Percentage of voting equity interests acquired at the acquisition date in the business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Business Segments - Additional Information (Detail)	12 Months Ended
Business Segments - Additional Information (Detail)	Dec. 31, 2017 Store Segment	Dec. 31, 2016	Dec. 01, 2016
Business Acquisition [Line Items]
Number of reportable segments	4
Number of stores \| Store	3
Number of segments combined	2
GRT Acquisition
Business Acquisition [Line Items]
Ownership interest (as a percent)		65.00%	65.00%