2. Investment Properties (Detail)	Dec. 31, 2012
Minimum [Member]
Operating Leases of Lessee, Contingent Rentals, Basis Spread on Variable Rate	8.00%
Capital Leases of Lessee, Contingent Rentals, Basis Spread on Variable Rate	8.00%
Maximum [Member]
Capital Leases of Lessee, Contingent Rentals, Basis Spread on Variable Rate	15.00%

The percentage points added to the reference rate to compute the variable rate on the lessee's operating lease.

No definition available.

Name:	us-gaap_OperatingLeasesOfLesseeContingentRentalsBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant