Commitment and Contingencies (Nigeria Marketing Agent Litigation) - Additional Information (Detail) - Federal Government of Nigeria £ in Millions, NGN in Millions, $ in Millions	1 Months Ended	4 Months Ended
Jun. 30, 2016 USD ($)	Jun. 30, 2016 NGN	Jun. 30, 2016 GBP (£)	Sep. 30, 2016 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Due to affiliates				$ 12.0
Loss contingency, damages awarded, value	$ 5.3	NGN 1.9	£ 0.3
Loss contingency damages awarded, aggregate value				$ 5.5

Amount of damages awarded to the plaintiff in the legal matter.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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