Loans Receivable, Net - Risk Category of Loans by Loan Portfolio Segment Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	$ 3,472,730	$ 3,060,579
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	3,374,850	2,964,585
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	30,201	29,504
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	67,679	66,490
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	0	0
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	396,091	304,994
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	378,154	291,265
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	2,657	2,777
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	15,280	10,952
Commercial and industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	0	0
Commercial real estate – owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	791,941	740,375
Commercial real estate – owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	756,592	706,825
Commercial real estate – owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	3,985	3,000
Commercial real estate – owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	31,364	30,550
Commercial real estate – owner occupied | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	0	0
Commercial real estate - investor
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	2,284,698	2,015,210
Commercial real estate - investor | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	2,240,104	1,966,495
Commercial real estate - investor | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	23,559	23,727
Commercial real estate - investor | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	21,035	24,988
Commercial real estate - investor | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loan	$ 0	$ 0