Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2010	Dec. 31, 2011
Debt Instrument [Line Items]
2010 Credit Agreement, term loan and revolving credit facility maturity	5 years
2010 Credit Agreement, expansion feature by which the term loan and revolving credit facility may be increased	$ 150.0	$ 150.0
2010 Credit Agreement, interest rate description	either (i) the greatest of: the administrative agent’s prime rate; the average rate on overnight federal funds plus 1/2 of 1%; and the eurodollar rate (adjusted for statutory reserves) plus 1%, in each case plus a margin equal to between 0.50% and 1.25% depending on the Company’s leverage ratio as of the end of the four consecutive fiscal quarters most recently ended, or (ii) the eurodollar rate (adjusted for statutory reserves) plus a margin equal to between 1.50% and 2.25%
Average rate on overnight federal funds plus 1/2 of	1.00%
Eurodollar rate plus	1.00%
Write off of Deferred Debt Issuance Cost		0.4
Interest rate swap fair value			9.9
Outstanding letters of credit and guarantees			4.7
Notional fixed-for-floating interest rate swap contract			200
Base fixed rate			2.26%
Interest rate swap contracts
Debt Instrument [Line Items]
Deferred Gain Losses In Other Comprehensive Income		(3.3)
Euro Dollar Rate
Debt Instrument [Line Items]
Plus minimum margin	1.50%	1.50%
Plus maximum margin	2.25%	2.25%
Federal Funds Rate | Euro Dollar Rate
Debt Instrument [Line Items]
Plus minimum margin	0.50%	0.50%
Plus maximum margin	1.25%	1.25%
Term Loan
Debt Instrument [Line Items]
2010 Credit Agreement, maximum borrowing capacity	200.0	200.0
Term loan repayment	19 consecutive quarterly installments
Debt instrument, final payment due	Dec. 22, 2015
Revolver
Debt Instrument [Line Items]
2010 Credit Agreement, maximum borrowing capacity	400.0	400.0
Debt instrument, final payment due	Dec. 22, 2015
Revolver | Letter of Credit
Debt Instrument [Line Items]
2010 Credit Agreement, maximum borrowing capacity	$ 40.0	$ 40.0