Guarantee of Securities of Subsidiaries Guarantee of Securities of Subsidiaries Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	$ 129.3	$ 109.8
Investing Activities:
Capital expenditures	(70.6)	(26.0)
Proceeds from sale of operating assets	1.0	1.7
Proceeds from insurance and other recoveries	1.4	0.4
Advances to affiliates, net	0	0
Investment in consolidated subsidiary	0	0
Net cash used in investing activities	(68.2)	(23.9)
Financing Activities:
Proceeds from borrowings on revolving credit agreement	263.0	370.0
Repayment of borrowings on revolving credit agreement	(195.0)	(330.0)
Contribution from parent	0	0
Advances from affiliates, net	(0.4)	4.7
Repayment of contribution received related to predecessor equity	0	(284.8)
Distributions paid	(128.3)	(114.0)
Proceeds from sale of common units	0	245.0
Capital contribution from general partner	0	5.2
Net cash used in financing activities	(60.7)	(103.9)
Increase (decrease) in cash and cash equivalents	0.4	(18.0)
Cash and cash equivalents at beginning of period	3.9	21.9
Cash and cash equivalents at end of period	4.3	3.9
Parent Guarantor [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	9.4	8.0
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	119.2	(134.0)
Investment in consolidated subsidiary	0	(15.4)
Net cash used in investing activities	119.2	(149.4)
Financing Activities:
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement	0	0
Contribution from parent	0	0
Advances from affiliates, net	(0.4)	4.7
Repayment of contribution received related to predecessor equity		0
Distributions paid	(128.3)	(114.0)
Proceeds from sale of common units		245.0
Capital contribution from general partner		5.2
Net cash used in financing activities	(128.7)	140.9
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	(27.0)	29.8
Investing Activities:
Capital expenditures	(0.3)	0
Proceeds from sale of operating assets	0	0
Proceeds from insurance and other recoveries	0	0
Advances to affiliates, net	(31.3)	(4.1)
Investment in consolidated subsidiary	(12.0)	(15.4)
Net cash used in investing activities	(43.6)	(19.5)
Financing Activities:
Proceeds from borrowings on revolving credit agreement	0	180.0
Repayment of borrowings on revolving credit agreement	0	(165.0)
Contribution from parent	0	15.4
Advances from affiliates, net	71.6	235.3
Repayment of contribution received related to predecessor equity		(284.8)
Distributions paid	0	0
Proceeds from sale of common units		0
Capital contribution from general partner		0
Net cash used in financing activities	71.6	(19.1)
Increase (decrease) in cash and cash equivalents	1.0	(8.8)
Cash and cash equivalents at beginning of period	1.0	10.7
Cash and cash equivalents at end of period	2.0	1.9
Non-Guarantor Subsidiaries [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	146.9	131.7
Investing Activities:
Capital expenditures	(70.3)	(26.0)
Proceeds from sale of operating assets	1.0	1.7
Proceeds from insurance and other recoveries	1.4	0.4
Advances to affiliates, net	(190.8)	(102.1)
Investment in consolidated subsidiary	0	0
Net cash used in investing activities	(258.7)	(126.0)
Financing Activities:
Proceeds from borrowings on revolving credit agreement	263.0	190.0
Repayment of borrowings on revolving credit agreement	(195.0)	(165.0)
Contribution from parent	12.0	15.4
Advances from affiliates, net	31.3	4.9
Repayment of contribution received related to predecessor equity		0
Distributions paid	0	(59.7)
Proceeds from sale of common units		0
Capital contribution from general partner		0
Net cash used in financing activities	111.3	(14.4)
Increase (decrease) in cash and cash equivalents	(0.5)	(8.7)
Cash and cash equivalents at beginning of period	2.8	10.7
Cash and cash equivalents at end of period	2.3	2.0
Consolidation, Eliminations [Member]
Statement of Cash Flows
Net Cash Provided by (Used in) Operating Activities	0	(59.7)
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	102.9	240.2
Investment in consolidated subsidiary	12.0	30.8
Net cash used in investing activities	114.9	271.0
Financing Activities:
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement	0	0
Contribution from parent	(12.0)	(30.8)
Advances from affiliates, net	(102.9)	(240.2)
Repayment of contribution received related to predecessor equity		0
Distributions paid	0	59.7
Proceeds from sale of common units		0
Capital contribution from general partner		0
Net cash used in financing activities	(114.9)	(211.3)
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