Common and Subordinated Units - At the Market Offering Program (Details) - Common Units - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Equity distribution agreement, maximum	$ 100,000,000
Proceeds from the sale of common units		$ 40,500,000	$ 32,500,000
Number of shares issued (in shares)	0	2,243,775	2,001,823