Components of Income Tax Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current tax (benefit) expense:
Federal	$ (77)	$ 26	$ (463)
U.S. State and local	(61)	104	113
Total current	(138)	130	(350)
Deferred tax expense (benefit):
Federal			418
U.S. State and local			(25)
Total deferred			393
Income tax (benefit) expense	$ (138)	$ 130	$ 43