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Share and Unit-Based Plans (Tables) | 9 Months Ended
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Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Summary of activity of non-vested LTIP Units, stock awards, phantom stock and stock units | The following table summarizes the activity of the non-vested LTIP Units, phantom stock units and stock units:
| LTIP Units |  | Phantom Stock Units |  | Stock Units
| Units |  | Value(1) |  | Units |  | Value(1) |  | Units |  | Value(1)
Balance at January 1, 2018 | 636,632 |  |  | $ | 52.36 |  |  | 4,054 |  |  | $ | 79.82 |  |  | 151,355 |  |  | $ | 73.32 |
Granted | 569,136 |  |  | 51.78 |  |  | 8,765 |  |  | 61.46 |  |  | 87,193 |  |  | 58.85 |
Vested | (189,044 | ) |  | 57.49 |  |  | (10,581 | ) |  | 54.70 |  |  | (108,201 | ) |  | 74.21 |
Forfeited | (23,666 | ) |  | 44.28 |  |  | (845 | ) |  | 77.91 |  |  | — |  |  | — |
Balance at September 30, 2018 | 993,058 |  |  | $ | 51.24 |  |  | 1,393 |  |  | $ | 66.79 |  |  | 130,347 |  |  | $ | 64.24 |
(1) Value represents the weighted average grant date fair value.
During the nine months ended September 30, 2018, the Company granted the following LTIP Units:
Grant Date |  | Units |  | Type |  | Fair Value per LTIP Unit |  | Vest Date
1/1/2018 |  | 65,466 |  |  | Service-based |  | $ | 65.68 |  |  | 12/31/2020
1/1/2018 |  | 291,326 |  |  | Market-indexed |  | $ | 44.28 |  |  | 12/31/2020
1/29/2018 |  | 13,632 |  |  | Service-based |  | $ | 66.02 |  |  | 2/1/2022
1/29/2018 |  | 1,893 |  |  | Service-based |  | $ | 66.02 |  |  | 12/31/2020
1/29/2018 |  | 7,775 |  |  | Market-indexed |  | $ | 48.23 |  |  | 12/31/2020
3/2/2018 |  | 99,407 |  |  | Service-based |  | $ | 59.04 |  |  | 3/2/2018
4/26/2018 |  | 89,637 |  |  | Service-based |  | $ | 55.78 |  |  | 4/26/2018
|  | 569,136 |  |  |  |  |  |  |
Summary of activity of SARs and stock options outstanding | The following table summarizes the activity of the stock appreciations rights ("SARs") and stock options outstanding:
| SARs |  | Stock Options
| Units |  | Value(1) |  | Units |  | Value(1)
Balance at January 1, 2018 | 235,439 |  |  | $ | 53.83 |  |  | 35,565 |  |  | $ | 57.32 |
Granted | — |  |  | — |  |  | — |  |  | — |
Exercised | (235,439 | ) |  | 53.83 |  |  | — |  |  | — |
Balance at September 30, 2018 | — |  |  | $ | — |  |  | 35,565 |  |  | $ | 57.32 |
(1) Value represents the weighted average exercise price.
Compensation cost under the share and unit-based plans | The following summarizes the compensation cost under the share and unit-based plans:
| For the Three Months Ended September 30, |  | For the Nine Months Ended September 30,
| 2018 |  | 2017 |  | 2018 |  | 2017
LTIP Units | $ | 3,440 |  |  | $ | 5,269 |  |  | $ | 21,823 |  |  | $ | 24,892 |
Stock units | 972 |  |  | 1,002 |  |  | 5,717 |  |  | 4,947 |
Stock options | 32 |  |  | 34 |  |  | 94 |  |  | 53 |
Phantom stock units | 172 |  |  | 185 |  |  | 585 |  |  | 545 |
| $ | 4,616 |  |  | $ | 6,490 |  |  | $ | 28,219 |  |  | $ | 30,437 |

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- Definition Tabular disclosure of the changes in outstanding nonvested Long-Term Incentive Plan ("LTIP") units, stock awards, phantom stock and stock units. + References No definition available. + Details
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- Definition Tabular disclosure of the amount of total share-based compensation cost, including the amounts attributable to each share-based compensation plan and any related tax benefits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure of the number and weighted-average exercise prices (or conversion ratios) for stock appreciation rights awards that were outstanding at the beginning and end of the year, and the number of stock appreciation rights awards that were granted, exercised or converted, forfeited, and expired during the year. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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