Mortgage Servicing Rights and Mortgage Servicing Activity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012
Mortage Servicing Rights Amortized Value [Roll Forward]
Mortgage Servicing Rights Beginning of Period	$ 21,316		$ 21,179	$ 21,179
Mortgage Servicing Rights Additions	1,267		1,394
Amortization of Mortgage Servicing Rights (MSRs)	(1,205)		1,627
Mortgage Servicing Rights, End of Period	21,378		20,946	21,316
Mortage Servicing Rights Valuation Rollforward [Roll Forward]
Mortgage Servicing rights Valuation Allowance Beginning of Period	(2,564)		(3,539)	(3,539)
Mortgage Servicing Rights (MSR) Impairment (Recovery)	1,330		1,346	975
Mortgage Servicing rights Valuation Allowance, End of Period	(1,234)		(2,193)	(2,564)
Mortgage Servicing Rights Net Carrying balance	20,144		18,753
Fair Value of Mortgage Servicing Rights	20,223	[1]	18,869	18,833	[1]
Fair Value, Inputs, Level 3 [Member]
Mortage Servicing Rights Valuation Rollforward [Roll Forward]
Fair Value of Mortgage Servicing Rights	$ 20,223	[1]	$ 18,869	$ 18,833

[1] (b) - MSRs with a recorded investment of $21.4 million were reduced by a specific valuation allowance totaling $1.2 million to a reported carrying value of $20.1 million resulting in recognition of $1.3 million in expense included in loans sales and servicing income in the three months ended March 31, 2013.