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Description of Business and Basis of Presentation - Additional Information (Detail) |  | 6 Months Ended
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Mar. 01, 2017 | Jun. 30, 2017
Description Of Business And Basis Of Presentation [Line Items] |  |
Number of Reportable Segments |  | 2
HST & WHC & MPLXT [Member] |  |
Description Of Business And Basis Of Presentation [Line Items] |  |
Business Acquisition, Effective Date of Acquisition | Mar. 01, 2017 |

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- Definition Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e845-128460 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e848-128460 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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