Discontinued Operations - Summary of Significant Noncash Items and Cash Paid for Capital Expenditures of Discontinued Operations (Detail) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and amortization	$ 0	$ 6,111
Acquisition of property, plant and equipment		$ 5,208

Amount of deprecation and amortization expense attributable to property, plant and equipment and intangible assets of discontinued operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Name:	us-gaap_DepreciationAndAmortizationDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration