Net Income Per Limited Partner Unit - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015		Dec. 31, 2014
Partners' Capital Notes [Abstract]
Distributions paid per limited partner unit (in dollars per unit)	$ 0.2350	$ 0.2200	$ 0.2050	$ 0.1900	$ 0.1750	[1]	$ 0.1042
Distributions declared and/or paid	$ 41.7	$ 35.3	$ 30.3	$ 27.7	$ 24.1		$ 14.4

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