Derivative Financial Instruments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 15, 2013	Dec. 31, 2012
Derivative [Line Items]
Securities pledged as collateral	$ 248,844		$ 207,088
Interest rate swap
Derivative [Line Items]
Fixed payment rate	3.795%
Derivative, Description of Variable Rate Basis	three month LIBOR
Basis spread on floating rate	1.33%
Cash pledged as collateral	1,974		1,973
Net settlement payment		157
Estimated interest expense to be recognized during remainder of 2012	501
Estimated interest expense to be recognized over the next 12 months	665
Interest rate swap | U.S Government sponsored entities
Derivative [Line Items]
Securities pledged as collateral	$ 1,518		$ 1,520