Deposits - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deposits [Line Items]
Related-party deposits	$ 6,100	$ 3,500
Brokered deposits with Home Savings	156,500	76,500
Certificates of deposit	705,341	488,426
Federal Home Loan Bank \| Certificates of Deposit
Deposits [Line Items]
Certificates of deposit	$ 12,700	$ 12,900

Amount of time deposit liabilities, including certificates of deposit.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Industry Guide
-Number 3
-Section V
-Paragraph D-E

Name:	us-gaap_TimeDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant