Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2006
Business Acquisition, Contingent Consideration [Line Items]
Operating lease commitment	$ 26.8
Operating lease termination year	2022
2006 Gulf Coast Acquisition [Member]
Business Acquisition, Contingent Consideration [Line Items]
Escrow deposit related to abandonment and remediation obligations	10.7	10.7
Period of time escrow in effect after abandonment and remediation obligations	3 years
Maximum date escrow will be returned	December 31, 2026
Issued letter of credit in addition to escrow	23.4	23.4	3.0
Addtional line of credit issued each year to seller	3.0
Prize [Member]
Business Acquisition, Contingent Consideration [Line Items]
Estimated environmental liability	$ 1.7	$ 1.9