Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Dec. 31, 2009
Impaired Intangible Assets [Line Items]
Goodwill	$ 35,043	$ 35,696	$ 28,354	$ 26,784	$ 26,554	$ 25,869
Other Intangible assets	24,615		2,959	1,096
Amortization expense for intangible assets	599
Estimated amortization expense for intangible assets for remainder year	313
Estimated amortization expense for intangible assets for year one	1,254
Estimated amortization expense for intangible assets for year two	1,254
Estimated amortization expense for intangible assets for year three	1,254
Estimated amortization expense for intangible assets for year four	1,254
Estimated amortization expense for intangible assets for year five	1,229
Estimated amortization expense for intangible assets for five year after	$ 1,326