Partners' Capital, Mezzanine Equity and Distributions (Additional Information Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Mar. 24, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Partners Capital And Distributions [Line Items]
Common units outstanding (in units)		122,579,218	122,579,218
Cash or stock available for distributions, percent usually distributed		100.00%
Days to distribute		45 days
Common units issued (in units)		122,579,218	122,579,218
Price per share of common units issued (in dollars per unit)	$ 30.65
Net proceeds received from sale of units, net of underwriter discounts	$ 140,513
Accumulated distributions attributable to Class A Preferred Unitholders		$ 74,467	$ 69,801	$ 21,995
Class A
Partners Capital And Distributions [Line Items]
Common units issued (in units)	4,600,000
Price per share of common units issued (in dollars per unit)	$ 30.65
Additional common units to purchase (in units)	600,000
Net proceeds received from sale of units, net of underwriter discounts	$ 140,500
Class A | Partners' Capital
Partners Capital And Distributions [Line Items]
Common units outstanding (in units)		122,539,221
Class B | Partners' Capital
Partners Capital And Distributions [Line Items]
Common units outstanding (in units)		39,997
Class A Convertible Preferred Units
Partners Capital And Distributions [Line Items]
Convertible preferred units outstanding (in units)		25,336,778	24,438,022	22,411,728	0
Accumulated distributions attributable to Class A Preferred Unitholders		$ 74,500