Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Inventory Disclosure [Abstract]

Schedule of inventory classes

The classes of inventory as of December 31 are summarized as follows ($ in millions):

	2017		2016
Finished goods	$	217.2	$	198.3
Work in process	78.9		79.3
Raw materials	284.5		267.0
Total	$	580.6	$	544.6