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Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) (USD $)
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3 Months Ended | 6 Months Ended | 6 Months Ended | 0 Months Ended | 6 Months Ended | ||||||||||
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Jun. 30, 2013
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Jun. 30, 2012
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Jun. 30, 2013
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Jun. 30, 2012
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Dec. 31, 2012
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Jun. 30, 2013
Restricted Stock [Member]
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Jun. 30, 2013
LTIP Units [Member]
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Jan. 28, 2013
MYLTIP [Member]
Y
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Jun. 30, 2013
MYLTIP [Member]
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Jun. 30, 2013
LTIPs And Restricted Stock [Member]
VestingInstallments
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Jun. 30, 2013
LTIPs and OPP Awards [Member]
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Jun. 30, 2013
Non Qualified Stock Options [Member]
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Jun. 30, 2013
Unvested 2011 and 2012 OPP Units and 2013 MYLTIPS [Member]
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Jun. 30, 2013
Board of Directors Chairman [Member]
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Jun. 30, 2012
Executive Vice President [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||||||||||||
| Shares issued | 152,463,640 | 152,463,640 | 151,680,119 | 36,730 | |||||||||||
| LTIP units issued (in shares) | 184,733 | ||||||||||||||
| MYLTIP units issued (in shares) | 318,926 | ||||||||||||||
| Non-qualified stock options issued | 252,220 | ||||||||||||||
| Employee and director payment per share (in dollars per share) | $ 0.01 | $ 0.25 | |||||||||||||
| Vesting annual installments | 4 | ||||||||||||||
| Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units and 2013 MYLTIPS | $ 6,400,000 | $ 6,400,000 | $ 31,900,000 | $ 17,400,000 | $ 2,700,000 | ||||||||||
| Acceleration of Stock Basec Compensation and Stock Based Compensation Associated with Transition Agreement | 18,600,000 | ||||||||||||||
| TRS Measurement, Years | 3 | ||||||||||||||
| Unrecognized compensation expenses | 22,900,000 | 14,300,000 | |||||||||||||
| Weighted-average period (years) | 3 years 0 months 0 days | ||||||||||||||
| Value of shares of common stock | 1,524,000 | 1,524,000 | 1,516,000 | 3,900,000 | |||||||||||
| Employee's weighted average cost per share (in dollars per share) | $ 105.30 | ||||||||||||||
| Value of LTIP units issued | $ 14,800,000 | ||||||||||||||
| Per unit fair value weighted-average (in dollars per share) | $ 96.33 | ||||||||||||||
| Expected life assumed to calculate per unit fair value per LTIP unit (years) | 5 years 8 months 12 days | 6 years 0 months 0 days | |||||||||||||
| Risk-free rate | 1.03% | 1.11% | |||||||||||||
| Expected price volatility | 26.00% | 26.00% | |||||||||||||
| Expected dividend rate | 3.00% | ||||||||||||||
| Method of valuation | Monte Carlo simulation method | The non-qualified stock options granted during the nine months ended March 31, 2013 had a weighted-average fair value on the date of grant of $18.64 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 6.3 years, a risk-free interest rate of 1.19%, an expected price volatility of 26% and an expected dividend yield of 3%. | |||||||||||||
| Weighted-average grant date fair value (in dollars per share) | $ 18.46 | ||||||||||||||
| Weighted-average exercise price (in dollars per share) | $ 105.10 | ||||||||||||||