Basis of Presentation - Merger - Additional Information (Detail) - Memorial or MRD Merger	Sep. 16, 2016 shares
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Common stock issued in connection with exchange of outstanding shares	77,042,749
Exchange ratio of common shares for acquired company	0.375

Number of shares of equity interests issued or issuable to acquire entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration