Revenues (Tables)

3 Months Ended

Mar. 31, 2018

Revenue From Contract With Customer [Abstract]

Schedule of Change In Customer Advances Balance

The table below shows the change in the customer advances balance for the three months ended March 31, 2018 ($ in millions).

	Customer Advances Balance as of January 1, 2018		Cash Received in Advance of Satisfying Performance Obligation		Revenue Recognized		Customer Advances Balance as of March 31, 2018
Total	$	12.7	$	26.3	$	24.6	$	14.4