Accounts Receivable - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
United States and Italy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables sold with recourse	$ 6.8	$ 10.0	$ 21.4
Spain and Italy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables sold without recourse	$ 4.3	$ 5.7	$ 5.9