Loans and Leases Receivable and Allowance for Credit Losses - Credit Ratings of Covered and Non-Covered Loan Portfolio (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 891,660
2019	1,891,375
2018	797,094
2017	984,026
2016	651,888
2015	1,305,516
Revolving loans amortized cost basis	750,888
Revolving loans converted to term	0
Total loans and leases receivable	7,272,447	$ 7,318,988
Financing receivable, at amortized cost or lower of cost or market		7,316,903
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	5,599,660	5,690,820
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,672,787	1,628,168
Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		5,442,307
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		111,157
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		139,744
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		1,597,188
Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		26,507
Commercial loans and leases receivable | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	723,566
2019	889,210
2018	594,456
2017	909,938
2016	603,678
2015	1,150,188
Revolving loans amortized cost basis	728,624
Revolving loans converted to term	0
Total loans and leases receivable	5,599,660
Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,581,839	1,909,274
Multi-family | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	124,920
2019	23,534
2018	170,856
2017	449,457
2016	280,602
2015	532,470
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,581,839	1,907,331
Multi-family | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		1,816,200
Multi-family | Pass/Satisfactory | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	124,920
2019	23,534
2018	170,856
2017	417,942
2016	264,780
2015	507,568
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,509,600
Multi-family | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		69,637
Multi-family | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	19,509
2016	1,960
2015	17,753
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	39,222
Multi-family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		23,437
Multi-family | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	12,006
2016	13,862
2015	7,149
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	33,017
Multi-family | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Multi-family | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Multi-family | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	2,099,442	1,889,980
Commercial and industrial | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	445,443
2019	475,302
2018	167,630
2017	128,766
2016	60,116
2015	97,450
Revolving loans amortized cost basis	724,735
Revolving loans converted to term	0
Total loans and leases receivable	2,099,442
Commercial and industrial | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		1,841,074
Commercial and industrial | Pass/Satisfactory | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	439,083
2019	462,717
2018	152,557
2017	109,701
2016	52,470
2015	94,383
Revolving loans amortized cost basis	698,721
Revolving loans converted to term	0
Total loans and leases receivable	2,009,632
Commercial and industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		26,285
Commercial and industrial | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	7,258
2018	2,297
2017	17,402
2016	116
2015	25
Revolving loans amortized cost basis	17,957
Revolving loans converted to term	0
Total loans and leases receivable	45,055
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		22,621
Commercial and industrial | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,360
2019	5,327
2018	12,776
2017	1,663
2016	7,530
2015	3,042
Revolving loans amortized cost basis	8,057
Revolving loans converted to term	0
Total loans and leases receivable	44,755
Commercial and industrial | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Commercial and industrial | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Commercial and industrial | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Commercial real estate owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	544,772	552,007
Commercial real estate owner occupied | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	31,240
2019	184,684
2018	87,091
2017	82,542
2016	50,898
2015	106,689
Revolving loans amortized cost basis	1,628
Revolving loans converted to term	0
Total loans and leases receivable	544,772
Commercial real estate owner occupied | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		536,777
Commercial real estate owner occupied | Pass/Satisfactory | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	31,240
2019	184,684
2018	86,611
2017	72,708
2016	48,643
2015	95,921
Revolving loans amortized cost basis	1,628
Revolving loans converted to term	0
Total loans and leases receivable	521,435
Commercial real estate owner occupied | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		8,286
Commercial real estate owner occupied | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	480
2017	9,484
2016	0
2015	392
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	10,356
Commercial real estate owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		6,944
Commercial real estate owner occupied | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	350
2016	2,255
2015	10,376
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	12,981
Commercial real estate owner occupied | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Commercial real estate owner occupied | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Commercial real estate owner occupied | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Commercial real estate non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,244,773	1,223,529
Commercial real estate non-owner occupied | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	117,101
2019	117,140
2018	145,521
2017	249,173
2016	202,259
2015	413,579
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,244,773
Commercial real estate non-owner occupied | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		1,129,838
Commercial real estate non-owner occupied | Pass/Satisfactory | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	117,101
2019	117,140
2018	117,600
2017	249,173
2016	199,822
2015	376,641
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	1,177,477
Commercial real estate non-owner occupied | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		6,949
Commercial real estate non-owner occupied | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	10,477
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	10,477
Commercial real estate non-owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		86,742
Commercial real estate non-owner occupied | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	2,437
2015	26,461
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	28,898
Commercial real estate non-owner occupied | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	27,921
2017	0
2016	0
2015	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	27,921
Commercial real estate non-owner occupied | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Commercial real estate non-owner occupied | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	128,834	118,418
Construction | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,862
2019	88,550
2018	23,358
2017	0
2016	9,803
2015	0
Revolving loans amortized cost basis	2,261
Revolving loans converted to term	0
Total loans and leases receivable	128,834	117,617
Construction | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		118,418
Construction | Pass/Satisfactory | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,862
2019	88,550
2018	23,358
2017	0
2016	9,803
2015	0
Revolving loans amortized cost basis	2,261
Revolving loans converted to term	0
Total loans and leases receivable	128,834
Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Construction | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	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 receivable		0
Construction | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	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
2015	0
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	0
Construction | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Construction | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Consumer loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	168,094
2019	1,002,165
2018	202,638
2017	74,088
2016	48,210
2015	155,328
Revolving loans amortized cost basis	22,264
Revolving loans converted to term	0
Total loans and leases receivable	1,672,787
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	348,109	375,014
Residential real estate | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,415
2019	54,663
2018	65,219
2017	67,951
2016	47,519
2015	88,110
Revolving loans amortized cost basis	22,232
Revolving loans converted to term	0
Total loans and leases receivable	348,109	382,634
Residential real estate | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Residential real estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Residential real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Residential real estate | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		362,962
Residential real estate | Performing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,349
2019	54,663
2018	64,362
2017	67,128
2016	46,654
2015	83,669
Revolving loans amortized cost basis	21,803
Revolving loans converted to term	0
Total loans and leases receivable	340,628
Residential real estate | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		12,052
Residential real estate | Non-performing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	66
2019	0
2018	857
2017	823
2016	865
2015	4,441
Revolving loans amortized cost basis	429
Revolving loans converted to term	0
Total loans and leases receivable	7,481
Manufactured housing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	66,865	70,398
Manufactured housing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	311
2018	640
2017	80
2016	43
2015	65,791
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	66,865	71,359
Manufactured housing | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Manufactured housing | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Manufactured housing | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Manufactured housing | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		63,250
Manufactured housing | Performing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	311
2018	640
2017	80
2016	43
2015	62,072
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	63,146
Manufactured housing | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		7,148
Manufactured housing | Non-performing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	3,719
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	3,719
Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable	1,257,813	1,178,283
Other consumer | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	165,679
2019	947,191
2018	136,779
2017	6,057
2016	648
2015	1,427
Revolving loans amortized cost basis	32
Revolving loans converted to term	0
Total loans and leases receivable	1,257,813	1,174,175
Other consumer | Pass/Satisfactory
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Other consumer | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Other consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		0
Other consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		1,170,976
Other consumer | Performing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	165,436
2019	943,581
2018	135,926
2017	6,034
2016	648
2015	1,292
Revolving loans amortized cost basis	32
Revolving loans converted to term	0
Total loans and leases receivable	1,252,949
Other consumer | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases receivable		$ 7,307
Other consumer | Non-performing | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	243
2019	3,610
2018	853
2017	23
2016	0
2015	135
Revolving loans amortized cost basis	0
Revolving loans converted to term	0
Total loans and leases receivable	$ 4,864