Borrowings - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended							3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Credit Agreement [Member]	May 31, 2012 Credit Agreement [Member]	Jun. 30, 2012 Credit Agreement [Member] Nonvoting Common Stock Direct Foreign Subsidiaries [Member]	Jun. 30, 2012 Credit Agreement [Member] Voting Common Stock Direct Foreign Subsidiaries [Member]	May 03, 2012 2012 Credit Agreement [Member]	Sep. 30, 2011 2010 Credit Agreement [Member]	Sep. 30, 2011 2010 Credit Agreement [Member]	May 03, 2012 2010 Credit Agreement [Member]	Aug. 20, 2012 Revolving Credit Facility [Member]	May 03, 2012 Alternate currency sub-facility [Member]	May 03, 2012 Swingline sub-facility [Member]	May 03, 2012 Letter of credit sub-facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity									$ 245,000,000			$ 75,000,000		$ 184,000,000	$ 10,000,000	$ 35,000,000
Proceeds from borrowings under credit agreement													108,000,000
Line of Credit Facility, Expiration Date			May 02, 2017
No varying installments due			0
Credit agreement interest rate description					Borrowings under the New Credit Agreement bear interest at either LIBOR or the base rate plus, in each case, an applicable margin based on the Company’s leverage ratio. The applicable interest rate is determined quarterly based on the Company’s leverage ratio at such time. The base rate is a rate per annum equal to the greatest of (i) the rate of interest established by KeyBank, from time to time, as its “prime rate”; (ii) the Federal Funds effective rate in effect from time to time, plus 1/2 of 1% per annum; and (iii) the then-applicable LIBOR rate for one month interest periods, plus 1.00%. Swingline loans bear interest only at the base rate plus the base rate margin.
Fixed component added to federal fund effective rate to compute base rate					0.50%
Fixed component added to LIBOR to compute base rate					1.00%
Credit agreement customary fees description					the Company is required to pay certain customary fees, including a commitment fee of 0.175%, which is due quarterly in arrears and calculated on the average unused amount of the New Credit Agreement.
Commitment fee					0.175%
Underwriting fee for the New Credit Agreement						900,000
Interest expense and amortization of deferred loan fees for credit agreement	$ 300,000		$ 800,000							$ 300,000	$ 900,000
Weighted average interest rate	1.60%	0.00%	1.60%	0.00%
Percentage of capital stock pledged under credit agreement							100.00%	65.00%