Condensed Consolidating Financial Information (Statements Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities	$ 134.3	$ 156.6
Cash flows from investing activities:
Purchases of property, plant and equipment	(55.6)	(47.4)
Investment in unconsolidated affiliates	(5.5)	(18.1)
Proceeds from sale of assets	0.8	0.5
Payments for (Proceeds from) Other Investing Activities	0.0	(0.2)
Net cash used in investing activities	(60.3)	(65.2)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	313.5	1,252.7
Principal payments on long-term debt	(286.2)	(1,169.9)
Payments on capital leases	(0.5)	(0.7)
Payments for debt-related deferred costs	(0.1)	(11.1)
Distributions to partners	(95.6)	(25.8)
Distributions paid to non-controlling partners	(3.8)	(74.3)
Taxes paid for unit-based compensation vesting	(0.6)	(3.1)
Other	(0.1)	(0.3)
Net cash provided by (used in) financing activities	(73.4)	(32.5)
Net change in cash	0.6	58.9
Cash at beginning of period	0.5
Cash at end of period	1.1	67.7
Crestwood Midstream Partners LP
Cash flows from operating activities	135.7	105.7
Cash flows from investing activities:
Purchases of property, plant and equipment	(55.6)	(47.4)
Investment in unconsolidated affiliates	(5.5)	(17.9)
Proceeds from sale of assets	0.8	0.5
Capital contributions to consolidated affiliates	0.0	0.0
Payments for (Proceeds from) Other Investing Activities	0.0	(0.2)
Net cash used in investing activities	(60.3)	(65.0)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	313.5	1,114.6
Principal payments on long-term debt	(286.0)	(970.4)
Payments on capital leases	(0.5)	(0.7)
Payments for debt-related deferred costs	(0.1)	(11.1)
Distributions to partners	(101.0)	(111.4)
Distributions paid to non-controlling partners	0.0	0.0
Taxes paid for unit-based compensation vesting	(0.6)	(1.7)
Change in intercompany balances	0.0	0.0
Other	0.0	(0.2)
Net cash provided by (used in) financing activities	(74.7)	19.1
Net change in cash	0.7	59.8
Cash at beginning of period	0.1	7.6
Cash at end of period	0.8	67.4
Crestwood Midstream Partners LP | Parent Company
Cash flows from operating activities	(42.7)	(54.8)
Cash flows from investing activities:
Purchases of property, plant and equipment	(0.9)	(0.1)
Investment in unconsolidated affiliates	0.0	0.0
Proceeds from sale of assets	0.0	0.0
Capital contributions to consolidated affiliates	(3.7)	(17.9)
Payments for (Proceeds from) Other Investing Activities		0.0
Net cash used in investing activities	(4.6)	(18.0)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	313.5	1,114.6
Principal payments on long-term debt	(286.0)	(970.4)
Payments on capital leases	0.0	(0.5)
Payments for debt-related deferred costs	(0.1)	(11.1)
Distributions to partners	(97.2)	(111.4)
Distributions paid to non-controlling partners	0.0	0.0
Taxes paid for unit-based compensation vesting	0.0	0.0
Change in intercompany balances	117.8	51.8
Other		(0.2)
Net cash provided by (used in) financing activities	48.0	72.8
Net change in cash	0.7	0.0
Cash at beginning of period	0.1	0.0
Cash at end of period	0.8	0.0
Crestwood Midstream Partners LP | Guarantor Subsidiaries
Cash flows from operating activities	172.8	160.5
Cash flows from investing activities:
Purchases of property, plant and equipment	(54.7)	(47.3)
Investment in unconsolidated affiliates	0.0	0.0
Proceeds from sale of assets	0.8	0.5
Capital contributions to consolidated affiliates	0.0	0.0
Payments for (Proceeds from) Other Investing Activities		(0.2)
Net cash used in investing activities	(53.9)	(47.0)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0.0	0.0
Principal payments on long-term debt	0.0	0.0
Payments on capital leases	(0.5)	(0.2)
Payments for debt-related deferred costs	0.0	0.0
Distributions to partners	0.0	0.0
Distributions paid to non-controlling partners	0.0	0.0
Taxes paid for unit-based compensation vesting	(0.6)	(1.7)
Change in intercompany balances	(117.8)	(51.8)
Other		0.0
Net cash provided by (used in) financing activities	(118.9)	(53.7)
Net change in cash	0.0	59.8
Cash at beginning of period	0.0	7.6
Cash at end of period	0.0	67.4
Crestwood Midstream Partners LP | Non-Guarantor Subsidiaries
Cash flows from operating activities	5.6	0.0
Cash flows from investing activities:
Purchases of property, plant and equipment	0.0	0.0
Investment in unconsolidated affiliates	(5.5)	(17.9)
Proceeds from sale of assets	0.0	0.0
Capital contributions to consolidated affiliates	0.0	0.0
Payments for (Proceeds from) Other Investing Activities		0.0
Net cash used in investing activities	(5.5)	(17.9)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0.0	0.0
Principal payments on long-term debt	0.0	0.0
Payments on capital leases	0.0	0.0
Payments for debt-related deferred costs	0.0	0.0
Distributions to partners	(3.8)	0.0
Distributions paid to non-controlling partners	3.7	17.9
Taxes paid for unit-based compensation vesting	0.0	0.0
Change in intercompany balances	0.0	0.0
Other		0.0
Net cash provided by (used in) financing activities	(0.1)	17.9
Net change in cash	0.0	0.0
Cash at beginning of period	0.0	0.0
Cash at end of period	0.0	0.0
Crestwood Midstream Partners LP | Eliminations
Cash flows from operating activities	0.0	0.0
Cash flows from investing activities:
Purchases of property, plant and equipment	0.0	0.0
Investment in unconsolidated affiliates	0.0	0.0
Proceeds from sale of assets	0.0	0.0
Capital contributions to consolidated affiliates	3.7	17.9
Payments for (Proceeds from) Other Investing Activities		0.0
Net cash used in investing activities	3.7	17.9
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0.0	0.0
Principal payments on long-term debt	0.0	0.0
Payments on capital leases	0.0	0.0
Payments for debt-related deferred costs	0.0	0.0
Distributions to partners	0.0	0.0
Distributions paid to non-controlling partners	(3.7)	(17.9)
Taxes paid for unit-based compensation vesting	0.0	0.0
Change in intercompany balances	0.0	0.0
Other		0.0
Net cash provided by (used in) financing activities	(3.7)	(17.9)
Net change in cash	0.0	0.0
Cash at beginning of period	0.0	0.0
Cash at end of period	$ 0.0	$ 0.0