Other Balance Sheet Information - Additional Detail (Detail) $ in Millions	3 Months Ended
Mar. 31, 2017 USD ($)
Minority Interest [Line Items]
Gain on dilution of Stock in Subsidiary	$ 59.7

Amount of gain (loss) on sale or disposal of equity in securities of subsidiaries or equity method investee.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(g))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration