Business (Narratives) (Details)	3 Months Ended
	Mar. 31, 2014 tenant sqft property
Additional disclosures
Number of real estate properties	700
Number of tenants	230
Square footage of real estate properties	82,800,000
Occupancy rate	98.30%
Managed REITs
Additional disclosures
Number of real estate properties	363
Number of tenants	112
Square footage of real estate properties	37,900,000
Occupancy rate	99.96%
Managed REITs | Operating real estate
Additional disclosures
Number of real estate properties	95
Square footage of real estate properties	9,400,000