Litigation (Details)	Apr. 24, 2012 item
Litigation
Number of cause of action not asserted against the Company	1

Represents the number of cause of action not asserted against the entity.

No definition available.

Name:	al_NumberOfCauseOfActionNotAssertedAgainstEntity
Namespace Prefix:	al_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant