Equity-Based Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ (985)	$ 1,919	$ 1,971
2010 Plan \| Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Phantom units awarded during the period (in units)	107,572	29,606	28,484
Weighted average grant date fair value of phantom unit (in dollars per unit)	$ 5.86	$ 21.28	$ 22.12
Compensation expense	$ 1,000	$ 1,800
Liability for compensation awards	$ 1,100	$ 2,800

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

+ References

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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