Organization (Narrative) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012 Y acre Vehicle sqft	Sep. 30, 2011
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership	88.60%	88.00%
Restriction on redemption of OP units from date of issuance (years)	1
One OP unit is equivalent to one share of Common Stock	1
Number of series of preferred units outstanding	1
OP unit conversion rate	1
Number of Vehicles in structured parking	44,703
Area of parking in square feet	15,200,000
Area of undeveloped land parcels owned in acres	510.7
Value-added fund institutional investors	2
Series Two Preferred Units [Member]
Real Estate Properties [Line Items]
OP Units for each preferred unit	1.312336
Liquidation preference	50.00
Series Four Preferred Units [Member]
Real Estate Properties [Line Items]
Liquidation preference	50.00
Distributions to Series Four Preferred Units	0.25
Liquidation preference percentage	2.00%
Hotel Property [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Retail Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	3
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	3
Residential Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	152
Net rentable area	43,400,000
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	8
Net rentable area	2,700,000
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	145
Class A Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	128
Office Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	7
Office/Technical Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	17
Investments Through Value-Added Fund [Member]
Real Estate Properties [Line Items]
Number of real estate properties	23