Partners' Capital (Common Unit Activity) (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Partners' Capital [Roll Forward]
Number of common units at beginning of year (in shares)	82,665,057
Number of common units at end of year (in shares)	82,985,941	82,665,057
Common Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Number of common units at beginning of year (in shares)	82,665,057	99,667,999
Common units repurchase		(17,286,859)
Phantom unit vesting (in shares)	320,884	283,917
Number of common units at end of year (in shares)	82,985,941	82,665,057