Fair Value Measurements - Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Assets:
Cash equivalents	$ 43,202	$ 43,194
Total cash equivalents	43,202	43,194
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Cash equivalents	43,202	43,194
Total cash equivalents	43,202	43,194
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash equivalents	0	0
Total cash equivalents	0	0
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Cash equivalents	0	0
Total cash equivalents	$ 0	$ 0

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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