Guarantee of Securities of Subsidiaries Guarantee of Securities of Subsidiaries Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	$ 285.2	$ 284.3
Investing Activities:
Capital expenditures	(132.2)	(90.9)
Proceeds from sale of operating assets	21.2	2.4
Proceeds from insurance and other recoveries	1.4	5.4
Advances to affiliates, net	0	0
Investment in consolidated subsidiary	0	0
Investment in unconsolidated affiliates	(21.4)	0
Net cash used in investing activities	(131.0)	(83.1)
Financing Activities:
Proceeds from long-term debt, net of issuance costs	0	296.5
Proceeds from borrowings on revolving credit agreement	458.0	1,000.0
Repayment of borrowings on revolving credit agreement	(740.0)	(1,243.5)
Payments of financing fees related to revolving credit facility	0	(3.8)
Contribution from parent	0	0
Advances from affiliates, net	(2.4)	2.6
Repayment of contribution received related to predecessor equity	0	(284.8)
Distributions paid	(256.4)	(228.9)
Capital contributions from noncontrolling interests	16.1	0
Proceeds from sale of common units	368.7	245.0
Capital contribution from general partner	7.8	5.2
Net cash used in financing activities	(148.2)	(211.7)
Increase (decrease) in cash and cash equivalents	6.0	(10.5)
Cash and cash equivalents at beginning of period	3.9	21.9
Cash and cash equivalents at end of period	9.9	11.4
Parent Guarantor [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	17.6	(4.1)
Investing Activities:
Capital expenditures	0	0
Proceeds from sale of operating assets	0	0
Proceeds from insurance and other recoveries	0	0
Advances to affiliates, net	(135.4)	(20.3)
Investment in consolidated subsidiary	0	0
Investment in unconsolidated affiliates	0
Net cash used in investing activities	(135.4)	(20.3)
Financing Activities:
Proceeds from long-term debt, net of issuance costs		0
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement	0	0
Payments of financing fees related to revolving credit facility		0
Contribution from parent	0	0
Advances from affiliates, net	(2.4)	2.6
Repayment of contribution received related to predecessor equity		0
Distributions paid	(256.4)	(228.9)
Capital contributions from noncontrolling interests	0
Proceeds from sale of common units	368.7	245.0
Capital contribution from general partner	7.8	5.2
Net cash used in financing activities	117.7	23.9
Increase (decrease) in cash and cash equivalents	(0.1)	(0.5)
Cash and cash equivalents at beginning of period	0.1	0.5
Cash and cash equivalents at end of period	0	0
Subsidiary Issuer [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	(52.5)	53.4
Investing Activities:
Capital expenditures	0	0
Proceeds from sale of operating assets	0	0
Proceeds from insurance and other recoveries	0	0
Advances to affiliates, net	(56.5)	(36.9)
Investment in consolidated subsidiary	(15.1)	(26.1)
Investment in unconsolidated affiliates	0
Net cash used in investing activities	(71.6)	(63.0)
Financing Activities:
Proceeds from long-term debt, net of issuance costs		0
Proceeds from borrowings on revolving credit agreement	0	270.0
Repayment of borrowings on revolving credit agreement	0	(370.0)
Payments of financing fees related to revolving credit facility		(3.8)
Contribution from parent	0	0
Advances from affiliates, net	124.3	390.6
Repayment of contribution received related to predecessor equity		(284.8)
Distributions paid	0	0
Capital contributions from noncontrolling interests	0
Proceeds from sale of common units	0	0
Capital contribution from general partner	0	0
Net cash used in financing activities	124.3	2.0
Increase (decrease) in cash and cash equivalents	0.2	(7.6)
Cash and cash equivalents at beginning of period	1.0	10.7
Cash and cash equivalents at end of period	1.2	3.1
Non-Guarantor Subsidiaries [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	320.1	329.1
Investing Activities:
Capital expenditures	(132.2)	(90.9)
Proceeds from sale of operating assets	21.2	2.4
Proceeds from insurance and other recoveries	1.4	5.4
Advances to affiliates, net	11.1	(370.7)
Investment in consolidated subsidiary	0	0
Investment in unconsolidated affiliates	(21.4)
Net cash used in investing activities	(119.9)	(453.8)
Financing Activities:
Proceeds from long-term debt, net of issuance costs		296.5
Proceeds from borrowings on revolving credit agreement	458.0	730.0
Repayment of borrowings on revolving credit agreement	(740.0)	(873.5)
Payments of financing fees related to revolving credit facility		0
Contribution from parent	15.1	26.1
Advances from affiliates, net	56.5	37.4
Repayment of contribution received related to predecessor equity		0
Distributions paid	0	(94.2)
Capital contributions from noncontrolling interests	16.1
Proceeds from sale of common units	0	0
Capital contribution from general partner	0	0
Net cash used in financing activities	(194.3)	122.3
Increase (decrease) in cash and cash equivalents	5.9	(2.4)
Cash and cash equivalents at beginning of period	2.8	10.7
Cash and cash equivalents at end of period	8.7	8.3
Consolidation, Eliminations [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	0	(94.1)
Investing Activities:
Capital expenditures	0	0
Proceeds from sale of operating assets	0	0
Proceeds from insurance and other recoveries	0	0
Advances to affiliates, net	180.8	427.9
Investment in consolidated subsidiary	15.1	26.1
Investment in unconsolidated affiliates	0
Net cash used in investing activities	195.9	454.0
Financing Activities:
Proceeds from long-term debt, net of issuance costs		0
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement	0	0
Payments of financing fees related to revolving credit facility		0
Contribution from parent	(15.1)	(26.1)
Advances from affiliates, net	(180.8)	(428.0)
Repayment of contribution received related to predecessor equity		0
Distributions paid	0	94.2
Capital contributions from noncontrolling interests	0
Proceeds from sale of common units	0	0
Capital contribution from general partner	0	0
Net cash used in financing activities	(195.9)	(359.9)
Increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0