Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Equity [Line Items]
Common stock issued in connection with business	60,855	372,992
Shares of common stock issued to trustee under 401(k) savings and retirement plan			0	110,881	110,881
Net proceeds from issuance of common stock to the trustee under 401(k) savings and retirement plan			$ 0	$ 4,745	$ 4,745
Number of shares held in treasury	0		0	0	0
Shares remaining under the current authorization repurchase program	3,411,416		3,411,416