Units Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Changes in Limited Partnership Units Outstanding
Outstanding as of January 1,	273,040,452	268,373,419
Options exercised	541,073	1,110,070
Units issued	4,600,583	4,193,445
Units retired	(5,880,281)	(636,482)
Outstanding as of December 31,	272,301,827	273,040,452
AB Units [Member]
Changes in Limited Partnership Units Outstanding
Units retired	(26,111)	(61,472)