Income taxes - Schedule of Provision for (Benefit from) Income Taxes on Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
U.S.
Current	$ 17,897	$ 25,148	$ 19,336
Deferred	1,788	(12,657)	2,282
Total U.S	19,685	12,491	21,618
Non-U.S.
Current	4,609	2,735	253
Deferred	844	(1,061)	2,160
Total Non U.S	5,453	1,674	2,413
Income tax expense	$ 25,138	$ 14,165	$ 24,031