Fair Value of Financial Instruments (Detail) - Quantitative information regarding the assumptions used for valuing Level 3 assets (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2012 Collateralized Debt Obligations [Member] Minimum [Member]	Sep. 30, 2012 Collateralized Debt Obligations [Member] Maximum [Member]	Sep. 30, 2012 Collateralized Debt Obligations [Member] Weighted Average [Member]	Sep. 30, 2012 Collateralized Debt Obligations [Member]		Sep. 30, 2012 Mortgage Servicing Rights [Member]
Collateralized debt obligations (in Dollars)								$ 3,112	[1]
Collateralized debt obligations								Discounted cash flow	[1]
Collateralized debt obligations					10.50%	16.80%	12.30%
					0.25%	2.25%	0.59%
					14.22%	45.50%	33.12%
MSRs (in Dollars)	$ 2,887	[2]	$ 2,238	[2]						$ 12,504	[1]
MSRs										Discounted cash flow	[1]
MSRs										18.10%
										10.45%
										1.97%

[1] Other level 3 securities totaling $1.5 million are valued based on data provided by the issuer

[2] Included as part of Other Assets in the Consolidated Balance Sheets.