Tax (Benefit) Allocated in Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Income tax (benefit) expense	$ 387	$ (55,658)	$ (23,849)
Excess tax expense on stock compensation		907	362
Deferred tax expense on accumulated other comprehensive income		7,888	1,335
Total		8,795	1,697
Total income tax (benefit)	$ 387	$ (46,863)	$ (22,152)