Income taxes - Schedule of Effective Income Tax Rate Reconciliation for Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components Of Income Tax Expense Benefit [Line Items]
Statutory U.S. federal income tax rate			35.00%	35.00%	35.00%
State taxes, net			2.40%	10.20%	4.20%
Foreign rate differential			(3.30%)	6.20%	0.60%
Valuation allowance-foreign losses			8.30%	21.90%	7.20%
SRL Intangible			(2.70%)	(12.50%)	(5.20%)
Domestic manufacturing deduction			(1.90%)	(6.80%)	(3.00%)
Settlement of U.S. Government resolutions			(1.50%)	50.10%	0.00%
Other items, net			(1.50%)	4.80%	6.10%
Income tax expense/effective rate			34.80%	108.90%	44.90%
Statutory U.S. federal income tax rate			$ 28,955	$ 6,804	$ 17,627
State taxes, net			1,946	1,981	2,093
Foreign rate differential			(2,749)	1,204	280
Valuation allowance-foreign losses			6,833	4,254	3,644
SRL Intangible			(2,214)	(2,421)	(2,607)
Domestic manufacturing deduction			(1,533)	(1,316)	(1,530)
Settlement of U.S. Government resolutions	10,500	46,000	(1,260)	9,745
Other items, net			(1,186)	930	3,099
Income tax expense/effective rate			$ 28,792	$ 21,181	$ 22,606