Securities (Summary of Amounts Relating to Sales of Securities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	$ 46,560	[1]	$ 56,461	[1]	$ 99,097	[1]
Gross realized gains	1,224	[1]	919	[1]	852	[1]
Gross realized losses	(1)		(221)		(123)
Net realized gains on securities	1,223		698		729
Perpetual preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains			331
Cost of contribution for appreciated equity securities included in other noninterest expense			$ 990

[1] Includes a contribution of appreciated equity securities to the Corporation’s charitable foundation in 2011. The cost of the contribution, included in noninterest expenses, amounted to $990 thousand in 2011. This transaction resulted in a realized security gain of $331 thousand for the same period.