Loans Receivable and Allowance for Loan Losses - Schedule of FDIC Loss Sharing Receivable (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
FDIC Indemnification Asset [Roll Forward]
Beginning Balance	$ 0	$ 0	$ (2,083)
Increased (decreased) estimated cash flows	0	0	289
Other activity, net	0	0	(255)
Cash receipts from FDIC	0	0	2,049
Ending Balance	0	0	0
Provision for loan losses	5,642	6,768	3,330
Effect attributable to FDIC loss sharing arrangements	0	0	(289)
Net amount reported as provision for loan losses	$ 5,642	$ 6,768	$ 3,041

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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Period Type:	duration