer contributions 90 152 Benefits paid (90 ) (152 ) Funded status at year end $ (889 ) (1,332 ) The following table sets forth information for the defined benefit pension plans’ funded status at December 31, 2019 and 2018 : December 31, 2019 2018 Change in benefit obligation: Benefit obligation at beginning of year $ 181,121 193,142 Service cost 5,949 6,864 Interest cost 7,353 6,712 Actuarial (gain)/loss 35,203 (19,015 ) Benefits paid (7,129 ) (6,582 ) Benefit obligation at end of year $ 222,497 181,121 Change in plan assets: Fair value of plan assets at beginning of year $ 160,766 173,668 Actual return on plan assets 34,582 (8,820 ) Employer contributions 5,322 2,500 Benefits paid (7,129 ) (6,582 ) Fair value of plan assets at end of period $ 193,541 160,766 Funded status at end of year $ (28,956 ) (20,355 )
Schedule of assumptions used to develop the net periodic pension cost	The assumptions used to develop the preceding information for post-retirement healthcare benefits are as follows: Years ended December 31, 2019 2018 2017 Discount rate 4.15 % 3.53 % 4.06 % Monthly cost of healthcare insurance per beneficiary (1) $ 391 507 548 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, 2019 2018 2017 Discount rate 4.15 % 3.53 % 4.06 % 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 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, 2019 2018 2017 Discount rate 3.14 % 4.15 % 3.53 % Expected long-term rate of return on assets 6.50 % 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, 2019 2018 Projected benefit obligation $ 222,497 181,121 Accumulated benefit obligation 222,497 181,121 Fair value of plan assets 193,541 160,766
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 2019 2018 Debt securities 20 – 50% 24 % 27 % Equity securities 30 – 60% 70 % 70 % Other 5 – 50% 6 % 3 % Total 100 % 100 %
Schedule of allocation of plan assets	The following table sets forth the pension plan assets as of December 31, 2019 and 2018 : December 31, 2019 2018 Mutual funds - debt $ 46,563 43,549 Mutual funds - equity 134,773 112,580 Cash and cash equivalents 12,204 4,637
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, 2019 2018 Projected benefit obligation $ 889 1,332 Accumulated benefit obligation 889 1,332
Schedule of activity under option plans	The following table summarizes the activity in our option plans during the years ended December 31, 2019 , 2018 and 2017 (amounts in this table are not in thousands): Years ended December 31, 2019 2018 2017 Number Weighted average exercise price Number Weighted average exercise price Number Weighted average exercise price Balance at beginning of year 5,612,812 $ 13.49 5,695,570 $ 12.75 5,804,105 $ 12.25 Granted (1) 612,210 17.27 895,960 16.59 819,010 15.57 Exercised (2) (917,845 ) 11.77 (830,712 ) 10.38 (630,591 ) 11.66 Forfeited/expired (205,826 ) 14.28 (148,006 ) 12.52 (296,954 ) 12.43 Balance at end of year 5,101,351 14.28 5,612,812 13.49 5,695,570 12.75 Exercisable at end of year 2,803,918 13.36 3,016,175 12.61 3,016,367 11.99 (1) Weighted average fair value of options at grant date: $1.14 , $1.49 and $1.55 , respectively. (2) The total intrinsic value of options exercised was $5.2 million , $4.8 million and $3.5 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, 2019 : Exercise Exercise Exercise Exercise Exercise Exercise Options outstanding: Number of options 67,501 280,681 136,425 3,200 917,438 420,660 Weighted average remaining contract life (years) 0.25 2.50 1.00 1.25 1.50 5.50 Options exercisable: Number of options 67,501 229,262 136,425 3,200 812,791 225,735 Weighted average remaining term - vested (years) 0.25 2.50 1.00 1.25 1.50 5.50 Exercise Exercise Exercise Exercise Exercise Exercise Total Options outstanding: Number of options 326,824 351,842 536,889 660,074 813,975 585,842 5,101,351 Weighted average remaining contract life (years) 3.50 4.50 6.50 7.50 5.50 6.50 4.71 Options exercisable: Number of options 238,918 222,818 243,507 242,244 284,495 97,022 2,803,918 Weighted average remaining term - vested (years) 3.50 4.50 6.50 7.50 5.50 6.50 3.79

Disclosures About Fair Value _2

Disclosures About Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 and 2018 : December 31, 2019 Carrying amount Estimated fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 60,846 60,846 60,846 — — Securities available-for-sale 819,901 819,901 — 819,901 — Securities held-to-maturity 18,036 18,223 — 18,223 — Loans receivable, net 8,743,024 8,666,149 — — 8,666,149 Residential mortgage loans held-for-sale 7,709 7,709 — — 7,709 Accrued interest receivable 25,755 25,755 25,755 — — Interest rate lock commitments 559 559 — — 559 Forward commitments 145 145 — 145 — Interest rate swaps 20,889 20,889 — 20,889 — FHLB stock 14,740 14,740 — — — Total financial assets $ 9,711,604 9,634,916 86,601 859,158 8,674,417 Financial liabilities: Savings and checking accounts $ 7,022,597 7,022,597 7,022,597 — — Time deposits 1,569,410 1,574,063 — — 1,574,063 Borrowed funds 246,336 246,341 246,341 — — Junior subordinated debentures 121,800 115,518 — — 115,518 Interest rate swaps 20,952 20,952 — 20,952 — Risk participation agreements 39 39 — 39 — Accrued interest payable 1,142 1,142 1,142 — — Total financial liabilities $ 8,982,276 8,980,652 7,270,080 20,991 1,689,581 December 31, 2018 Carrying amount Estimated fair value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 68,789 68,789 68,789 — — Securities available-for-sale 801,450 801,450 — 801,450 — Securities held-to-maturity 22,765 22,446 — 22,446 — Loans receivable, net 7,996,225 7,845,313 — — 7,845,313 Accrued interest receivable 24,490 24,490 24,490 — — Interest rate swaps 6,445 6,445 — 6,445 — FHLB stock 15,635 15,635 — — — Total financial assets $ 8,935,799 8,784,568 93,279 830,341 7,845,313 Financial liabilities: Savings and checking deposits $ 6,489,338 6,489,338 6,489,338 — — Time deposits 1,404,841 1,434,410 — — 1,434,410 Borrowed funds 234,389 234,389 234,389 — — Junior subordinated debentures 111,213 102,572 — — 102,572 Interest rate swaps 6,445 6,445 — 6,445 — Accrued interest payable 744 744 744 — — Total financial liabilities $ 8,246,970 8,267,898 6,724,471 6,445 1,536,982
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, 2019 : Level 1 Level 2 Level 3 Total at fair value Debt securities: U.S. government and agencies $ — 14,991 — 14,991 Government sponsored enterprises — 104,784 — 104,784 States and political subdivisions — 26,048 — 26,048 Corporate — 919 — 919 Total debt securities — 146,742 — 146,742 Residential mortgage-backed securities: GNMA — 23,264 — 23,264 FNMA — 89,259 — 89,259 FHLMC — 50,139 — 50,139 Non-agency — 497 — 497 Collateralized mortgage obligations: GNMA — 207,016 — 207,016 FNMA — 184,682 — 184,682 FHLMC — 118,302 — 118,302 Total mortgage-backed securities — 673,159 — 673,159 Interest rate lock commitments — — 559 559 Forward commitments — 145 — 145 Interest rate swaps — 20,889 — 20,889 Total assets $ — 840,935 559 841,494 Interest rate swaps $ — 20,952 — 20,952 Total liabilities $ — 20,952 — 20,952 The following table represents assets and liabilities measured at fair value on a recurring basis as of December 31, 2018 : Level 1 Level 2 Level 3 Total at fair value Debt securities: U.S. government and agencies $ — 14,780 — 14,780 Government sponsored enterprises — 187,335 — 187,335 States and political subdivisions — 21,163 — 21,163 Corporate — 914 — 914 Total debt securities — 224,192 — 224,192 Residential mortgage-backed securities: GNMA — 27,041 — 27,041 FNMA — 73,196 — 73,196 FHLMC — 51,621 — 51,621 Non-agency — 528 — 528 Collateralized mortgage obligations: GNMA — 52,331 — 52,331 FNMA — 207,033 — 207,033 FHLMC — 165,508 — 165,508 Total mortgage-backed securities — 577,258 — 577,258 Interest rate swaps — 6,445 — 6,445 Total assets $ — 807,895 — 807,895 Interest rate swaps $ — 6,445 — 6,445 Total liabilities $ — 6,445 — 6,445
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, 2019 and 2018 : December 31, 2019 2018 Beginning balance January 1, $ — — Total gains or losses: Included in net income — — Purchases 559 — Sales — — Transfers into Level 3 — — Transfers out of Level 3 — — Ending balance December 31, $ 559 —
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, 2019 : Level 1 Level 2 Level 3 Total assets at fair value Loans measured for impairment $ — — 46,238 46,238 Real estate owned, net — — 950 950 Total assets $ — — 47,188 47,188 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, 2018 : Level 1 Level 2 Level 3 Total assets at fair value Loans measured for impairment $ — — 40,333 40,333 Real estate owned, net — — 2,498 2,498 Total assets $ — — 42,831 42,831
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, 2019 : Fair value Valuation techniques Significant unobservable inputs Range (weighted average) Loans measured for impairment $ 46,238 Appraisal value (1) Estimated costs to sell 10% Discounted cash flow Discount rate 4.25% to 11.0% (7.50%) Real estate owned, net $ 950 Appraisal value (1) Estimated costs to sell 10% (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 Requiremen_2

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2019
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Schedule of actual, required, and well capitalized levels	The actual, required, and well capitalized levels as of December 31, 2019 and 2018 were as follows: At December 31, 2019 Actual Minimum capital requirements (1) Well capitalized requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,300,321 15.701 % $ 869,585 10.500 % $ 828,176 10.000 % Northwest Bank 1,146,641 13.858 % 868,768 10.500 % 827,398 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,242,380 15.001 % 703,950 8.500 % 662,541 8.000 % Northwest Bank 1,087,727 13.146 % 703,288 8.500 % 661,918 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,124,259 13.575 % 579,723 7.000 % 538,314 6.500 % Northwest Bank 1,087,727 13.146 % 579,178 7.000 % 537,809 6.500 % Tier 1 capital (leverage) (to average assets) Northwest Bancshares, Inc. 1,242,380 11.913 % 417,143 4.000 % 521,428 5.000 % Northwest Bank 1,087,727 10.515 % 413,772 4.000 % 517,216 5.000 % (1) Amounts and ratios include the 2019 capital conservation buffer of 2.5% 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, 2018 Actual Minimum capital requirements (1) Well capitalized requirements Amount Ratio Amount Ratio Amount Ratio Total capital (to risk weighted assets) Northwest Bancshares, Inc. $ 1,183,619 15.833 % $ 738,212 9.875 % $ 747,557 10.000 % Northwest Bank 1,026,027 13.736 % 737,647 9.875 % 746,984 10.000 % Tier 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,128,405 15.095 % 588,701 7.875 % 598,045 8.000 % Northwest Bank 970,813 12.996 % 588,250 7.875 % 597,587 8.000 % CET 1 capital (to risk weighted assets) Northwest Bancshares, Inc. 1,020,530 13.652 % 476,567 6.375 % 485,912 6.500 % Northwest Bank 970,813 12.996 % 476,202 6.375 % 448,190 6.500 % Tier I capital (leverage) (to average assets) Northwest Bancshares, Inc. 1,128,405 11.899 % 379,342 4.000 % 474,177 5.000 % Northwest Bank 970,813 10.240 % 379,236 4.000 % 474,045 5.000 % (1) Amounts and ratios include the 2018 capital conservation buffer of 1.875% 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 Oth_2

Components of Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2019
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 loss as of December 31, 2019 and 2018 : December 31, 2019 2018 Unrealized gain/(loss) on marketable securities available-for-sale $ 3,147 (6,832 ) Defined benefit pension plans (40,088 ) (32,864 ) Accumulated other comprehensive loss $ (36,941 ) (39,696 )
Schedule of the changes in accumulated other comprehensive income by component	The following table shows the changes in accumulated other comprehensive loss by component for the year ended December 31, 2019 : Unrealized gains and losses on securities available-for- sale Change in defined benefit pension plans Total Balance as of January 1, $ (6,832 ) (32,864 ) (39,696 ) Other comprehensive income/(loss) before reclassification adjustments 9,984 (8,059 ) 1,925 Amounts reclassified from accumulated other comprehensive income (1), (2) (5 ) 835 830 Net other comprehensive income/(loss) 9,979 (7,224 ) 2,755 Balance as of December 31, $ 3,147 (40,088 ) (36,941 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $7 , net of tax (income tax expense) of $2 . (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 $(3,492) , net of tax (income tax expense) of $334 . The following table shows the changes in accumulated other comprehensive loss by component for the year ended December 31, 2018 : 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, $ (4,409 ) (691 ) (26,980 ) (32,080 ) Reclassification due to adoption of ASU No. 2018-02 (991 ) (149 ) (5,606 ) (6,746 ) Other comprehensive income/(loss) before reclassification adjustments (1,277 ) 840 (1,181 ) (1,618 ) Amounts reclassified from accumulated other comprehensive income (1), (2) (155 ) — 903 748 Net other comprehensive income/(loss) (2,423 ) 691 (5,884 ) (7,616 ) Balance as of December 31, $ (6,832 ) — (32,864 ) (39,696 ) (1) Consists of realized gains on securities (gain on sales of investments, net) of $215 , net of tax (income tax expense) of $60 . (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 $(3,587) , net of tax (income tax expense) of $361 . The following table shows the changes in accumulated other comprehensive loss 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 losses 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 .

Parent Company Only Financial_2

Parent Company Only Financial Statements - Condensed (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule of statements of financial condition	Statements of Financial Condition December 31, 2019 2018 Assets Cash and cash equivalents $ 150,926 155,524 Investment in bank subsidiary 1,314,724 1,211,258 Other assets 9,817 2,298 Total assets $ 1,475,467 1,369,080 Liabilities and shareholders’ equity Liabilities: Debentures payable $ 121,801 111,213 Other liabilities 381 230 Total liabilities 122,182 111,443 Shareholders’ equity 1,353,285 1,257,637 Total liabilities and shareholders’ equity $ 1,475,467 1,369,080
Schedule of statements of income	Statements of Income Years ended December 31, 2019 2018 2017 Income: Interest income $ 209 198 137 Other income 628 752 2,297 Dividends from bank subsidiary 110,000 105,000 90,000 Undistributed earnings from equity investment in bank subsidiary 5,102 5,149 7,255 Total income 115,939 111,099 99,689 Expense: Compensation and benefits 1,124 1,225 1,282 Other expense 791 660 553 Interest expense 4,833 4,961 4,666 Total expense 6,748 6,846 6,501 Income before income taxes 109,191 104,253 93,188 Federal and state income taxes (1,241 ) (1,238 ) (1,279 ) Net income $ 110,432 105,491 94,467
Schedule of statements of cash flows	Statements of Cash Flows Years ended December 31, 2019 2018 2017 Operating activities: Net income $ 110,432 105,491 94,467 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed earnings of subsidiary (5,102 ) (5,149 ) (7,255 ) Noncash stock benefit plan compensation expense — — 4,894 Gain on sale of marketable securities (29 ) (146 ) (1,615 ) Net change in other assets and liabilities (43,453 ) 91,520 (43,513 ) Net cash provided by/(used in) operating activities 61,848 191,716 46,978 Investing activities: Net (purchase)/sale of marketable securities — (550 ) 2,800 Net cash provided by/(used in) investing activities — (550 ) 2,800 Financing activities: Cash dividends paid on common stock (76,173 ) (69,921 ) (65,212 ) Proceeds from stock options exercised 9,727 8,191 7,001 Net cash used in financing activities (66,446 ) (61,730 ) (58,211 ) Net increase/(decrease) in cash and cash equivalents $ (4,598 ) 129,436 (8,433 ) Cash and cash equivalents at beginning of year $ 155,524 26,088 34,521 Net increase/(decrease) in cash and cash equivalents (4,598 ) 129,436 (8,433 ) Cash and cash equivalents at end of year $ 150,926 155,524 26,088

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
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 At December 31, 2019 Derivatives not designated as hedging instruments: Interest rate swap agreements $ 391,502 20,889 391,502 20,952 Interest rate lock commitments 24,373 559 — — Forward commitments 5,151 145 — — Risk participation agreements — — 41,164 39 Total derivatives $ 421,026 21,593 432,666 20,991 At December 31, 2018 Derivatives not designated as hedging instruments: Interest rate swap agreements $ 221,919 6,445 221,919 6,445 Total derivatives $ 221,919 6,445 221,919 6,445
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, 2019 2018 2017 Non-hedging swap derivatives: Decrease in other income $ (63 ) (288 ) (373 ) Hedging interest rate derivatives: Increase in interest expense — 949 1,599

Selected Quarterly Financial _2

Selected Quarterly Financial Data - Unaudited (Tables)	12 Months Ended
	Dec. 31, 2019
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) 2019 Interest income $ 100,289 106,807 106,866 103,418 Interest expense 12,307 14,204 15,930 14,473 Net interest income 87,982 92,603 90,936 88,945 Provision for loan losses 6,467 4,667 3,302 8,223 Noninterest income 21,662 23,363 26,169 28,213 Noninterest expense 71,424 77,512 70,596 76,571 Income before income taxes 31,753 33,787 43,207 32,364 Income tax expense 6,709 7,404 9,793 6,773 Net income $ 25,044 26,383 33,414 25,591 Basic earnings per share $ 0.24 0.25 0.32 0.24 Diluted earnings per share $ 0.24 0.25 0.31 0.24 Quarters ended March 31, June 30, September 30, December 31, (In thousands, except per share data) 2018 Interest income $ 89,533 92,875 95,605 97,768 Interest expense 7,766 8,649 9,788 10,937 Net interest income 81,767 84,226 85,817 86,831 Provision for loan losses 4,209 5,349 6,982 3,792 Noninterest income 21,788 24,109 22,557 23,248 Noninterest expense 67,421 69,787 66,617 72,273 Income before income taxes 31,925 33,199 34,775 34,014 Income tax expense 6,940 6,900 7,035 7,547 Net income $ 24,985 26,299 27,740 26,467 Basic earnings per share $ 0.25 0.26 0.27 0.26 Diluted earnings per share $ 0.24 0.25 0.27 0.26 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

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Loans Receivable and Allowance for Loan Losses and Other Narrative Information (Details)	12 Months Ended
	Dec. 31, 2019USD ($)bank	Dec. 31, 2018USD ($)
Nature of Operations
Number of banking locations | bank	181
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	$ 7,700,000	$ 0
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 Accoun_4

Summary of Significant Accounting Policies - Premises and Equipment and Goodwill (Details)	12 Months Ended
	Dec. 31, 2019segment
Premises and Equipment
Number of reportable segments	1
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 Accoun_5

Summary of Significant Accounting Policies - Stock Related Compensation and Segments (Details) $ in Millions	May 22, 2019shares	May 14, 2018shares	May 18, 2016shares	Apr. 20, 2011shares	Dec. 31, 2019USD ($)segmentshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares
Segment Reporting
Number of reportable segments | segment					1
Maximum
Stock Related Compensation
Risk-free interest rates, maximum					3.10%
Stock options
Stock Related Compensation
Expected volatility, minimum					13.00%
Expected volatility, maximum					22.00%
Number of shares awarded					612,210	895,960	819,010
Vesting period					7 years	7 years
Stock-based aggregate disclosure
Compensation expense for unvested common share awards which is yet to be recognized | $					$ 3.5
Weighted average period over which stock option expense will be recognized					3 years 9 months 14 days
Stock options | Minimum
Stock Related Compensation
Dividend yields					3.20%
Risk-free interest rates, minimum					1.70%
Expected lives					7 years
Stock options | Maximum
Stock Related Compensation
Dividend yields					4.70%
Expected lives					10 years
Stock options | Employees
Stock Related Compensation
Number of shares awarded	547,410	831,160	754,210		547,410	831,160
Stock options | Director
Stock Related Compensation
Number of shares awarded	64,800	64,800	64,800		64,800	64,800
Restricted common shares
Stock Related Compensation
Vesting period					7 years	7 years
Stock-based aggregate disclosure
Stock-based employee compensation expense | $					$ 5.7	$ 5.8	$ 3.8
Effect of compensation expense on net income included in income before income taxes | $					$ 4.1	$ 4.2	$ 2.3
Restricted common shares | Employees
Stock Related Compensation
Number of shares awarded	256,800	390,030		353,750	256,800	390,030
Restricted common shares | Director
Stock Related Compensation
Number of shares awarded	24,300	24,300		24,300	24,300

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating lease ROU assets (other assets)	$ 49,380
Operating lease liabilities (other liabilities)	52,092
Retained earnings	$ 583,407		$ 550,374
Accounting Standards Update 2016-02
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating lease ROU assets (other assets)		$ 40,200
Operating lease liabilities (other liabilities)		42,200
Retained earnings		$ 1,200

Acquisition - Narrative (Detail

Acquisition - Narrative (Details) $ / shares in Units, $ in Thousands	Dec. 01, 2019USD ($)	Mar. 08, 2019USD ($)shareholderoffice$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Acquisition
Cash paid to DFSC			$ 45,600	$ 0	$ 0
Goodwill			346,103	$ 307,420	$ 307,420
Donegal Financial Services Corporation
Acquisition
Total consideration		$ 85,788
Number of offices acquired | office		12
Number of counterparty shareholders | shareholder		2
Cash as percent of total consideration		50.00%
Stock as percent of total consideration		50.00%
Cash paid to DFSC		$ 42,500
Stock issued for acquisition (in shares) | shares		2,462,373
Value of stock issued for purchase		$ 43,288
Closing price of Company's stock issued for purchase (in dollars per share) | $ / shares		$ 17.58
Restructuring/acquisition expense			$ 3,100
Intangible asset acquired		$ 7,498
Goodwill		37,300
Cash and cash equivalents		$ 16,667
Sundahl & Co. Insurance
Acquisition
Total consideration	$ 3,100
Fair value of total assets acquired	3,800
Goodwill	1,400
Cash and cash equivalents	154,000
Fair value of total liabilities assumed	746,000
Core Deposits | Donegal Financial Services Corporation
Acquisition
Acquired finite-lived intangible assets weighted average useful life		7 years
Customer Lists | Sundahl & Co. Insurance
Acquisition
Intangible asset acquired	$ 2,300

Acquisition - Assets Acquired a

Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 08, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consideration paid:
Cash paid to DFSC		$ 45,600	$ 0	$ 0
Recognized amounts of identifiable assets acquired and (liabilities assumed), at fair value
Goodwill		$ 346,103	$ 307,420	$ 307,420
Donegal Financial Services Corporation
Consideration paid:
Northwest Bancshares, Inc. common stock issued	$ 43,288
Cash paid to DFSC	42,500
Total consideration paid	85,788
Recognized amounts of identifiable assets acquired and (liabilities assumed), at fair value
Cash and cash equivalents	16,667
Investment securities available-for-sale	78,594
Loans	407,840
Federal Home Loan Bank stock	453
Premises and equipment	6,520
Core deposit intangible	7,498
Other assets	25,535
Deposits	(479,379)
Other liabilities	(15,240)
Total identifiable net assets	48,488
Goodwill	$ 37,300

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Rental expense	$ 6,199
Rental expense		$ 5,400	$ 5,600
Minimum
Lessee, Lease, Description [Line Items]
Lease renewal term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease term of contract (up to)	35 years
Lease renewal term	10 years

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease costs (office operations)	$ 5,603
Variable lease costs (office operations)	596
Total operating lease costs	$ 6,199

Leases - Schedule of Lease Asse

Leases - Schedule of Lease Assets and Liabilities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease ROU assets (other assets)	$ 49,380
Operating lease liabilities (other liabilities)	$ 52,092

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating cash flow from operating leases	$ 5,564
ROU assets obtained in exchange for lease obligations	$ 13,268
Weighted average remaining lease term	15 years 8 months 12 days
Weighted average discount rate	3.70%

Leases - Schedule of Lease Matu

Leases - Schedule of Lease Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 5,692
2021	5,362
2022	5,042
2023	4,734
2024	4,408
Thereafter	44,758
Total lease payments	69,996
Less amount of lease payments representing interest	17,904
Total present value of lease payments	$ 52,092
Lease Maturities Before Topic 842
2019		$ 4,677
2020		3,884
2021		3,179
2022		2,465
2023		2,040
Thereafter		7,784
Total		$ 24,029

Loans Receivable and Allowanc_3

Loans Receivable and Allowance for Loan Losses - Summary of Originated and Acquired Loans (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	$ 9,038,493,000	$ 8,257,652,000
Deferred loan costs	52,099,000	37,618,000
Allowance for loan losses	(57,941,000)	(55,214,000)	$ (56,795,000)	$ (60,939,000)
Total loans receivable, net	8,750,733,000	7,996,225,000
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(14,937,000)	(11,513,000)
Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(210,518,000)	(167,553,000)
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(56,463,000)	(64,765,000)
Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	5,299,015,000	4,956,500,000
Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,862,702,000	2,860,212,000
Loans held-for-sale	7,700,000	0
Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,342,918,000	1,258,422,000
Personal Banking | Consumer finance loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	509,000	3,817,000
Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,092,886,000	834,049,000
Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	3,739,478,000	3,301,152,000
Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,964,907,000	2,639,374,000
Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	774,571,000	661,778,000
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	8,214,552,000	7,618,512,000
Deferred loan costs	51,616,000	36,820,000
Allowance for loan losses	(51,439,000)	(51,751,000)	(50,572,000)	(55,293,000)
Total loans receivable, net	7,935,618,000	7,361,434,000
Originated | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(14,937,000)	(11,513,000)
Originated | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(208,857,000)	(167,029,000)
Originated | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(55,317,000)	(63,605,000)
Originated | Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	4,937,171,000	4,589,503,000
Allowance for loan losses	(17,348,000)	(18,318,000)	(20,339,000)	(16,116,000)
Originated | Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,779,764,000	2,766,430,000
Allowance for loan losses	(2,463,000)	(4,054,000)	(3,824,000)	(4,656,000)
Originated | Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,099,514,000	1,043,878,000
Allowance for loan losses	(2,830,000)	(3,184,000)	(4,072,000)	(3,486,000)
Originated | Personal Banking | Consumer finance loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	509,000	3,817,000
Allowance for loan losses	(76,000)	(676,000)	(3,968,000)	(3,445,000)
Originated | Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,057,384,000	775,378,000
Allowance for loan losses	(11,979,000)	(10,404,000)	(8,475,000)	(4,529,000)
Originated | Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	3,277,381,000	3,029,009,000
Allowance for loan losses	(34,091,000)	(33,433,000)	(30,233,000)	(39,177,000)
Originated | Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,557,904,000	2,416,047,000
Allowance for loan losses	(17,292,000)	(26,379,000)	(19,911,000)	(23,667,000)
Originated | Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	719,477,000	612,962,000
Allowance for loan losses	(16,799,000)	(7,054,000)	(10,322,000)	(15,510,000)
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	823,941,000	639,140,000
Deferred loan costs	483,000	798,000
Allowance for loan losses	(6,502,000)	(3,463,000)	(6,223,000)	(5,646,000)
Total loans receivable, net	815,115,000	634,791,000
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	(1,661,000)	(524,000)
Acquired | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Undisbursed loan proceeds	(1,146,000)	(1,160,000)
Acquired | Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	361,844,000	366,997,000
Allowance for loan losses	(1,008,000)	(850,000)	(1,783,000)	(1,771,000)
Acquired | Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	82,938,000	93,782,000
Allowance for loan losses	(111,000)	(83,000)	(131,000)	(71,000)
Acquired | Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	243,404,000	214,544,000
Allowance for loan losses	(359,000)	(348,000)	(762,000)	(1,047,000)
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	35,502,000	58,671,000
Allowance for loan losses	(538,000)	(419,000)	(890,000)	(653,000)
Acquired | Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	462,097,000	272,143,000
Allowance for loan losses	(5,494,000)	(2,613,000)	(4,440,000)	(3,875,000)
Acquired | Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	407,003,000	223,327,000
Allowance for loan losses	(4,296,000)	(1,996,000)	(3,549,000)	(3,008,000)
Acquired | Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	55,094,000	48,816,000
Allowance for loan losses	$ (1,198,000)	$ (617,000)	$ (891,000)	$ (867,000)

Marketable Securities - Availab

Marketable Securities - Available For Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized cost
Residential mortgage-backed securities, amortized cost	$ 815,495	$ 811,015
Gross unrealized holding gains
Residential mortgage-backed securities, gross unrealized holding gains	7,351	2,958
Gross unrealized holding losses
Residential mortgage-backed securities, gross unrealized holding losses	(2,945)	(12,523)
Fair value
Securities available-for-sale	819,901	801,450
U.S. government and agencies
Amortized cost
Due in less than one year	14,951	14,756
Gross unrealized holding gains
Due in less than one year	40	24
Gross unrealized holding losses
Due in less than one year	0	0
Fair value
Due in less than one year	14,991	14,780
Government sponsored enterprises
Amortized cost
Due in less than one year	50,777	85,089
Due in one year through five years	50,229	101,078
Due after five years through ten years	3,716
Due after ten years		3,546
Gross unrealized holding gains
Due in less than one year	345	0
Due in one year through five years	0	71
Due after five years through ten years	53
Due after ten years		0
Gross unrealized holding losses
Due in less than one year	0	(795)
Due in one year through five years	(227)	(1,512)
Due after five years through ten years	(109)
Due after ten years		(142)
Fair value
Due in less than one year	51,122	84,294
Due in one year through five years	50,002	99,637
Due after five years through ten years	3,660
Due after ten years		3,404
Municipal securities
Amortized cost
Due in less than one year	809	1,333
Due in one year through five years	2,891	3,985
Due after five years through ten years	10,155	10,603
Due after ten years	11,695	5,105
Gross unrealized holding gains
Due in less than one year	4	2
Due in one year through five years	79	54
Due after five years through ten years	148	60
Due after ten years	267	31
Gross unrealized holding losses
Due in less than one year	0	(6)
Due in one year through five years	0	(4)
Due after five years through ten years	0	0
Due after ten years	0	0
Fair value
Due in less than one year	813	1,329
Due in one year through five years	2,970	4,035
Due after five years through ten years	10,303	10,663
Due after ten years	11,962	5,136
Corporate debt issues
Amortized cost
Due after five years through ten years	919
Due after ten years		914
Gross unrealized holding gains
Due after five years through ten years	0
Due after ten years		0
Gross unrealized holding losses
Due after five years through ten years	0
Due after ten years		0
Fair value
Due after five years through ten years	919
Due after ten years		914
Residential mortgage-backed securities
Amortized cost
Residential mortgage-backed securities, amortized cost	669,353	584,606
Gross unrealized holding gains
Residential mortgage-backed securities, gross unrealized holding gains	6,415	2,716
Gross unrealized holding losses
Residential mortgage-backed securities, gross unrealized holding losses	(2,609)	(10,064)
Fair value
Securities available-for-sale	673,159	577,258
Fixed rate | Pass-through
Amortized cost
Residential mortgage-backed securities, amortized cost	142,421	130,172
Gross unrealized holding gains
Residential mortgage-backed securities, gross unrealized holding gains	1,941	568
Gross unrealized holding losses
Residential mortgage-backed securities, gross unrealized holding losses	(881)	(4,113)
Fair value
Securities available-for-sale	143,481	126,627
Fixed rate | Agency CMOs
Amortized cost
Residential mortgage-backed securities, amortized cost	452,256	365,427
Gross unrealized holding gains
Residential mortgage-backed securities, gross unrealized holding gains	3,518	865
Gross unrealized holding losses
Residential mortgage-backed securities, gross unrealized holding losses	(1,606)	(5,921)
Fair value
Securities available-for-sale	454,168	360,371
Variable rate | Pass-through
Amortized cost
Residential mortgage-backed securities, amortized cost	18,933	24,761
Gross unrealized holding gains
Residential mortgage-backed securities, gross unrealized holding gains	749	1,003
Gross unrealized holding losses
Residential mortgage-backed securities, gross unrealized holding losses	(4)	(5)
Fair value
Securities available-for-sale	19,678	25,759
Variable rate | Agency CMOs
Amortized cost
Residential mortgage-backed securities, amortized cost	55,743	64,246
Gross unrealized holding gains
Residential mortgage-backed securities, gross unrealized holding gains	207	280
Gross unrealized holding losses
Residential mortgage-backed securities, gross unrealized holding losses	(118)	(25)
Fair value
Securities available-for-sale	$ 55,832	$ 64,501

Loans Receivable and Allowanc_4

Loans Receivable and Allowance for Loan Losses - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Serviced loans for others	$ 793.1	$ 794.2	$ 887.3
Percentage of loan portfolio secured by properties located in Pennsylvania	50.00%	58.00%
Adjustable rate loans	$ 3,090	$ 2,810
Fixed rate loans	$ 5,948	$ 5,448

Marketable Securities - Held To

Marketable Securities - Held To Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized cost
Held-to-maturity securities, amortized cost	$ 18,036	$ 22,765
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	187	103
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	(422)
Fair value
Investment securities held-to-maturity, fair value	18,223	22,446
Residential mortgage-backed securities
Amortized cost
Held-to-maturity securities, amortized cost	18,036	22,765
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	187	103
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	(422)
Fair value
Investment securities held-to-maturity, fair value	18,223	22,446
Fixed rate | Pass-through
Amortized cost
Held-to-maturity securities, amortized cost	2,197	2,896
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	83	53
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	0
Fair value
Investment securities held-to-maturity, fair value	2,280	2,949
Fixed rate | Agency CMOs
Amortized cost
Held-to-maturity securities, amortized cost	14,016	17,552
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	68	0
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	(422)
Fair value
Investment securities held-to-maturity, fair value	14,084	17,130
Variable rate | Pass-through
Amortized cost
Held-to-maturity securities, amortized cost	1,210	1,666
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	28	39
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	0
Fair value
Investment securities held-to-maturity, fair value	1,238	1,705
Variable rate | Agency CMOs
Amortized cost
Held-to-maturity securities, amortized cost	613	651
Gross unrealized holding gains
Held-to-maturity securities, gross unrealized holding gains	8	11
Gross unrealized holding losses
Held-to-maturity securities, gross unrealized holding losses	0	0
Fair value
Investment securities held-to-maturity, fair value	$ 621	$ 662

Loans Receivable and Allowanc_5

Loans Receivable and Allowance for Loan Losses - Outstanding Principal Balance and Related Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	$ 833,599	$ 645,359
Carrying value	821,617	638,254
Acquired loans evaluated individually for future credit losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	7,187	8,189
Carrying value	4,975	5,690
Acquired loans evaluated collectively for future credit losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	826,412	637,170
Carrying value	$ 816,642	$ 632,564

Marketable Securities - Issuers

Marketable Securities - Issuers and the Carrying Values of Mortgage-Backed Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Marketable Securities
Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings	$ 0	$ 0	$ 0
Total residential mortgage-backed securities	837,900,000
Carrying value of marketable securities pledged	121,800,000
Proceeds from sale of marketable securities available-for-sale	32,389,000	5,206,000	36,811,000
Realized gains	29,000	189,000	1,800,000
Realized losses	0	37,000	$ 626,000
Residential mortgage-backed securities
Marketable Securities
Total residential mortgage-backed securities	691,195,000	600,023,000
FNMA
Marketable Securities
Total residential mortgage-backed securities	280,832,000	288,825,000
GNMA
Marketable Securities
Total residential mortgage-backed securities	231,491,000	81,444,000
FHLMC
Marketable Securities
Total residential mortgage-backed securities	178,375,000	229,226,000
Other (including non-agency)
Marketable Securities
Total residential mortgage-backed securities	$ 497,000	$ 528,000

Loans Receivable and Allowanc_6

Loans Receivable and Allowance for Loan Losses - Changes in the Accretable Discount (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Beginning balance	$ 755	$ 1,540
Accretion	(551)	(785)
Net reclassification from nonaccretable yield	966	0
Ending balance	$ 1,170	$ 755

Marketable Securities - Fair Va

Marketable Securities - Fair Value and Gross Unrealized Losses on Marketable Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)investment	Dec. 31, 2018USD ($)
Marketable Securities
Less than 12 months - Fair value	$ 173,112	$ 34,960
Less than 12 months - Unrealized loss	(858)	(31)
12 months or more - Fair value	161,944	484,809
12 months or more - Unrealized loss	(2,087)	(12,915)
Total - Fair value	335,056	519,769
Total - Unrealized loss	$ (2,945)	(12,946)
Number of investments that are temporarily impaired | investment	119
Total residential mortgage-backed securities	$ 837,900
Number of investment securities with other-than-temporary impairment | investment	0
U.S. government sponsored enterprises
Marketable Securities
Less than 12 months - Fair value	$ 0	0
Less than 12 months - Unrealized loss	0	0
12 months or more - Fair value	52,620	136,425
12 months or more - Unrealized loss	(336)	(2,449)
Total - Fair value	52,620	136,425
Total - Unrealized loss	(336)	(2,449)
Municipal securities
Marketable Securities
Less than 12 months - Fair value		929
Less than 12 months - Unrealized loss		(1)
12 months or more - Fair value		1,709
12 months or more - Unrealized loss		(10)
Total - Fair value		2,638
Total - Unrealized loss		(11)
Residential mortgage-backed securities - agency | Agency CMOs
Marketable Securities
Less than 12 months - Fair value	173,112	34,031
Less than 12 months - Unrealized loss	(858)	(30)
12 months or more - Fair value	109,324	346,675
12 months or more - Unrealized loss	(1,751)	(10,456)
Total - Fair value	282,436	380,706
Total - Unrealized loss	$ (2,609)	$ (10,486)

Loans Receivable and Allowanc_7

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	$ 105,993	$ 98,283	$ 84,625
Average recorded investment in impaired loans	88,643	84,338	97,193
Interest income/accretion recognized	3,070	3,762	3,982
Acquired loans evaluated individually for future credit losses
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	4,975	5,690
Outstanding principal balance	7,187	8,189
Related impairment reserve	40	18
Average recorded investment in impaired loans	5,332	6,940
Interest income/accretion recognized	551	785
Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	33,918	35,723	36,833
Average recorded investment in impaired loans	32,180	33,824	35,102
Interest income/accretion recognized	1,235	1,656	1,552
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	1,464	2,027
Outstanding principal balance	2,835	3,633
Related impairment reserve	33	17
Average recorded investment in impaired loans	1,745	2,830
Interest income/accretion recognized	273	418
Personal Banking | Residential mortgage loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	21,293	22,508	21,605
Average recorded investment in impaired loans	19,767	20,733	21,531
Interest income/accretion recognized	688	910	892
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	742	990
Outstanding principal balance	1,232	1,598
Related impairment reserve	7	6
Average recorded investment in impaired loans	866	1,294
Interest income/accretion recognized	147	226
Personal Banking | Home equity loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	8,399	8,893	10,356
Average recorded investment in impaired loans	8,571	9,075	9,150
Interest income/accretion recognized	368	511	452
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	715	1,008
Outstanding principal balance	1,569	1,959
Related impairment reserve	25	7
Average recorded investment in impaired loans	861	1,483
Interest income/accretion recognized	114	157
Personal Banking | Consumer loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	4,225	4,300	4,673
Average recorded investment in impaired loans	3,842	3,992	4,042
Interest income/accretion recognized	179	235	188
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	7	29
Outstanding principal balance	34	76
Related impairment reserve	1	4
Average recorded investment in impaired loans	18	53
Interest income/accretion recognized	12	35
Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	72,075	62,560	47,792
Average recorded investment in impaired loans	56,463	50,514	62,091
Interest income/accretion recognized	1,835	2,106	2,430
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	3,511	3,663
Outstanding principal balance	4,352	4,556
Related impairment reserve	7	1
Average recorded investment in impaired loans	3,587	4,110
Interest income/accretion recognized	278	367
Commercial Banking | Commercial real estate loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	46,126	49,919	37,027
Average recorded investment in impaired loans	46,284	41,328	49,981
Interest income/accretion recognized	1,490	1,599	1,758
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	3,433	3,584
Outstanding principal balance	4,268	4,471
Related impairment reserve	6	1
Average recorded investment in impaired loans	3,509	4,028
Interest income/accretion recognized	273	358
Commercial Banking | Commercial loans
Composition of impaired loans by portfolio segment and by class of financing receivable
Carrying value	25,949	12,641	10,765
Average recorded investment in impaired loans	10,179	9,186	12,110
Interest income/accretion recognized	345	507	$ 672
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	78	79
Outstanding principal balance	84	85
Related impairment reserve	1	0
Average recorded investment in impaired loans	78	82
Interest income/accretion recognized	$ 5	$ 9

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, 2019	Dec. 31, 2018
Cumulative roll forward of credit related impairment losses recognized in earnings for debt securities held and not intended to be sold:
Beginning balance	$ 0	$ 352
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	0	0
Reduction for securities sold/called realized during the year	0	(352)
Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized	0	0
Ending balance	$ 0	$ 0

Loans Receivable and Allowanc_8

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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				$ 55,214				$ 56,795				$ 60,939	$ 55,214	$ 56,795	$ 60,939
Provision	$ 8,223	$ 3,302	$ 4,667	6,467	$ 3,792	$ 6,982	$ 5,349	4,209	$ 6,525	$ 3,027	$ 5,562	4,637	22,659	20,332	19,751
Charge-offs													(26,212)	(29,641)	(31,254)
Recoveries													6,280	7,728	7,359
Balance at the end of the period	57,941				55,214				56,795				57,941	55,214	56,795
Originated
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				51,751				50,572				55,293	51,751	50,572	55,293
Provision													16,190	20,939	14,689
Charge-offs													(21,406)	(26,695)	(25,217)
Recoveries													4,904	6,935	5,807
Balance at the end of the period	51,439				51,751				50,572				51,439	51,751	50,572
Originated | Personal Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				18,318				20,339				16,116	18,318	20,339	16,116
Provision													8,982	11,652	23,129
Charge-offs													(13,091)	(17,924)	(21,411)
Recoveries													3,139	4,251	2,505
Balance at the end of the period	17,348				18,318				20,339				17,348	18,318	20,339
Originated | Personal Banking | Residential mortgage loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				4,054				3,824				4,656	4,054	3,824	4,656
Provision													(1,089)	808	(390)
Charge-offs													(935)	(1,067)	(834)
Recoveries													433	489	392
Balance at the end of the period	2,463				4,054				3,824				2,463	4,054	3,824
Originated | Personal Banking | Home equity loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,184				4,072				3,486	3,184	4,072	3,486
Provision													46	(25)	1,474
Charge-offs													(619)	(1,183)	(1,080)
Recoveries													219	320	192
Balance at the end of the period	2,830				3,184				4,072				2,830	3,184	4,072
Originated | Personal Banking | Consumer finance loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				676				3,968				3,445	676	3,968	3,445
Provision													(671)	(1,282)	8,444
Charge-offs													(320)	(2,813)	(8,369)
Recoveries													391	803	448
Balance at the end of the period	76				676				3,968				76	676	3,968
Originated | Personal Banking | Consumer loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				10,404				8,475				4,529	10,404	8,475	4,529
Provision													10,696	12,151	13,601
Charge-offs													(11,217)	(12,861)	(11,128)
Recoveries													2,096	2,639	1,473
Balance at the end of the period	11,979				10,404				8,475				11,979	10,404	8,475
Originated | Commercial Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				33,433				30,233				39,177	33,433	30,233	39,177
Provision													7,208	9,287	(8,440)
Charge-offs													(8,315)	(8,771)	(3,806)
Recoveries													1,765	2,684	3,302
Balance at the end of the period	34,091				33,433				30,233				34,091	33,433	30,233
Originated | Commercial Banking | Commercial real estate loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				26,379				19,911				23,667	26,379	19,911	23,667
Provision													(5,241)	11,349	(3,663)
Charge-offs													(5,078)	(6,096)	(1,344)
Recoveries													1,232	1,215	1,251
Balance at the end of the period	17,292				26,379				19,911				17,292	26,379	19,911
Originated | Commercial Banking | Commercial loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				7,054				10,322				15,510	7,054	10,322	15,510
Provision													12,449	(2,062)	(4,777)
Charge-offs													(3,237)	(2,675)	(2,462)
Recoveries													533	1,469	2,051
Balance at the end of the period	16,799				7,054				10,322				16,799	7,054	10,322
Acquired
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				3,463				6,223				5,646	3,463	6,223	5,646
Provision													6,469	(607)	5,062
Charge-offs													(4,806)	(2,946)	(6,037)
Recoveries													1,376	793	1,552
Balance at the end of the period	6,502				3,463				6,223				6,502	3,463	6,223
Acquired | Personal Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				850				1,783				1,771	850	1,783	1,771
Provision													662	(419)	1,453
Charge-offs													(1,003)	(1,005)	(2,179)
Recoveries													499	491	738
Balance at the end of the period	1,008				850				1,783				1,008	850	1,783
Acquired | Personal Banking | Residential mortgage loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				83				131				71	83	131	71
Provision													184	(61)	185
Charge-offs													(231)	(112)	(205)
Recoveries													75	125	80
Balance at the end of the period	111				83				131				111	83	131
Acquired | Personal Banking | Home equity loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				348				762				1,047	348	762	1,047
Provision													322	(23)	503
Charge-offs													(502)	(602)	(1,179)
Recoveries													191	211	391
Balance at the end of the period	359				348				762				359	348	762
Acquired | Personal Banking | Consumer loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				419				890				653	419	890	653
Provision													156	(335)	765
Charge-offs													(270)	(291)	(795)
Recoveries													233	155	267
Balance at the end of the period	538				419				890				538	419	890
Acquired | Commercial Banking
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				2,613				4,440				3,875	2,613	4,440	3,875
Provision													5,807	(188)	3,609
Charge-offs													(3,803)	(1,941)	(3,858)
Recoveries													877	302	814
Balance at the end of the period	5,494				2,613				4,440				5,494	2,613	4,440
Acquired | Commercial Banking | Commercial real estate loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				1,996				3,549				3,008	1,996	3,549	3,008
Provision													2,092	(467)	2,631
Charge-offs													(389)	(1,291)	(2,830)
Recoveries													597	205	740
Balance at the end of the period	4,296				1,996				3,549				4,296	1,996	3,549
Acquired | Commercial Banking | Commercial loans
Changes in allowance for losses on allocated loans receivable
Balance at the beginning of the period				$ 617				$ 891				$ 867	617	891	867
Provision													3,715	279	978
Charge-offs													(3,414)	(650)	(1,028)
Recoveries													280	97	74
Balance at the end of the period	$ 1,198				$ 617				$ 891				$ 1,198	$ 617	$ 891

Loans Receivable and Allowanc_9

Loans Receivable and Allowance for Loan Losses - Loan Portfolio by Portfolio Segment and by Class of Financing Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	$ 8,808,674	$ 8,051,439
Allowance for loan losses	57,941	55,214
Nonaccrual loans	68,870	72,281
Loans 90 days past maturity and accruing	32	166
TDRs	31,999	33,608	$ 32,104
Allowance related to TDRs	3,002	3,089
Additional commitments to customers with loans classified as TDRs	566	388
Nonaccrual TDRs	9,043	15,306
Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	5,336,177	4,982,605
Allowance for loan losses	18,356	19,168
Nonaccrual loans	25,447	27,245
Loans 90 days past maturity and accruing	32	166
TDRs	9,523	9,884
Allowance related to TDRs	953	2,513
Additional commitments to customers with loans classified as TDRs	26	4
Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	2,868,127	2,864,470
Allowance for loan losses	2,574	4,137
Nonaccrual loans	14,476	15,848
Loans 90 days past maturity and accruing	0	0
TDRs	7,550	5,382
Allowance related to TDRs	560	993
Additional commitments to customers with loans classified as TDRs	0	0
Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	1,342,918	1,258,422
Allowance for loan losses	3,189	3,532
Nonaccrual loans	6,745	7,075
Loans 90 days past maturity and accruing	32	136
TDRs	1,973	4,502
Allowance related to TDRs	393	1,520
Additional commitments to customers with loans classified as TDRs	26	4
Personal Banking | Consumer finance loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	509	3,817
Allowance for loan losses	76	676
Nonaccrual loans	1	22
Loans 90 days past maturity and accruing	0	3
TDRs	0	0
Allowance 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]
Total loans receivable	1,124,623	855,896
Allowance for loan losses	12,517	10,823
Nonaccrual loans	4,225	4,300
Loans 90 days past maturity and accruing	0	27
TDRs	0	0
Allowance 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]
Total loans receivable	3,472,497	3,068,834
Allowance for loan losses	39,585	36,046
Nonaccrual loans	43,423	45,036
Loans 90 days past maturity and accruing	0	0
TDRs	22,476	23,724
Allowance related to TDRs	2,049	576
Additional commitments to customers with loans classified as TDRs	540	384
Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	2,754,390	2,471,821
Allowance for loan losses	21,588	28,375
Nonaccrual loans	34,864	36,935
Loans 90 days past maturity and accruing	0	0
TDRs	19,358	19,859
Allowance related to TDRs	1,384	313
Additional commitments to customers with loans classified as TDRs	476	310
Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	718,107	597,013
Allowance for loan losses	17,997	7,671
Nonaccrual loans	8,559	8,101
Loans 90 days past maturity and accruing	0	0
TDRs	3,118	3,865
Allowance related to TDRs	665	263
Additional commitments to customers with loans classified as TDRs	$ 64	$ 74

Loans Receivable and Allowan_10

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	$ 68,870	$ 72,281
Total impaired loans	105,993	98,283	$ 84,625
Average recorded investment in impaired loans	88,643	84,338	97,193
Interest income/accretion recognized	3,070	3,762	3,982
Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	25,447	27,245
Total impaired loans	33,918	35,723	36,833
Average recorded investment in impaired loans	32,180	33,824	35,102
Interest income/accretion recognized	1,235	1,656	1,552
Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	43,423	45,036
Total impaired loans	72,075	62,560	47,792
Average recorded investment in impaired loans	56,463	50,514	62,091
Interest income/accretion recognized	1,835	2,106	2,430
Residential mortgage loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	14,476	15,848
Total impaired loans	21,293	22,508	21,605
Average recorded investment in impaired loans	19,767	20,733	21,531
Interest income/accretion recognized	688	910	892
Home equity loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	6,745	7,075
Total impaired loans	8,399	8,893	10,356
Average recorded investment in impaired loans	8,571	9,075	9,150
Interest income/accretion recognized	368	511	452
Consumer finance loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	1	22
Total impaired loans	1	22	199
Average recorded investment in impaired loans	0	24	379
Interest income/accretion recognized	0	0	20
Consumer loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	4,225	4,300
Total impaired loans	4,225	4,300	4,673
Average recorded investment in impaired loans	3,842	3,992	4,042
Interest income/accretion recognized	179	235	188
Commercial real estate loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	34,864	36,935
Total impaired loans	46,126	49,919	37,027
Average recorded investment in impaired loans	46,284	41,328	49,981
Interest income/accretion recognized	1,490	1,599	1,758
Commercial loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	8,559	8,101
Total impaired loans	25,949	12,641	10,765
Average recorded investment in impaired loans	10,179	9,186	12,110
Interest income/accretion recognized	345	507	672
90 days or greater delinquent
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	51,680	50,730	43,077
90 days or greater delinquent | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	21,927	22,211	24,576
90 days or greater delinquent | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	29,753	28,519	18,501
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	12,682	12,965	13,509
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	5,635	5,996	7,251
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	1	22	199
90 days or greater delinquent | Consumer loans | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	3,609	3,228	3,617
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	25,014	25,509	15,361
90 days or greater delinquent | Commercial loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	4,739	3,010	3,140
Less than 90 days delinquent
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	17,190	21,551	21,378
Loans less than 90 days delinquent reviewed for impairment	16,849	11,002	5,337
TDRs less than 90 days delinquent not included elsewhere	20,274	15,000	14,833
Less than 90 days delinquent | Personal Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	3,520	5,034	3,994
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	8,471	8,478	8,263
Less than 90 days delinquent | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	13,670	16,517	17,384
Loans less than 90 days delinquent reviewed for impairment	16,849	11,002	5,337
TDRs less than 90 days delinquent not included elsewhere	11,803	6,522	6,570
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	1,794	2,883	1,282
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	6,817	6,660	6,814
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	1,110	1,079	1,656
Loans less than 90 days delinquent reviewed for impairment	0	0	0
TDRs less than 90 days delinquent not included elsewhere	1,654	1,818	1,449
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	616	1,072	1,056
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	9,850	11,426	13,112
Loans less than 90 days delinquent reviewed for impairment	933	8,549	4,431
TDRs less than 90 days delinquent not included elsewhere	10,329	4,435	4,123
Less than 90 days delinquent | Commercial loans | Commercial Banking
Composition of impaired loans by portfolio segment and by class of financing receivable
Nonaccrual loans	3,820	5,091	4,272
Loans less than 90 days delinquent reviewed for impairment	15,916	2,453	906
TDRs less than 90 days delinquent not included elsewhere	$ 1,474	$ 2,087	$ 2,447

Loans Receivable and Allowan_11

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, 2019	Dec. 31, 2018
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	$ 8,739,372	$ 7,997,835
Loans individually evaluated for impairment	69,302	53,604
Loans individually evaluated for impairment for which there is a related impairment reserve	57,999	48,875
Related impairment reserve	11,762	8,542
Loans individually evaluated for impairment for which there is no related reserve	11,303	4,729
Personal Banking
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	5,326,093	4,972,298
Loans individually evaluated for impairment	10,084	10,307
Loans individually evaluated for impairment for which there is a related impairment reserve	10,084	10,307
Related impairment reserve	956	1,276
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	2,860,026	2,856,359
Loans individually evaluated for impairment	8,101	8,111
Loans individually evaluated for impairment for which there is a related impairment reserve	8,101	8,111
Related impairment reserve	560	747
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	1,340,944	1,256,255
Loans individually evaluated for impairment	1,974	2,167
Loans individually evaluated for impairment for which there is a related impairment reserve	1,974	2,167
Related impairment reserve	393	523
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	509	3,817
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	1,124,614	855,867
Loans individually evaluated for impairment	9	29
Loans individually evaluated for impairment for which there is a related impairment reserve	9	29
Related impairment reserve	3	6
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	3,413,279	3,025,537
Loans individually evaluated for impairment	59,218	43,297
Loans individually evaluated for impairment for which there is a related impairment reserve	47,915	38,568
Related impairment reserve	10,806	7,266
Loans individually evaluated for impairment for which there is no related reserve	11,303	4,729
Commercial Banking | Commercial real estate loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	2,718,855	2,436,605
Loans individually evaluated for impairment	35,535	35,216
Loans individually evaluated for impairment for which there is a related impairment reserve	29,578	31,830
Related impairment reserve	2,679	6,499
Loans individually evaluated for impairment for which there is no related reserve	5,957	3,386
Commercial Banking | Commercial loans
Evaluation of impaired loans by portfolio segment and by class of financing receivable
Loans collectively evaluated for impairment	694,424	588,932
Loans individually evaluated for impairment	23,683	8,081
Loans individually evaluated for impairment for which there is a related impairment reserve	18,337	6,738
Related impairment reserve	8,127	767
Loans individually evaluated for impairment for which there is no related reserve	$ 5,346	$ 1,343

Loans Receivable and Allowan_12

Loans Receivable and Allowance for Loan Losses - Roll Forward of Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)contract
Number of contract
Beginning balance | contract	195	205
Number of contracts new TDRs | contract	14	29
Number of re-modified TDRs | contract	8	6
Ending balance | contract	176	195
Roll forward of troubled debt restructurings
Beginning TDR balance:	$ 33,608	$ 32,104
New TDRs	3,344	1,800
Re-modified TDRs	5,678	3,086
Net paydowns	(7,806)	(6,606)
Ending TDR balance:	31,999	33,608
Accruing TDRs	22,956	18,302
Non-accrual TDRs	$ 9,043	$ 15,306
Residential mortgage loans
Number of contract
Number of contracts charged off | contract	0	1
Number of contracts paid off | contract	5	5
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ 0	$ (135)
Amount of contracts paid off	$ (225)	$ 258
Home equity loans
Number of contract
Number of contracts charged off | contract	0	0
Number of contracts paid off | contract	9	5
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ 0	$ 0
Amount of contracts paid off	$ (196)	$ 83
Commercial real estate loans
Number of contract
Number of contracts charged off | contract	0	2
Number of contracts paid off | contract	12	10
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ 0	$ (294)
Amount of contracts paid off	$ (2,122)	$ 2,254
Commercial loans
Number of contract
Number of contracts charged off | contract	2	7
Number of contracts paid off | contract	5	9
Roll forward of troubled debt restructurings
Amount of contracts charged off	$ (235)	$ (1,345)
Amount of contracts paid off	$ (47)	$ 2,403

Loans Receivable and Allowan_13

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, 2019USD ($)contract	Dec. 31, 2018USD ($)contract	Dec. 31, 2017USD ($)contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	22	35	29
Recorded investment at the time of modification	$ 9,022	$ 4,886	$ 7,549
Current recorded investment	8,023	4,815	7,118
Current allowance	$ 665	$ 460	$ 599
Troubled debt restructurings that subsequently defaulted:
Number of contracts	0		3
Recorded investment at the time of modification			$ 774
Current recorded investment			760
Current allowance			$ 69
Personal Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	8	26	11
Recorded investment at the time of modification	$ 468	$ 1,390	$ 1,756
Current recorded investment	462	1,359	1,703
Current allowance	$ 31	$ 222	$ 198
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract			1
Recorded investment at the time of modification			$ 336
Current recorded investment			334
Current allowance			$ 34
Personal Banking | Residential mortgage loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	3	9	8
Recorded investment at the time of modification	$ 297	$ 754	$ 1,604
Current recorded investment	297	749	1,555
Current allowance	$ 19	$ 72	$ 158
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract			1
Recorded investment at the time of modification			$ 336
Current recorded investment			334
Current allowance			$ 34
Personal Banking | Home equity loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	5	17	3
Recorded investment at the time of modification	$ 171	$ 636	$ 152
Current recorded investment	165	610	148
Current allowance	$ 12	$ 150	$ 40
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract			0
Recorded investment at the time of modification			$ 0
Current recorded investment			0
Current allowance			$ 0
Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	14	9	18
Recorded investment at the time of modification	$ 8,554	$ 3,496	$ 5,793
Current recorded investment	7,561	3,456	5,415
Current allowance	$ 634	$ 238	$ 401
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract			2
Recorded investment at the time of modification			$ 438
Current recorded investment			426
Current allowance			$ 35
Commercial Banking | Commercial real estate loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	10	5	11
Recorded investment at the time of modification	$ 8,333	$ 3,157	$ 5,232
Current recorded investment	7,369	3,114	4,889
Current allowance	$ 613	$ 169	$ 364
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract			2
Recorded investment at the time of modification			$ 438
Current recorded investment			426
Current allowance			$ 35
Commercial Banking | Commercial loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of contracts | contract	4	4	7
Recorded investment at the time of modification	$ 221	$ 339	$ 561
Current recorded investment	192	342	526
Current allowance	$ 21	$ 69	$ 37
Troubled debt restructurings that subsequently defaulted:
Number of contracts | contract			0
Recorded investment at the time of modification			$ 0
Current recorded investment			0
Current allowance			$ 0

Loans Receivable and Allowan_14

Loans Receivable and Allowance for Loan Losses - Troubled Debt Restructurings by Type of Modification (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)contract	Dec. 31, 2017USD ($)contract
Troubled debt restructurings
Number of contracts | contract	22	35	29
Total	$ 8,023	$ 4,815	$ 7,118
Number of re-modified TDRs | contract	8	6
Total	$ 4,705	$ 3,046
Rate
Troubled debt restructurings
Total	146	71
Total	0	0
Payment
Troubled debt restructurings
Total	2,541	590
Total	219	0
Maturity date
Troubled debt restructurings
Total	5,336	3,876
Total	4,486	3,046
Other
Troubled debt restructurings
Total	0	278
Total	$ 0	$ 0
Personal Banking
Troubled debt restructurings
Number of contracts | contract	8	26	11
Total	$ 462	$ 1,359	$ 1,703
Number of re-modified TDRs | contract	0	0
Total	$ 0	$ 0
Personal Banking | Rate
Troubled debt restructurings
Total	109	71
Total	0	0
Personal Banking | Payment
Troubled debt restructurings
Total	0	590
Total	0	0
Personal Banking | Maturity date
Troubled debt restructurings
Total	353	420
Total	0	0
Personal Banking | Other
Troubled debt restructurings
Total	0	278
Total	$ 0	$ 0
Personal Banking | Residential mortgage loans
Troubled debt restructurings
Number of contracts | contract	3	9	8
Total	$ 297	$ 749	$ 1,555
Number of re-modified TDRs | contract	0	0
Total	$ 0	$ 0
Personal Banking | Residential mortgage loans | Rate
Troubled debt restructurings
Total	0	7
Total	0	0
Personal Banking | Residential mortgage loans | Payment
Troubled debt restructurings
Total	0	326
Total	0	0
Personal Banking | Residential mortgage loans | Maturity date
Troubled debt restructurings
Total	297	330
Total	0	0
Personal Banking | Residential mortgage loans | Other
Troubled debt restructurings
Total	0	86
Total	$ 0	$ 0
Personal Banking | Home equity loans
Troubled debt restructurings
Number of contracts | contract	5	17	3
Total	$ 165	$ 610	$ 148
Number of re-modified TDRs | contract	0	0
Total	$ 0	$ 0
Personal Banking | Home equity loans | Rate
Troubled debt restructurings
Total	109	64
Total	0	0
Personal Banking | Home equity loans | Payment
Troubled debt restructurings
Total	0	264
Total	0	0
Personal Banking | Home equity loans | Maturity date
Troubled debt restructurings
Total	56	90
Total	0	0
Personal Banking | Home equity loans | Other
Troubled debt restructurings
Total	0	192
Total	$ 0	$ 0
Commercial Banking
Troubled debt restructurings
Number of contracts | contract	14	9	18
Total	$ 7,561	$ 3,456	$ 5,415
Number of re-modified TDRs | contract	8	6
Total	$ 4,705	$ 3,046
Commercial Banking | Rate
Troubled debt restructurings
Total	37	0
Total	0	0
Commercial Banking | Payment
Troubled debt restructurings
Total	2,541	0
Total	219	0
Commercial Banking | Maturity date
Troubled debt restructurings
Total	4,983	3,456
Total	4,486	3,046
Commercial Banking | Other
Troubled debt restructurings
Total	0	0
Total	$ 0	$ 0
Commercial Banking | Commercial real estate loans
Troubled debt restructurings
Number of contracts | contract	10	5	11
Total	$ 7,369	$ 3,114	$ 4,889
Number of re-modified TDRs | contract	7	3
Total	$ 4,667	$ 2,854
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	2,541	0
Total	219	0
Commercial Banking | Commercial real estate loans | Maturity date
Troubled debt restructurings
Total	4,828	3,114
Total	4,448	2,854
Commercial Banking | Commercial real estate loans | Other
Troubled debt restructurings
Total	0	0
Total	$ 0	$ 0
Commercial Banking | Commercial loans
Troubled debt restructurings
Number of contracts | contract	4	4	7
Total	$ 192	$ 342	$ 526
Number of re-modified TDRs | contract	1	3
Total	$ 38	$ 192
Commercial Banking | Commercial loans | Rate
Troubled debt restructurings
Total	37	0
Total	0	0
Commercial Banking | Commercial loans | Payment
Troubled debt restructurings
Total	0	0
Total	0	0
Commercial Banking | Commercial loans | Maturity date
Troubled debt restructurings
Total	155	342
Total	38	192
Commercial Banking | Commercial loans | Other
Troubled debt restructurings
Total	0	0
Total	$ 0	$ 0

Loans Receivable and Allowan_15

Loans Receivable and Allowance for Loan Losses - Loan Delinquencies (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loan payment delinquencies
Total delinquency	$ 119,401	$ 121,534
Current	8,689,273	7,929,905
Total loans receivable	8,808,674	8,051,439
90 days or greater delinquent and accruing	147	143
Personal Banking
Loan payment delinquencies
Total loans receivable	5,336,177	4,982,605
Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total loans receivable	2,868,127	2,864,470
Personal Banking | Home equity loans
Loan payment delinquencies
Total loans receivable	1,342,918	1,258,422
Personal Banking | Consumer finance loans
Loan payment delinquencies
Total loans receivable	509	3,817
Personal Banking | Consumer loans
Loan payment delinquencies
Total loans receivable	1,124,623	855,896
Commercial Banking
Loan payment delinquencies
Total loans receivable	3,472,497	3,068,834
Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total loans receivable	2,754,390	2,471,821
Commercial Banking | Commercial loans
Loan payment delinquencies
Total loans receivable	718,107	597,013
Originated
Loan payment delinquencies
Total delinquency	101,108	109,605
Current	7,885,949	7,303,580
Total loans receivable	7,987,057	7,413,185
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking
Loan payment delinquencies
Total delinquency	64,521	73,809
Current	4,909,329	4,541,001
Total loans receivable	4,973,850	4,614,810
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	37,099	44,645
Current	2,748,090	2,714,474
Total loans receivable	2,785,189	2,759,119
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	11,788	13,406
Current	1,087,726	1,030,472
Total loans receivable	1,099,514	1,043,878
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Consumer finance loans
Loan payment delinquencies
Total delinquency	99	854
Current	410	2,963
Total loans receivable	509	3,817
90 days or greater delinquent and accruing	0	0
Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	15,535	14,904
Current	1,073,103	793,092
Total loans receivable	1,088,638	807,996
90 days or greater delinquent and accruing	0	0
Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	36,587	35,796
Current	2,976,620	2,762,579
Total loans receivable	3,013,207	2,798,375
90 days or greater delinquent and accruing	0	0
Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	24,944	31,913
Current	2,324,104	2,217,105
Total loans receivable	2,349,048	2,249,018
90 days or greater delinquent and accruing	0	0
Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	11,643	3,883
Current	652,516	545,474
Total loans receivable	664,159	549,357
90 days or greater delinquent and accruing	0	0
Acquired
Loan payment delinquencies
Total delinquency	18,293	11,929
Current	803,324	626,325
Total loans receivable	821,617	638,254
90 days or greater delinquent and accruing	147	143
Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	7,926	6,705
Current	354,401	361,090
Total loans receivable	362,327	367,795
90 days or greater delinquent and accruing	147	65
Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	4,665	2,542
Current	78,273	91,240
Total loans receivable	82,938	93,782
90 days or greater delinquent and accruing	93	19
Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	2,774	3,345
Current	240,630	211,199
Total loans receivable	243,404	214,544
90 days or greater delinquent and accruing	53	40
Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	487	818
Current	35,498	58,651
Total loans receivable	35,985	59,469
90 days or greater delinquent and accruing	1	6
Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	10,367	5,224
Current	448,923	265,235
Total loans receivable	459,290	270,459
90 days or greater delinquent and accruing	0	78
Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	9,681	4,564
Current	395,661	218,239
Total loans receivable	405,342	222,803
90 days or greater delinquent and accruing	0	78
Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	686	660
Current	53,262	46,996
Total loans receivable	53,948	47,656
90 days or greater delinquent and accruing	0	0
30-59 days delinquent
Loan payment delinquencies
Total delinquency	48,081	53,010
30-59 days delinquent | Originated
Loan payment delinquencies
Total delinquency	41,120	49,716
30-59 days delinquent | Originated | Personal Banking
Loan payment delinquencies
Total delinquency	34,535	43,716
30-59 days delinquent | Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	20,447	27,245
30-59 days delinquent | Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	5,119	6,810
30-59 days delinquent | Originated | Personal Banking | Consumer finance loans
Loan payment delinquencies
Total delinquency	63	661
30-59 days delinquent | Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	8,906	9,000
30-59 days delinquent | Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	6,585	6,000
30-59 days delinquent | Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	5,598	5,391
30-59 days delinquent | Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	987	609
30-59 days delinquent | Acquired
Loan payment delinquencies
Total delinquency	6,961	3,294
30-59 days delinquent | Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	4,438	2,818
30-59 days delinquent | Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	2,849	532
30-59 days delinquent | Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	1,350	1,839
30-59 days delinquent | Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	239	447
30-59 days delinquent | Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	2,523	476
30-59 days delinquent | Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	2,323	112
30-59 days delinquent | Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	200	364
60-89 days delinquent
Loan payment delinquencies
Total delinquency	19,493	17,651
60-89 days delinquent | Originated
Loan payment delinquencies
Total delinquency	18,613	15,903
60-89 days delinquent | Originated | Personal Banking
Loan payment delinquencies
Total delinquency	10,866	10,542
60-89 days delinquent | Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	5,572	5,732
60-89 days delinquent | Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	2,096	1,771
60-89 days delinquent | Originated | Personal Banking | Consumer finance loans
Loan payment delinquencies
Total delinquency	35	172
60-89 days delinquent | Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	3,163	2,867
60-89 days delinquent | Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	7,747	5,361
60-89 days delinquent | Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	1,387	4,801
60-89 days delinquent | Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	6,360	560
60-89 days delinquent | Acquired
Loan payment delinquencies
Total delinquency	880	1,748
60-89 days delinquent | Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	534	1,162
60-89 days delinquent | Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	121	693
60-89 days delinquent | Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	309	294
60-89 days delinquent | Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	104	175
60-89 days delinquent | Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	346	586
60-89 days delinquent | Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	303	586
60-89 days delinquent | Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	43	0
90 days or greater delinquent
Loan payment delinquencies
Total delinquency	51,827	50,873
90 days or greater delinquent | Originated
Loan payment delinquencies
Total delinquency	41,375	43,986
90 days or greater delinquent | Originated | Personal Banking
Loan payment delinquencies
Total delinquency	19,120	19,551
90 days or greater delinquent | Originated | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	11,080	11,668
90 days or greater delinquent | Originated | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	4,573	4,825
90 days or greater delinquent | Originated | Personal Banking | Consumer finance loans
Loan payment delinquencies
Total delinquency	1	21
90 days or greater delinquent | Originated | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	3,466	3,037
90 days or greater delinquent | Originated | Commercial Banking
Loan payment delinquencies
Total delinquency	22,255	24,435
90 days or greater delinquent | Originated | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	17,959	21,721
90 days or greater delinquent | Originated | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	4,296	2,714
90 days or greater delinquent | Acquired
Loan payment delinquencies
Total delinquency	10,452	6,887
90 days or greater delinquent | Acquired | Personal Banking
Loan payment delinquencies
Total delinquency	2,954	2,725
90 days or greater delinquent | Acquired | Personal Banking | Residential mortgage loans
Loan payment delinquencies
Total delinquency	1,695	1,317
90 days or greater delinquent | Acquired | Personal Banking | Home equity loans
Loan payment delinquencies
Total delinquency	1,115	1,212
90 days or greater delinquent | Acquired | Personal Banking | Consumer loans
Loan payment delinquencies
Total delinquency	144	196
90 days or greater delinquent | Acquired | Commercial Banking
Loan payment delinquencies
Total delinquency	7,498	4,162
90 days or greater delinquent | Acquired | Commercial Banking | Commercial real estate loans
Loan payment delinquencies
Total delinquency	7,055	3,866
90 days or greater delinquent | Acquired | Commercial Banking | Commercial loans
Loan payment delinquencies
Total delinquency	$ 443	$ 296

Loans Receivable and Allowan_16

Loans Receivable and Allowance for Loan Losses - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Credit quality indicators
Total loans	$ 8,808,674	$ 8,051,439
Pass
Credit quality indicators
Total loans	8,471,224	7,753,667
Special mention
Credit quality indicators
Total loans	122,950	113,969
Substandard
Credit quality indicators
Total loans	214,500	183,803
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	5,336,177	4,982,605
Personal Banking | Residential mortgage loans
Credit quality indicators
Total loans	2,868,127	2,864,470
Personal Banking | Home equity loans
Credit quality indicators
Total loans	1,342,918	1,258,422
Personal Banking | Consumer finance loans
Credit quality indicators
Total loans	509	3,817
Personal Banking | Consumer loans
Credit quality indicators
Total loans	1,124,623	855,896
Commercial Banking
Credit quality indicators
Total loans	3,472,497	3,068,834
Commercial Banking | Commercial real estate loans
Credit quality indicators
Total loans	2,754,390	2,471,821
Commercial Banking | Commercial loans
Credit quality indicators
Total loans	718,107	597,013
Originated
Credit quality indicators
Total loans	7,987,057	7,413,185
Originated | Pass
Credit quality indicators
Total loans	7,715,665	7,161,796
Originated | Special mention
Credit quality indicators
Total loans	112,679	106,902
Originated | Substandard
Credit quality indicators
Total loans	158,713	144,487
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	4,973,850	4,614,810
Originated | Personal Banking | Pass
Credit quality indicators
Total loans	4,955,831	4,595,403
Originated | Personal Banking | Special mention
Credit quality indicators
Total loans	0	0
Originated | Personal Banking | Substandard
Credit quality indicators
Total loans	18,019	19,407
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	2,785,189	2,759,119
Originated | Personal Banking | Residential mortgage loans | Pass
Credit quality indicators
Total loans	2,776,971	2,749,266
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	8,218	9,853
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	1,099,514	1,043,878
Originated | Personal Banking | Home equity loans | Pass
Credit quality indicators
Total loans	1,093,874	1,038,245
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	5,640	5,633
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	509	3,817
Originated | Personal Banking | Consumer finance loans | Pass
Credit quality indicators
Total loans		3,817
Originated | Personal Banking | Consumer finance loans | Special mention
Credit quality indicators
Total loans		0
Originated | Personal Banking | Consumer finance loans | Substandard
Credit quality indicators
Total loans		0
Originated | Personal Banking | Consumer finance loans | Doubtful
Credit quality indicators
Total loans		0
Originated | Personal Banking | Consumer finance loans | Loss
Credit quality indicators
Total loans		0
Originated | Personal Banking | Consumer loans
Credit quality indicators
Total loans	1,089,147
Originated | Personal Banking | Consumer loans | Pass
Credit quality indicators
Total loans	1,084,986
Originated | Personal Banking | Consumer loans | Special mention
Credit quality indicators
Total loans	0
Originated | Personal Banking | Consumer loans | Substandard
Credit quality indicators
Total loans	4,161
Originated | Personal Banking | Consumer loans | Doubtful
Credit quality indicators
Total loans	0
Originated | Personal Banking | Consumer loans | Loss
Credit quality indicators
Total loans	0
Originated | Personal Banking | Consumer loans
Credit quality indicators
Total loans	1,088,638	807,996
Originated | Personal Banking | Consumer loans | Pass
Credit quality indicators
Total loans		804,075
Originated | Personal Banking | Consumer loans | Special mention
Credit quality indicators
Total loans		0
Originated | Personal Banking | Consumer loans | Substandard
Credit quality indicators
Total loans		3,921
Originated | Personal Banking | Consumer loans | Doubtful
Credit quality indicators
Total loans		0
Originated | Personal Banking | Consumer loans | Loss
Credit quality indicators
Total loans		0
Originated | Commercial Banking
Credit quality indicators
Total loans	3,013,207	2,798,375
Originated | Commercial Banking | Pass
Credit quality indicators
Total loans	2,759,834	2,566,393
Originated | Commercial Banking | Special mention
Credit quality indicators
Total loans	112,679	106,902
Originated | Commercial Banking | Substandard
Credit quality indicators
Total loans	140,694	125,080
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	2,349,048	2,249,018
Originated | Commercial Banking | Commercial real estate loans | Pass
Credit quality indicators
Total loans	2,188,823	2,062,728
Originated | Commercial Banking | Commercial real estate loans | Special mention
Credit quality indicators
Total loans	70,327	91,142
Originated | Commercial Banking | Commercial real estate loans | Substandard
Credit quality indicators
Total loans	89,898	95,148
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	664,159	549,357
Originated | Commercial Banking | Commercial loans | Pass
Credit quality indicators
Total loans	571,011	503,665
Originated | Commercial Banking | Commercial loans | Special mention
Credit quality indicators
Total loans	42,352	15,760
Originated | Commercial Banking | Commercial loans | Substandard
Credit quality indicators
Total loans	50,796	29,932
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	821,617	638,254
Acquired | Pass
Credit quality indicators
Total loans	755,559	591,871
Acquired | Special mention
Credit quality indicators
Total loans	10,271	7,067
Acquired | Substandard
Credit quality indicators
Total loans	55,787	39,316
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	362,327	367,795
Acquired | Personal Banking | Pass
Credit quality indicators
Total loans	359,594	364,852
Acquired | Personal Banking | Special mention
Credit quality indicators
Total loans	0	0
Acquired | Personal Banking | Substandard
Credit quality indicators
Total loans	2,733	2,943
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	82,938	93,782
Acquired | Personal Banking | Residential mortgage loans | Pass
Credit quality indicators
Total loans	81,611	92,625
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	1,327	1,157
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	243,404	214,544
Acquired | Personal Banking | Home equity loans | Pass
Credit quality indicators
Total loans	242,237	213,273
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	1,167	1,271
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	35,985	59,469
Acquired | Personal Banking | Consumer loans | Pass
Credit quality indicators
Total loans	35,746	58,954
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	239	515
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	459,290	270,459
Acquired | Commercial Banking | Pass
Credit quality indicators
Total loans	395,965	227,019
Acquired | Commercial Banking | Special mention
Credit quality indicators
Total loans	10,271	7,067
Acquired | Commercial Banking | Substandard
Credit quality indicators
Total loans	53,054	36,373
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	405,342	222,803
Acquired | Commercial Banking | Commercial real estate loans | Pass
Credit quality indicators
Total loans	349,993	191,622
Acquired | Commercial Banking | Commercial real estate loans | Special mention
Credit quality indicators
Total loans	10,243	3,546
Acquired | Commercial Banking | Commercial real estate loans | Substandard
Credit quality indicators
Total loans	45,106	27,635
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	53,948	47,656
Acquired | Commercial Banking | Commercial loans | Pass
Credit quality indicators
Total loans	45,972	35,397
Acquired | Commercial Banking | Commercial loans | Special mention
Credit quality indicators
Total loans	28	3,521
Acquired | Commercial Banking | Commercial loans | Substandard
Credit quality indicators
Total loans	7,948	8,738
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 Allowan_17

Loans Receivable and Allowance for Loan Losses - Off-Balance Sheet Financial Instruments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	$ 1,191,601,000	$ 957,603,000
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	234,137,000	136,760,000
Outstanding loan commitments for fixed rate loans	129,600,000
Outstanding loan commitments for adjustable rate loans	104,500,000
Undisbursed lines of credit
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	917,161,000	788,262,000
Standby letters of credit
Financial instruments with off-balance-sheet risk
Financial instruments with off-balance-sheet risk	40,303,000	32,581,000
Maximum potential amount of future payments	40,300,000
Maximum potential amount of future payments fully collateralized	34,100,000
Liability recognized for the obligations	$ 444,000	$ 267,000

Loans Receivable and Allowan_18

Loans Receivable and Allowance for Loan Losses - Mortgage Servicing Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Servicing Asset at Amortized Cost, Gross, Balance [Roll Forward]
Servicing rights, beginning balance	$ 2,103	$ 3,523
Additions	862	50
Amortization	(1,117)	(1,470)
Servicing rights, ending balance	1,848	2,103
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Valuation allowance, beginning balance	0	0
Additions	(1)	0
Valuation allowance, ending balance	(1)	0
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Net carrying and fair value, beginning balance	2,103	3,523
Additions	861	50
Amortization	(1,117)	(1,470)
Net carrying and fair value, ending balance	$ 1,847	$ 2,103

Accrued Interest Receivable (De

Accrued Interest Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Interest Receivable and Other Assets [Abstract]
Investment securities	$ 941	$ 1,035
Mortgage-backed securities	1,508	1,333
Loans receivable	23,306	22,122
Accrued interest receivable	$ 25,755	$ 24,490

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, 2019USD ($)capital_stock	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
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
FHLB stock		$ 14,700	$ 15,600
Dividend received on capital stock	$ 1,100	$ 452
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, 2019	Dec. 31, 2018	Dec. 31, 2017
Premises and Equipment
Total, at cost	$ 321,715	$ 308,618
Less accumulated depreciation and amortization	(174,306)	(165,228)
Premises and equipment, net	147,409	143,390
Depreciation and amortization expense	11,700	12,100	$ 12,400
Land and land improvements
Premises and Equipment
Total, at cost	22,194	21,042
Office buildings and improvements
Premises and Equipment
Total, at cost	154,535	150,328
Furniture, fixtures and equipment
Premises and Equipment
Total, at cost	124,216	119,829
Leasehold improvements
Premises and Equipment
Total, at cost	$ 20,770	$ 17,419

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amortizable intangible assets:
Intangible asset - net	$ 23,076	$ 19,821
Amortization expense	6,543	5,848	$ 6,764
Estimated amortization expense
For the year ended December 31, 2020	6,237
For the year ending December 31, 2021	5,058
For the year ending December 31, 2022	3,976
For the year ending December 31, 2023	3,016
For the year ending December 31, 2024	2,249
Core Deposits
Amortizable intangible assets:
Intangible asset - gross	71,183	63,685
Less: accumulated amortization	(50,934)	(45,027)
Intangible asset - net	20,249	18,658
Customer and Contract
Amortizable intangible assets:
Intangible asset - gross	12,775	10,474
Less: accumulated amortization	(9,948)	(9,311)
Intangible asset - net	$ 2,827	$ 1,163

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Changes in the Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Changes in the carrying amount of goodwill
Balance at the beginning of the period	$ 307,420,000	$ 307,420,000
Goodwill acquired	38,683,000	0
Balance at the end of the period	346,103,000	307,420,000
Goodwill impairment	$ 0	$ 0

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Noninterest-bearing demand deposits	$ 1,609,653	$ 1,736,156
Interest-bearing demand deposits	1,944,108	1,455,460
Money market deposit accounts	1,863,998	1,661,623
Savings deposits	1,604,838	1,636,099
Time deposits	1,569,410	1,404,841
Total deposits	8,592,007	7,894,179
Aggregate amount of certificates of deposit with a minimum denomination of $100,000	521,100	460,800
Deposits in accounts exceeding $250,000	2,211,000
Contractual maturity of the certificate accounts
Due within 12 months	909,509	553,173
Due between 12 and 24 months	300,656	352,074
Due between 24 and 36 months	214,301	213,591
Due between 36 and 48 months	106,065	171,866
Due between 48 and 60 months	35,358	108,068
After 60 months	3,521	6,069
Total time deposits	1,569,410	1,404,841
Interest expense incurred on deposits
Interest-bearing demand deposits	6,012	3,607	$ 1,027
Money market deposit accounts	13,010	5,740	4,203
Savings deposits	3,115	3,064	3,062
Time deposits	27,079	18,574	14,765
Total interest expense on deposits	$ 49,216	$ 30,985	$ 23,057

Borrowed Funds - Schedule of Bo

Borrowed Funds - Schedule of Borrowed Funds (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Borrowed funds	$ 246,336	$ 234,389
Term notes payable to the FHLB of Pittsburgh:
Debt Instrument [Line Items]
Due within one year, amount	153,600	128,600
Borrowed funds	$ 153,600	$ 128,600
Due within one year, average rate	2.38%	2.60%
Collateralized borrowings, due within one year
Debt Instrument [Line Items]
Due within one year, amount	$ 92,736	$ 105,789
Due within one year, average rate	0.25%	0.20%

Borrowed Funds - Narrative (Det

Borrowed Funds - Narrative (Details)	Mar. 07, 2019USD ($)trust$ / sharesshares	Dec. 15, 2005USD ($)$ / sharesshares	Dec. 05, 2005USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 08, 2019trust
Debt Instrument [Line Items]
Number of statutory business trusts owned | trust	3
Junior subordinated debentures				$ 121,800,000	$ 111,213,000
Number of additional business trusts owned | trust							2
FHLB of Pittsburgh
Debt Instrument [Line Items]
Maximum commitment				250,000,000
Collateralized borrowings, due within one year
Debt Instrument [Line Items]
Due within one year, amount				92,736,000	105,789,000
Average amount of agreements outstanding				91,100,000	102,300,000	$ 121,000,000
Maximum amount of outstanding security repurchase agreement				101,100,000	110,300,000	$ 137,200,000
Trust preferred investments
Debt Instrument [Line Items]
Capital debt securities				118,875,000
Junior subordinated debentures				$ 121,800,000	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
Capital debt securities			$ 50,000,000	$ 50,000,000
Variable rate basis			three-month LIBOR
Spread on variable rate basis (as a percent)			1.38%	1.38%
Junior subordinated debentures				$ 51,547,000	51,547,000
Effective interest rate (as a percent)				3.34%
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
Capital debt securities		$ 50,000,000		$ 50,000,000
Variable rate basis				three-month LIBOR
Spread on variable rate basis (as a percent)		1.38%		1.38%
Junior subordinated debentures				$ 51,547,000	51,547,000
Effective interest rate (as a percent)				3.27%
Trust preferred investments | LNB Trust II
Debt Instrument [Line Items]
Capital debt securities				$ 7,875,000
Junior subordinated debentures				$ 8,119,000	8,119,000
Effective interest rate (as a percent)				3.37%
Trust preferred investments | Union National Capital Trust I (1)
Debt Instrument [Line Items]
Cumulative trust preferred securities issued (in shares) | shares				8,000
Cumulative trust preferred securities issued, liquidation value per preferred security (in dollars per security) | $ / shares				$ 1,000
Capital debt securities				$ 8,000,000
Junior subordinated debentures				$ 7,900,000	0
Effective interest rate (as a percent)				4.79%
Trust preferred investments | Union National Capital Trust II (1)
Debt Instrument [Line Items]
Cumulative trust preferred securities issued (in shares) | shares				3,000
Cumulative trust preferred securities issued, liquidation value per preferred security (in dollars per security) | $ / shares				$ 1,000
Capital debt securities				$ 3,000,000
Junior subordinated debentures				$ 2,687,000	$ 0
Effective interest rate (as a percent)				3.91%
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%			1.48%
LIBOR | Trust preferred investments | Union National Capital Trust I (1)
Debt Instrument [Line Items]
Spread on variable rate basis (as a percent)				2.85%
LIBOR | Trust preferred investments | Union National Capital Trust II (1)
Debt Instrument [Line Items]
Spread on variable rate basis (as a percent)				2.00%
Interest rate swaps | Union National Capital Trust I (1)
Debt Instrument [Line Items]
Junior subordinated debentures				$ 8,248,000
Interest rate swaps | Union National Capital Trust II (1)
Debt Instrument [Line Items]
Junior subordinated debentures				$ 3,093,000

Borrowed Funds - Schedule of Ca

Borrowed Funds - Schedule of Capital Debt Securities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 15, 2005	Dec. 05, 2005
Debt Instrument [Line Items]
Junior subordinated debentures	$ 121,800,000	$ 111,213,000
Trust preferred investments
Debt Instrument [Line Items]
Capital debt securities	118,875,000
Junior subordinated debentures	121,800,000	111,213,000
Trust preferred investments | Northwest Bancorp Capital Trust III
Debt Instrument [Line Items]
Capital debt securities	50,000,000			$ 50,000,000
Junior subordinated debentures	51,547,000	51,547,000
Trust preferred investments | Northwest Bancorp Statutory Trust IV
Debt Instrument [Line Items]
Capital debt securities	50,000,000		$ 50,000,000
Junior subordinated debentures	51,547,000	51,547,000
Trust preferred investments | LNB Trust II
Debt Instrument [Line Items]
Capital debt securities	7,875,000
Junior subordinated debentures	8,119,000	8,119,000
Trust preferred investments | Union National Capital Trust I (1)
Debt Instrument [Line Items]
Capital debt securities	8,000,000
Junior subordinated debentures	7,900,000	0
Trust preferred investments | Union National Capital Trust II (1)
Debt Instrument [Line Items]
Capital debt securities	3,000,000
Junior subordinated debentures	$ 2,687,000	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allocation of total income tax
Income tax expense	$ 6,773	$ 9,793	$ 7,404	$ 6,709	$ 7,547	$ 7,035	$ 6,900	$ 6,940	$ 6,576	$ 12,414	$ 14,402	$ 8,052	$ 30,679	$ 28,422	$ 41,444
Shareholders’ equity for unrealized gain/(loss) on securities available-for-sale													3,992	(573)	(3,403)
Shareholders’ equity for pension adjustment													(2,859)	(24)	(213)
Shareholders’ equity for swap fair value adjustment													0	223	585
Unallocated income tax													31,812	28,048	38,413
Income tax expense applicable to income before taxes
Current													27,903	31,192	30,127
Deferred													2,776	(2,770)	11,317
Total provision for income taxes	6,773	$ 9,793	$ 7,404	$ 6,709	7,547	$ 7,035	$ 6,900	$ 6,940	$ 6,576	$ 12,414	$ 14,402	$ 8,052	$ 30,679	$ 28,422	$ 41,444
Reconciliation of the expected federal statutory income tax rate to the effective rate
Expected tax rate													21.00%	21.00%	35.00%
Tax-exempt interest income													(0.80%)	(0.90%)	(1.50%)
State income tax, net of federal benefit													3.70%	3.80%	3.20%
Bank-owned life insurance													(0.60%)	(0.90%)	(1.60%)
Stock-based compensation													(0.60%)	(0.80%)	(0.90%)
Dividends on stock plans													(0.60%)	(0.60%)	(1.10%)
Low income housing and historic tax credits													(0.50%)	(0.60%)	(0.50%)
Adjustment to net deferred tax liabilities for enacted changes in tax laws and rates													0.00%	0.00%	(2.30%)
Other													0.10%	0.20%	0.20%
Effective tax rate													21.70%	21.20%	30.50%
Deferred tax assets:
Deferred rent	0				115								$ 0	$ 115
Deferred compensation expense	1,974				2,357								1,974	2,357
Bad debts	12,609				11,257								12,609	11,257
Other reserves	961				1,065								961	1,065
Accrued post-retirement benefit cost	436				410								436	410
Stock benefit plans	994				904								994	904
Pension and post-retirement benefits	15,916				13,057								15,916	13,057
Unrealized loss on the fair value of securities available-for-sale	0				2,733								0	2,733
Deferred income	728				822								728	822
Lease liability	11,493												11,493
Net operating loss	504				0								504	0
Other	626				219								626	219
Total deferred tax assets	46,241				32,939								46,241	32,939
Deferred tax liabilities:
Pension expense	5,864				5,686								5,864	5,686
Purchase accounting	291				180								291	180
Intangible assets	14,464				13,839								14,464	13,839
Mortgage servicing rights	407				460								407	460
Fixed assets	5,755				4,602								5,755	4,602
Net deferred loan costs	5,042				4,558								5,042	4,558
Right of use asset	10,895												10,895
Unrealized gain on fair value of securities available-for-sale	1,259				0								1,259	0
Other	314				331								314	331
Total deferred tax liabilities	44,291				29,656								44,291	29,656
Net deferred tax asset	$ 1,950				$ 3,283								$ 1,950	$ 3,283

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details)	12 Months Ended
	Dec. 31, 2019USD ($)
Operating loss carryforwards
Valuation allowance for deferred tax assets	$ 0
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
Operating loss carryforwards
Operating loss carryforwards	2,400,000
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, 2019	Dec. 31, 2018
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, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock options
Antidilutive securities excluded from the calculation of earnings per share
Average share price during the reporting period (in dollars per share)	$ 17.07	$ 17.20	$ 16.64

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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 25,591	$ 33,414	$ 26,383	$ 25,044	$ 26,467	$ 27,740	$ 26,299	$ 24,985	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 110,432	$ 105,491	$ 94,467
Weighted average common shares outstanding (in shares)													104,878,774	102,073,888	101,015,083
Dilutive potential shares due to effect of stock options (in shares)													960,375	1,492,013	1,549,822
Total weighted average common shares and dilutive potential shares (in shares)													105,839,149	103,565,901	102,564,905
Basic earnings per share (in dollars per share)	$ 0.24	$ 0.32	$ 0.25	$ 0.24	$ 0.26	$ 0.27	$ 0.26	$ 0.25	$ 0.22	$ 0.23	$ 0.31	$ 0.18	$ 1.05	$ 1.03	$ 0.94
Diluted earnings per share (in dollars per share)	$ 0.24	$ 0.31	$ 0.25	$ 0.24	$ 0.26	$ 0.27	$ 0.25	$ 0.24	$ 0.22	$ 0.23	$ 0.30	$ 0.17	$ 1.04	$ 1.02	$ 0.92

Employee Benefit Plans - Pensio

Employee Benefit Plans - Pension Plans, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee benefit plans
Employer matching contribution	100.00%
Employee matching contribution	4.00%
Total expense for all retirement plans	$ 6.7	$ 5.8	$ 6.8
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	3.6
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	217.3	175.1	186.9
Accumulated benefit obligation for unfunded defined benefit pension plan	$ 5.2	$ 4.8	$ 6.2
Target allocation of any one stock, maximum (as a percent)	10.00%
Maximum average maturity of bond portfolio	10 years
2020	$ 7.7
2021	8
2022	8.1
2023	8
2024	8.4
2025 to 2029	46.3
Pension Plans | Minimum
Employee benefit plans
Contributions to defined benefit pension plan	2
Pension Plans | Maximum
Employee benefit plans
Contributions to defined benefit pension plan	$ 4
Pension Plans | Equity securities | Minimum
Employee benefit plans
Target allocation, (as a percent)	30.00%	30.00%
Pension Plans | Equity securities | Maximum
Employee benefit plans
Target allocation, (as a percent)	60.00%	60.00%
Pension Plans | Debt securities | Minimum
Employee benefit plans
Target allocation, (as a percent)	20.00%	20.00%
Pension Plans | Debt securities | Maximum
Employee benefit plans
Target allocation, (as a percent)	50.00%	50.00%

Employee Benefit Plans - Pens_2

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of net periodic pension cost
Service cost	$ 5,949	$ 6,864	$ 6,149
Interest cost	7,353	6,712	6,879
Expected return on plan assets	(11,037)	(11,968)	(10,512)
Net amortization and deferral	1,101	1,167	1,388
Net periodic pension cost	3,366	2,775	3,904
Changes in the defined benefit pension plans’ plan assets and benefit obligations recognized in other comprehensive income
Net (gain)/loss	8,235	(1,716)	(1,647)
Amortization of prior service cost	2,323	2,323	2,323
Total recognized in other comprehensive income	10,558	607	676
Total recognized in net periodic benefit cost and other comprehensive income/(loss)	$ 13,924	$ 3,382	$ 4,580

Employee Benefit Plans - Define

Employee Benefit Plans - Defined Benefit Pension Plans' Funded Status (Details) - Pension Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Benefit obligation at beginning of year	$ 181,121	$ 193,142
Service cost	5,949	6,864	$ 6,149
Interest cost	7,353	6,712	6,879
Actuarial (gain)/loss	35,203	(19,015)
Benefits paid	(7,129)	(6,582)
Benefit obligation at end of year	222,497	181,121	193,142
Change in plan assets:
Fair value of plan assets at beginning of year	160,766	173,668
Actual return on plan assets	34,582	(8,820)
Employer contributions	5,322	2,500
Benefits paid	(7,129)	(6,582)
Fair value of plan assets at end of period	193,541	160,766	$ 173,668
Funded status at end of year	$ (28,956)	$ (20,355)
Assumptions used to develop the net periodic pension cost
Discount rate	4.15%	3.53%	4.06%
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%
Assumptions used to determine benefit obligations
Discount rate	3.14%	4.15%	3.53%
Expected long-term rate of return on assets	6.50%	7.00%	7.00%
Rate of increase in compensation levels	3.00%	3.00%	3.00%

Employee Benefit Plans - Defi_2

Employee Benefit Plans - Defined Benefit Plans Certain Information and Weighted Average Asset Allocation (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee benefit plans
Projected benefit obligation	$ 222,497	$ 181,121	$ 193,142
Accumulated benefit obligation	222,497	181,121
Fair value of plan assets	$ 193,541	$ 160,766	$ 173,668
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)	24.00%	27.00%
Equity securities
Weighted average asset allocation of defined benefit plans
Total (as a percent)	70.00%	70.00%
Other
Weighted average asset allocation of defined benefit plans
Total (as a percent)	6.00%	3.00%
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 - Pens_3

Employee Benefit Plans - Pension Plan Assets (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee benefit plans
Fair value of plan assets	$ 193,541	$ 160,766	$ 173,668
Level 1 | Mutual funds - debt
Employee benefit plans
Fair value of plan assets	46,563	43,549
Level 1 | Mutual funds - equity
Employee benefit plans
Fair value of plan assets	134,773	112,580
Level 1 | Cash and cash equivalents
Employee benefit plans
Fair value of plan assets	$ 12,204	$ 4,637

Employee Benefit Plans - Post-r

Employee Benefit Plans - Post-retirement Healthcare Plan, Narrative (Details) - Postretirement Healthcare Plan $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
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	$ 18,000
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	$ 4
Effect of 1-percent increase in assumed health care cost trend rates on postretirement benefit obligation	$ 24

Employee Benefit Plans - Post_2

Employee Benefit Plans - Post-retirement 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, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	$ 52	$ 54	$ 68
Net amortization and deferral	68	98	108
Net periodic pension cost	120	152	176
Net (gain)/loss	(475)	(305)	(156)
Total recognized in other comprehensive income	(475)	(305)	(156)
Total recognized in net periodic benefit cost and other comprehensive income/(loss)	$ (355)	$ (153)	$ 20

Employee Benefit Plans - Post_3

Employee Benefit Plans - Post-retirement Healthcare Plan - Funded Status (Details) - Postretirement Healthcare Plan - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligation:
Benefit obligation at beginning of year	$ 1,332,000	$ 1,637,000
Interest cost	52,000	54,000	$ 68,000
Actuarial (gain)/loss	(405,000)	(207,000)
Benefits paid	(90,000)	(152,000)
Benefit obligation at end of year	889,000	1,332,000	$ 1,637,000
Change in plan assets:
Employer contributions	90,000	152,000
Benefits paid	(90,000)	(152,000)
Funded status at end of year	$ (889,000)	$ (1,332,000)
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Discount rate	4.15%	3.53%	4.06%
Monthly cost of healthcare insurance per beneficiary	$ 391	$ 507	$ 548
Annual rate of increase in healthcare costs	4.00%	4.00%	4.00%
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Projected benefit obligation	$ 889,000	$ 1,332,000	$ 1,637,000	$ 889,000	$ 1,332,000
Accumulated benefit obligation				$ 889,000	$ 1,332,000

Employee Benefit Plans - Common

Employee Benefit Plans - Common Stock Awards, Narrative (Details) - Restricted common shares - USD ($) $ / shares in Units, $ in Millions	May 22, 2019	May 14, 2018	Apr. 20, 2011	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2019	Apr. 18, 2018
Stock Related Compensation
Weighted average grant date fair value of shares issued (in dollars per share)	$ 17.27	$ 16.59	$ 15.24
Market value of shares issued	$ 4.9	$ 6.9	$ 5.8
Vesting period				7 years	7 years
2011 Equity Incentive Plan
Stock Related Compensation
Number of shares authorized			2,806,233
Number of shares forfeited				58,199			539,853
Vesting period				10 years
2018 Equity Incentive Plan
Stock Related Compensation
Number of shares authorized								1,500,000
Number of shares forfeited				32,898		42,610
Vesting period				7 years
Employees
Stock Related Compensation
Number of shares awarded	256,800	390,030	353,750	256,800	390,030
Director
Stock Related Compensation
Number of shares awarded	24,300	24,300	24,300	24,300

Employee Benefit Plans - Stock

Employee Benefit Plans - Stock Option Plans, Narrative (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	May 22, 2019	May 14, 2018	May 18, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Outstanding and exercisable options
Granted (in shares)				612,210	895,960	819,010
Granted (in dollars per share)	$ 17.27	$ 16.59	$ 15.57	$ 17.27	$ 16.59	$ 15.57
Vesting period				7 years	7 years
Exercise period				10 years
Aggregate intrinsic value of all options expected to vest				$ 3.2
Aggregate intrinsic value of all options fully vested				$ 20.7
2011 Equity Incentive Plan
Outstanding and exercisable options
Number of shares authorized				7,015,583
2018 Equity Incentive Plan
Outstanding and exercisable options
Number of shares authorized				3,500,000
Employees
Outstanding and exercisable options
Granted (in shares)	547,410	831,160	754,210	547,410	831,160
Director
Outstanding and exercisable options
Granted (in shares)	64,800	64,800	64,800	64,800	64,800

Employee Benefit Plans - Share-

Employee Benefit Plans - Share-Based Awards (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	May 22, 2019	May 14, 2018	May 18, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number
Balance at beginning of year (in shares)				5,612,812	5,695,570	5,804,105
Granted (in shares)				612,210	895,960	819,010
Exercised (in shares)				(917,845)	(830,712)	(630,591)
Forfeited/ expired (in shares)				(205,826)	(148,006)	(296,954)
Balance at end of year (in shares)				5,101,351	5,612,812	5,695,570
Exercisable at end of year (in shares)				2,803,918	3,016,175	3,016,367
Weighted average exercise price
Balance at beginning of year (in dollars per share)				$ 13.49	$ 12.75	$ 12.25
Granted (in dollars per share)	$ 17.27	$ 16.59	$ 15.57	17.27	16.59	15.57
Exercised (in dollars per share)				11.77	10.38	11.66
Forfeited (in dollars per share)				14.28	12.52	12.43
Balance at end of year (in dollars per share)				14.28	13.49	12.75
Exercisable at end of year (in dollars per share)				13.36	12.61	11.99
Weighted average fair value of options at grant date (in dollars per share)				$ 1.14	$ 1.49	$ 1.55
Intrinsic value of options exercised				$ 5.2	$ 4.8	$ 3.5

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, 2019	Dec. 31, 2018
Exercise price $11.49
Options outstanding:
Number of options (in shares)	67,501
Weighted average remaining contract life (years)	3 months
Options exercisable:
Number of options (in shares)	67,501
Weighted average remaining term - vested (years)	3 months
Exercise price $11.70
Options outstanding:
Number of options (in shares)	280,681
Weighted average remaining contract life (years)	2 years 6 months
Options exercisable:
Number of options (in shares)	229,262
Weighted average remaining term - vested (years)	2 years 6 months
Exercise price $12.12
Options outstanding:
Number of options (in shares)	136,425
Weighted average remaining contract life (years)	1 year
Options exercisable:
Number of options (in shares)	136,425
Weighted average remaining term - vested (years)	1 year
Exercise price $12.17
Options outstanding:
Number of options (in shares)	3,200
Weighted average remaining contract life (years)	1 year 3 months
Options exercisable:
Number of options (in shares)	3,200
Weighted average remaining term - vested (years)	1 year 3 months
Exercise price $12.32
Options outstanding:
Number of options (in shares)	917,438
Weighted average remaining contract life (years)	1 year 6 months
Options exercisable:
Number of options (in shares)	812,791
Weighted average remaining term - vested (years)	1 year 6 months
Exercise price $12.37
Options outstanding:
Number of options (in shares)	420,660
Weighted average remaining contract life (years)	5 years 6 months
Options exercisable:
Number of options (in shares)	225,735
Weighted average remaining term - vested (years)	5 years 6 months
Exercise price $12.44
Options outstanding:
Number of options (in shares)	326,824
Weighted average remaining contract life (years)	3 years 6 months
Options exercisable:
Number of options (in shares)	238,918
Weighted average remaining term - vested (years)	3 years 6 months
Exercise price $13.15
Options outstanding:
Number of options (in shares)	351,842
Weighted average remaining contract life (years)	4 years 6 months
Options exercisable:
Number of options (in shares)	222,818
Weighted average remaining term - vested (years)	4 years 6 months
Exercise price $14.15
Options outstanding:
Number of options (in shares)	536,889
Weighted average remaining contract life (years)	6 years 6 months
Options exercisable:
Number of options (in shares)	243,507
Weighted average remaining term - vested (years)	6 years 6 months
Exercise price $15.57
Options outstanding:
Number of options (in shares)	660,074
Weighted average remaining contract life (years)	7 years 6 months
Options exercisable:
Number of options (in shares)	242,244
Weighted average remaining term - vested (years)	7 years 6 months
Exercise price $16.59
Options outstanding:
Number of options (in shares)	813,975
Weighted average remaining contract life (years)	5 years 6 months
Options exercisable:
Number of options (in shares)	284,495
Weighted average remaining term - vested (years)	5 years 6 months
Exercise price $17.27
Options outstanding:
Number of options (in shares)	585,842
Weighted average remaining contract life (years)	6 years 6 months
Options exercisable:
Number of options (in shares)	97,022
Weighted average remaining term - vested (years)	6 years 6 months
Total $14.28
Options outstanding:
Number of options (in shares)	5,101,351
Weighted average remaining contract life (years)	4 years 8 months 15 days
Options exercisable:
Number of options (in shares)	2,803,918
Weighted average remaining term - vested (years)	3 years 9 months 14 days
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 | Exercise price $16.59
Outstanding and exercisable options
Exercise price (in dollars per share)		16.59
Stock options | Exercise price $17.27
Outstanding and exercisable options
Exercise price (in dollars per share)		17.27
Stock options | Total $14.28
Outstanding and exercisable options
Exercise price (in dollars per share)		$ 14.28

Disclosures About Fair Value _3

Disclosures About Fair Value of Financial Instruments - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Significant unrealized appreciation or depreciation in financial instruments	$ 0	$ 0
Financial assets:
Securities available-for-sale	819,901,000	801,450,000
Securities held-to-maturity	18,223,000	22,446,000
Accrued interest receivable	25,755,000	24,490,000
Derivative asset	21,593,000	6,445,000
Financial liabilities:
Junior subordinated debentures	121,800,000	111,213,000
Interest rate swaps	20,991,000	6,445,000
Assets transferred between Level 1 and Level 2	0	0
Level 1
Financial assets:
Cash and cash equivalents	60,846,000	68,789,000
Securities available-for-sale	0	0
Securities held-to-maturity	0	0
Loans receivable, net	0	0
Residential mortgage loans held-for-sale	0
Accrued interest receivable	25,755,000	24,490,000
Derivative asset		0
FHLB stock	0	0
Total assets	86,601,000	93,279,000
Financial liabilities:
Savings and checking accounts	7,022,597,000	6,489,338,000
Time deposits	0	0
Borrowed funds	246,341,000	234,389,000
Junior subordinated debentures	0	0
Accrued interest payable	1,142,000	744,000
Total financial liabilities	7,270,080,000	6,724,471,000
Level 2
Financial assets:
Cash and cash equivalents	0	0
Securities available-for-sale	819,901,000	801,450,000
Securities held-to-maturity	18,223,000	22,446,000
Loans receivable, net	0	0
Residential mortgage loans held-for-sale	0
Accrued interest receivable	0	0
Derivative asset		6,445,000
FHLB stock	0	0
Total assets	859,158,000	830,341,000
Financial liabilities:
Savings and checking accounts	0	0
Time deposits	0	0
Borrowed funds	0	0
Junior subordinated debentures	0	0
Accrued interest payable	0	0
Total financial liabilities	20,991,000	6,445,000
Level 3
Financial assets:
Cash and cash equivalents	0	0
Securities available-for-sale	0	0
Securities held-to-maturity	0	0
Loans receivable, net	8,666,149,000	7,845,313,000
Residential mortgage loans held-for-sale	7,709,000
Accrued interest receivable	0	0
Derivative asset		0
FHLB stock	0	0
Total assets	8,674,417,000	7,845,313,000
Financial liabilities:
Savings and checking accounts	0	0
Time deposits	1,574,063,000	1,434,410,000
Borrowed funds	0	0
Junior subordinated debentures	115,518,000	102,572,000
Accrued interest payable	0	0
Total financial liabilities	1,689,581,000	1,536,982,000
Carrying amount
Financial assets:
Cash and cash equivalents	60,846,000	68,789,000
Securities available-for-sale	819,901,000	801,450,000
Securities held-to-maturity	18,036,000	22,765,000
Loans receivable, net	8,743,024,000	7,996,225,000
Residential mortgage loans held-for-sale	7,709,000
Accrued interest receivable	25,755,000	24,490,000
Derivative asset		6,445,000
FHLB stock	14,740,000	15,635,000
Total assets	9,711,604,000	8,935,799,000
Financial liabilities:
Savings and checking accounts	7,022,597,000	6,489,338,000
Time deposits	1,569,410,000	1,404,841,000
Borrowed funds	246,336,000	234,389,000
Junior subordinated debentures	121,800,000	111,213,000
Accrued interest payable	1,142,000	744,000
Total financial liabilities	8,982,276,000	8,246,970,000
Estimated fair value
Financial assets:
Cash and cash equivalents	60,846,000	68,789,000
Securities available-for-sale	819,901,000	801,450,000
Securities held-to-maturity	18,223,000	22,446,000
Loans receivable, net	8,666,149,000	7,845,313,000
Residential mortgage loans held-for-sale	7,709,000
Accrued interest receivable	25,755,000	24,490,000
Derivative asset		6,445,000
FHLB stock	14,740,000	15,635,000
Total assets	9,634,916,000	8,784,568,000
Financial liabilities:
Savings and checking accounts	7,022,597,000	6,489,338,000
Time deposits	1,574,063,000	1,434,410,000
Borrowed funds	246,341,000	234,389,000
Junior subordinated debentures	115,518,000	102,572,000
Accrued interest payable	1,142,000	744,000
Total financial liabilities	8,980,652,000	8,267,898,000
Interest rate lock commitments | Level 1
Financial assets:
Derivative asset	0
Interest rate lock commitments | Level 2
Financial assets:
Derivative asset	0
Interest rate lock commitments | Level 3
Financial assets:
Derivative asset	559,000
Interest rate lock commitments | Carrying amount
Financial assets:
Derivative asset	559,000
Interest rate lock commitments | Estimated fair value
Financial assets:
Derivative asset	559,000
Forward commitments | Level 1
Financial assets:
Derivative asset	0
Forward commitments | Level 2
Financial assets:
Derivative asset	145,000
Forward commitments | Level 3
Financial assets:
Derivative asset	0
Forward commitments | Carrying amount
Financial assets:
Derivative asset	145,000
Forward commitments | Estimated fair value
Financial assets:
Derivative asset	145,000
Interest rate swaps | Level 1
Financial assets:
Derivative asset	0
Financial liabilities:
Interest rate swaps	0	0
Interest rate swaps | Level 2
Financial assets:
Derivative asset	20,889,000
Financial liabilities:
Interest rate swaps	20,952,000	6,445,000
Interest rate swaps | Level 3
Financial assets:
Derivative asset	0
Financial liabilities:
Interest rate swaps	0	0
Interest rate swaps | Carrying amount
Financial assets:
Derivative asset	20,889,000
Financial liabilities:
Interest rate swaps	20,952,000	6,445,000
Interest rate swaps | Estimated fair value
Financial assets:
Derivative asset	20,889,000
Financial liabilities:
Interest rate swaps	20,952,000	$ 6,445,000
Risk participation agreements | Level 1
Financial liabilities:
Interest rate swaps	0
Risk participation agreements | Level 2
Financial liabilities:
Interest rate swaps	39,000
Risk participation agreements | Level 3
Financial liabilities:
Interest rate swaps	0
Risk participation agreements | Carrying amount
Financial liabilities:
Interest rate swaps	39,000
Risk participation agreements | Estimated fair value
Financial liabilities:
Interest rate swaps	$ 39,000

Disclosures About Fair Value _4

Disclosures About Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	$ 819,901	$ 801,450
Derivative asset	21,593	6,445
Cash flow hedges - interest rate swaps	20,991	6,445
Level 1
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Derivative asset		0
Total assets	86,601	93,279
Level 2
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	819,901	801,450
Derivative asset		6,445
Total assets	859,158	830,341
Level 3
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	0	0
Derivative asset		0
Total assets	8,674,417	7,845,313
Measured on recurring basis
Assets and liabilities measured at fair value on a recurring basis
Total assets	841,494	807,895
Total liabilities	20,952	6,445
Measured on recurring basis | Debt securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	146,742	224,192
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	14,991	14,780
Measured on recurring basis | Debt securities | Government sponsored enterprises
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	104,784	187,335
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	26,048	21,163
Measured on recurring basis | Debt securities | Corporate
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	919	914
Measured on recurring basis | Interest rate lock commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	559
Measured on recurring basis | Forward commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	145
Measured on recurring basis | Interest rate swaps
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	20,889	6,445
Cash flow hedges - interest rate swaps	20,952	6,445
Measured on recurring basis | Mortgage-backed securities
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	673,159	577,258
Measured on recurring basis | Residential mortgage-backed securities | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	23,264	27,041
Measured on recurring basis | Residential mortgage-backed securities | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	89,259	73,196
Measured on recurring basis | Residential mortgage-backed securities | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	50,139	51,621
Measured on recurring basis | Residential mortgage-backed securities | Non-agency
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	497	528
Measured on recurring basis | Collateralized mortgage obligations | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	207,016	52,331
Measured on recurring basis | Collateralized mortgage obligations | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	184,682	207,033
Measured on recurring basis | Collateralized mortgage obligations | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	118,302	165,508
Measured on recurring basis | Level 1
Assets and liabilities measured at fair value on a recurring basis
Total assets	0	0
Total liabilities	0	0
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 lock commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	0
Measured on recurring basis | Level 1 | Forward commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	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 - interest rate 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 2
Assets and liabilities measured at fair value on a recurring basis
Total assets	840,935	807,895
Total liabilities	20,952	6,445
Measured on recurring basis | Level 2 | Debt securities
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	146,742	224,192
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	14,991	14,780
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	104,784	187,335
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	26,048	21,163
Measured on recurring basis | Level 2 | Debt securities | Corporate
Assets and liabilities measured at fair value on a recurring basis
Securities available-for-sale	919	914
Measured on recurring basis | Level 2 | Interest rate lock commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	0
Measured on recurring basis | Level 2 | Forward commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	145
Measured on recurring basis | Level 2 | Interest rate swaps
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	20,889	6,445
Cash flow hedges - interest rate swaps	20,952	6,445
Measured on recurring basis | Level 2 | Mortgage-backed securities
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	673,159	577,258
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	23,264	27,041
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	89,259	73,196
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	50,139	51,621
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	497	528
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | GNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	207,016	52,331
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | FNMA
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	184,682	207,033
Measured on recurring basis | Level 2 | Collateralized mortgage obligations | FHLMC
Assets and liabilities measured at fair value on a recurring basis
Mortgage-backed securities	118,302	165,508
Measured on recurring basis | Level 3
Assets and liabilities measured at fair value on a recurring basis
Total assets	559	0
Total liabilities	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	0
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	0
Measured on recurring basis | Level 3 | Interest rate lock commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	559
Measured on recurring basis | Level 3 | Forward commitments
Assets and liabilities measured at fair value on a recurring basis
Derivative asset	0
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 - interest rate 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

Disclosures About Fair Value _5

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, 2019	Dec. 31, 2018
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	$ 0	$ 0
Total gains or losses:
Included in net income	0	0
Purchases	559	0
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at the end of the period	$ 559	$ 0

Disclosures About Fair Value _6

Disclosures About Fair Value of Financial Instruments - Nonrecurring Assets that had Fair Market Values Below the Carrying Amount (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	$ 86,601	$ 93,279
Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	859,158	830,341
Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	8,674,417	7,845,313
Loans measured for impairment
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	46,238
Real estate owned, net
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	950
Fair Value, Measurements, Nonrecurring
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	47,188	42,831
Fair Value, Measurements, Nonrecurring | Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	0	0
Fair Value, Measurements, Nonrecurring | Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	0	0
Fair Value, Measurements, Nonrecurring | Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	47,188	42,831
Fair Value, Measurements, Nonrecurring | Loans measured for impairment
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	46,238	40,333
Fair Value, Measurements, Nonrecurring | Loans measured for impairment | Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	0	0
Fair Value, Measurements, Nonrecurring | Loans measured for impairment | Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	0	0
Fair Value, Measurements, Nonrecurring | Loans measured for impairment | Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	46,238	40,333
Fair Value, Measurements, Nonrecurring | Real estate owned, net
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	950	2,498
Fair Value, Measurements, Nonrecurring | Real estate owned, net | Level 1
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	0	0
Fair Value, Measurements, Nonrecurring | Real estate owned, net | Level 2
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	0	0
Fair Value, Measurements, Nonrecurring | Real estate owned, net | Level 3
Fair value measurement for nonrecurring assets that had a fair market value below the carrying amount
Fair value	$ 950	$ 2,498

Disclosures About Fair Value _7

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, 2019USD ($)
Loans measured for impairment
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value	$ 46,238
Loans measured for impairment | Appraisal Value
Quantitative information for Level 3 Fair Value Measurements Assets
Estimated costs to sell	10.00%
Real estate owned, net
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value	$ 950
Real estate owned, net | Appraisal Value
Quantitative information for Level 3 Fair Value Measurements Assets
Estimated costs to sell	10.00%
Measurement Input, Discount Rate | Loans measured for impairment | Discounted Cash Flow | Minimum
Quantitative information for Level 3 Fair Value Measurements Assets
Discount rate	0.0425
Measurement Input, Discount Rate | Loans measured for impairment | Discounted Cash Flow | Maximum
Quantitative information for Level 3 Fair Value Measurements Assets
Discount rate	0.110
Measurement Input, Discount Rate | Loans measured for impairment | Discounted Cash Flow | Weighted Average
Quantitative information for Level 3 Fair Value Measurements Assets
Discount rate	0.0750

Regulatory Capital Requiremen_3

Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Tier 1 capital (leverage) (to average assets)
Minimum capital requirements (as a percent)	2.50%	1.875%
Northwest Bank
Total capital (to risk weighted assets)
Actual amount	$ 1,146,641	$ 1,026,027
Actual ratio (as a percent)	13.858%	13.736%
Capital required for capital adequacy	$ 868,768	$ 737,647
Minimum capital requirements ratio (as a percent)	10.50%	9.875%
Well capitalized requirements amount	$ 827,398	$ 746,984
Well capitalized requirements ratio (as a percent)	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Actual amount	$ 1,087,727	$ 970,813
Actual ratio (as a percent)	13.146%	12.996%
Minimum capital requirements amount	$ 703,288	$ 588,250
Minimum capital requirements ratio (as a percent)	8.50%	7.875%
Well capitalized requirements amount	$ 661,918	$ 597,587
Well capitalized requirements ratio (as a percent)	8.00%	8.00%
CET 1 capital (to risk weighted assets)
Actual amount	$ 1,087,727	$ 970,813
Actual ratio (as a percent)	13.146%	12.996%
Minimum capital requirements amount	$ 579,178	$ 476,202
Minimum capital requirements ratio (as a percent)	7.00%	6.375%
Well capitalized requirements amount	$ 537,809	$ 448,190
Well capitalized requirements ratio (as a percent)	6.50%	6.50%
Tier 1 capital (leverage) (to average assets)
Actual amount	$ 1,087,727	$ 970,813
Actual ratio (as a percent)	10.515%	10.24%
Minimum capital requirements amount	$ 413,772	$ 379,236
Minimum capital requirements ratio (as a percent)	4.00%	4.00%
Well capitalized requirements amount	$ 517,216	$ 474,045
Well capitalized requirements ratio (as a percent)	5.00%	5.00%
Northwest Bancshares, Inc.
Total capital (to risk weighted assets)
Actual amount	$ 1,300,321	$ 1,183,619
Actual ratio (as a percent)	15.701%	15.833%
Capital required for capital adequacy	$ 869,585	$ 738,212
Minimum capital requirements ratio (as a percent)	10.50%	9.875%
Well capitalized requirements amount	$ 828,176	$ 747,557
Well capitalized requirements ratio (as a percent)	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Actual amount	$ 1,242,380	$ 1,128,405
Actual ratio (as a percent)	15.001%	15.095%
Minimum capital requirements amount	$ 703,950	$ 588,701
Minimum capital requirements ratio (as a percent)	8.50%	7.875%
Well capitalized requirements amount	$ 662,541	$ 598,045
Well capitalized requirements ratio (as a percent)	8.00%	8.00%
CET 1 capital (to risk weighted assets)
Actual amount	$ 1,124,259	$ 1,020,530
Actual ratio (as a percent)	13.575%	13.652%
Minimum capital requirements amount	$ 579,723	$ 476,567
Minimum capital requirements ratio (as a percent)	7.00%	6.375%
Well capitalized requirements amount	$ 538,314	$ 485,912
Well capitalized requirements ratio (as a percent)	6.50%	6.50%
Tier 1 capital (leverage) (to average assets)
Actual amount	$ 1,242,380	$ 1,128,405
Actual ratio (as a percent)	11.913%	11.899%
Minimum capital requirements amount	$ 417,143	$ 379,342
Minimum capital requirements ratio (as a percent)	4.00%	4.00%
Well capitalized requirements amount	$ 521,428	$ 474,177
Well capitalized requirements ratio (as a percent)	5.00%	5.00%

Components of Accumulated Oth_3

Components of Accumulated Other Comprehensive Income - (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	$ 1,353,285	$ 1,257,638	$ 1,207,724	$ 1,170,663
Unrealized gain/(loss) on marketable securities available-for-sale
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	3,147	(6,832)	(4,409)	395
Defined benefit pension plans
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	(40,088)	(32,864)	(26,980)	(26,608)
Accumulated other comprehensive loss
Accumulated other comprehensive income (net of tax)
Shareholders’ equity	$ (36,941)	$ (39,696)	$ (32,080)	$ (27,991)

Components of Accumulated Oth_4

Components of Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	$ 1,257,638	$ 1,207,724	$ 1,170,663
Reclassification due to adoption of ASU No. 2018-02		(6,746)
Other comprehensive income/(loss) before reclassification adjustments	1,925	(1,618)
Amounts reclassified from accumulated other comprehensive income	830	748
Other comprehensive income/(loss)	2,755	(7,616)
Balance at end of the period	1,353,285	1,257,638	1,207,724
Reclassification adjustment for gains (losses) on securities, net of tax	5	155	2,326
Income tax (expense) benefit related to (gain) loss on securities	(2)	(60)	(1,488)
Amortization of prior service cost (compensation and employee benefits)	835	903	882
Income tax expense (benefit) related to compensation and employee benefits	334	746	613
Unrealized gain/(loss) on marketable securities available-for-sale
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	(6,832)	(4,409)	395
Reclassification due to adoption of ASU No. 2018-02		(991)
Other comprehensive income/(loss) before reclassification adjustments	9,984	(1,277)	(2,478)
Amounts reclassified from accumulated other comprehensive income	(5)	(155)	(2,326)
Other comprehensive income/(loss)	9,979	(2,423)	(4,804)
Balance at end of the period	3,147	(6,832)	(4,409)
Reclassification adjustment for gains (losses) on securities, net of tax	7	215	3,814
Income tax (expense) benefit related to (gain) loss on securities	(2)	60	1,488
Change in fair value of interest rate swaps
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	0	(691)	(1,778)
Reclassification due to adoption of ASU No. 2018-02		(149)
Other comprehensive income/(loss) before reclassification adjustments		840	1,087
Amounts reclassified from accumulated other comprehensive income		0	0
Other comprehensive income/(loss)		691	1,087
Balance at end of the period		0	(691)
Defined benefit pension plans
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	(32,864)	(26,980)	(26,608)
Reclassification due to adoption of ASU No. 2018-02		(5,606)
Other comprehensive income/(loss) before reclassification adjustments	(8,059)	(1,181)	(1,254)
Amounts reclassified from accumulated other comprehensive income	835	903	882
Other comprehensive income/(loss)	(7,224)	(5,884)	(372)
Balance at end of the period	(40,088)	(32,864)	(26,980)
Amortization of prior service cost (compensation and employee benefits)	2,323	2,323	2,323
Amortization of net loss (compensation and employee benefits)	(3,492)	(3,587)	(3,818)
Income tax expense (benefit) related to compensation and employee benefits	334	361	613
Accumulated other comprehensive loss
Changes in accumulated other comprehensive income by component
Balance at beginning of the period	(39,696)	(32,080)	(27,991)
Reclassification due to adoption of ASU No. 2018-02		(6,746)
Other comprehensive income/(loss) before reclassification adjustments			(2,645)
Amounts reclassified from accumulated other comprehensive income			(1,444)
Other comprehensive income/(loss)			(4,089)
Balance at end of the period	$ (36,941)	$ (39,696)	$ (32,080)

Parent Company Only Financial_3

Parent Company Only Financial Statements - Condensed - Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 60,846	$ 68,789
Other assets	97,268	34,211
Total assets	10,493,908	9,607,773
Liabilities:
Debentures payable	121,800	111,213
Other liabilities	134,782	66,312
Total liabilities	9,140,623	8,350,135
Shareholders’ equity	1,353,285	1,257,638	$ 1,207,724	$ 1,170,663
Total liabilities and shareholders’ equity	10,493,908	9,607,773
Parent Company
Assets
Cash and cash equivalents	150,926	155,524
Investment in bank subsidiary	1,314,724	1,211,258
Other assets	9,817	2,298
Total assets	1,475,467	1,369,080
Liabilities:
Debentures payable	121,801	111,213
Other liabilities	381	230
Total liabilities	122,182	111,443
Shareholders’ equity	1,353,285	1,257,637
Total liabilities and shareholders’ equity	$ 1,475,467	$ 1,369,080

Parent Company Only Financial_4

Parent Company Only Financial Statements - Condensed - Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income:
Interest income	$ 103,418	$ 106,866	$ 106,807	$ 100,289	$ 97,768	$ 95,605	$ 92,875	$ 89,533	$ 91,561	$ 90,231	$ 89,797	$ 87,267	$ 417,380	$ 375,781	$ 358,856
Expense:
Other expense													13,995	11,333	10,562
Interest expense	14,473	15,930	14,204	12,307	10,937	9,788	8,649	7,766	7,321	6,994	7,066	6,690	56,914	37,140	28,071
Income before income taxes	32,364	43,207	33,787	31,753	34,014	34,775	33,199	31,925	28,724	36,005	45,384	25,798	141,111	133,913	135,911
Federal and state income taxes	6,773	9,793	7,404	6,709	7,547	7,035	6,900	6,940	6,576	12,414	14,402	8,052	30,679	28,422	41,444
Net income	$ 25,591	$ 33,414	$ 26,383	$ 25,044	$ 26,467	$ 27,740	$ 26,299	$ 24,985	$ 22,148	$ 23,591	$ 30,982	$ 17,746	110,432	105,491	94,467
Parent Company
Income:
Interest income													209	198	137
Other income													628	752	2,297
Dividends from bank subsidiary													110,000	105,000	90,000
Undistributed earnings from equity investment in bank subsidiary													5,102	5,149	7,255
Total income													115,939	111,099	99,689
Expense:
Compensation and benefits													1,124	1,225	1,282
Other expense													791	660	553
Interest expense													4,833	4,961	4,666
Total expense													6,748	6,846	6,501
Income before income taxes													109,191	104,253	93,188
Federal and state income taxes													(1,241)	(1,238)	(1,279)
Net income													$ 110,432	$ 105,491	$ 94,467

Parent Company Only Financial_5

Parent Company Only Financial Statements - Condensed - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net income	$ 25,591	$ 33,414	$ 26,383	$ 25,044	$ 26,467	$ 27,740	$ 26,299	$ 24,985	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 110,432	$ 105,491	$ 94,467
Adjustments to reconcile net income to net cash provided by operating activities:
Noncash stock benefit plan compensation expense													6,845	7,023	4,894
Gain on sale of marketable securities													(50)	(157)	(1,148)
Net cash provided by operating activities													127,462	138,909	151,798
Investing activities:
Net (purchase)/sale of marketable securities													32,389	5,206	36,811
Net cash provided used in investing activities													(300,593)	(281,913)	(104,040)
Financing activities:
Cash dividends paid on common stock													(76,173)	(69,921)	(65,212)
Proceeds from stock options exercised													9,727	8,190	7,001
Net cash provided by/(used) in financing activities													165,188	134,083	(359,915)
Net decrease in cash and cash equivalents													(7,943)	(8,921)	(312,157)
Cash and cash equivalents at beginning of period				68,789				77,710				389,867	68,789	77,710	389,867
Cash and cash equivalents at end of period	60,846				68,789				77,710				60,846	68,789	77,710
Parent Company
Operating activities:
Net income													110,432	105,491	94,467
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiary													(5,102)	(5,149)	(7,255)
Noncash stock benefit plan compensation expense													0	0	4,894
Gain on sale of marketable securities													(29)	(146)	(1,615)
Net change in other assets and liabilities													(43,453)	91,520	(43,513)
Net cash provided by operating activities													61,848	191,716	46,978
Investing activities:
Net (purchase)/sale of marketable securities													0	(550)	2,800
Net cash provided used in investing activities													0	(550)	2,800
Financing activities:
Cash dividends paid on common stock													(76,173)	(69,921)	(65,212)
Proceeds from stock options exercised													9,727	8,191	7,001
Net cash provided by/(used) in financing activities													(66,446)	(61,730)	(58,211)
Net decrease in cash and cash equivalents													(4,598)	129,436	(8,433)
Cash and cash equivalents at beginning of period				$ 155,524				$ 26,088				$ 34,521	155,524	26,088	34,521
Cash and cash equivalents at end of period	$ 150,926				$ 155,524				$ 26,088				$ 150,926	$ 155,524	$ 26,088

Derivative Financial Instrume_3

Derivative Financial Instruments - Narrative (Details) $ in Millions	Dec. 31, 2019USD ($)
Cash flow hedges | Interest rate swaps
Derivative [Line Items]
Notional amount	$ 50

Derivative Financial Instrume_4

Derivative Financial Instruments - Schedule of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative asset, notional amount	$ 421,026	$ 221,919
Derivative asset	21,593	6,445
Derivative liability, notional amount	432,666	221,919
Cash flow hedges - interest rate swaps	20,991	6,445
Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Derivative asset, notional amount	391,502	221,919
Derivative asset	20,889	6,445
Derivative liability, notional amount	391,502	221,919
Cash flow hedges - interest rate swaps	20,952	$ 6,445
Derivatives not designated as hedging instruments: | Interest rate lock commitments
Derivative [Line Items]
Derivative asset, notional amount	24,373
Derivative asset	559
Derivative liability, notional amount	0
Cash flow hedges - interest rate swaps	0
Derivatives not designated as hedging instruments: | Forward commitments
Derivative [Line Items]
Derivative asset, notional amount	5,151
Derivative asset	145
Derivative liability, notional amount	0
Cash flow hedges - interest rate swaps	0
Derivatives not designated as hedging instruments: | Risk participation agreements
Derivative [Line Items]
Derivative asset, notional amount	0
Derivative asset	0
Derivative liability, notional amount	41,164
Cash flow hedges - interest rate swaps	$ 39

Derivative Financial Instrume_5

Derivative Financial Instruments - Gain (Loss) on Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Increase in interest expense	$ 0
Increase in interest expense		$ 949	$ 1,599
Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on non-hedging swap derivatives	$ (63)	$ (288)	$ (373)

Selected Quarterly Financial _3

Selected Quarterly Financial Data - Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 103,418	$ 106,866	$ 106,807	$ 100,289	$ 97,768	$ 95,605	$ 92,875	$ 89,533	$ 91,561	$ 90,231	$ 89,797	$ 87,267	$ 417,380	$ 375,781	$ 358,856
Interest expense	14,473	15,930	14,204	12,307	10,937	9,788	8,649	7,766	7,321	6,994	7,066	6,690	56,914	37,140	28,071
Net interest income	88,945	90,936	92,603	87,982	86,831	85,817	84,226	81,767	84,240	83,237	82,731	80,577	360,466	338,641	330,785
Provision for loan losses	8,223	3,302	4,667	6,467	3,792	6,982	5,349	4,209	6,525	3,027	5,562	4,637	22,659	20,332	19,751
Noninterest income	28,213	26,169	23,363	21,662	23,248	22,557	24,109	21,788	22,905	24,594	41,477	21,504	99,407	91,702	110,480
Noninterest expense	76,571	70,596	77,512	71,424	72,273	66,617	69,787	67,421	71,896	68,799	73,262	71,646	296,103	276,098	285,603
Income before income taxes	32,364	43,207	33,787	31,753	34,014	34,775	33,199	31,925	28,724	36,005	45,384	25,798	141,111	133,913	135,911
Income tax expense/ (benefit)	6,773	9,793	7,404	6,709	7,547	7,035	6,900	6,940	6,576	12,414	14,402	8,052	30,679	28,422	41,444
Net income	$ 25,591	$ 33,414	$ 26,383	$ 25,044	$ 26,467	$ 27,740	$ 26,299	$ 24,985	$ 22,148	$ 23,591	$ 30,982	$ 17,746	$ 110,432	$ 105,491	$ 94,467
Basic earnings per share (in dollars per share)	$ 0.24	$ 0.32	$ 0.25	$ 0.24	$ 0.26	$ 0.27	$ 0.26	$ 0.25	$ 0.22	$ 0.23	$ 0.31	$ 0.18	$ 1.05	$ 1.03	$ 0.94
Diluted earnings per share (in dollars per share)	$ 0.24	$ 0.31	$ 0.25	$ 0.24	$ 0.26	$ 0.27	$ 0.25	$ 0.24	$ 0.22	$ 0.23	$ 0.30	$ 0.17	$ 1.04	$ 1.02	$ 0.92

Subsequent Events -Narrative (D

Subsequent Events -Narrative (Details) - Mutual First Financial, Inc. $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Subsequent Event [Line Items]
Entity shares issued per acquiree share (in shares) | shares	2.4
Value of stock issued for purchase | $	$ 346
Value of stock issued (in dollars per share) | $ / shares	$ 39.89

Uncategorized Items - nwbi-1231

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (1,226,000)
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (1,226,000)