Loans Receivable, Net - Risk Category of Loans by Loan Portfolio Segment Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 3,294,080	$ 3,060,579
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans	391,588	304,994
Commercial real estate – owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans	770,730	740,375
Commercial real estate – investor
Financing Receivable, Recorded Investment [Line Items]
Loans	2,131,762	2,015,210
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,196,928	2,964,585
Pass | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans	372,954	291,265
Pass | Commercial real estate – owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans	740,212	706,825
Pass | Commercial real estate – investor
Financing Receivable, Recorded Investment [Line Items]
Loans	2,083,762	1,966,495
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	43,312	29,504
Special Mention | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans	4,553	2,777
Special Mention | Commercial real estate – owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans	7,171	3,000
Special Mention | Commercial real estate – investor
Financing Receivable, Recorded Investment [Line Items]
Loans	31,588	23,727
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	53,840	66,490
Substandard | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans	14,081	10,952
Substandard | Commercial real estate – owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans	23,347	30,550
Substandard | Commercial real estate – investor
Financing Receivable, Recorded Investment [Line Items]
Loans	16,412	24,988
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Doubtful | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Doubtful | Commercial real estate – owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Doubtful | Commercial real estate – investor
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	$ 0