Earnings Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Allocated to Limited Partners	$ (49.5)	$ 198.2	$ (97.8)	$ 193.3
Net Income (Loss) Allocated to Preferred Unit Holders	0.0	15.0	0.0	0.0
Net income attributable to preferred unit holders	15.0	15.0	30.0	30.0
Subordinated unitholders’ interest in net income	0.0	1.2	0.0	1.2
Net Income (Loss) Available to Common Stockholders, Diluted	$ (49.5)	$ 214.4	$ (97.8)	$ 194.5
Basic (units)	73.2	71.8	73.0	71.8
Dilutive units (units)	0.0	11.2	0.0	5.2
Weighted Average Limited Partnership Units Outstanding, Diluted	73.2	83.0	73.0	77.0
Basic (in dollars per share)	$ (0.68)	$ 2.76	$ (1.34)	$ 2.69
Diluted (in dollars per share)	$ (0.68)	$ 2.58	$ (1.34)	$ 2.53
Preferred Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	7.1	0.0	7.1	7.1
Dilutive units (units)	0.0	7.1		0.0
Niobrara Preferred Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive units (units)	0.0	3.4	0.0	4.5
Performance Shares
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.2	0.0	0.3	0.0
Dilutive units (units)	0.0	0.3	0.0	0.3
Subordinated Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.4	0.0	0.4	0.0
Dilutive units (units)	0.0	0.4	0.0	0.4
Crestwood Niobrara LLC | Preferred Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	8.2	0.0	8.2	0.0