v2.4.0.8

Stock Option and Incentive Plan Stock Option and Incentive Plan (Narrative) (Details) (USD $) | 3 Months Ended | 6 Months Ended |  | 0 Months Ended | 6 Months Ended |  |
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Jun. 30, 2013 | Jun. 30, 2012 | Jun. 30, 2013 | Jun. 30, 2012 | Mar. 11, 2013 | Jan. 28, 2013 MYLTIP [Member] indices Y | Jan. 28, 2013 Cohen & Steers Realty Majors Portfolio Index [Member] MYLTIP [Member] | Jan. 28, 2013 NAREIT Office Index adjusted [Member] MYLTIP [Member] | Jan. 28, 2013 Minimum [Member] MYLTIP [Member] | Jan. 28, 2013 Maximum [Member] MYLTIP [Member] | Jan. 28, 2013 Threshold [Member] MYLTIP [Member] | Jan. 28, 2013 Target [Member] MYLTIP [Member] | Jan. 28, 2013 High [Member] MYLTIP [Member] | Jan. 28, 2013 Exceptional [Member] MYLTIP [Member] | Jan. 28, 2013 MYLTIP Vesting 2018 [Member] MYLTIP [Member] | Jan. 28, 2013 MYLTIP Vesting 2017 [Member] MYLTIP [Member] | Jan. 28, 2013 MYLTIP Vesting 2016 [Member] MYLTIP [Member] | Jun. 30, 2013 Board of Directors Chairman [Member] | Mar. 11, 2013 Board of Directors Chairman [Member] | Mar. 10, 2013 Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Allocated Share-based Compensation Expense | $ 6,400,000 | $ 6,400,000 | $ 31,900,000 | $ 17,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
TRS Measurement, Years |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted Percentage of Index Used to Compare to TRS |  |  |  |  |  |  | 50.00% | 50.00% |  |  |  |  |  |  |  |  |  |  |  |
Potential Awards Earned |  |  |  |  |  |  |  |  | 0 | 30,700,000 |  |  |  |  |  |  |  |  |  |
Indices Used to Compare TRS |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Tiers |  |  |  |  |  | 4 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Each Tier |  |  |  |  |  |  |  |  |  |  | 5,100,000 | 10,200,000 | 20,500,000 | 30,700,000 |  |  |  |  |  |
Percentage of annualized TRS for Reduction of Earned Awards |  |  |  |  |  | 2.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Vesting Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% | 25.00% | 25.00% |  |  | 33.33333%
Vesting Date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Feb. 04, 2018 | Feb. 04, 2017 | Feb. 04, 2016 |  |  |
Distributions Percent Before Measurement Date |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Value of MYLTIP Awards |  |  |  |  |  | 9,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
MYLTIP Value Amortized Into Earnings, Years |  |  |  |  |  | 5 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Payment Related to Transition Agreement |  |  |  |  | 6,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Target Equity Award Compensation Associated with Transition Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,100,000 |
Compensation Expense associated with Transition Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,200,000 |  |
Acceleration of Stock Based Compensation in Association with Transition Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12,900,000 |  |

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