Inventoried Costs (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 25, 2011
Inventory Disclosure [Abstract]
Raw materials	$ 48.4	$ 43.3
Work in process	41.9	25.7
Finished goods	7.8	6.9
Supplies and other	1.9	4.0
Total inventoried costs	100.0	79.9
Less customer advances and progress payments	(0.1)	(3.3)
Total inventoried costs	$ 99.9	$ 76.6