Changes in Liability for Unrecognized Gross Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Contingency [Line Items]
Uncertain tax positions at beginning of year	$ 13,068	$ 9,327	$ 24,153
Additions for tax positions relating to current-year operations	457	6,103	762
Additions for tax positions relating to prior tax years		2,221	778
Subtractions for tax positions relating to prior tax years	(4,603)	(2,677)	(13,509)
Reductions in balance due to settlements		(1,906)	(2,857)
Uncertain tax positions at end of year	$ 8,922	$ 13,068	$ 9,327