Summary Of Significant Accounting Policies - Additional Information (Detail) - Regeneron Corporation [Member] - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2015	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Research collaboration and license agreement revenue		$ 0.8
Scenario Forecast [Member]
Summary Of Significant Accounting Policies [Line Items]
Research collaboration and license agreement revenue	$ 0.7

Research collaboration and license agreement revenue

No definition available.

Name:	aavl_ResearchCollaborationAndLicenseAgreementRevenue
Namespace Prefix:	aavl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration