Net Income Per Limited Partner Unit - Schedule of Basic and Diluted Net Income Per Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Distribution Made To Limited Partner [Line Items]
Distribution declared	$ 63.6	$ 41.7
Income in excess of distributions	7.2	13.6
Net income attributable to the Partnership	70.8	55.3
General Partner
Distribution Made To Limited Partner [Line Items]
Distribution declared	12.0	2.9
Income in excess of distributions	0.1	0.2
Net income attributable to the Partnership	12.1	3.1
Limited Partners' Common Units
Distribution Made To Limited Partner [Line Items]
Distribution declared	51.6	23.0
Income in excess of distributions	7.1	7.5
Net income attributable to the Partnership	$ 58.7	$ 30.5
Weighted average units outstanding (in millions):
Weighted average units outstanding, basic and diluted (in shares)	177.3	84.9
Net income per Limited Partner Unit (in dollars):
Net income per Limited Partner Unit, basic and diluted (in dollars per share)	$ 0.33	$ 0.36
Limited Partner's Subordinated Units
Distribution Made To Limited Partner [Line Items]
Distribution declared	$ 0.0	$ 15.8
Income in excess of distributions		5.9
Net income attributable to the Partnership		$ 21.7
Weighted average units outstanding (in millions):
Weighted average units outstanding, basic and diluted (in shares)		67.5
Net income per Limited Partner Unit (in dollars):
Net income per Limited Partner Unit, basic and diluted (in dollars per share)	$ 0.00	$ 0.32