Goodwill, Core Deposit Premium and Other Intangible Assets (Carrying amount of intangible assets (incl accumulated amortization) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 55,380	$ 54,406
Accumulated Amortization	22,690	21,447
Net Carrying Amount	32,690	32,959
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,069	21,069
Accumulated Amortization	10,959	10,345
Net Carrying Amount	10,110	10,724
Mortgage Servicing Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	33,134	32,160
Accumulated Amortization	10,990	10,372
Net Carrying Amount	22,144	21,788
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,177	1,177
Accumulated Amortization	741	730
Net Carrying Amount	$ 436	$ 447