Segment Reporting - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Community Banking | Non Cash
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 0.4	$ 0.4	$ 0.7	$ 0.7
Insurance Segment | Non Cash
Segment Reporting Information [Line Items]
Amortization of intangibles	0	0	0	0
Investment Management Segment
Segment Reporting Information [Line Items]
Assets Under Management	808		808
Investment Banking | Non Cash
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 0	$ 0	$ 0	$ 0