Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of intangible assets, excluding goodwill [Line Items]
Amortizing	$ 24.2	$ 7.4
Non-amortizing	7.0	7.0
Weighted average remaining life for amortizing customer-related assets and all amortizing intangibles (in years)	14
Amortization expense	2.3	0.6	0.6
Amortization expense - year one	2.6
Amortization expense - year two	2.3
Amortization expense - year three	2.3
Amortization expense - year four	2.2
Amortization expense - year five	1.6
Customer Related Assets [Member]
Schedule of intangible assets, excluding goodwill [Line Items]
Amortizing	20.6	7.4
Non-amortizing	0	0
Accumulated amortization	5.1	3.4
Market Related Assets [Member]
Schedule of intangible assets, excluding goodwill [Line Items]
Amortizing	3.6	0
Non-amortizing	7.0	7.0
Accumulated amortization	$ 0.9	$ 0.3