Schedule II - Valuation and Qualifying Accounts and Reserves (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Allowance for doubtful accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year (1)	[1]	$ 2.6	$ 3.2		$ 2.7
Charged to Expenses / Against Revenue	[2]	2.2	0.8		1.3
Deductions - Write-offs	[3]	(1.4)	(1.4)		(0.8)
Balance at End of Year		3.4	2.6	[1]	3.2	[1]
Valuation allowance for income taxes [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year (1)	[1]	0.9	0.7		0.7
Charged to Expenses / Against Revenue	[2]	7.2	0.2		0.0
Deductions - Write-offs	[3]	0.0	0.0		0.0
Balance at End of Year		$ 8.1	$ 0.9	[1]	$ 0.7	[1]

[1] Excludes discontinued operations

[2] Primarily additional reserves for bad debts

[3] Primarily accounts receivable balances written off, net of recoveries, and the expiration of loss carryforwards