LOANS AND LEASES AND ALLOWANCE FOR LOAN AND LEASE LOSSES - Allowance for Loan and Lease Losses and Recorded Investment Excluding Accrued Interest in Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 37,483	$ 34,787	$ 35,533	$ 29,480
Charge-offs	(393)	(788)	(1,267)	(1,224)
Recoveries	551	40	1,285	309
Provision	2,592	735	4,682	6,209
Balance at end of period	40,233	34,774	40,233	34,774
Individually evaluated for impairment					$ 665		$ 512
Collectively evaluated for impairment					39,464		34,056
Total ending ALLL balance	37,483	34,787	35,533	29,480	40,233	$ 35,533	34,774
Loans:
Individually evaluated for impairment					32,284		32,712
Collectively evaluated for impairment					5,894,140		4,324,808
Total ending loan balances					6,568,791	5,184,394	4,730,077
Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	104	206	104	206
Total ending ALLL balance	104	206	104	206	104		206
Loans:
Total ending loan balances					642,367	712,731	372,557
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	0	2,243	0	0
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	0	(2,243)	0	0
Balance at end of period	0	0	0	0
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					0		0
Total ending ALLL balance	0	2,243	0	0	0	0	0
Loans:
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					0		0
Total ending loan balances					0		0
Unallocated | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	0	0	0	0
Total ending ALLL balance	0	0	0	0	0		0
Loans:
Total ending loan balances					0		0
Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	8,004	6,884	5,850	6,910
Charge-offs	0	0	(137)	(33)
Recoveries	224	0	224	8
Provision	(2)	(904)	2,289	(905)
Balance at end of period	8,226	5,980	8,226	5,980
Individually evaluated for impairment					0		76
Collectively evaluated for impairment					8,169		5,846
Total ending ALLL balance	8,004	6,884	5,850	6,910	8,226	5,850	5,980
Loans:
Individually evaluated for impairment					3,397		5,980
Collectively evaluated for impairment					1,522,848		816,254
Total ending loan balances					1,531,041	876,999	822,690
Commercial | Commercial and industrial | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	57	58	57	58
Total ending ALLL balance	57	58	57	58	57		58
Loans:
Total ending loan balances					4,796	853	456
Commercial | Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	3,554	4,445	4,252	3,840
Charge-offs	0	0	0	(259)
Recoveries	0	0	371	132
Provision	1,472	(526)	403	206
Balance at end of period	5,026	3,919	5,026	3,919
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					5,015		3,807
Total ending ALLL balance	3,554	4,445	4,252	3,840	5,026	4,252	3,919
Loans:
Individually evaluated for impairment					0		333
Collectively evaluated for impairment					719,420		680,039
Total ending loan balances					721,838	727,707	690,862
Commercial | Commercial real estate | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	11	112	11	112
Total ending ALLL balance	11	112	11	112	11		112
Loans:
Total ending loan balances					2,418	9,599	10,490
Commercial | Multi-family
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	6,914	3,680	6,012	7,179
Charge-offs	0	0	0	0
Recoveries	0	0	0	3
Provision	1,795	2,030	2,697	(1,472)
Balance at end of period	8,709	5,710	8,709	5,710
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					8,709		5,710
Total ending ALLL balance	6,914	3,680	6,012	7,179	8,709	6,012	5,710
Loans:
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					1,199,207		823,415
Total ending loan balances					1,199,207	904,300	823,415
Commercial | Multi-family | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	0	0	0	0
Total ending ALLL balance	0	0	0	0	0		0
Loans:
Total ending loan balances					0	0	0
Commercial | SBA
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	697	674	683	335
Charge-offs	0	(29)	0	(84)
Recoveries	67	40	343	153
Provision	144	(70)	(118)	211
Balance at end of period	908	615	908	615
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					889		596
Total ending ALLL balance	697	674	683	335	908	683	615
Loans:
Individually evaluated for impairment					0		8
Collectively evaluated for impairment					64,977		49,854
Total ending loan balances					67,737	57,706	52,985
Commercial | SBA | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	19	19	19	19
Total ending ALLL balance	19	19	19	19	19		19
Loans:
Total ending loan balances					2,760	3,049	3,123
Commercial | Construction
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	1,677	579	1,530	846
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	40	612	187	345
Balance at end of period	1,717	1,191	1,717	1,191
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					1,717		1,191
Total ending ALLL balance	1,677	579	1,530	846	1,717	1,530	1,191
Loans:
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					99,086		39,475
Total ending loan balances					99,086	55,289	39,475
Commercial | Construction | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	0	0	0	0
Total ending ALLL balance	0	0	0	0	0		0
Loans:
Total ending loan balances					0	0	0
Commercial | Lease financing
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	2,540	1,646	2,195	873
Charge-offs	(393)	(759)	(974)	(848)
Recoveries	98	0	183	0
Provision	722	1,196	1,563	2,058
Balance at end of period	2,967	2,083	2,967	2,083
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					2,967		2,083
Total ending ALLL balance	2,540	1,646	2,195	873	2,967	2,195	2,083
Loans:
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					234,540		162,504
Total ending loan balances					234,540	192,424	162,504
Commercial | Lease financing | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	0	0	0	0
Total ending ALLL balance	0	0	0	0	0		0
Loans:
Total ending loan balances					0	0	0
Consumer | Single Family Residential Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	13,143	12,950	13,854	7,192
Charge-offs	0	0	(149)	0
Recoveries	157	0	157	0
Provision	(1,573)	1,051	(2,135)	6,809
Balance at end of period	11,727	14,001	11,727	14,001
Individually evaluated for impairment					665		436
Collectively evaluated for impairment					11,045		13,548
Total ending ALLL balance	13,143	12,950	13,854	7,192	11,727	13,854	14,001
Loans:
Individually evaluated for impairment					28,593		25,837
Collectively evaluated for impairment					1,940,389		1,629,125
Total ending loan balances					2,601,375		2,013,450
Consumer | Single Family Residential Mortgage | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	17	17	17	17
Total ending ALLL balance	17	17	17	17	17		17
Loans:
Total ending loan balances					632,393		358,488
Consumer | Other Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	954	1,686	1,157	2,305
Charge-offs	0	0	(7)	0
Recoveries	5	0	7	13
Provision	(6)	(411)	(204)	(1,043)
Balance at end of period	953	1,275	953	1,275
Individually evaluated for impairment					0		0
Collectively evaluated for impairment					953		1,275
Total ending ALLL balance	954	1,686	1,157	2,305	953	$ 1,157	1,275
Loans:
Individually evaluated for impairment					294		554
Collectively evaluated for impairment					113,673		124,142
Total ending loan balances					113,967		124,696
Consumer | Other Consumer | Purchased Credit Impaired
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of period	0	0	0	0
Total ending ALLL balance	$ 0	$ 0	$ 0	$ 0	0		0
Loans:
Total ending loan balances					$ 0		$ 0