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	$ 23,149	$ 16,508	$ 18,658
Deferred	(503)	365	1,047
Total U.S	22,646	16,873	19,705
Non-U.S.
Current	5,800	3,208	948
Deferred	346	1,100	1,953
Total Non U.S	6,146	4,308	2,901
Income tax expense/effective rate	$ 28,792	$ 21,181	$ 22,606