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Stock Option And Incentive Plan (Restricted Stock) (Narrative) (Details) (USD $)
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3 Months Ended | 3 Months Ended | 65 Months Ended | 3 Months Ended | 3 Months Ended | |||||||
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Mar. 31, 2012
Y
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Mar. 31, 2011
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Dec. 31, 2011
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Mar. 31, 2012
Restricted Stock [Member]
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Mar. 31, 2012
LTIP Units [Member]
Y
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Mar. 31, 2012
LTIPs And Restricted Stock [Member]
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Mar. 31, 2012
LTIPs and OPP Awards [Member]
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Mar. 31, 2012
OPP Units 2012 [Member]
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Mar. 31, 2012
OPP Units 2012 [Member]
SNL Equity REIT [Member]
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Mar. 31, 2012
Non Qualified Stock Options [Member]
Y
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Mar. 31, 2012
Unvested 2011 and 2012 OPP Units [Member]
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Mar. 31, 2012
Executive Vice President [Member]
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| Stock Option And Incentive Plan And Stock Purchase Plan [Line Items] | ||||||||||||
| Shares issued | 149,463,241 | 148,186,511 | 19,521 | |||||||||
| LTIP units issued | 169,301 | |||||||||||
| Non-qualified stock options issued | 186,007 | |||||||||||
| 2012 OPP units issued | 400,000 | |||||||||||
| Employee and director payment per share | $ 0.01 | $ 0.25 | ||||||||||
| Vesting annual installments | 4 | |||||||||||
| Stock-based compensation associated with restricted stock, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units | $ 10,900,000 | $ 11,600,000 | $ 2,700,000 | |||||||||
| Accelerated Compensation Expenses Related To 2008 Opp Units | 4,300,000 | |||||||||||
| Unrecognized compensation expenses | 34,400,000 | 11,400,000 | ||||||||||
| Weighted-average period (years) | 3.0 | |||||||||||
| Value of shares of common stock | 1,494,000 | 1,481,000 | 2,100,000 | |||||||||
| Employee's weighted average cost per share | $ 107.57 | |||||||||||
| Value of LTIP units issued | 16,800,000 | |||||||||||
| Per unit fair value weighted-average | $ 98.94 | |||||||||||
| Expected life assumed to calculate per unit fair value per LTIP unit (years) | 5.8 | 5.4 | ||||||||||
| Risk-free rate | 0.94% | 0.35% | 0.92% | |||||||||
| Expected price volatility | 29.10% | 31.00% | 30.00% | 28.40% | ||||||||
| Expected dividend rate | 2.90% | |||||||||||
| Value of OPP units | 7,700,000 | |||||||||||
| Method of valuation | The Monte Carlo simulation used a statistical formula underlying the Black-Scholes and binomial formulas and such simulation was run approximately 100,000 times. | The non-qualified stock options granted during the three months ended March 31, 2012 had a weighted-average fair value on the date of grant of $19.50 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 5.4 years, a risk-free interest rate of 0.92%, an expected price volatility of 28.4% and an expected dividend yield of 2.9%. | ||||||||||
| Estimated dividend payments, per share | $ 7.28 | |||||||||||
| Weighted-average grant date fair value | $ 19.50 | |||||||||||
| Weighted-average exercise price | $ 107.23 | |||||||||||