Noncontrolling Interests (Common Units) (Narrative) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012 Y	Sep. 17, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 27, 2012
Quarter 4 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividends payable	Jan. 27, 2012
Distribution, record date	Dec. 31, 2011
Quarter 1 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividends payable	Apr. 30, 2012
Distribution, record date	Mar. 30, 2012
Quarter 2 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividends payable	Jul. 31, 2012
Distribution, record date	Jun. 29, 2012
Quarter 3 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend declared date	Sep. 17, 2012
Dividends payable	Oct. 31, 2012
Distribution, record date	Sep. 28, 2012
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units	400,000
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units	400,000
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption	365,688
Redemption of OP units issued on conversion of Series Two Preferred Units	153,605
Redemption Of OP Units Issued On Conversion Of LTIP Units	149,477
Outperformance Awards LTIP Units distribution as percentage of OP Unit distribution prior to measurement date	10.00%
Distributions declared to OP and LTIP units per unit			$ 0.55	$ 0.55	$ 0.55
Distributions made to outperformance awards long term incentive plan Units Per Unit			$ 0.055	$ 0.055	$ 0.055
Distributions declared to OP and LTIP units per unit		$ 0.55
Distributions made to outperformance awards long term incentive plan Units Per Unit		$ 0.055
Restriction On Redemption	1
Op Unit Equivalence To Common Stock	1
Common units of operating partnership if converted value	$ 2,000,000,000
Value Of Series Two Preferred Units If Converted To Common Stock	$ 144,600,000
Closing price of common stock	$ 110.61