Operating Leases - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
Multifamily Residential Real Estate [Member] | Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease term	7 months
Multifamily Residential Real Estate [Member] | Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease term	15 months
Multifamily Residential Real Estate [Member] | Majority [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease term	12 months
Apartment Leases [Member] | Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease term	1 year
Commercial Tenant Lease [Member] | Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease term	5 years
Commercial Tenant Lease [Member] | Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease term	20 years