LOANS AND LEASES AND ALLOWANCE FOR LOAN AND LEASE LOSSES - Aging of Recorded Investment in Past Due Loans and Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 53,751	$ 62,013
Current	6,051,570	5,972,739
Total ending loan balances	6,105,321	6,034,752	$ 5,463,068
30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	28,820	38,180
60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	10,186	7,038
Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14,745	16,795
Purchased Credit Impaired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	21,353	17,655
Current	118,346	124,171
Total ending loan balances	139,699	141,826	683,976
Purchased Credit Impaired | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14,152	10,783
Purchased Credit Impaired | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,258	4,295
Purchased Credit Impaired | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,943	2,577
Non-Traditional Mortgages (NTM)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	818,010	885,148
Traditional Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	31,125	39,698
Current	5,116,487	4,968,080
Total ending loan balances	5,147,612	5,007,778
Traditional Loans | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13,863	23,204
Traditional Loans | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,928	2,743
Traditional Loans | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,334	13,751
Traditional Loans | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	142,164	125,100
Consumer | Single family residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	1,889,390	2,019,161
Consumer | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	122,265	107,063
Consumer | Purchased Credit Impaired | Single family residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	16,274	16,639
Current	114,979	116,573
Total ending loan balances	131,253	133,212
Consumer | Purchased Credit Impaired | Single family residential mortgage | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,783	10,483
Consumer | Purchased Credit Impaired | Single family residential mortgage | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,258	4,063
Consumer | Purchased Credit Impaired | Single family residential mortgage | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,233	2,093
Consumer | Purchased Credit Impaired | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Consumer | Non-Traditional Mortgages (NTM)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,273	4,660
Current	816,737	880,488
Total ending loan balances	818,010	885,148
Consumer | Non-Traditional Mortgages (NTM) | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	805	4,193
Consumer | Non-Traditional Mortgages (NTM) | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	468	467
Consumer | Non-Traditional Mortgages (NTM) | Green Loans (HELOC) - first liens
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	814,461	881,589
Consumer | Non-Traditional Mortgages (NTM) | Green Loans (HELOC) - second liens
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	3,549	3,559
Consumer | Non-Traditional Mortgages (NTM) | Single family residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,273	4,660
Current	727,523	789,460
Total ending loan balances	728,796	794,120
Consumer | Non-Traditional Mortgages (NTM) | Single family residential mortgage | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	805	4,193
Consumer | Non-Traditional Mortgages (NTM) | Single family residential mortgage | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Single family residential mortgage | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	468	467
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - first liens
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	85,665	87,469
Total ending loan balances	85,665	87,469
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - first liens | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - first liens | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - first liens | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - second liens
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	3,549	3,559
Total ending loan balances	3,549	3,559
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - second liens | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - second liens | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Consumer home equity loan | Green Loans (HELOC) - second liens | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Consumer | Non-Traditional Mortgages (NTM) | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Consumer | Traditional Loans | Single family residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19,245	21,963
Current	1,010,096	1,069,866
Total ending loan balances	1,029,341	1,091,829
Consumer | Traditional Loans | Single family residential mortgage | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	10,174	11,225
Consumer | Traditional Loans | Single family residential mortgage | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,527	1,345
Consumer | Traditional Loans | Single family residential mortgage | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,544	9,393
Consumer | Traditional Loans | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,027	11,338
Current	120,238	95,725
Total ending loan balances	122,265	107,063
Consumer | Traditional Loans | Other consumer | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,325	10,023
Consumer | Traditional Loans | Other consumer | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11	933
Consumer | Traditional Loans | Other consumer | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	691	382
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	1,585,656	1,522,960	983,961
Commercial | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	750,592	729,959	713,693
Commercial | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	1,449,715	1,365,262	1,021,097
Commercial | SBA
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	76,040	73,840	71,640
Commercial | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	142,164	125,100	68,241
Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	285	379	212,836
Commercial | Purchased Credit Impaired | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,158	156
Current	529	4,604
Total ending loan balances	4,687	4,760	819
Commercial | Purchased Credit Impaired | Commercial and industrial | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,004	0
Commercial | Purchased Credit Impaired | Commercial and industrial | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Purchased Credit Impaired | Commercial and industrial | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	154	156
Commercial | Purchased Credit Impaired | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	1,152	1,182
Total ending loan balances	1,152	1,182	8,218
Commercial | Purchased Credit Impaired | Commercial real estate | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Purchased Credit Impaired | Commercial real estate | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Purchased Credit Impaired | Commercial real estate | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Purchased Credit Impaired | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0	0
Commercial | Purchased Credit Impaired | SBA
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	921	860
Current	1,686	1,812
Total ending loan balances	2,607	2,672	2,940
Commercial | Purchased Credit Impaired | SBA | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	365	300
Commercial | Purchased Credit Impaired | SBA | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	232
Commercial | Purchased Credit Impaired | SBA | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	556	328
Commercial | Purchased Credit Impaired | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0	0
Commercial | Purchased Credit Impaired | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0	$ 0
Commercial | Non-Traditional Mortgages (NTM) | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Commercial | Non-Traditional Mortgages (NTM) | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Commercial | Non-Traditional Mortgages (NTM) | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Commercial | Non-Traditional Mortgages (NTM) | SBA
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Commercial | Non-Traditional Mortgages (NTM) | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Commercial | Non-Traditional Mortgages (NTM) | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total ending loan balances	0	0
Commercial | Traditional Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,379	4,260
Current	1,574,590	1,513,940
Total ending loan balances	1,580,969	1,518,200
Commercial | Traditional Loans | Commercial and industrial | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	978	412
Commercial | Traditional Loans | Commercial and industrial | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,390	463
Commercial | Traditional Loans | Commercial and industrial | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,011	3,385
Commercial | Traditional Loans | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	749,440	728,777
Total ending loan balances	749,440	728,777
Commercial | Traditional Loans | Commercial real estate | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Commercial real estate | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Commercial real estate | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	1,449,715	1,365,262
Total ending loan balances	1,449,715	1,365,262
Commercial | Traditional Loans | Multi-family | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Multi-family | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Multi-family | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | SBA
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,849	499
Current	71,584	70,669
Total ending loan balances	73,433	71,168
Commercial | Traditional Loans | SBA | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,386	15
Commercial | Traditional Loans | SBA | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	2
Commercial | Traditional Loans | SBA | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	463	482
Commercial | Traditional Loans | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,528	1,529
Current	140,636	123,571
Total ending loan balances	142,164	125,100
Commercial | Traditional Loans | Construction | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	1,529
Commercial | Traditional Loans | Construction | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Construction | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,528	0
Commercial | Traditional Loans | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	97	109
Current	188	270
Total ending loan balances	285	379
Commercial | Traditional Loans | Lease financing | 30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Lease financing | 60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Traditional Loans | Lease financing | Greater than 89 Days Past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 97	$ 109