Loans and Leases - Reserve for Loan and Lease Losses and Recorded Investment in Loans and Leases (Detail) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		$ 2,108	$ 1,415
Ending balance: collectively evaluated for impairment		33,223	27,901
Ending balance: acquired non-credit impaired loans evaluated for impairment			48
Total ending balance		35,331	29,364	$ 21,555	$ 17,499
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)	[1]	38,403	26,581
Ending balance: collectively evaluated for impairment		4,115,240	3,615,247
Loans measured at fair value		317	1,779
Acquired non-impaired loans		232,612	362,272
Acquired credit impaired loans		264	695
Total loans and leases held for investment		4,386,836	4,006,574
Valley Green Bank and Fox Chase Bank [Member]
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		13,500	14,400
Commercial, Financial and Agricultural [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		44	413
Ending balance: collectively evaluated for impairment		8,715	7,570
Ending balance: acquired non-credit impaired loans evaluated for impairment			0
Total ending balance		8,759	7,983	6,742	7,037
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		3,442	3,747
Ending balance: collectively evaluated for impairment		936,122	909,489
Loans measured at fair value		0	0
Acquired non-impaired loans		7,465	24,449
Acquired credit impaired loans		0	0
Total loans and leases held for investment		947,029	937,685
Real Estate-Commercial and Construction [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		1,562	675
Ending balance: collectively evaluated for impairment		16,634	13,183
Ending balance: acquired non-credit impaired loans evaluated for impairment			45
Total ending balance		18,196	13,903	9,839	7,505
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		28,185	18,321
Ending balance: collectively evaluated for impairment		2,099,512	1,714,996
Loans measured at fair value		317	1,779
Acquired non-impaired loans		144,816	221,415
Acquired credit impaired loans		206	206
Total loans and leases held for investment		2,273,036	1,956,717
Real Estate-Residential Secured for Business Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		306	0
Ending balance: collectively evaluated for impairment		2,316	2,233
Ending balance: acquired non-credit impaired loans evaluated for impairment			3
Total ending balance		2,622	2,236	1,661	774
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		2,980	1,478
Ending balance: collectively evaluated for impairment		336,577	301,289
Loans measured at fair value		0	0
Acquired non-impaired loans		34,416	59,603
Acquired credit impaired loans		0	426
Total loans and leases held for investment		373,973	362,796
Real Estate-Residential and Home Equity Secured for Personal Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		196	327
Ending balance: collectively evaluated for impairment		3,593	2,872
Ending balance: acquired non-credit impaired loans evaluated for impairment			0
Total ending balance		3,789	3,199	1,754	993
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		3,519	3,035
Ending balance: collectively evaluated for impairment		564,141	514,900
Loans measured at fair value		0	0
Acquired non-impaired loans		45,776	56,663
Acquired credit impaired loans		58	63
Total loans and leases held for investment		613,494	574,661
Loans to Individuals [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		0	0
Ending balance: collectively evaluated for impairment		470	484
Ending balance: acquired non-credit impaired loans evaluated for impairment			0
Total ending balance		470	484	373	364
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		0	0
Ending balance: collectively evaluated for impairment		29,744	32,617
Loans measured at fair value		0	0
Acquired non-impaired loans		139	142
Acquired credit impaired loans		0	0
Total loans and leases held for investment		29,883	32,759
Lease Financings [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment		0	0
Ending balance: collectively evaluated for impairment		1,311	1,288
Ending balance: acquired non-credit impaired loans evaluated for impairment			0
Total ending balance		1,311	1,288	1,132	788
Loans and leases held for investment:
Ending balance: individually evaluated for impairment (1)		277	0
Ending balance: collectively evaluated for impairment		149,144	141,956
Loans measured at fair value		0	0
Acquired non-impaired loans		0	0
Acquired credit impaired loans		0	0
Total loans and leases held for investment		149,421	141,956
Unallocated [Member]
Reserve for loan and lease losses:
Ending balance: collectively evaluated for impairment		184	271
Ending balance: acquired non-credit impaired loans evaluated for impairment			0
Total ending balance		$ 184	$ 271	$ 54	$ 38

[1] Includes $13.5 million and $14.4 million of acquired loans which were individually evaluated for impairment at December 31, 2019 and 2018, respectively.