CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Receivables, trade and other, allowance for doubtful accounts (in dollars)	$ 2.4	$ 2.5
Preferred units, authorized (in shares)	48,000,000	48,000,000
Preferred units, issued (in shares)	48,000,000	48,000,000
Class D Units [Member]
Common units, authorized (in shares)	66,100,000	66,100,000
Common units, issued (in shares)	66,100,000	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)	262,208,428	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)	81,857,168	73,285,739
Common units, issued (in shares)	81,857,168	73,285,739
Incentive Distribution Units [Member]
Common units, authorized (in shares)	1,000	1,000
Common units, issued (in shares)	1,000	1,000