Quarterly Results Quarterly Results (Unaudited) - Additional Information (Detail) $ in Millions	3 Months Ended
Dec. 31, 2015 USD ($)
Selected Quarterly Financial Information [Abstract]
Effect of Fourth Quarter Events, Amount	$ 6

Amount of the item included in the fourth quarter that affected period-to-period comparability (excluding restatement adjustments), or the extraordinary item or unusual or infrequent item recognized in the fourth quarter in the absence of either a fourth-quarter report or disclosure in the annual report for the fourth quarter.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=51825399&loc=d3e1570-108306

Name:	us-gaap_EffectOfFourthQuarterEventsAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration