Goodwill and Intangible Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 17,780	$ 17,780
Intangible assets:
Accumulated amortization	(3,821)	(1,442)
Total intangible assets	4,329	6,708
Intangible liabilities:
Lease	100	100
Accumulated amortization	(47)	(14)
Total intangible liabilities	53	86
Customer relationships
Intangible assets:
Intangible assets gross	7,300	7,300
Trade names
Intangible assets:
Intangible assets gross	$ 850	$ 850