Fair Values of Financial Instruments - Summary of Equity Investments (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Year To Date [Member]
Schedule of Equity Method Investments [Line Items]
Amortized cost	$ 44
Impairment	0
Observable price changes	2
Carrying value	46
Life To Date [Member]
Schedule of Equity Method Investments [Line Items]
Amortized cost	44
Impairment	0
Observable price changes	2
Carrying value	$ 46

Value of the other investment not readily marketable determined by management based upon fair value methods, including pricing of similar securities and valuation techniques, that was used to record the investment for financial reporting purposes.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 820
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35710923&loc=d3e45360-110995

Name:	us-gaap_OtherInvestmentNotReadilyMarketableFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant