Share Based Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended			1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2012 Installment	Sep. 30, 2012 Stock options [Member]	Sep. 30, 2011 Stock options [Member]	Jan. 31, 2011 Restricted stock [Member]	Mar. 31, 2012 Restricted stock [Member]	Sep. 30, 2012 Restricted stock [Member]	Sep. 30, 2011 Restricted stock [Member]	Dec. 31, 2006 Stock appreciation rights [Member]	Sep. 30, 2012 Stock appreciation rights (SARs) [Member]	Sep. 30, 2011 Stock appreciation rights (SARs) [Member]	Dec. 31, 2006 Stock appreciation rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants under nonqualified stock option	From 2005 to 2007
Expense recorded for stock options		$ 9	$ 0			$ 220	$ 140		$ 5	$ 0
Vesting Description	The maximum option term is ten years and the options generally vest over three years as follows one-third after one year from the grant date, two-thirds after two years and completely after three years.								The SAR vest over three years as follows one-third after one year from the grant date, two-thirds after two years and completely after three years.
Purchase price of long term restricted share	$ 5.39			$ 5.28	$ 5.39	$ 5.39
Total intrinsic value of options exercised	0
Total intrinsic value of options outstanding	$ 26
Shares issued	35,000			40,000	62,105	62,105
Forfeited due to employee terminations	2,500
Number of installment	2
Stock appreciation rights shares issued								30,000
Stock appreciation rights price of long term restricted share								$ 19.00
Shares expired due to employee terminations								15,500
General vesting period											3 years
Maximum option term											Jan. 01, 2016