Amount of noncash expense for award of restricted stock or unit under share-based payment arrangement.

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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).

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Gross number of share options (or share units) granted during the period.

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Aggregate value of stock related to Restricted Stock Awards issued during the period.

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Value, before forfeiture, of shares issued under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

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Unit-Based Compensation (Details) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
Unit-Based Compensation (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted unit-based compensation granted to Partnership's employee (in units)	80,100	62,283	60,809
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 1.2	$ 1.2				$ 1.0
Restricted units, vesting period (in years)				3 years
Restricted units expense				$ 1.6	$ 1.3	$ 1.0
Non-management Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common units granted	35,419				17,498	17,345
Aggregate value of units issued	$ 0.5