CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - shares	Sep. 30, 2017	Dec. 31, 2016
Preferred units, authorized (in shares)		48,000,000
Preferred units, issued (in shares)		48,000,000
Class D Units [Member]
Common units, authorized (in shares)		66,100,000
Common units, issued (in shares)		66,100,000
Class E Units [Member]
Common units, authorized (in shares)	18,114,975	18,114,975
Common units, issued (in shares)	18,114,975	18,114,975
Class A Common Units [Member]
Common units, outstanding (in shares)	326,517,110	262,208,428
Class B Common Units [Member]
Common units, authorized (in shares)	7,825,500	7,825,500
Common units, issued (in shares)	7,825,500	7,825,500
i-Units [Member]
Common units, authorized (in shares)	87,569,475	81,857,168
Common units, issued (in shares)	87,569,475	81,857,168
Incentive Distribution Units [Member]
Common units, authorized (in shares)		1,000
Common units, issued (in shares)		1,000
Class F Units [Member]
Common units, authorized (in shares)	1,000
Common units, issued (in shares)	1,000