Loans and Leases Receivable and Allowance for Credit Losses - Credit Ratings of Covered and Non-Covered Loan Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 1,515,239
2019	1,599,431
2018	786,506
2017	1,055,134
2016	578,390
Prior	1,130,969
Revolving loans amortized cost basis	909,699
Revolving loans converted to term	0
Total loans and leases receivable	7,575,368	$ 7,318,988
Total loans and leases		7,316,903
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		1,597,188
Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		26,507
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	5,960,549	5,690,820
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,614,819	1,628,168
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		5,442,307
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		111,157
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		139,744
Commercial loans and leases receivable \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,188,773
2019	791,958
2018	663,454
2017	1,038,646
2016	538,340
Prior	994,535
Revolving loans amortized cost basis	744,843
Revolving loans converted to term	0
Total loans and leases receivable	5,960,549
Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,761,301
Total loans and leases		1,909,274
Multi-family \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Multi-family \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Multi-family \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	150,835
2019	23,716
2018	299,319
2017	590,608
2016	245,946
Prior	450,877
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,761,301	1,907,331
Multi-family \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		1,816,200
Multi-family \| Pass \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	150,835
2019	23,716
2018	299,319
2017	535,510
2016	227,296
Prior	420,809
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,657,485
Multi-family \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		69,637
Multi-family \| Special Mention \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	20,901
2016	10,394
Prior	26,708
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	58,003
Multi-family \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		23,437
Multi-family \| Substandard \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	34,197
2016	8,256
Prior	3,360
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	45,813
Multi-family \| Doubtful \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	2,289,441
Total loans and leases		1,889,980
Commercial and industrial \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Commercial and industrial \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Commercial and industrial \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	752,438
2019	381,057
2018	161,444
2017	122,807
2016	54,201
Prior	74,245
Revolving loans amortized cost basis	743,249
Revolving loans converted to term	0
Total loans and leases receivable	2,289,441
Commercial and industrial \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		1,841,074
Commercial and industrial \| Pass \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	729,270
2019	373,050
2018	141,943
2017	116,793
2016	45,367
Prior	71,502
Revolving loans amortized cost basis	717,007
Revolving loans converted to term	0
Total loans and leases receivable	2,194,932
Commercial and industrial \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		26,285
Commercial and industrial \| Special Mention \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	13,200
2019	1,117
2018	436
2017	113
2016	516
Prior	21
Revolving loans amortized cost basis	17,524
Revolving loans converted to term	0
Total loans and leases receivable	32,927
Commercial and industrial \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		22,621
Commercial and industrial \| Substandard \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9,968
2019	6,890
2018	19,065
2017	5,901
2016	8,318
Prior	2,722
Revolving loans amortized cost basis	8,718
Revolving loans converted to term	0
Total loans and leases receivable	61,582
Commercial and industrial \| Doubtful \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Commercial real estate owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	572,338
Total loans and leases		552,007
Commercial real estate owner occupied \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Commercial real estate owner occupied \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Commercial real estate owner occupied \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	82,343
2019	176,289
2018	82,114
2017	80,040
2016	48,741
Prior	102,070
Revolving loans amortized cost basis	741
Revolving loans converted to term	0
Total loans and leases receivable	572,338	551,948
Commercial real estate owner occupied \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		536,777
Commercial real estate owner occupied \| Pass \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	82,343
2019	168,977
2018	72,615
2017	70,642
2016	46,510
Prior	91,798
Revolving loans amortized cost basis	741
Revolving loans converted to term	0
Total loans and leases receivable	533,626
Commercial real estate owner occupied \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		8,286
Commercial real estate owner occupied \| Special Mention \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	4,464
2018	0
2017	9,056
2016	0
Prior	555
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	14,075
Commercial real estate owner occupied \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		6,944
Commercial real estate owner occupied \| Substandard \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	2,848
2018	9,499
2017	342
2016	2,231
Prior	9,717
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	24,637
Commercial real estate owner occupied \| Doubtful \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Commercial real estate non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,196,564
Total loans and leases		1,223,529
Commercial real estate non-owner occupied \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Commercial real estate non-owner occupied \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Commercial real estate non-owner occupied \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	183,225
2019	105,430
2018	115,623
2017	245,191
2016	179,752
Prior	367,343
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,196,564	1,222,772
Commercial real estate non-owner occupied \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		1,129,838
Commercial real estate non-owner occupied \| Pass \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	143,231
2019	105,430
2018	97,882
2017	157,835
2016	155,168
Prior	313,559
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	973,105
Commercial real estate non-owner occupied \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		6,949
Commercial real estate non-owner occupied \| Special Mention \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	39,994
2019	0
2018	0
2017	66,745
2016	24,218
Prior	14,613
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	145,570
Commercial real estate non-owner occupied \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		86,742
Commercial real estate non-owner occupied \| Substandard \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	17,741
2017	20,611
2016	366
Prior	39,171
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	77,889
Commercial real estate non-owner occupied \| Doubtful \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	140,905
Total loans and leases		118,418
Construction \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Construction \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Construction \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	19,932
2019	105,466
2018	4,954
2017	0
2016	9,700
Prior	0
Revolving loans amortized cost basis	853
Revolving loans converted to term	0
Total loans and leases receivable	140,905	117,617
Construction \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		118,418
Construction \| Pass \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	19,932
2019	105,466
2018	4,954
2017	0
2016	9,700
Prior	0
Revolving loans amortized cost basis	853
Revolving loans converted to term	0
Total loans and leases receivable	140,905
Construction \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Construction \| Special Mention \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Construction \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Construction \| Substandard \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Construction \| Doubtful \| Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Consumer loans \| Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	326,466
2019	807,473
2018	123,052
2017	16,488
2016	40,050
Prior	136,434
Revolving loans amortized cost basis	164,856
Revolving loans converted to term	0
Total loans and leases receivable	1,614,819
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	317,170
Total loans and leases		375,014
Residential real estate \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		362,962
Residential real estate \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		12,052
Residential real estate \| Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,708
2019	13,617
2018	6,970
2017	11,635
2016	39,493
Prior	73,891
Revolving loans amortized cost basis	164,856
Revolving loans converted to term	0
Total loans and leases receivable	317,170	382,634
Residential real estate \| Consumer \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,708
2019	13,617
2018	6,810
2017	10,850
2016	38,143
Prior	69,496
Revolving loans amortized cost basis	161,576
Revolving loans converted to term	0
Total loans and leases receivable	307,200
Residential real estate \| Consumer \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	160
2017	785
2016	1,350
Prior	4,395
Revolving loans amortized cost basis	3,280
Revolving loans converted to term	0
Total loans and leases receivable	9,970
Residential real estate \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Residential real estate \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Residential real estate \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		0
Manufactured housing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	62,243
Total loans and leases		70,398
Manufactured housing \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		63,250
Manufactured housing \| Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases		7,148
Manufactured housing \| Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	295
2018	609
2017	76
2016	41
Prior	61,222
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	62,243	71,359
Manufactured housing \| Consumer \| Performing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0

Loans and Leases Receivable and Allowance for Credit Losses - Credit Ratings of Covered and Non-Covered Loan Portfolio (Detail) - USD ($)
$ in Thousands