Meridian Bancorp (EBSB) 10-Q 10 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 03, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Trading Symbol	EBSB
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Registrant Name	Meridian Bancorp, Inc.
Entity Central Index Key	0001600125
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	001-36573
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	46-5396964
Entity Address, Address Line One	67 Prospect Street
Entity Address, City or Town	Peabody
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01960
City Area Code	617
Local Phone Number	567-1500
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		52,454,271

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
ASSETS
Cash and due from banks	$ 1,034,107	$ 914,586
Securities available for sale, at fair value	10,518	11,326
Marketable equity securities, at fair value	8,900	12,189
Federal Home Loan Bank stock, at cost	28,447	30,658
Loans held for sale	7,422	8,224
Loans, net of deferred fees and costs	5,287,431	5,512,629
Less: allowance for credit losses on loans	(63,436)	(68,824)
Loans, net	5,223,995	5,443,805
Bank-owned life insurance	42,138	41,877
Premises and equipment, net	65,394	66,850
Accrued interest receivable	22,498	23,173
Deferred tax asset, net	21,418	21,355
Goodwill	20,378	20,378
Core deposit intangible	1,548	1,651
Other assets	17,162	23,776
Total assets	6,503,925	6,619,848
Deposits:
Non interest-bearing	751,809	711,573
Interest-bearing	4,345,560	4,369,594
Total deposits	5,097,369	5,081,167
Long-term debt	560,625	708,245
Accrued expenses and other liabilities	56,847	61,551
Total liabilities	5,714,841	5,850,963
Stockholders' equity:
Preferred stock, $0.01 par value, 50,000,000 shares authorized; none issued
Common stock, $0.01 par value, 100,000,000 shares authorized; 52,430,554 and 52,415,061 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	524	524
Additional paid-in capital	364,751	363,995
Retained earnings	439,593	420,297
Accumulated other comprehensive loss	(131)	(58)
Unearned compensation - ESOP, 2,161,304 and 2,191,745 shares at March 31, 2021 and December 31, 2020, respectively	(15,653)	(15,873)
Total stockholders' equity	789,084	768,885
Total liabilities and stockholders' equity	$ 6,503,925	$ 6,619,848

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	52,430,554	52,415,061
Common stock, shares outstanding	52,430,554	52,415,061
Unearned compensation, ESOP	2,161,304	2,191,745

Consolidated Statements of Net

Consolidated Statements of Net Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest and dividend income:
Interest and fees on loans	$ 57,162	$ 64,037
Interest on debt securities	65	100
Dividends on marketable equity securities	124	94
Other interest and dividend income	370	1,787
Total interest and dividend income	57,721	66,018
Interest expense:
Interest on deposits	5,729	16,769
Interest on short-term borrowings		8
Interest on borrowings	3,591	4,143
Total interest expense	9,320	20,920
Net interest income	48,401	45,098
Provision (reversal) for credit losses	(5,236)	725
Net interest income, after provision (reversal) for credit losses	53,637	44,373
Non-interest income:
Customer service fees	2,199	2,097
Loan fees	95	674
Mortgage banking gains, net	582	411
Gain (loss) on marketable equity securities, net	1,785	(4,344)
Income from bank-owned life insurance	261	297
Other income	9	34
Total non-interest income (loss)	4,931	(831)
Non-interest expenses:
Salaries and employee benefits	15,516	15,914
Occupancy and equipment	4,231	3,924
Data processing	2,241	2,137
Marketing and advertising	896	1,230
Professional services	730	997
Deposit insurance	513	669
Other general and administrative	1,416	1,449
Total non-interest expenses	25,543	26,320
Income before income taxes	33,025	17,222
Provision for income taxes	8,705	4,245
Net income	$ 24,320	$ 12,977
Earnings per share:
Basic	$ 0.48	$ 0.26
Diluted	$ 0.48	$ 0.25
Weighted average shares outstanding:
Basic	50,239,611	50,634,983
Diluted	50,565,459	50,920,259

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 24,320	$ 12,977
Securities available for sale:
Net unrealized (loss) gain	(102)	230
Tax effect	29	(64)
Total other comprehensive (loss) income	(73)	166
Comprehensive income	$ 24,247	$ 13,143

Consolidated Statements of Chan

Consolidated Statements of Changes In Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Unearned Compensation - ESOP [Member]
Beginning Balance at Dec. 31, 2019	$ 726,587	$ 534	$ 377,213	$ 365,742	$ (147)	$ (16,755)
Beginning balance, shares at Dec. 31, 2019		53,377,506
Comprehensive income	13,143			12,977	166
Dividends declared	(4,007)			(4,007)
Repurchased stock related to buyback program	(17,680)	$ (10)	(17,670)
Repurchased stock related to buyback program, shares		(1,000,000)
ESOP shares committed to be allocated	507		287			220
Share-based compensation expense - restricted stock, net of awards forfeited	640		640
Share-based compensation expense - restricted stock, net of awards forfeited, shares		(5,245)
Share-based compensation expense - stock options, net of awards forfeited	380		380
Stock options exercised	51		51
Stock options exercised, shares		30,134
Ending Balance at Mar. 31, 2020	719,621	$ 524	360,901	374,712	19	(16,535)
Ending balance, shares at Mar. 31, 2020		52,402,395
Beginning Balance at Dec. 31, 2020	$ 768,885	$ 524	363,995	420,297	(58)	(15,873)
Beginning balance, shares at Dec. 31, 2020	52,415,061	52,415,061
Comprehensive income	$ 24,247			24,320	(73)
Dividends declared	(5,024)			(5,024)
ESOP shares committed to be allocated	512		292			220
Share-based compensation expense - restricted stock, net of awards forfeited	235		235
Share-based compensation expense - restricted stock, net of awards forfeited, shares		(2,800)
Share-based compensation expense - stock options, net of awards forfeited	137		137
Stock options exercised	92		92
Stock options exercised, shares		18,293
Ending Balance at Mar. 31, 2021	$ 789,084	$ 524	$ 364,751	$ 439,593	$ (131)	$ (15,653)
Ending balance, shares at Mar. 31, 2021	52,430,554	52,430,554

Consolidated Statements of Ch_2

Consolidated Statements of Changes In Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Dividends declared per share	$ 0.10	$ 0.08
ESOP shares earned	30,441	30,441
Common Stock [Member]
Dividends declared per share	$ 0.10	$ 0.08
ESOP shares earned	30,441	30,441
Additional Paid-in Capital [Member]
Dividends declared per share	$ 0.10	$ 0.08
ESOP shares earned	30,441	30,441
Retained Earnings [Member]
Dividends declared per share	$ 0.10	$ 0.08
ESOP shares earned	30,441	30,441
Accumulated Other Comprehensive Income (Loss) [Member]
Dividends declared per share	$ 0.10	$ 0.08
ESOP shares earned	30,441	30,441
Unearned Compensation - ESOP [Member]
Dividends declared per share	$ 0.10	$ 0.08
ESOP shares earned	30,441	30,441

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 24,320	$ 12,977
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization of acquisition fair value adjustments	32	16
Amortization of core deposit intangible	103	118
ESOP shares expense	512	507
Provision (reversal) for credit losses	(5,236)	725
Accretion of net deferred loan origination fees	(1,664)	(959)
Net amortization of securities available for sale	15	13
Depreciation and amortization expense	919	841
(Gain) loss on marketable equity securities, net	(1,785)	4,344
Deferred income tax benefit	(34)	(120)
Income from bank-owned life insurance	(261)	(297)
Share-based compensation expense	372	1,020
Net changes in:
Loans held for sale	802	(948)
Accrued interest receivable	675	613
Other assets	6,614	(9,052)
Accrued expenses and other liabilities	(5,078)	1,168
Net cash provided by operating activities	20,306	10,966
Activity in securities, at fair value:
Proceeds from maturities, calls and principal payments	693	1,473
Proceeds from sales	6,484	541
Purchases	(1,412)	(2,772)
Loan principal payments, net	226,673	57,898
Proceeds from bank-owned life insurance distribution		391
Purchases of premises and equipment	(105)	(1,650)
Purchase of Federal Home Loan Bank stock		(4,331)
Redemption of Federal Home Loan Bank stock	2,211
Net cash provided by investing activities	234,544	51,550
Cash flows from financing activities:
Net change in deposits	16,207	(99,579)
Proceeds from Federal Home Loan Bank advances with maturities of three months or more		135,000
Repayment of Federal Home Loan Bank advances with maturities of three months or more	(50,000)	(25,372)
Cash dividends paid on common stock	(4,008)	(4,270)
Stock options exercised, net of cash paid in connection with income taxes	92	51
Repurchase of common stock		(17,680)
Net cash used by financing activities	(135,329)	(11,850)
Net change in cash and cash equivalents	119,521	50,666
Cash and cash equivalents at beginning of period	914,586	406,382
Cash and cash equivalents at end of period	1,034,107	457,048
Supplemental cash flow information:
Interest paid on deposits	6,453	18,246
Interest paid on borrowings	3,839	4,115
Income taxes paid, net of refunds	3,958	$ 3,075
Paycheck Protection Program Liquidity Facility [Member]
Cash flows from financing activities:
Repayment of Federal Reserve PPPLF borrowings with maturities of three months or more	$ (97,620)

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	1 . The consolidated financial statements include the accounts of Meridian Bancorp, Inc. (the “Company”) and all other entities in which it has a controlling financial interest. The Company owns 100% of the outstanding shares of East Boston Savings Bank (the “Bank”). The Bank’s subsidiaries include: (1) Prospect, Inc., which engages in securities transactions on its own behalf; (2) EBOSCO, LLC, which can hold foreclosed real estate; and (3) East Boston Investment Services, Inc., which is authorized for third-party investment sales and is currently inactive and Investment in Affordable Home Ownership, LLC, which is authorized to form partnerships with agencies to develop projects for affordable housing and is currently inactive. All significant intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited interim consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by such generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation have been included. Such adjustments were of a normal recurring nature. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results that may be expected for the entire year or any other interim period. For additional information, refer to the financial statements and footnotes thereto of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 which was filed with the Securities and Exchange Commission (“SEC”) on March 1, 2021, and is available through the SEC’s website at www.sec.gov In preparing consolidated financial statements in conformity with GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the consolidated balance sheet and reported amounts of revenues and expenses during the reported period. Actual results could differ from those estimates. A material estimate that is particularly susceptible to significant change in the near term relates to the determination of the allowance for credit losses. On April 22, 2021, the Company entered into an Agreement and Plan of Merger (the "Merger Agreement") with Independent Bank Corp., a Massachusetts corporation ("Independent"), Bradford Merger Sub Inc. a direct, wholly owned subsidiary of Independent (“Merger Sub”), Rockland Trust Company, a Massachusetts-chartered trust company and wholly owned subsidiary of Independent ("Rockland Trust"), and the Bank. Pursuant to the Merger Agreement, Merger Sub will merge with and into the Company (the "Merger"), with the Company being the surviving corporation, and as soon as reasonably practicable following the Merger, the Company will merge with and into Independent, with Independent as the surviving entity (the “Holdco Merger”) .

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	2. EARNINGS PER SHARE Basic earnings per share excludes dilution and is calculated by dividing net income available to common stockholders by the weighted-average number of common shares outstanding during the period. Rights to dividends on unvested stock awards are non-forfeitable, therefore these unvested stock awards are considered outstanding in the computation of basic earnings per share. Diluted earnings per share is computed in a manner similar to that of basic earnings per share except that the weighted-average number of common shares outstanding is increased to include the number of incremental common shares (computed using the treasury method) that would have been outstanding if all potentially dilutive common stock equivalents (such as options) were issued during the period. Unallocated common shares held by the ESOP are shown as a reduction in stockholders’ equity and are not included in the weighted-average number of common shares outstanding for either basic or diluted earnings per share calculations. Basic and diluted earnings per share have been computed based on the following: Three Months Ended March 31, 2021 2020 (Dollars in thousands, except share information) Net income available to common stockholders $ 24,320 $ 12,977 Basic weighted average shares outstanding 50,239,611 50,634,983 Effect of dilutive stock options 325,848 285,276 Diluted weighted average shares outstanding 50,565,459 50,920,259 Earnings per share: Basic $ 0.48 $ 0.26 Diluted $ 0.48 $ 0.25 For the three months ended March 31, 2021 and 2020, options for the exercise of 53,381 shares and 93,545 shares, respectively, were not included in the calculation of diluted earnings per share because to do so would have been anti-dilutive. An anti-dilutive option exists when the average stock price for the period is less than the exercise price of the option.

Securities

Securities	3 Months Ended
	Mar. 31, 2021
Investments Debt And Equity Securities [Abstract]
Securities	3. SECURITIES Securities Available for Sale The amortized cost and fair values of securities available for sale, with gross unrealized gains and losses, follows: Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (In thousands) March 31, 2021 Debt securities: Government-sponsored enterprises $ 346 $ 17 $ — $ 363 Municipal bonds 2,073 125 — 2,198 Residential mortgage-backed securities: Government-sponsored enterprises 7,006 290 (10 ) 7,286 Private label 563 108 — 671 Total securities available for sale $ 9,988 $ 540 $ (10 ) $ 10,518 December 31, 2020 Debt securities: Government-sponsored enterprises $ 346 $ 21 $ — $ 367 Municipal bonds 2,075 146 — 2,221 Residential mortgage-backed securities: Government-sponsored enterprises 7,706 359 (10 ) 8,055 Private label 567 116 — 683 Total securities available for sale $ 10,694 $ 642 $ (10 ) $ 11,326 At March 31, 2021 debt securities with a fair value of $1.7 million and $273,000 were pledged as collateral for Federal Home Loan Bank of Boston (“FHLB”) borrowings and for the Federal Reserve Bank discount window borrowings, respectively. The amortized cost and fair value of debt securities by contractual maturity at March 31, 2021 are as follows. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without prepayment penalties. After One Year Through Five Years After Five Years Total Amortized Fair Amortized Fair Amortized Fair Cost Value Cost Value Cost Value (In thousands) Government-sponsored enterprises $ — $ — $ 346 $ 363 $ 346 $ 363 Municipal bonds 521 562 1,552 1,636 2,073 2,198 Residential mortgage-backed securities: Government-sponsored enterprises 402 412 6,604 6,874 7,006 7,286 Private label — — 563 671 563 671 Total $ 923 $ 974 $ 9,065 $ 9,544 $ 9,988 $ 10,518 Information pertaining to securities available for sale as of March 31, 2021 and December 31, 2020, with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: Less Than Twelve Months Twelve Months or Longer Gross Gross Unrealized Fair Unrealized Fair Losses Value Losses Value (In thousands) March 31, 2021 Debt securities: Residential mortgage-backed securities: Government-sponsored enterprises $ — $ — $ 10 $ 595 Total temporarily impaired securities $ — $ — $ 10 $ 595 Less Than Twelve Months Twelve Months or Longer Gross Gross Unrealized Fair Unrealized Fair Losses Value Losses Value (In thousands) December 31, 2020 Debt securities: Residential mortgage-backed securities: Government-sponsored enterprises $ 7 $ 511 $ 3 $ 142 Total temporarily impaired securities $ 7 $ 511 $ 3 $ 142 The Company determined no debt securities were other-than-temporarily impaired for the three months ended March 31, 2021 and 2020. Management evaluates debt securities for other-than-temporary impairment on a quarterly basis, with more frequent evaluation for selected issuers or when economic or market concerns warrant such evaluations. Marketable Equity Securities Marketable equity securities consist of common stocks and money market mutual funds. The Company held marketable equity securities with an aggregate fair value of $8.9 million and $12.2 million at March 31, 2021 and December 31, 2020, respectively. The following is a summary of unrealized and realized gains and losses recognized in net income on marketable equity securities during the three months ended March 31, 2021 and 20 20 : Three Months Ended March 31, 2021 March 31, 2020 (In thousands) Net realized gain (loss) on marketable equity securities sold during the period $ 972 $ (337 ) Net unrealized gain (loss) recognized during the reporting period on marketable equity securities still held at the reporting date 813 (4,007 ) Net gain (loss) recognized during the period on marketable equity securities $ 1,785 $ (4,344 )

Loans

Loans	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Loans	4. LOANS A summary of loans follows: March 31, December 31, 2021 2020 (Dollars in thousands) Real estate loans: Residential real estate: One- to four-family $ 517,442 $ 564,146 Home equity lines of credit 64,370 68,721 Multi-family 878,331 880,552 Commercial real estate 2,419,715 2,499,660 Construction 625,961 731,432 Total real estate loans 4,505,819 4,744,511 Commercial and industrial 779,603 765,195 Consumer 10,307 10,707 Total loans 5,295,729 5,520,413 Allowance for credit losses (63,436 ) (68,824 ) Net deferred loan origination fees (8,298 ) (7,784 ) Loans, net $ 5,223,995 $ 5,443,805 The Company has transferred a portion of its originated commercial real estate loans to participating lenders. The amounts transferred have been accounted for as sales and are therefore not included in the Company’s accompanying balance sheets. The Company and participating lenders share ratably in any gains or losses that may result from a borrower’s lack of compliance with contractual terms of the loan. The Company continues to service the loans on behalf of the participating lenders and, as such, collects cash payments from the borrowers, remits payments to participating lenders and disburses required escrow funds to relevant parties. At March 31, 2021 and December 31, 2020, the Company was servicing loans for participants aggregating $187.2 million and $176.4 million, respectively. At March 31, 2021, multi-family and commercial real estate loans with carrying values totaling $269.3 million and $1.305 billion, respectively, were pledged as collateral for FHLB borrowings. An analysis of the allowance for credit losses and related information follows: Three Months Ended March 31, 2021 One- to four- family Multi- family Home equity lines of credit Commercial real estate Construction Commercial and industrial Consumer Total (In thousands) Balance at December 31, 2020 $ 2,076 $ 2,251 $ 206 $ 30,145 $ 25,197 $ 8,453 $ 496 $ 68,824 Provision (reversal) for credit losses (391 ) (529 ) (40 ) (712 ) (3,611 ) 88 (41 ) (5,236 ) Charge-offs (68 ) — — — — (89 ) (34 ) (191 ) Recoveries — — — — — 15 24 39 Balance at March 31, 2021 $ 1,617 $ 1,722 $ 166 $ 29,433 $ 21,586 $ 8,467 $ 445 $ 63,436 Three Months Ended March 31, 2020 One- to four- family Multi- family Home equity lines of credit Commercial real estate Construction Commercial and industrial Consumer Total (In thousands) Balance at December 31, 2019 $ 691 $ 7,825 $ 69 $ 26,943 $ 8,913 $ 5,765 $ 116 $ 50,322 Provision (reversal) for credit losses 103 (145 ) 24 (215 ) 544 398 16 725 Charge-offs — — — — — (50 ) (64 ) (114 ) Recoveries — — 1 — — 1 11 13 Balance at March 31, 2020 $ 794 $ 7,680 $ 94 $ 26,728 $ 9,457 $ 6,114 $ 79 $ 50,946 One- to four- family Multi- family Home equity lines of credit Commercial real estate Construction Commercial and industrial Consumer Total (In thousands) March 31, 2021 Amount of allowance for credit losses for loans deemed to be impaired $ — $ — $ — $ — $ — $ 166 $ — $ 166 Amount of allowance for credit losses for loans not deemed to be impaired 1,617 1,722 166 29,433 21,586 8,301 445 63,270 $ 1,617 $ 1,722 $ 166 $ 29,433 $ 21,586 $ 8,467 $ 445 $ 63,436 Loans deemed to be impaired $ 597 $ — $ — $ — $ — $ 1,914 $ — $ 2,511 Loans not deemed to be impaired 516,845 878,331 64,370 2,419,715 625,961 777,689 10,307 5,293,218 $ 517,442 $ 878,331 $ 64,370 $ 2,419,715 $ 625,961 $ 779,603 $ 10,307 $ 5,295,729 December 31, 2020 Amount of allowance for credit losses for loans deemed to be impaired $ — $ — $ — $ — $ — $ — $ — $ — Amount of allowance for credit losses for loans not deemed to be impaired 2,076 2,251 206 30,145 25,197 8,453 496 68,824 $ 2,076 $ 2,251 $ 206 $ 30,145 $ 25,197 $ 8,453 $ 496 $ 68,824 Loans deemed to be impaired $ 602 $ — $ — $ 1,648 $ — $ 2,075 $ — $ 4,325 Loans not deemed to be impaired 563,544 880,552 68,721 2,498,012 731,432 763,120 10,707 5,516,088 $ 564,146 $ 880,552 $ 68,721 $ 2,499,660 $ 731,432 $ 765,195 $ 10,707 $ 5,520,413 The following table provides information about the Company’s past due and non-accrual loans: 30-59 60-89 90 Days Days Days or Greater Total Loans on Past Due Past Due Past Due Past Due Non-accrual (In thousands) March 31, 2021 Real estate loans: Residential real estate: One- to four-family $ 195 $ — $ 929 $ 1,124 $ 2,466 Home equity lines of credit 200 — 20 220 20 Total real estate loans 395 — 949 1,344 2,486 Commercial and industrial — — 489 489 635 Consumer 622 281 — 903 — Total $ 1,017 $ 281 $ 1,438 $ 2,736 $ 3,121 December 31, 2020 Real estate loans: Residential real estate: One- to four-family $ 504 $ 231 $ 1,116 $ 1,851 $ 2,617 Home equity lines of credit — — 20 20 20 Total real estate loans 504 231 1,136 1,871 2,637 Commercial and industrial 390 — 360 750 527 Consumer 448 245 — 693 — Total $ 1,342 $ 476 $ 1,496 $ 3,314 $ 3,164 At March 31, 2021 and December 31, 2020, the Company did not have any accruing loans past due 90 days or more. The following tables provide information with respect to the Company’s impaired loans: March 31, 2021 December 31, 2020 Unpaid Unpaid Recorded Principal Related Recorded Principal Related Investment Balance Allowance Investment Balance Allowance (In thousands) Impaired loans without a valuation allowance: One- to four-family $ 597 $ 933 $ 602 $ 940 Multi-family — — — — Commercial real estate — — 1,648 1,648 Commercial and industrial 1,748 2,078 2,075 2,404 Total 2,345 3,011 4,325 4,992 Impaired loans with a valuation allowance: One- to four-family — — $ — — — $ — Commercial and industrial 166 207 166 — — — Total 166 207 166 — $ — — Total impaired loans $ 2,511 $ 3,218 $ 166 $ 4,325 $ 4,992 $ — Three Months Ended March 31, 2021 2020 Interest Interest Average Interest Income Average Interest Income Recorded Income Recognized Recorded Income Recognized Investment Recognized on Cash Basis Investment Recognized on Cash Basis (In thousands) One- to four-family $ 763 $ 10 $ 9 $ 1,512 $ 14 $ 8 Multi-family — — — — — — Commercial real estate — — — 1,963 21 — Commercial and industrial 1,967 25 15 2,539 26 — Total impaired loans $ 2,730 $ 35 $ 24 $ 6,014 $ 61 $ 8 The following table summarizes the Company’s troubled debt restructurings (“TDRs”) at the dates indicated: March 31, December 31, 2021 2020 (In thousands) TDRs on accrual status: One- to four-family $ 1,580 $ 1,731 Total TDRs on accrual status 1,580 1,731 TDRs on non-accrual status: One- to four-family 417 420 Total TDRs on non-accrual status 417 420 Total TDRs $ 1,997 $ 2,151 The Company generally places loans modified as TDRs on non-accrual status for a minimum period of six months. Loans modified as TDRs qualify for return to accrual status once they have demonstrated performance with the modified terms of the loan agreement for a minimum of six consecutive months and future payments are reasonably assured. TDRs are initially reported as impaired loans with an allowance established as part of the allocated component of the allowance for credit losses when the discounted cash flows of the impaired loan is lower than the carrying value of that loan. TDRs may be removed from impairment disclosures in the year following the restructure if the borrower demonstrates compliance with the modified terms and the restructuring agreement specifies an interest rate equal to that which would be provided to a borrower with similar credit at the time of restructuring. Refer to Troubled Debt Restructurings and Other Loan Modifications, in Management’s Discussion and Analysis of Financial Condition and Results of Operations within this report for more detail regarding loans deferred or modified under the CARES Act and not included in TDRs. In response to COVID-19, the Company has provided temporary relief in the form of short-term loan modifications, generally with deferred payments and associated accrued interest due and payable based on the specific terms of the modification. As of March 31, 2021, the Company had $402.7 million in loans making interest-only payments under COVID-19 related loan modifications, representing 7.6% of the total loan portfolio. The Company utilizes a ten-grade internal loan rating system for multi-family, commercial real estate, construction, and commercial and industrial loans as follows: • Loans rated 1 - 6: Loans in these categories are considered “pass” rated loans with low to average risk. • Loans rated 7: Loans in these categories are considered “special mention.” These loans are starting to show signs of potential weakness and are being closely monitored by management. • Loans rated 8: Loans in this category are considered “substandard.” Generally, a loan is considered substandard if it is inadequately protected by the current net worth, generation of cash flows, and paying capacity of the obligors and/or the collateral pledged. There is a distinct possibility that the Company will sustain some loss if the weakness is not corrected. • Loans rated 9: Loans in this category are considered “doubtful.” Loans classified as doubtful have all the weaknesses inherent in those classified substandard with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of currently existing facts, highly questionable and improbable. • Loans rated 10: Loans in this category are considered uncollectible (“loss”) and of such little value that their continuance as loans is not warranted. On an annual basis, or more often if needed, the Company formally reviews the ratings on multi-family, commercial real estate, construction, and commercial and industrial loans. The Company also engages an independent third-party to review a significant portion of loans within these segments on at least an annual basis. Management uses the results of these reviews as part of its annual review process. The following table provides the Company’s risk-rated loans by class: March 31, 2021 December 31, 2020 Multi-family Commercial Multi-family Commercial residential Commercial and residential Commercial and real estate real estate Construction industrial real estate real estate Construction industrial (In thousands) Loans rated 1 - 6 $ 878,331 $ 2,404,053 $ 625,961 $ 722,477 $ 880,552 $ 2,483,867 $ 731,432 $ 704,534 Loans rated 7 — 15,662 — 36,465 — 15,793 — 37,093 Loans rated 8 — — — 20,661 — — — 23,568 Loans rated 9 — — — — — — — — Loans rated 10 — — — — — — — — Total $ 878,331 $ 2,419,715 $ 625,961 $ 779,603 $ 880,552 $ 2,499,660 $ 731,432 $ 765,195 For one- to four-family residential real estate loans, home equity lines of credit and consumer loans, management uses delinquency reports as the key credit quality indicator.

Deposits

Deposits	3 Months Ended
	Mar. 31, 2021
Banking Deposits And Thrift [Abstract]
Deposits	5. DEPOSITS A summary of deposit balances, by type, follows: March 31, December 31, 2021 2020 (In thousands) Noninterest-bearing demand deposits $ 751,809 $ 711,573 Interest-bearing demand deposits 1,461,236 1,364,548 Money market deposits 852,747 930,507 Regular savings and other deposits 870,961 855,329 Total non-certificate accounts 3,936,753 3,861,957 Term certificates less than $250,000 809,835 883,133 Term certificates $250,000 and greater 350,781 336,077 Total certificate accounts 1,160,616 1,219,210 Total deposits $ 5,097,369 $ 5,081,167 A summary of term certificates, by maturity, follows: March 31, 2021 December 31, 2020 Weighted Weighted Maturing Amount Average Rate Amount Average Rate (Dollars in thousands) Within 1 year $ 893,949 0.91 % $ 883,747 1.03 % Over 1 year to 2 years 140,128 1.26 194,698 1.29 Over 2 years to 3 years 35,826 0.77 40,338 1.21 Over 3 years to 4 years 53,561 0.72 53,580 0.75 Over 4 years to 5 years 36,962 0.51 46,847 0.68 Greater than 5 years 190 1.05 — — $ 1,160,616 0.93 % $ 1,219,210 1.05 % The Company had certificates of deposit accounts obtained through a listing service included in term certificates in the table above, totaling $43.6 million with a weighted average rate of 1.06% and $50.6 million with a weighted average rate of 1.01% at March 31, 2021 and December 31, 2020, respectively. The Company had brokered certificates of deposit, which are included in term certificates in the table above, totaling $152.1 million with a weighted average rate of 1.20% and $212.0 million with a weighted average rate of 1.29% at March 31, 2021 and December 31, 2020, respectively. In addition, the Company had $175.6 million in brokered interest-bearing demand deposits at March 31, 2021 and December 31, 2020, respectively.

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Borrowings	6. BORROWINGS At March 31, 2021, and December 31, 2020, the Company had no short-term borrowings. At March 31, 2021, long-term debt consisted of $560.6 million in FHLB advances. The Company has an available line of credit of $10.0 million with the FHLB at an interest rate that adjusts daily. No amounts were drawn on the line of credit at March 31, 2021 or December 31, 2020. Long-term, fixed rate FHLB advances and maturities are as follows: March 31, 2021 December 31, 2020 Weighted Weighted Amount Average Rate Amount Average Rate (Dollars in thousands) 2021 $ — — % $ 50,000 1.18 % 2022 150,625 2.00 150,625 2.00 2023 295,000 3.10 295,000 3.10 2024 20,000 2.61 20,000 2.61 2025 85,000 1.00 85,000 1.00 2026 — — — — Thereafter 10,000 1.21 10,000 1.21 $ 560,625 2.44 % $ 610,625 2.33 % At March 31, 2021, FHLB advances totaling $445.0 million, with a weighted average rate of 2.53%, are callable by the FHLB prior to maturity. All borrowings from the FHLB are secured by investment securities and qualified collateral, consisting of a blanket lien on one- to four-family loans and certain multi-family and commercial real estate loans held in the Company’s portfolio. At March 31, 2021, the Company pledged multi-family and commercial real estate loans with carrying values totaling $269.3 million and $1.305 billion, respectively. At March 31, 2021, the Company had no borrowings through the PPPLF program. At December 31, 2020, the Company had $97.6 million in borrowings from the PPPLF program. These borrowings had maturities ranging from two to five years and a rate of 0.35%.

Commitments and Contingencies a

Commitments and Contingencies and Derivatives	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies and Derivatives	7. COMMITMENTS AND CONTINGENCIES AND DERIVATIVES In the normal course of business, there are outstanding commitments and contingencies which are not reflected in the accompanying consolidated financial statements. Loan Commitments The Company is party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers and to reduce its own exposure to fluctuations in interest rates. The instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the accompanying consolidated balance sheets. The contract amounts of those instruments reflect the extent of involvement the Company has in particular classes of financial instruments. The Company’s exposure to credit loss in the event of nonperformance by the counterparty to the financial instrument for loan commitments is represented by the contractual amount of those instruments. The Company uses the same credit policies in making commitments as it does for on-balance sheet instruments. A summary of outstanding loan commitments whose contract amounts represent credit risk is as follows: March 31, December 31, 2021 2020 (In thousands) Unadvanced portion of existing loans: Construction $ 492,454 $ 501,911 Home equity lines of credit 77,602 79,579 Other lines and letters of credit 352,556 350,708 Commitments to originate: One- to four-family 27,641 41,454 Commercial real estate 20,866 16,540 Construction 126,301 76,615 Commercial and industrial 5,771 8,413 Total loan commitments outstanding $ 1,103,191 $ 1,075,220 Commitments to originate loans are agreements to lend to a customer provided there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since a portion of the commitments are expected to expire without being drawn upon, the total commitments do not necessarily represent future cash requirements. The Company evaluates each customer’s credit worthiness on a case by case basis. The amount of collateral obtained, if deemed necessary by the Company for the extension of credit, is based upon management’s credit evaluation of the borrower. Collateral held includes, but is not limited to, residential real estate and deposit accounts. Unfunded commitments under lines of credit are commitments for possible future extensions of credit to existing customers. These lines of credit are collateralized if deemed necessary and usually do not contain a specified maturity date and may not be drawn upon to the total extent to which the Company is committed. Letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. Those letters of credit are primarily issued to support borrowing arrangements. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. Interest Rate Swaps The Company is a party to interest rate derivatives that are not designated as hedging instruments. These derivatives relate to interest rate swaps that the Company enters into with commercial business customers to synthetically convert their loans from a variable rate to a fixed rate. The Company pays interest to the customer at a floating rate on the notional amount and receives interest from the customer at a fixed rate for the same notional amount. Concurrently, the Company enters into an offsetting interest rate swap with a third-party financial institution. In the offsetting swap, the Company pays the other financial institution interest at the same fixed rate on the same notional amount as the swap entered into with the customer and receives interest from the financial institution for the same floating rate on the same notional amount. The changes in the fair value of the swaps offset each other, except for the credit risk of the counterparties, which is determined by taking into consideration the risk rating and probability of default. At March 31, 2021, the Company had $6.4 million in cash pledged for collateral on its interest rate swaps with the third-party financial institution. At December 31, 2020, the Company had $11.4 million in cash pledged for collateral on its interest rate swaps with the third-party financial institution. Summary information regarding these derivatives is presented below: March 31, 2021 December 31, 2020 Maturity Interest Rate Paid Interest Rate Received Notional Amount Fair Value Asset (Liability) Notional Amount Fair Value Asset (Liability) (Dollars in thousands) Customer interest rate swap 06/07/32 1 Mo. Libor + 200bp Fixed (4.40%) $ 60,348 $ 4,336 $ 60,782 $ 8,886 Third-party interest rate swap 06/07/32 Fixed (4.40%) 1 Mo. Libor + 200bp 60,348 (4,336 ) 60,782 (8,886 ) Customer interest rate swap 10/17/33 1 Mo. Libor + 175bp Fixed (4.1052%) $ 9,738 $ 957 $ 9,831 $ 1,401 Third-party interest rate swap 10/17/33 Fixed (4.1052%) 1 Mo. Libor + 175bp 9,738 (957 ) 9,831 (1,401 ) Customer interest rate swap 12/13/26 1 Mo. Libor + 205bp Fixed (3.82%) $ 2,346 $ 88 $ 2,390 $ 154 Third-party interest rate swap 12/13/26 Fixed (3.82%) 1 Mo. Libor + 205bp 2,346 (88 ) 2,390 (154 ) Other Commitments As of March 31, 2021, the Company has an outstanding commitment of $3.2 million with its core data processing provider through December 2021. Employment and Change in Control Agreements The Company has entered into employment agreements with certain senior executives which provide for a minimum annual salary, subject to increase at the discretion of the Board of Directors, and other benefits, including a severance payment in the event employment is terminated in conjunction with a defined change in control. The agreements may be terminated for cause by the Company without further liability on the part of the Company, or by the executives with prior written notice to the Board of Directors. The Company also has change in control agreements with several officers which provide a severance payment in the event employment is terminated in conjunction with a defined change in control. Legal Claims Various legal claims may arise from time to time in the normal course of business, but in the opinion of management, these claims are not expected to have a material effect on the Company’s consolidated financial statements. Cold Spring Green, LLC and Hisham Ashkouri v. East Boston Savings Bank and Meridian Interstate Bancorp, Inc. The Bank is a defendant in a lawsuit that was filed in 2015 in Middlesex Superior Court in Massachusetts. The plaintiffs seek damages related to the foreclosure of a loan that was originated in 2007 by Mt. Washington Bank, which the Bank acquired in 2010. A similar suit by the same plaintiffs was filed in 2013 but subsequently dismissed. Following a trial in October 2019, the jury returned a verdict that rejected each of the plaintiffs’ claims for breach of contract, fraudulent inducement and unjust enrichment. However, the jury found, in an advisory verdict, that the Bank intentionally acted unfairly and deceptively in violation of Massachusetts General Laws Chapter 93A (“G.L. c. 93A”), which states: "Unfair methods of competition and unfair or deceptive acts or practices in the conduct of any trade or commerce are hereby declared unlawful." The jury found that the Bank caused the plaintiffs damages in the amount of $1.0 million. On November 25, 2019, the trial judge issued an opinion on the G.L. c. 93A count, adopting the jury’s advisory verdict and awarding the plaintiffs $1.0 million, which was then doubled as provided for in the statute for what was deemed to be a knowing and willing act on the part of the Bank. The trial judge also awarded the plaintiffs their reasonable attorneys’ fees and costs, resulting in a total award of $2.1 million plus attorneys’ fees, costs and interest. If the judgment is upheld in full, the Company has estimated that the award, which includes attorney's fees, costs and interest, could be as high as $3 million. However, the Company believes there are strong grounds for appeal based on significant appellate case law and the intentions to vigorously defend its interests in this matter, including arguing for complete reversal on appeal. A Notice of Appeal was filed on March 9, 2020. Although the Company believes there is a strong basis to vacate the award, there remains a reasonable possibility that the judgment will be affirmed in whole or in part, with the possible range of loss from $0 to $3 million. The Company does not believe that the loss is probable at this time and, in accordance with the authoritative guidance in the evaluation of contingencies, the Company has not recorded an accrual related to this matter.

Fair Values of Assets and Liabi

Fair Values of Assets and Liabilities	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Values of Assets and Liabilities	8. FAIR VALUES OF ASSETS AND LIABILITIES Determination of Fair Value The Company uses fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The fair value of assets and liabilities is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is best determined based upon quoted market prices. However, in many instances, there are no quoted market prices for the Company’s various assets and liabilities. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used including the discount rate and estimates of future cash flows. Accordingly, the fair value estimates may not be realized in an immediate settlement of the asset or liability. The following methods and assumptions were used by the Company in estimating fair value disclosures: Securities, at fair value market data, benchmark yields, reported trades, broker/dealer quotes, credit spreads, benchmark securities, as well as new issue data, monthly payment information, and collateral performance, among others (Level 2). Loan level interest rate swaps Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets measured at fair value on a recurring basis are summarized as follows. Total Fair Level 1 Level 2 Level 3 Value (In thousands) March 31, 2021 Assets: Debt securities $ — $ 10,518 $ — $ 10,518 Marketable equity securities 8,900 — — 8,900 Loan level interest rate swaps — — 5,381 5,381 Total assets $ 8,900 $ 10,518 $ 5,381 $ 24,799 Liabilities: Loan level interest rate swaps $ — $ — $ 5,381 $ 5,381 Total liabilities $ — $ — $ 5,381 $ 5,381 Total Fair Level 1 Level 2 Level 3 Value (In thousands) December 31, 2020 Assets: Debt securities $ — $ 11,326 $ — $ 11,326 Marketable equity securities 12,189 — — 12,189 Loan level interest rate swaps — — 10,441 10,441 Total assets $ 12,189 $ 11,326 $ 10,441 $ 33,956 Liabilities: Loan level interest rate swaps $ — $ — $ 10,441 $ 10,441 Total liabilities $ — $ — $ 10,441 $ 10,441 Assets Measured at Fair Value on a Non-recurring Basis The Company may also be required, from time to time, to measure certain other assets at fair value on a non-recurring basis in accordance with generally accepted accounting principles. These adjustments to fair value usually result from the application of lower-of-cost-or market accounting or write-downs of individual assets. Certain impaired loans were adjusted to fair value, less cost to sell, of the underlying collateral securing these loans resulting in losses. The loss is not recorded directly as an adjustment to current earnings, but rather as a component in determining the allowance for credit losses. Fair value was measured using appraised values of collateral and adjusted as necessary by management based on unobservable inputs for specific properties. Impaired loans measured at fair value at March 31, 2021 and December 31, 2020 were $1.9 million and $3.7 million, respectively. The related gains and losses were immaterial for the three months ended March 31, 2021 and 2020. Summary of Fair Values of Financial Instruments The estimated fair values, and related carrying amounts, of the Company’s financial instruments are as follows. Certain financial instruments and all nonfinancial instruments are exempt from disclosure requirements. Accordingly, the aggregate fair value amounts presented herein do not represent the underlying fair value of the Company. Carrying Fair Value Amount Level 1 Level 2 Level 3 Total (In thousands) March 31, 2021 Financial assets: Cash and due from banks $ 1,034,107 $ 1,034,107 $ — $ — $ 1,034,107 Securities available for sale, at fair value 10,518 — 10,518 — 10,518 Marketable equity securities, at fair value 8,900 8,900 — — 8,900 Federal Home Loan Bank stock 28,447 — — 28,447 28,447 Loans and loans held for sale, net 5,231,417 — — 5,276,764 5,276,764 Accrued interest receivable 22,498 — — 22,498 22,498 Loan level interest rate swaps 5,381 — — 5,381 5,381 Financial liabilities: Deposits 5,097,369 — — 5,015,299 5,015,299 Borrowings 560,625 — 580,616 — 580,616 Accrued interest payable 1,864 — — 1,864 1,864 Loan level interest rate swaps 5,381 — — 5,381 5,381 Carrying Fair Value Amount Level 1 Level 2 Level 3 Total (In thousands) December 31, 2020 Financial assets: Cash and due from banks $ 914,586 $ 914,586 $ — $ — $ 914,586 Securities available for sale, at fair value 11,326 — 11,326 — 11,326 Marketable equity securities, at fair value 12,189 12,189 — — 12,189 Federal Home Loan Bank stock 30,658 — — 30,658 30,658 Loans and loans held for sale, net 5,452,029 — — 5,480,258 5,480,258 Accrued interest receivable 23,173 — — 23,173 23,173 Loan level interest rate swaps 10,441 — — 10,441 10,441 Financial liabilities: Deposits 5,081,167 — — 5,172,060 5,172,060 Borrowings 708,245 — 732,302 — 732,302 Accrued interest payable 2,832 — — 2,832 2,832 Loan level interest rate swaps 10,441 — — 10,441 10,441

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	Basic and diluted earnings per share have been computed based on the following: Three Months Ended March 31, 2021 2020 (Dollars in thousands, except share information) Net income available to common stockholders $ 24,320 $ 12,977 Basic weighted average shares outstanding 50,239,611 50,634,983 Effect of dilutive stock options 325,848 285,276 Diluted weighted average shares outstanding 50,565,459 50,920,259 Earnings per share: Basic $ 0.48 $ 0.26 Diluted $ 0.48 $ 0.25

Securities (Tables)

Securities (Tables)	3 Months Ended
	Mar. 31, 2021
Investments Debt And Equity Securities [Abstract]
Amortized Cost and Fair Values of Securities Available for Sale	The amortized cost and fair values of securities available for sale, with gross unrealized gains and losses, follows: Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (In thousands) March 31, 2021 Debt securities: Government-sponsored enterprises $ 346 $ 17 $ — $ 363 Municipal bonds 2,073 125 — 2,198 Residential mortgage-backed securities: Government-sponsored enterprises 7,006 290 (10 ) 7,286 Private label 563 108 — 671 Total securities available for sale $ 9,988 $ 540 $ (10 ) $ 10,518 December 31, 2020 Debt securities: Government-sponsored enterprises $ 346 $ 21 $ — $ 367 Municipal bonds 2,075 146 — 2,221 Residential mortgage-backed securities: Government-sponsored enterprises 7,706 359 (10 ) 8,055 Private label 567 116 — 683 Total securities available for sale $ 10,694 $ 642 $ (10 ) $ 11,326
Amortized Cost and Fair Value of Debt Securities by Contractual Maturity	The amortized cost and fair value of debt securities by contractual maturity at March 31, 2021 are as follows. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without prepayment penalties. After One Year Through Five Years After Five Years Total Amortized Fair Amortized Fair Amortized Fair Cost Value Cost Value Cost Value (In thousands) Government-sponsored enterprises $ — $ — $ 346 $ 363 $ 346 $ 363 Municipal bonds 521 562 1,552 1,636 2,073 2,198 Residential mortgage-backed securities: Government-sponsored enterprises 402 412 6,604 6,874 7,006 7,286 Private label — — 563 671 563 671 Total $ 923 $ 974 $ 9,065 $ 9,544 $ 9,988 $ 10,518
Schedule of Information Pertaining to Securities Available for Sale	Information pertaining to securities available for sale as of March 31, 2021 and December 31, 2020, with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: Less Than Twelve Months Twelve Months or Longer Gross Gross Unrealized Fair Unrealized Fair Losses Value Losses Value (In thousands) March 31, 2021 Debt securities: Residential mortgage-backed securities: Government-sponsored enterprises $ — $ — $ 10 $ 595 Total temporarily impaired securities $ — $ — $ 10 $ 595 Less Than Twelve Months Twelve Months or Longer Gross Gross Unrealized Fair Unrealized Fair Losses Value Losses Value (In thousands) December 31, 2020 Debt securities: Residential mortgage-backed securities: Government-sponsored enterprises $ 7 $ 511 $ 3 $ 142 Total temporarily impaired securities $ 7 $ 511 $ 3 $ 142
Unrealized and Realized Gains and Losses Recognized in Net Income on Marketable Equity Securities	The following is a summary of unrealized and realized gains and losses recognized in net income on marketable equity securities during the three months ended March 31, 2021 and 20 20 : Three Months Ended March 31, 2021 March 31, 2020 (In thousands) Net realized gain (loss) on marketable equity securities sold during the period $ 972 $ (337 ) Net unrealized gain (loss) recognized during the reporting period on marketable equity securities still held at the reporting date 813 (4,007 ) Net gain (loss) recognized during the period on marketable equity securities $ 1,785 $ (4,344 )

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Summary of Loans	A summary of loans follows: March 31, December 31, 2021 2020 (Dollars in thousands) Real estate loans: Residential real estate: One- to four-family $ 517,442 $ 564,146 Home equity lines of credit 64,370 68,721 Multi-family 878,331 880,552 Commercial real estate 2,419,715 2,499,660 Construction 625,961 731,432 Total real estate loans 4,505,819 4,744,511 Commercial and industrial 779,603 765,195 Consumer 10,307 10,707 Total loans 5,295,729 5,520,413 Allowance for credit losses (63,436 ) (68,824 ) Net deferred loan origination fees (8,298 ) (7,784 ) Loans, net $ 5,223,995 $ 5,443,805
Allowance for Credit Losses	An analysis of the allowance for credit losses and related information follows: Three Months Ended March 31, 2021 One- to four- family Multi- family Home equity lines of credit Commercial real estate Construction Commercial and industrial Consumer Total (In thousands) Balance at December 31, 2020 $ 2,076 $ 2,251 $ 206 $ 30,145 $ 25,197 $ 8,453 $ 496 $ 68,824 Provision (reversal) for credit losses (391 ) (529 ) (40 ) (712 ) (3,611 ) 88 (41 ) (5,236 ) Charge-offs (68 ) — — — — (89 ) (34 ) (191 ) Recoveries — — — — — 15 24 39 Balance at March 31, 2021 $ 1,617 $ 1,722 $ 166 $ 29,433 $ 21,586 $ 8,467 $ 445 $ 63,436 Three Months Ended March 31, 2020 One- to four- family Multi- family Home equity lines of credit Commercial real estate Construction Commercial and industrial Consumer Total (In thousands) Balance at December 31, 2019 $ 691 $ 7,825 $ 69 $ 26,943 $ 8,913 $ 5,765 $ 116 $ 50,322 Provision (reversal) for credit losses 103 (145 ) 24 (215 ) 544 398 16 725 Charge-offs — — — — — (50 ) (64 ) (114 ) Recoveries — — 1 — — 1 11 13 Balance at March 31, 2020 $ 794 $ 7,680 $ 94 $ 26,728 $ 9,457 $ 6,114 $ 79 $ 50,946 One- to four- family Multi- family Home equity lines of credit Commercial real estate Construction Commercial and industrial Consumer Total (In thousands) March 31, 2021 Amount of allowance for credit losses for loans deemed to be impaired $ — $ — $ — $ — $ — $ 166 $ — $ 166 Amount of allowance for credit losses for loans not deemed to be impaired 1,617 1,722 166 29,433 21,586 8,301 445 63,270 $ 1,617 $ 1,722 $ 166 $ 29,433 $ 21,586 $ 8,467 $ 445 $ 63,436 Loans deemed to be impaired $ 597 $ — $ — $ — $ — $ 1,914 $ — $ 2,511 Loans not deemed to be impaired 516,845 878,331 64,370 2,419,715 625,961 777,689 10,307 5,293,218 $ 517,442 $ 878,331 $ 64,370 $ 2,419,715 $ 625,961 $ 779,603 $ 10,307 $ 5,295,729 December 31, 2020 Amount of allowance for credit losses for loans deemed to be impaired $ — $ — $ — $ — $ — $ — $ — $ — Amount of allowance for credit losses for loans not deemed to be impaired 2,076 2,251 206 30,145 25,197 8,453 496 68,824 $ 2,076 $ 2,251 $ 206 $ 30,145 $ 25,197 $ 8,453 $ 496 $ 68,824 Loans deemed to be impaired $ 602 $ — $ — $ 1,648 $ — $ 2,075 $ — $ 4,325 Loans not deemed to be impaired 563,544 880,552 68,721 2,498,012 731,432 763,120 10,707 5,516,088 $ 564,146 $ 880,552 $ 68,721 $ 2,499,660 $ 731,432 $ 765,195 $ 10,707 $ 5,520,413
Past Due and Non Accrual	The following table provides information about the Company’s past due and non-accrual loans: 30-59 60-89 90 Days Days Days or Greater Total Loans on Past Due Past Due Past Due Past Due Non-accrual (In thousands) March 31, 2021 Real estate loans: Residential real estate: One- to four-family $ 195 $ — $ 929 $ 1,124 $ 2,466 Home equity lines of credit 200 — 20 220 20 Total real estate loans 395 — 949 1,344 2,486 Commercial and industrial — — 489 489 635 Consumer 622 281 — 903 — Total $ 1,017 $ 281 $ 1,438 $ 2,736 $ 3,121 December 31, 2020 Real estate loans: Residential real estate: One- to four-family $ 504 $ 231 $ 1,116 $ 1,851 $ 2,617 Home equity lines of credit — — 20 20 20 Total real estate loans 504 231 1,136 1,871 2,637 Commercial and industrial 390 — 360 750 527 Consumer 448 245 — 693 — Total $ 1,342 $ 476 $ 1,496 $ 3,314 $ 3,164
Impaired Loans of Company	The following tables provide information with respect to the Company’s impaired loans: March 31, 2021 December 31, 2020 Unpaid Unpaid Recorded Principal Related Recorded Principal Related Investment Balance Allowance Investment Balance Allowance (In thousands) Impaired loans without a valuation allowance: One- to four-family $ 597 $ 933 $ 602 $ 940 Multi-family — — — — Commercial real estate — — 1,648 1,648 Commercial and industrial 1,748 2,078 2,075 2,404 Total 2,345 3,011 4,325 4,992 Impaired loans with a valuation allowance: One- to four-family — — $ — — — $ — Commercial and industrial 166 207 166 — — — Total 166 207 166 — $ — — Total impaired loans $ 2,511 $ 3,218 $ 166 $ 4,325 $ 4,992 $ — Three Months Ended March 31, 2021 2020 Interest Interest Average Interest Income Average Interest Income Recorded Income Recognized Recorded Income Recognized Investment Recognized on Cash Basis Investment Recognized on Cash Basis (In thousands) One- to four-family $ 763 $ 10 $ 9 $ 1,512 $ 14 $ 8 Multi-family — — — — — — Commercial real estate — — — 1,963 21 — Commercial and industrial 1,967 25 15 2,539 26 — Total impaired loans $ 2,730 $ 35 $ 24 $ 6,014 $ 61 $ 8
Summary of Troubled Debt Restructurings (TDRs)	The following table summarizes the Company’s troubled debt restructurings (“TDRs”) at the dates indicated: March 31, December 31, 2021 2020 (In thousands) TDRs on accrual status: One- to four-family $ 1,580 $ 1,731 Total TDRs on accrual status 1,580 1,731 TDRs on non-accrual status: One- to four-family 417 420 Total TDRs on non-accrual status 417 420 Total TDRs $ 1,997 $ 2,151
Risk Rated Loans by Class	The following table provides the Company’s risk-rated loans by class: March 31, 2021 December 31, 2020 Multi-family Commercial Multi-family Commercial residential Commercial and residential Commercial and real estate real estate Construction industrial real estate real estate Construction industrial (In thousands) Loans rated 1 - 6 $ 878,331 $ 2,404,053 $ 625,961 $ 722,477 $ 880,552 $ 2,483,867 $ 731,432 $ 704,534 Loans rated 7 — 15,662 — 36,465 — 15,793 — 37,093 Loans rated 8 — — — 20,661 — — — 23,568 Loans rated 9 — — — — — — — — Loans rated 10 — — — — — — — — Total $ 878,331 $ 2,419,715 $ 625,961 $ 779,603 $ 880,552 $ 2,499,660 $ 731,432 $ 765,195

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2021
Banking Deposits And Thrift [Abstract]
Summary of Deposit Balances, by Type	A summary of deposit balances, by type, follows: March 31, December 31, 2021 2020 (In thousands) Noninterest-bearing demand deposits $ 751,809 $ 711,573 Interest-bearing demand deposits 1,461,236 1,364,548 Money market deposits 852,747 930,507 Regular savings and other deposits 870,961 855,329 Total non-certificate accounts 3,936,753 3,861,957 Term certificates less than $250,000 809,835 883,133 Term certificates $250,000 and greater 350,781 336,077 Total certificate accounts 1,160,616 1,219,210 Total deposits $ 5,097,369 $ 5,081,167
Summary of Term Certificates, by Maturity	A summary of term certificates, by maturity, follows: March 31, 2021 December 31, 2020 Weighted Weighted Maturing Amount Average Rate Amount Average Rate (Dollars in thousands) Within 1 year $ 893,949 0.91 % $ 883,747 1.03 % Over 1 year to 2 years 140,128 1.26 194,698 1.29 Over 2 years to 3 years 35,826 0.77 40,338 1.21 Over 3 years to 4 years 53,561 0.72 53,580 0.75 Over 4 years to 5 years 36,962 0.51 46,847 0.68 Greater than 5 years 190 1.05 — — $ 1,160,616 0.93 % $ 1,219,210 1.05 %

Borrowings (Tables)

Borrowings (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Long-term, Fixed Rate FHLB Advances	Long-term, fixed rate FHLB advances and maturities are as follows: March 31, 2021 December 31, 2020 Weighted Weighted Amount Average Rate Amount Average Rate (Dollars in thousands) 2021 $ — — % $ 50,000 1.18 % 2022 150,625 2.00 150,625 2.00 2023 295,000 3.10 295,000 3.10 2024 20,000 2.61 20,000 2.61 2025 85,000 1.00 85,000 1.00 2026 — — — — Thereafter 10,000 1.21 10,000 1.21 $ 560,625 2.44 % $ 610,625 2.33 %

Commitments and Contingencies_2

Commitments and Contingencies and Derivatives (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Loan Commitments Outstanding	A summary of outstanding loan commitments whose contract amounts represent credit risk is as follows: March 31, December 31, 2021 2020 (In thousands) Unadvanced portion of existing loans: Construction $ 492,454 $ 501,911 Home equity lines of credit 77,602 79,579 Other lines and letters of credit 352,556 350,708 Commitments to originate: One- to four-family 27,641 41,454 Commercial real estate 20,866 16,540 Construction 126,301 76,615 Commercial and industrial 5,771 8,413 Total loan commitments outstanding $ 1,103,191 $ 1,075,220
Summary Information Regarding the Derivatives	Summary information regarding these derivatives is presented below: March 31, 2021 December 31, 2020 Maturity Interest Rate Paid Interest Rate Received Notional Amount Fair Value Asset (Liability) Notional Amount Fair Value Asset (Liability) (Dollars in thousands) Customer interest rate swap 06/07/32 1 Mo. Libor + 200bp Fixed (4.40%) $ 60,348 $ 4,336 $ 60,782 $ 8,886 Third-party interest rate swap 06/07/32 Fixed (4.40%) 1 Mo. Libor + 200bp 60,348 (4,336 ) 60,782 (8,886 ) Customer interest rate swap 10/17/33 1 Mo. Libor + 175bp Fixed (4.1052%) $ 9,738 $ 957 $ 9,831 $ 1,401 Third-party interest rate swap 10/17/33 Fixed (4.1052%) 1 Mo. Libor + 175bp 9,738 (957 ) 9,831 (1,401 ) Customer interest rate swap 12/13/26 1 Mo. Libor + 205bp Fixed (3.82%) $ 2,346 $ 88 $ 2,390 $ 154 Third-party interest rate swap 12/13/26 Fixed (3.82%) 1 Mo. Libor + 205bp 2,346 (88 ) 2,390 (154 )

Fair Values of Assets and Lia_2

Fair Values of Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on a Recurring Basis	Assets measured at fair value on a recurring basis are summarized as follows. Total Fair Level 1 Level 2 Level 3 Value (In thousands) March 31, 2021 Assets: Debt securities $ — $ 10,518 $ — $ 10,518 Marketable equity securities 8,900 — — 8,900 Loan level interest rate swaps — — 5,381 5,381 Total assets $ 8,900 $ 10,518 $ 5,381 $ 24,799 Liabilities: Loan level interest rate swaps $ — $ — $ 5,381 $ 5,381 Total liabilities $ — $ — $ 5,381 $ 5,381 Total Fair Level 1 Level 2 Level 3 Value (In thousands) December 31, 2020 Assets: Debt securities $ — $ 11,326 $ — $ 11,326 Marketable equity securities 12,189 — — 12,189 Loan level interest rate swaps — — 10,441 10,441 Total assets $ 12,189 $ 11,326 $ 10,441 $ 33,956 Liabilities: Loan level interest rate swaps $ — $ — $ 10,441 $ 10,441 Total liabilities $ — $ — $ 10,441 $ 10,441
Summary of Fair Values of Financial Instruments	Accordingly, the aggregate fair value amounts presented herein do not represent the underlying fair value of the Company. Carrying Fair Value Amount Level 1 Level 2 Level 3 Total (In thousands) March 31, 2021 Financial assets: Cash and due from banks $ 1,034,107 $ 1,034,107 $ — $ — $ 1,034,107 Securities available for sale, at fair value 10,518 — 10,518 — 10,518 Marketable equity securities, at fair value 8,900 8,900 — — 8,900 Federal Home Loan Bank stock 28,447 — — 28,447 28,447 Loans and loans held for sale, net 5,231,417 — — 5,276,764 5,276,764 Accrued interest receivable 22,498 — — 22,498 22,498 Loan level interest rate swaps 5,381 — — 5,381 5,381 Financial liabilities: Deposits 5,097,369 — — 5,015,299 5,015,299 Borrowings 560,625 — 580,616 — 580,616 Accrued interest payable 1,864 — — 1,864 1,864 Loan level interest rate swaps 5,381 — — 5,381 5,381 Carrying Fair Value Amount Level 1 Level 2 Level 3 Total (In thousands) December 31, 2020 Financial assets: Cash and due from banks $ 914,586 $ 914,586 $ — $ — $ 914,586 Securities available for sale, at fair value 11,326 — 11,326 — 11,326 Marketable equity securities, at fair value 12,189 12,189 — — 12,189 Federal Home Loan Bank stock 30,658 — — 30,658 30,658 Loans and loans held for sale, net 5,452,029 — — 5,480,258 5,480,258 Accrued interest receivable 23,173 — — 23,173 23,173 Loan level interest rate swaps 10,441 — — 10,441 10,441 Financial liabilities: Deposits 5,081,167 — — 5,172,060 5,172,060 Borrowings 708,245 — 732,302 — 732,302 Accrued interest payable 2,832 — — 2,832 2,832 Loan level interest rate swaps 10,441 — — 10,441 10,441

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail) - shares	Apr. 22, 2021	Mar. 31, 2021
Basis of Presentation [Line Items]
Share in East Boston Savings Bank		100.00%
Subsequent Event [Member]
Basis of Presentation [Line Items]
Number of independent common stock right to receive per each common stock upon completion of merger	0.275

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income available to common stockholders	$ 24,320	$ 12,977
Basic weighted average shares outstanding	50,239,611	50,634,983
Effect of dilutive stock options	325,848	285,276
Diluted weighted average shares outstanding	50,565,459	50,920,259
Earnings per share:
Basic	$ 0.48	$ 0.26
Diluted	$ 0.48	$ 0.25

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Stock Option [Member]
Schedule of Available-for-sale Securities [Line Items]
Anti-dilutive Options	53,381	93,545

Securities - Amortized Cost and

Securities - Amortized Cost and Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost, Total	$ 9,988	$ 10,694
Debt Securities, Gross Unrealized Gains	540	642
Debt Securities, Gross Unrealized Losses	(10)	(10)
Debt Securities, Fair Value	10,518	11,326
Government-sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost, Total	346	346
Debt Securities, Gross Unrealized Gains	17	21
Debt Securities, Fair Value	363	367
Residential Mortgage-backed Securities, Government - sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost, Total	7,006	7,706
Debt Securities, Gross Unrealized Gains	290	359
Debt Securities, Gross Unrealized Losses	(10)	(10)
Debt Securities, Fair Value	7,286	8,055
Residential Mortgage-backed Securities, Private Label [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost, Total	563	567
Debt Securities, Gross Unrealized Gains	108	116
Debt Securities, Fair Value	671	683
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost, Total	2,073	2,075
Debt Securities, Gross Unrealized Gains	125	146
Debt Securities, Fair Value	$ 2,198	$ 2,221

Securities - Additional Informa

Securities - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Other-than-temporarily impaired debt securities	0	0
Marketable equity securities, at fair value	$ 8,900,000		$ 12,189,000
Federal Reserve Bank Discount Window Borrowings [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities with fair value, pledged as collateral	273,000
Federal Home Loan Bank of Boston Borrowings [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities with fair value, pledged as collateral	$ 1,700,000

Securities - Amortized Cost a_2

Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, After One Year Through Five Years	$ 923
Fair Value, After One Year Through Five Years	974
Amortized Cost, After Five Years	9,065
Fair Value, After Five Years	9,544
Debt Securities, Amortized Cost, Total	9,988	$ 10,694
Fair Value, Total	10,518	11,326
Government-sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, After Five Years	346
Fair Value, After Five Years	363
Debt Securities, Amortized Cost, Total	346	346
Fair Value, Total	363	367
Residential Mortgage-backed Securities, Government - sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, After One Year Through Five Years	402
Fair Value, After One Year Through Five Years	412
Amortized Cost, After Five Years	6,604
Fair Value, After Five Years	6,874
Debt Securities, Amortized Cost, Total	7,006	7,706
Fair Value, Total	7,286	8,055
Residential Mortgage-backed Securities, Private Label [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, After Five Years	563
Fair Value, After Five Years	671
Debt Securities, Amortized Cost, Total	563	567
Fair Value, Total	671	683
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost, After One Year Through Five Years	521
Fair Value, After One Year Through Five Years	562
Amortized Cost, After Five Years	1,552
Fair Value, After Five Years	1,636
Debt Securities, Amortized Cost, Total	2,073	2,075
Fair Value, Total	$ 2,198	$ 2,221

Securities - Schedule of Inform

Securities - Schedule of Information Pertaining to Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Debt securities, gross unrealized losses, less than twelve months		$ 7
Debt securities, fair value, less than twelve months		511
Debt securities, gross unrealized losses, over twelve months	$ 10	3
Debt securities, fair value, over twelve months	595	142
Residential Mortgage-backed Securities, Government - sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt securities, gross unrealized losses, less than twelve months		7
Debt securities, fair value, less than twelve months		511
Debt securities, gross unrealized losses, over twelve months	10	3
Debt securities, fair value, over twelve months	$ 595	$ 142

Securities - Unrealized and Rea

Securities - Unrealized and Realized Gains and Losses Recognized in Net Income on Marketable Equity Securities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Investments Debt And Equity Securities [Abstract]
Net realized gain (loss) on marketable equity securities sold during the period	$ 972	$ (337)
Net unrealized gain (loss) recognized during the reporting period on marketable equity securities still held at the reporting date	813	(4,007)
Net gain (loss) recognized during the period on marketable equity securities	$ 1,785	$ (4,344)

Loans - Summary of Loans (Detai

Loans - Summary of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	$ 5,295,729	$ 5,520,413
Less: allowance for credit losses on loans	(63,436)	(68,824)
Net deferred loan origination fees	(8,298)	(7,784)
Loans, net	5,223,995	5,443,805
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	779,603	765,195
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	625,961	731,432
Total Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	4,505,819	4,744,511
Residential Portfolio Segment [Member] | Multi-Family Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	878,331	880,552
Residential Portfolio Segment [Member] | One-to Four-Family [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	517,442	564,146
Residential Portfolio Segment [Member] | Home Equity Lines of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	64,370	68,721
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	2,419,715	2,499,660
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans, Amount	$ 10,307	$ 10,707

Loans - Additional Information

Loans - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)SecurityLoan	Dec. 31, 2020USD ($)SecurityLoan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Servicing loans for participants	$ 187.2	$ 176.4
Number of accruing loans | SecurityLoan	0	0
Loans modified as TDRs on non-accrual status, minimum period	6 months
Loans modified as TDRs qualify for return to accrual status if demonstrated performance with modified terms of loan agreement, minimum period	6 months
Amount of loans under modification	$ 402.7
Percentage of loan portfolio	7.60%
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of loan pledged	$ 1,305
Multi-Family Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of loan pledged	$ 269.3

Loans - Allowance for Credit Lo

Loans - Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 68,824	$ 50,322
Provision (reversal) for credit losses	(5,236)	725
Charge-offs	(191)	(114)
Recoveries	39	13
Ending balance	63,436	50,946
Amount of allowance for credit losses for loans deemed to be impaired	166
Amount of allowance for credit losses for loans not deemed to be impaired	63,270		$ 68,824
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	63,436		68,824
Loans deemed to be impaired	2,511		4,325
Loans not deemed to be impaired	5,293,218		5,516,088
Total, Amount of allowance impaired	5,295,729		5,520,413
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	30,145	26,943
Provision (reversal) for credit losses	(712)	(215)
Ending balance	29,433	26,728
Amount of allowance for credit losses for loans not deemed to be impaired	29,433		30,145
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	29,433		30,145
Loans deemed to be impaired			1,648
Loans not deemed to be impaired	2,419,715		2,498,012
Total, Amount of allowance impaired	2,419,715		2,499,660
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	496	116
Provision (reversal) for credit losses	(41)	16
Charge-offs	(34)	(64)
Recoveries	24	11
Ending balance	445	79
Amount of allowance for credit losses for loans not deemed to be impaired	445		496
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	445		496
Loans not deemed to be impaired	10,307		10,707
Total, Amount of allowance impaired	10,307		10,707
Multi-Family Residential Real Estate [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,251	7,825
Provision (reversal) for credit losses	(529)	(145)
Ending balance	1,722	7,680
Amount of allowance for credit losses for loans not deemed to be impaired	1,722		2,251
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	1,722		2,251
Loans not deemed to be impaired	878,331		880,552
Total, Amount of allowance impaired	878,331		880,552
One-to Four-Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,076	691
Provision (reversal) for credit losses	(391)	103
Charge-offs	(68)
Ending balance	1,617	794
Amount of allowance for credit losses for loans not deemed to be impaired	1,617		2,076
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	1,617		2,076
Loans deemed to be impaired	597		602
Loans not deemed to be impaired	516,845		563,544
Total, Amount of allowance impaired	517,442		564,146
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	206	69
Provision (reversal) for credit losses	(40)	24
Recoveries		1
Ending balance	166	94
Amount of allowance for credit losses for loans not deemed to be impaired	166		206
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	166		206
Loans not deemed to be impaired	64,370		68,721
Total, Amount of allowance impaired	64,370		68,721
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	25,197	8,913
Provision (reversal) for credit losses	(3,611)	544
Ending balance	21,586	9,457
Amount of allowance for credit losses for loans not deemed to be impaired	21,586		25,197
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	21,586		25,197
Loans not deemed to be impaired	625,961		731,432
Total, Amount of allowance impaired	625,961		731,432
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	8,453	5,765
Provision (reversal) for credit losses	88	398
Charge-offs	(89)	(50)
Recoveries	15	1
Ending balance	8,467	$ 6,114
Amount of allowance for credit losses for loans deemed to be impaired	166
Amount of allowance for credit losses for loans not deemed to be impaired	8,301		8,453
Amount of allowance for credit losses for loans deemed to be impaired and loans not deemed to be impaired	8,467		8,453
Loans deemed to be impaired	1,914		2,075
Loans not deemed to be impaired	777,689		763,120
Total, Amount of allowance impaired	$ 779,603		$ 765,195

Loans - Past Due and Non Accrua

Loans - Past Due and Non Accrual (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	$ 2,736	$ 3,314
Loans on Non-accrual	3,121	3,164
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	489	750
Loans on Non-accrual	635	527
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	1,344	1,871
Loans on Non-accrual	2,486	2,637
One-to Four-Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	1,124	1,851
Loans on Non-accrual	2,466	2,617
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	220	20
Loans on Non-accrual	20	20
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	903	693
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	1,017	1,342
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due		390
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	395	504
Financing Receivables, 30 to 59 Days Past Due [Member] | One-to Four-Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	195	504
Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	200
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	622	448
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	281	476
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due		231
Financing Receivables, 60 to 89 Days Past Due [Member] | One-to Four-Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due		231
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	281	245
Financing Receivables, 90 Days or Greater Past Due [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	1,438	1,496
Financing Receivables, 90 Days or Greater Past Due [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	489	360
Financing Receivables, 90 Days or Greater Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	949	1,136
Financing Receivables, 90 Days or Greater Past Due [Member] | One-to Four-Family [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	929	1,116
Financing Receivables, 90 Days or Greater Past Due [Member] | Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Past Due	$ 20	$ 20

Loans - Impaired Loans of Compa

Loans - Impaired Loans of Company (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financing Receivable, Impaired [Line Items]
Impaired Loans Without Valuation Allowance, Recorded Investment	$ 2,345		$ 4,325
Impaired Loans Without Valuation Allowance, Unpaid Principal Balance	3,011		4,992
Impaired Loans With Valuation Allowance, Recorded Investment	166
Impaired Loans With Valuation Allowance, Unpaid Principal Balance	207
Impaired Loans With Valuation Allowance, Related Allowance	166
Recorded Investment, Total	2,511		4,325
Unpaid Principal Balance, Total	3,218		4,992
Related Allowance, Total	166
Average Recorded Investment	2,730	$ 6,014
Interest Income Recognized	35	61
Interest Income Recognized on Cash Basis	24	8
One-to Four-Family [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans Without Valuation Allowance, Recorded Investment	597		602
Impaired Loans Without Valuation Allowance, Unpaid Principal Balance	933		940
Average Recorded Investment	763	1,512
Interest Income Recognized	10	14
Interest Income Recognized on Cash Basis	9	8
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans Without Valuation Allowance, Recorded Investment	1,748		2,075
Impaired Loans Without Valuation Allowance, Unpaid Principal Balance	2,078		2,404
Impaired Loans With Valuation Allowance, Recorded Investment	166
Impaired Loans With Valuation Allowance, Unpaid Principal Balance	207
Impaired Loans With Valuation Allowance, Related Allowance	166
Recorded Investment, Total	1,914		2,075
Related Allowance, Total	166
Average Recorded Investment	1,967	2,539
Interest Income Recognized	25	26
Interest Income Recognized on Cash Basis	15
Residential Portfolio Segment [Member] | One-to Four-Family [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment, Total	$ 597		602
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans Without Valuation Allowance, Recorded Investment			1,648
Impaired Loans Without Valuation Allowance, Unpaid Principal Balance			1,648
Recorded Investment, Total			$ 1,648
Average Recorded Investment		1,963
Interest Income Recognized		$ 21

Loans - Summary of Troubled Deb

Loans - Summary of Troubled Debt Restructurings (TDRs) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Modifications [Line Items]
Total TDRs on accrual status	$ 1,580	$ 1,731
Total TDRs on non-accrual status	417	420
Total TDRs	1,997	2,151
One-to Four-Family [Member]
Financing Receivable, Modifications [Line Items]
Total TDRs on accrual status	1,580	1,731
Total TDRs on non-accrual status	$ 417	$ 420

Loans - Risk Rated Loans by Cla

Loans - Risk Rated Loans by Class (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Multi-Family Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	$ 878,331	$ 880,552
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	2,419,715	2,499,660
Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	625,961	731,432
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	779,603	765,195
Loans rated 1 - 6 [Member] | Multi-Family Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	878,331	880,552
Loans rated 1 - 6 [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	2,404,053	2,483,867
Loans rated 1 - 6 [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	625,961	731,432
Loans rated 1 - 6 [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	722,477	704,534
Loans Rated 7 [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	15,662	15,793
Loans Rated 7 [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	36,465	37,093
Loans Rated 8 [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable Credit Quality Rating	$ 20,661	$ 23,568

Deposits - Summary of Deposit B

Deposits - Summary of Deposit Balances, by Type (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Banking Deposits And Thrift [Abstract]
Noninterest-bearing demand deposits	$ 751,809	$ 711,573
Interest-bearing demand deposits	1,461,236	1,364,548
Money market deposits	852,747	930,507
Regular savings and other deposits	870,961	855,329
Total non-certificate accounts	3,936,753	3,861,957
Term certificates less than $250,000	809,835	883,133
Term certificates $250,000 and greater	350,781	336,077
Total certificate accounts	1,160,616	1,219,210
Total deposits	$ 5,097,369	$ 5,081,167

Deposits - Summary of Term Cert

Deposits - Summary of Term Certificates, by Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Banking Deposits And Thrift [Abstract]
Within 1 year, Amount	$ 893,949	$ 883,747
Over 1 year to 2 years, Amount	140,128	194,698
Over 2 years to 3 years, Amount	35,826	40,338
Over 3 years to 4 years, Amount	53,561	53,580
Over 4 years to 5 years, Amount	36,962	46,847
Greater than 5 years, Amount	190
Total certificate accounts	$ 1,160,616	$ 1,219,210
Within 1 year, Weighted Average Rate	0.91%	1.03%
Over 1 year to 2 years, Weighted Average Rate	1.26%	1.29%
Over 2 year to 3 years, Weighted Average Rate	0.77%	1.21%
Over 3 year to 4 years, Weighted Average Rate	0.72%	0.75%
Over 4 years to 5 years, Weighted Average Rate	0.51%	0.68%
Greater than 5 Years, Weighted Average Rate	1.05%
Weighted average rate on term certificates	0.93%	1.05%

Deposits - Additional Informati

Deposits - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Banking Deposits And Thrift [Abstract]
Brokered certificate of deposit included in term certificates	$ 152.1	$ 212
Weighted average rate of deposit included in term certificates	1.20%	1.29%
Brokered certificate of deposit included in term certificates	$ 43.6	$ 50.6
Weighted average rate of deposit included in term certificates	1.06%	1.01%
Brokered interest-bearing demand deposits	$ 175.6	$ 175.6

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Debt Disclosure [Line Items]
Short-term borrowings	$ 0	$ 0
Available line of credit with the FHLB	10,000,000
Amounts drawn on the line of credit	0	0
Multi-Family Residential Real Estate [Member]
Debt Disclosure [Line Items]
Carrying value of commercial real estate loans pledged	269,300,000
Commercial Real Estate Portfolio Segment [Member]
Debt Disclosure [Line Items]
Carrying value of commercial real estate loans pledged	1,305,000,000
FHLB Callable [Member]
Debt Disclosure [Line Items]
FHLB, total advances callable prior to maturity	$ 445,000,000
Weighted Average [Member] | FHLB Callable [Member]
Debt Disclosure [Line Items]
FHLB advances, weighted average rate	2.53%
Paycheck Protection Program Liquidity Facility [Member]
Debt Disclosure [Line Items]
Long-term debt in FHLB advances	$ 560,600,000
Borrowing from Federal Reserve Bank discount window	$ 0	$ 97,600,000
Federal reserve bank discount window interest rate	0.35%
Paycheck Protection Program Liquidity Facility [Member] | Minimum [Member]
Debt Disclosure [Line Items]
Federal reserve bank discount window maturity period	2 years
Paycheck Protection Program Liquidity Facility [Member] | Maximum [Member]
Debt Disclosure [Line Items]
Federal reserve bank discount window maturity period	5 years

Borrowings - Long-term, Fixed R

Borrowings - Long-term, Fixed Rate FHLB Advances (Detail) - Fixed Interest Rate [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
2021		$ 50,000
2022	$ 150,625	150,625
2023	295,000	295,000
2024	20,000	20,000
2025	85,000	85,000
Thereafter	10,000	10,000
Total advances	$ 560,625	$ 610,625
Weighted Average Rate, 2021		1.18%
Weighted Average Rate, 2022	2.00%	2.00%
Weighted Average Rate, 2023	3.10%	3.10%
Weighted Average Rate, 2024	2.61%	2.61%
Weighted Average Rate, 2025	1.00%	1.00%
Weighted Average Rate, Thereafter	1.21%	1.21%
Weighted Average Rate	2.44%	2.33%

Commitments and Contingencies_3

Commitments and Contingencies and Derivatives - Loan Commitments Outstanding (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Total loan commitments outstanding	$ 1,103,191	$ 1,075,220
Construction [Member] | Unadvanced Portion of Existing Loans [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	492,454	501,911
Construction [Member] | Unfunded Loan Commitment [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	126,301	76,615
Home Equity Lines of Credit [Member] | Unadvanced Portion of Existing Loans [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	77,602	79,579
One-to Four-Family [Member] | Unfunded Loan Commitment [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	27,641	41,454
Commercial Real Estate Portfolio Segment [Member] | Unfunded Loan Commitment [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	20,866	16,540
Other Lines and Letters of Credit [Member] | Unadvanced Portion of Existing Loans [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	352,556	350,708
Commercial and Industrial [Member] | Unfunded Loan Commitment [Member]
Loss Contingencies [Line Items]
Total loan commitments outstanding	$ 5,771	$ 8,413

Commitments and Contingencies_4

Commitments and Contingencies and Derivatives - Additional Information (Detail) - USD ($)	Nov. 25, 2019	Oct. 31, 2019	Mar. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Cash pledged for collateral interest rate swap			$ 6,400,000	$ 11,400,000
Pending Litigation [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss contingency damages, amount	$ 1,000,000	$ 1,000,000
Loss contingency damages awarded, amount	2,100,000
Pending Litigation [Member] | Maximum [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss contingency, range of possible loss	3,000,000
Pending Litigation [Member] | Minimum [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss contingency, range of possible loss	$ 0
Core Data Processing Provider [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other outstanding commitments			$ 3,200,000

Commitments and Contingencies_5

Commitments and Contingencies and Derivatives - Summary Information Regarding the Derivatives (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Customer Interest Rate Swap Maturing on 06/07/32 [Member]
Loss Contingencies [Line Items]
Notional amount	$ 60,348,000	$ 60,782,000
Fair value asset (liability)	$ 4,336,000	8,886,000
Maturity	Jun. 7, 2032
Interest rate paid	1 Mo. Libor + 200bp
Interest rate received	Fixed (4.40%)
Fixed interest rate received	4.40%
Customer Interest Rate Swap Maturing on 06/07/32 [Member] | LIBOR [Member]
Loss Contingencies [Line Items]
Variable interest rate paid	2.00%
Third Party Interest Rate Swap Maturing on 06/07/32 [Member]
Loss Contingencies [Line Items]
Notional amount	$ 60,348,000	60,782,000
Fair value asset (liability)	$ (4,336,000)	(8,886,000)
Maturity	Jun. 7, 2032
Interest rate paid	Fixed (4.40%)
Fixed interest rate paid	4.40%
Interest rate received	1 Mo. Libor + 200bp
Third Party Interest Rate Swap Maturing on 06/07/32 [Member] | LIBOR [Member]
Loss Contingencies [Line Items]
Variable interest rate received	2.00%
Customer Interest Rate Swap Maturing on 10/17/33 [Member]
Loss Contingencies [Line Items]
Notional amount	$ 9,738,000	9,831,000
Fair value asset (liability)	$ 957,000	1,401,000
Maturity	Oct. 17, 2033
Interest rate paid	1 Mo. Libor + 175bp
Interest rate received	Fixed (4.1052%)
Fixed interest rate received	4.1052%
Customer Interest Rate Swap Maturing on 10/17/33 [Member] | LIBOR [Member]
Loss Contingencies [Line Items]
Variable interest rate paid	1.75%
Third Party Interest Rate Swap Maturing on 10/17/33 [Member]
Loss Contingencies [Line Items]
Notional amount	$ 9,738,000	9,831,000
Fair value asset (liability)	$ (957,000)	(1,401,000)
Maturity	Oct. 17, 2033
Interest rate paid	Fixed (4.1052%)
Fixed interest rate paid	4.1052%
Interest rate received	1 Mo. Libor + 175bp
Third Party Interest Rate Swap Maturing on 10/17/33 [Member] | LIBOR [Member]
Loss Contingencies [Line Items]
Variable interest rate received	1.75%
Customer Interest Rate Swap Maturing on 12/13/26 [Member]
Loss Contingencies [Line Items]
Notional amount	$ 2,346,000	2,390,000
Fair value asset (liability)	$ 88,000	154,000
Maturity	Dec. 13, 2026
Interest rate paid	1 Mo. Libor + 205bp
Interest rate received	Fixed (3.82%)
Fixed interest rate received	3.82%
Customer Interest Rate Swap Maturing on 12/13/26 [Member] | LIBOR [Member]
Loss Contingencies [Line Items]
Variable interest rate paid	2.05%
Third Party Interest Rate Swap Maturing on 12/13/26 [Member]
Loss Contingencies [Line Items]
Notional amount	$ 2,346,000	2,390,000
Fair value asset (liability)	$ (88,000)	$ (154,000)
Maturity	Dec. 13, 2026
Interest rate paid	Fixed (3.82%)
Fixed interest rate paid	3.82%
Interest rate received	1 Mo. Libor + 205bp
Third Party Interest Rate Swap Maturing on 12/13/26 [Member] | LIBOR [Member]
Loss Contingencies [Line Items]
Variable interest rate received	2.05%

Fair Values of Assets and Lia_3

Fair Values of Assets and Liabilities - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	$ 10,518	$ 11,326
Marketable equity securities	8,900	12,189
Total liabilities	5,381	10,441
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	24,799	33,956
Loan Level Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan level interest rate swaps	5,381	10,441
Loan Level Interest Rate Swaps [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan level interest rate swaps	5,381	10,441
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity securities	8,900	12,189
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	8,900	12,189
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	10,518	11,326
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	10,518	11,326
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	5,381	10,441
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	5,381	10,441
Fair Value, Inputs, Level 3 [Member] | Loan Level Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan level interest rate swaps	5,381	10,441
Fair Value, Inputs, Level 3 [Member] | Loan Level Interest Rate Swaps [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan level interest rate swaps	$ 5,381	$ 10,441

Fair Values of Assets and Lia_4

Fair Values of Assets and Liabilities - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans measured at fair value	$ 1.9	$ 3.7

Fair Values of Assets and Lia_5

Fair Values of Assets and Liabilities - Summary of Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financial assets:
Securities available for sale, at fair value	$ 10,518	$ 11,326
Marketable equity securities, at fair value	8,900	12,189
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Marketable equity securities, at fair value	8,900	12,189
Carrying Amount [Member]
Financial assets:
Cash and due from banks	1,034,107	914,586
Securities available for sale, at fair value	10,518	11,326
Marketable equity securities, at fair value	8,900	12,189
Federal Home Loan Bank stock	28,447	30,658
Loans and loans held for sale, net	5,231,417	5,452,029
Accrued interest receivable	22,498	23,173
Financial liabilities:
Deposits	5,097,369	5,081,167
Borrowings	560,625	708,245
Accrued interest payable	1,864	2,832
Carrying Amount [Member] | Interest Rate Swaps [Member]
Financial assets:
Loan level interest rate swaps	5,381	10,441
Financial liabilities:
Loan level interest rate swaps	5,381	10,441
Fair Value [Member]
Financial assets:
Cash and due from banks	1,034,107	914,586
Securities available for sale, at fair value	10,518	11,326
Marketable equity securities, at fair value	8,900	12,189
Federal Home Loan Bank stock	28,447	30,658
Loans and loans held for sale, net	5,276,764	5,480,258
Accrued interest receivable	22,498	23,173
Financial liabilities:
Deposits	5,015,299	5,172,060
Borrowings	580,616	732,302
Accrued interest payable	1,864	2,832
Fair Value [Member] | Interest Rate Swaps [Member]
Financial assets:
Loan level interest rate swaps	5,381	10,441
Financial liabilities:
Loan level interest rate swaps	5,381	10,441
Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and due from banks	1,034,107	914,586
Marketable equity securities, at fair value	8,900	12,189
Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Securities available for sale, at fair value	10,518	11,326
Financial liabilities:
Borrowings	580,616	732,302
Fair Value [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Federal Home Loan Bank stock	28,447	30,658
Loans and loans held for sale, net	5,276,764	5,480,258
Accrued interest receivable	22,498	23,173
Financial liabilities:
Deposits	5,015,299	5,172,060
Accrued interest payable	1,864	2,832
Fair Value [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Swaps [Member]
Financial assets:
Loan level interest rate swaps	5,381	10,441
Financial liabilities:
Loan level interest rate swaps	$ 5,381	$ 10,441