Litigation Settlement - Additional Information (Detail) (Buyer of Ardmore, Oklahoma, USD $) In Thousands, unless otherwise specified	1 Months Ended	9 Months Ended
	Mar. 31, 2012	Sep. 30, 2012	Dec. 31, 2010	Sep. 30, 2012 Additional allowance for doubtful accounts	Dec. 31, 2011 Additional allowance for doubtful accounts
Commitments Contingencies And Litigation [Line Items]
Aggregate principal notes receivable	$ 670
Interest on receivable	6.00%
Monthly installments date	from March 2012 through May 2014
Promissory note			480
Allowance for doubtful accounts			240	190	190
Litigation Settlement Net After Settlement		0
Litigation Settlement Net		430
Allowance for Loan and Lease Losses, Recoveries of Bad Debts		$ 29