v3.10.0.1

Long-Term Incentive Plan (Total Non-Vested Unit Awards) (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		501,403	417,172
Adjustment to Unit Awards in Anticipation of Achieving Above- Target Financial Results (in shares)		159,232
Total Unit Award Accrual (in shares)		660,635
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	[1]	$ 24.3
Performance Shares [Member]
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		390,015	356,068
Time-Based Awards [Member]
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		111,388	61,104
2017 Awards [Member] | Performance Shares [Member]
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		176,924
Adjustment to Unit Awards in Anticipation of Achieving Above- Target Financial Results (in shares)		159,232
Total Unit Award Accrual (in shares)		336,156
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	[1]	$ 9.0
Two Thousand Eighteen Awards [Member] | Performance Shares [Member]
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		213,091
Adjustment to Unit Awards in Anticipation of Achieving Above- Target Financial Results (in shares)		0
Total Unit Award Accrual (in shares)		213,091
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	[1]	$ 10.5
Retention Awards Vesting 2019 [Member] | Time-Based Awards [Member]
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		31,835
Adjustment to Unit Awards in Anticipation of Achieving Above- Target Financial Results (in shares)		0
Total Unit Award Accrual (in shares)		31,835
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	[1]	$ 0.9
Retention Awards Vesting 2020 [Member] | Time-Based Awards [Member]
Long Term Incentive Plan [Line Items]
Non-vested units (in shares)		79,553
Adjustment to Unit Awards in Anticipation of Achieving Above- Target Financial Results (in shares)		0
Total Unit Award Accrual (in shares)		79,553
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	[1]	$ 3.9
[1] Unrecognized compensation expense will be recognized over the remaining vesting period of the awards.

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Long Term Incentive Plan [Line Items]

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Total Unit Award Accrual Number

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ 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
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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ 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)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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