Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014
Fair Value Disclosures [Abstract]
Level 3 assets	$ 0	$ 0	$ 0
Level 3 activity	$ 0	$ 0

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant