Long-Term Incentive Plan (Details) - USD ($)
|
12 Months Ended |
80 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2015 |
| Long-Term Incentive Plan |
|
|
|
|
| Number of common units initially authorized for issuance under LTIP (in shares) |
4,300,000
|
|
|
|
| Unrecognized compensation cost related to the non-vested awards |
$ 9,900,000
|
|
|
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| Repurchase Program |
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| Aggregate common units authorized to be acquired (in shares) |
1,242,427
|
|
|
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| Common units repurchased by General Partner (in shares) |
0
|
|
|
838,505
|
| Common units repurchased by General Partner |
|
$ 3,892,000
|
$ 8,632,000
|
$ 24,800,000
|
| Repurchased units not deemed outstanding |
451,894
|
488,719
|
|
488,719
|
| CEO Authorized LTIP |
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| Long-Term Incentive Plan |
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| Number of years for which Plan was approved |
3 years
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|
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| Aggregate amount of CEO authorized shares to grant in each calendar year |
$ 2,000,000
|
|
|
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| Maximum value of grant |
$ 550,000
|
|
|
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| CEO Authorized LTIP expiration period |
6 years
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| Phantom Unit Awards [Member] |
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| Long-Term Incentive Plan |
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|
|
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| Phantom units granted (in shares) |
12,659
|
76,893
|
|
|
| Vested (in shares) |
(21,872)
|
(13,921)
|
|
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| Number of Non-vested Units |
|
|
|
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| Outstanding non-vested units at the beginning of the period (in shares) |
595,720
|
532,748
|
|
|
| Granted (in shares) |
12,659
|
76,893
|
|
|
| Vested (in shares) |
(21,872)
|
(13,921)
|
|
|
| Forfeited (in shares) |
(14,953)
|
|
|
|
| Outstanding non-vested units at the end of the period (in shares) |
571,554
|
595,720
|
532,748
|
595,720
|
| Weighted Average Grant Date Fair Value |
|
|
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| Outstanding non-vested units at the beginning of the period (in dollars per share) |
$ 38.85
|
$ 39.29
|
|
|
| Granted (in dollars per share) |
15.80
|
35.72
|
|
|
| Vested (in dollars per share) |
37.34
|
38.39
|
|
|
| Forfeited (in dollars per share) |
32.66
|
|
|
|
| Outstanding non-vested units at the end of the period (in dollars per share) |
$ 38.56
|
$ 38.85
|
$ 39.29
|
$ 38.85
|
| Phantom Unit Awards [Member] | Selling, general and administrative expenses |
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| Long-Term Incentive Plan |
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| Compensation expenses |
$ 4,200,000
|
$ 4,300,000
|
$ 3,500,000
|
|