Equity - 2015 Private Placement (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended	9 Months Ended
	Jun. 09, 2016	Mar. 29, 2016	May 18, 2015	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	[1]
Class of Stock [Line Items]
Units issued in connection with private placement (in units)					765,307
Net proceeds from private placement					$ 0.0	$ 297.7
Consideration for units issued in connection with private placement					$ 9.8	$ 6.1
Aggregate percentage of general partner interest					2.00%
Common Units
Class of Stock [Line Items]
Units issued in connection with private placement (in units)			7,692,308
Net proceeds from private placement			$ 297.7
Gross proceed issuance of private placement offering			$ 300.0
Common units per share (in units per share)			$ 39.00
Placement fees			$ 2.3
General Partner
Class of Stock [Line Items]
Units issued in connection with private placement (in units)			156,986	15,307	15,307
Consideration for units issued in connection with private placement	$ 1.1	$ 8.2	$ 6.1	$ 0.5
Aggregate percentage of general partner interest		2.00%	2.00%	2.00%	2.00%

[1] (1) The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.