Summary of Significant Accounting Policies - Summary of Estimated Useful Life of Asset (Detail)	12 Months Ended
Dec. 31, 2017
Land Improvements
Property, Plant and Equipment [Line Items]
Assets estimated useful life	15 years
Buildings and Other Improvements
Property, Plant and Equipment [Line Items]
Assets estimated useful life	39 years
Equipment
Property, Plant and Equipment [Line Items]
Assets estimated useful life	7 years

Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 35
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68071081&loc=d3e1205-110223

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration