Concentration of Risk - Additional Information (Detail)	Mar. 31, 2013 Bank Property	Mar. 31, 2012 Restaurants
Number of properties leased	5	5
Commercial bank	1

The number of units (items of property) under operating lease arrangements.

No definition available.

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNumberOfUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant