Financial Instruments Financial Instruments - Interest Rate Swap Agreements (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative, Number of Instruments Held	2
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 100.0
Net payments under derivative swap agreements	0.8	$ 1.4	$ 6.2
USD Interest Rate Swap Contract One [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 50.0
Interest rate swap agreements maturity period	2017
Derivative, Interest Rate	1.38%
USD Interest Rate Swap Contract Two [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 50.0
Interest rate swap agreements maturity period	2017
Derivative, Interest Rate	1.64%
Us Term Loan [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Effective interest rate on term loans	2.67%
Accrued Liabilities [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Fair value of liability of total outstanding swap agreements	$ 0.2	0.7
Other Liabilities [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Fair value of liability of total outstanding swap agreements		$ 0.1