Long-Term Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 28, 2014 Forecast Industrial Development Debt Issues Payable Through 2022, 0.30%	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Dec. 31, 2013 Revolving Credit Facility	Dec. 31, 2013 Unspecified Arrangement
Debt Instrument [Line Items]
Unsecured senior revolving credit facility	$ 300.0
Unsecured senior revolving credit facility, maturity date	Nov. 01, 2016
Line of Credit Facility Interest Rate					1.42%	1.71%
Increase in the senior credit facility	50.0
Unused senior revolving credit facility	184.0
Letters of Credit and Bank Guarantees Outstanding, Amount	9.0
Line of Credit Facility, Amount Outstanding							6.0
Restricted Cash and Cash Equivalents	2.8	0	0					2.2
Voluntary Retirement Payments Guaranteed	4.1
Maturity obligation, 2014	6.7
Maturity obligation, 2015	6.7
Maturity obligation, 2016	116.7
Maturity obligation, 2017	26.7
Maturity obligation, 2018	26.7
Maturity obligation, thereafter	83.8
Debt Instrument, Debt Amount Expected to be Redeemed				$ 4.0