Inventories - Long term contracts percentage-of-completion accounting (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Oct. 02, 2015	Sep. 30, 2016	Oct. 02, 2015
Inventory Disclosure [Abstract]
Decrease to operating income from the quarterly impact of revisions in long term contracts	$ 1.3		$ 3.9
Increase to operating income from the quarterly impact of revisions in long term contracts		$ 2.1		$ 5.0