Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended															12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2014	[1]	Sep. 30, 2014	[1]	Jun. 30, 2014	[1]	Mar. 31, 2014	[1]	Dec. 31, 2015	[2]	Dec. 31, 2014	[3]	Dec. 31, 2013	[3]
Quarterly Financial Information Disclosure [Abstract]
Total Revenues	$ 84.6	$ 96.2		$ 79.8		$ 65.9		$ 73.3		$ 63.2		$ 62.2		$ 51.6		$ 326.5		$ 250.3		$ 147.8
Income Before Income Taxes	72.4	90.3		60.8		49.3		45.9		39.1		40.4		23.7		272.8		149.1		70.6
Net income	72.5	90.6		60.7		49.1		45.7		$ 39.1		$ 40.4		$ 23.7		272.9	[3]	148.9		$ 70.5
Net Income Attributable to the Partnership	57.0	54.3		32.2		23.6		13.4								167.1		13.4
Limited Partners' Interest in Net Income Attributable to the Partnership	$ 54.7	$ 52.8		$ 31.5		$ 23.1		$ 13.1								$ 162.1		$ 13.1
Net Income per Common Unit Attributable to the Partnership - Basic and Diluted	$ 0.38	$ 0.37		$ 0.23		$ 0.17		$ 0.10

[1] Information has been retrospectively adjusted to include the Shell Auger and Lockport Operations for periods prior to October 1, 2015.

[2] The 2015 financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations from January 1, 2015 through September 30, 2015.

[3] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Auger and Lockport Operations.