Stock-based Compensation (Tables)
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12 Months Ended |
Dec. 31, 2015 |
Stock-based Compensation [Abstract] |
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Schedule Of Sharebased Compensation Restricted Operating Partnership Units Earned [Table Text Block] |
| | | | | | | | | | Plan Year | | Notional Amount | | Grant-Date Fair Value(1) | | OPP Units Earned | 2015 | | $ | 40,000,000 | | $ | 9,120,000 | | To be determined in 2017 | 2014 | | | 50,000,000 | | | 8,202,000 | | To be determined in 2016 | 2013 | | | 40,000,000 | | | 6,814,000 | | 85,420 | 2012 | | | 40,000,000 | | | 12,250,000 | | 303,202 | | | | | | | | | | | | | | | | | | | | | (1) | Such amounts are being amortized into expense over a five-year period from the date of grant, using a graded vesting attribution model. In the years ended December 31, 2015, 2014 and 2013, we recognized $15,531,000, $6,185,000 and $3,226,000, respectively, of compensation expense related to OPPs. As of December 31, 2015, there was $5,087,000 of total unrecognized compensation cost related to the OPPs, which will be recognized over a weighted-average period of 1.7 years. |
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Schedule Of Share Based Compensation Stock Options Activity [Table Text Block] |
| | | | | | | | | Weighted- | | | | | | | | | | Weighted- | | | Average | | | | | | | | | | Average | | | Remaining | | Aggregate | | | | | | | Exercise | | | Contractual | | Intrinsic | | | | | Shares | | Price | | | Term | | Value | | | Outstanding at January 1, 2015 (1) | 2,965,968 | | $ | 60.82 | | | | | | | | | Granted | 35,208 | | | 112.10 | | | | | | | | | Exercised | (160,266) | | | 82.21 | | | | | | | | | Cancelled or expired | (13,340) | | | 100.21 | | | | | | | | | Outstanding at December 31, 2015 | 2,827,570 | | $ | 60.06 | | | 4.0 | | $ | 115,796,000 | | | Options vested and expected to vest at | | | | | | | | | | | | | | December 31, 2015 | 2,826,685 | | $ | 60.06 | | | 4.0 | | $ | 115,788,000 | | | Options exercisable at December 31, 2015 | 2,741,863 | | $ | 59.08 | | | 3.8 | | $ | 114,653,000 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (1) | Adjusted for the effect of the UE spin-off. |
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Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Table Text Block] |
| | December 31, | | | | 2015 | | 2014 | | 2013 | | | Expected volatility | 35.00% | | 36.00% | | 36.00% | | | Expected life | 5.0 years | | 5.0 years | | 5.0 years | | | Risk free interest rate | 1.56% | | 1.81% | | 0.91% | | | Expected dividend yield | 3.30% | | 4.10% | | 4.30% | |
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Schedule Of Sharebased Compensation Restricted Stock And Restricted Stock Units Activity [Table Text Block] |
| | | | | | Weighted-Average | | | | | | | | Grant-Date | | | Unvested Shares | | Shares | | Fair Value | | | Unvested at January 1, 2015 (1) | | 24,478 | | $ | 78.32 | | | Granted | | 8,177 | | | 110.84 | | | Vested | | (11,298) | | | 78.08 | | | Cancelled or expired | | (1,765) | | | 88.69 | | | Unvested at December 31, 2015 | | 19,592 | | | 91.09 | | | | | | | | | | | | | | | | | | | | | | (1) | Adjusted for the effect of the UE spin-off. | |
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Schedule Of Sharebased Compensation Restricted Operating Partnership Units Activity [Table Text Block] |
| | | | | | Weighted-Average | | | | | | | | Grant-Date | | | Unvested Units | | Units | | Fair Value | | | Unvested at January 1, 2015 (1) | | 721,662 | | $ | 74.38 | | | Granted | | 197,497 | | | 102.75 | | | Vested | | (270,443) | | | 74.22 | | | Cancelled or expired | | (9,699) | | | 83.89 | | | Unvested at December 31, 2015 | | 639,017 | | | 83.07 | | | | | | | | | | | | | | | | | | | | | | (1) | Adjusted for the effect of the UE spin-off. | |
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