Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred tax assets, net, increase resulting from state tax legislation	$ 11.5
Income tax expense decrease resulting from state tax legislation	$ 11.5

Represents the increase in net deferred tax assets as a result of the effects of state tax legislation.

No definition available.

Name:	af_DeferredTaxAssetsNetIncreaseResultingFromStateTaxLegislation
Namespace Prefix:	af_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration