Long Term Obligations - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Debt Instrument [Line Items]
Total leverage ratio	2.7	2.7
Fixed charge coverage ratio	1.7	1.7
Revolving Credit Facilities [Member]
Debt Instrument [Line Items]
Principal amount	$ 165.0	$ 165.0
Availability under the revolving credit facility	143.3	143.3
Outstanding letters of credit	21.7	21.7
Term Loan [Member]
Debt Instrument [Line Items]
Term loan, period		5 years
Weighted-average interest rate for five year Term Loan	2.70%	2.70%
Principal amount	$ 60.0	$ 60.0