Partners' Capital and Distributions (Schedule of Capital Units) (Details)	3 Months Ended
	Mar. 31, 2019 shares
Increase (Decrease) in Partners' Capital [Roll Forward]
Limited partner units outstanding on January 1, 2018 (in shares)	228,195,160
Limited partner units outstanding on March 31, 2018 (in shares)	228,403,428
Management [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
During 2019–Other (in shares)	199,792
Director [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
During 2019–Other (in shares)	8,476