Summary of Significant Accounting Policies (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Summary of Significant Accounting Policies
Costs and estimated earnings in excess of billings	$ 355.9	$ 228.1
Billings in excess of costs and estimated earnings on uncompleted contracts	279.0	373.9
Net costs and estimated earnings in excess of billings (billings in excess of costs and estimated earnings)	$ (76.9)	$ 145.8