Loans Receivable, Net - Risk Category of Loans by Loan Portfolio Segment Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loan	$ 1,688,496	$ 962,772
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	491,118	307,509
Commercial Real Estate - Investor [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	1,014,611	510,725
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	182,767	144,538
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	1,621,444	925,752
Pass [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	449,297	288,701
Pass [Member] | Commercial Real Estate - Investor [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	992,247	494,664
Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	179,900	142,387
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	24,363	12,857
Special Mention [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	14,404	1,803
Special Mention [Member] | Commercial Real Estate - Investor [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	7,756	10,267
Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	2,203	787
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	42,689	24,163
Substandard [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	27,417	17,005
Substandard [Member] | Commercial Real Estate - Investor [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	14,608	5,794
Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan	$ 664	$ 1,364