Summary of Changes in Unrecognized Tax Positions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Income Tax Contingency [Line Items]
Unrecognized tax positions, beginning balance	$ 10,772	$ 9,239
Gross increases-tax positions in prior period	2,284	242
Gross decreases-tax positions in prior period	0	0
Gross increases-current period tax positions	4,119	2,609
Settlement	0	(108)
Lapse of statute of limitations	(1,071)	(1,210)
Unrecognized tax positions, ending balance	$ 16,104	$ 10,772