Changes in Unrecognized Tax Positions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Income Tax Contingency [Line Items]
Unrecognized tax positions, beginning balance	$ 9,132	$ 7,622
Gross increases- tax positions in prior period	242	828
Gross decreases- tax positions in prior period	0	(21)
Gross increases- current period tax positions	2,609	1,863
Settlement	(108)	0
Lapse of statute of limitations	(1,210)	(1,160)
Unrecognized tax positions, ending balance	$ 10,665	$ 9,132