Summary of Fair Values of Assets and Liabilities Assumed (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Jan. 17, 2012
Business Acquisition [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 393	$ 346
Intangible Assets, Net (Excluding Goodwill)	358	358	2,290
Equipment And Leasehold Improvements
Business Acquisition [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			$ 202