Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4568740-111683

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4I
-URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4590271-111686

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4568447-111683

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

Unaudited Condensed Consolidated Financial Statements - Schedule of Cumulative-Effect Adjustment to Retained Earnings (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
As of January 1, 2018, as originally presented	$ 157,927		$ 161,761
Retained Earnings [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
As of January 1, 2018, as originally presented		$ 38,348
Cumulative effect of ASU 2016-01		632
As of January 1, 2018, as adjusted		38,980
Accumulated Other Comprehensive Loss [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
As of January 1, 2018, as originally presented		(44,760)
Cumulative effect of ASU 2016-01		(632)
As of January 1, 2018, as adjusted		$ (45,392)