Leases (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Capital Leased Assets [Line Items]
Total rent expenses	$ 11.1	$ 9.0	$ 8.1
Depreciation expense	0.17	0	0
Accumulated depreciation on capital leases	0.15	0
Gross capital lease obligation	0.95
Property, Plant And Equipment [Member]
Capital Leased Assets [Line Items]
Leasehold Improvements on capital leases	1.12	0
Current Liability For Capital Lease Obligations [Member]
Capital Leased Assets [Line Items]
Gross capital lease obligation	0.18
Non Current Liability For Capital Lease Obligations [Member]
Capital Leased Assets [Line Items]
Gross capital lease obligation	$ 0.77