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								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Distribution Made To Limited Partner [Line Items]
Distributions declared									$ 203.2	$ 117.4	$ 14.4
Income in excess of distributions									41.7	49.7	(1.0)
Net income attributable to the Partnership	$ 69.5	$ 56.3	$ 63.8	$ 55.3	$ 57.0	$ 54.3	$ 32.2	$ 23.6	$ 244.9	$ 167.1	$ 13.4
Weighted average units outstanding (in millions):
Basic and diluted (in shares)									172.9	143.8	137.7
Net income per limited partner unit (in dollars):
Basic and diluted (in dollars per share)	$ 0.34	$ 0.28	$ 0.35	$ 0.36	$ 0.38	$ 0.37	$ 0.23	$ 0.17
General Partner
Distribution Made To Limited Partner [Line Items]
Distributions declared									$ 24.2	$ 4.0	$ 0.3
Income in excess of distributions									0.8	1.0	0.0
Net income attributable to the Partnership									$ 25.0	$ 5.0	$ 0.3
Weighted average units outstanding (in millions):
Basic and diluted (in shares)									3.5	2.9	2.7
Limited Partners' Common Units
Distribution Made To Limited Partner [Line Items]
Distributions declared									$ 109.8	$ 60.1	$ 7.0
Income in excess of distributions									24.6	25.4	(0.5)
Net income attributable to the Partnership									$ 134.4	$ 85.5	$ 6.5
Weighted average units outstanding (in millions):
Basic and diluted (in shares)									101.9	73.4	67.5
Net income per limited partner unit (in dollars):
Basic and diluted (in dollars per share)									$ 1.32	$ 1.16	$ 0.10
Limited Partner's Subordinated Units
Distribution Made To Limited Partner [Line Items]
Distributions declared									$ 69.2	$ 53.3	$ 7.1
Income in excess of distributions									16.3	23.3	(0.5)
Net income attributable to the Partnership									$ 85.5	$ 76.6	$ 6.6
Weighted average units outstanding (in millions):
Basic and diluted (in shares)									67.5	67.5	67.5
Net income per limited partner unit (in dollars):
Basic and diluted (in dollars per share)									$ 1.27	$ 1.14	$ 0.10