Provision Benefit for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components Of Income Tax Expense Benefit [Line Items]
Foreign									$ 180	$ 143	$ 94
Federal									0	0	0
State									0	0	0
Total Current									180	143	94
Foreign									0	0	0
Federal									48	0	0
State									14	0	0
Total Deferred									62	0	0
Provision for income taxes	$ 111	$ 55	$ 41	$ 35	$ 49	$ 44	$ 27	$ 23	$ 242	$ 143	$ 94