Securities (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Proceeds from sales of securities and the resulting gains and losses
Proceeds	$ 23,414	$ 375	$ 26,944	$ 2,280
Gross gains	279	32	310	59
Gross losses	(272)		(272)
Available-for-sale, Amortized Cost
Due after one through five years	2,032		2,032
Due after five through ten years	47,057		47,057
Due after ten years	20,809		20,809
Agency mortgage-backed securities	224,760		224,760
Total	294,658		294,658
Available-for-sale, Estimated Fair Value
Due after one through five years	2,115		2,115
Due after five through ten years	45,531		45,531
Due after ten years	20,735		20,735
Agency mortgage-backed securities	225,397		225,397
Estimated Fair Value	293,778		293,778		367,912
Held-to-maturity, Amortized Cost
Due after five through ten years	1,093		1,093
Due after ten years	66,427		66,427
Agency mortgage-backed securities	14,211		14,211
Total	81,731		81,731
Held-to-maturity, Estimated Fair Value
Due after five through ten years	1,011		1,011
Due after ten years	57,988		57,988
Agency mortgage-backed securities	13,773		13,773
Total	$ 72,772		$ 72,772