Investments (Details 4) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Investment securities continuous unrealized loss position
Fair value of Investment with Unrealized Losses, Less Than 12 months	$ 64,420	$ 43,211
Gross Unrealized Loss, Less Than 12 Months	597	579
Fair Value of Investment with unrealized Losses, 12 Months or Greater	6,329	10,610
Gross Unrealized Losses, 12 Months or Greater	698	1,231
Fair Value of Investment with Unrealized Losses, Total	70,749	53,821
Gross Unrealized Losses, Total	1,295	1,810
Total held-to-maturity securities [Member]
Investment securities continuous unrealized loss position
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	30,889	25,899
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months	119	148
Held-to-Maturity, Fair Value of Investments with Unrealized Losses 12 Months or Greater	6,329	10,610
Held-to-Maturity, Gross Unrealized Losses, 12 Months or Greater	698	1,231
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	37,218	36,509
Held-to-Maturity, Gross Unrealized Losses, Total	817	1,379
Total held-to-maturity securities [Member] | Corporate bonds [Member]
Investment securities continuous unrealized loss position
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	12,755	23,063
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months	28	130
Held-to-Maturity, Fair Value of Investments with Unrealized Losses 12 Months or Greater	203
Held-to-Maturity, Gross Unrealized Losses, 12 Months or Greater
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	12,958	23,063
Held-to-Maturity, Gross Unrealized Losses, Total	28	130
Total held-to-maturity securities [Member] | States and political subdivision [Member]
Investment securities continuous unrealized loss position
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	13,982	2,291
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months	87	3
Held-to-Maturity, Fair Value of Investments with Unrealized Losses 12 Months or Greater	2,978	5,718
Held-to-Maturity, Gross Unrealized Losses, 12 Months or Greater	41	357
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	16,960	8,009
Held-to-Maturity, Gross Unrealized Losses, Total	128	360
Total held-to-maturity securities [Member] | U.S. Treasury securities and obligations of U.S. Government agencies [Member]
Investment securities continuous unrealized loss position
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	4,152
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months	4
Held-to-Maturity, Fair Value of Investments with Unrealized Losses 12 Months or Greater
Held-to-Maturity, Gross Unrealized Losses, 12 Months or Greater
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	4,152
Held-to-Maturity, Gross Unrealized Losses, Total	4
Total held-to-maturity securities [Member] | U.S. agency-based mortgage-backed securities [Member]
Investment securities continuous unrealized loss position
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months
Held-to-Maturity, Fair Value of Investments with Unrealized Losses 12 Months or Greater	218	1,012
Held-to-Maturity, Gross Unrealized Losses, 12 Months or Greater	10	44
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	218	1,012
Held-to-Maturity, Gross Unrealized Losses, Total	10	44
Total held-to-maturity securities [Member] | Asset-backed securities [Member]
Investment securities continuous unrealized loss position
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months		545
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months		15
Held-to-Maturity, Fair Value of Investments with Unrealized Losses 12 Months or Greater	2,930	3,880
Held-to-Maturity, Gross Unrealized Losses, 12 Months or Greater	647	830
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	2,930	4,425
Held-to-Maturity, Gross Unrealized Losses, Total	647	845
Total available-for-sale securities [Member]
Investment securities continuous unrealized loss position
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	33,531	17,312
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	478	431
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	33,531	17,312
Available-for Sale, Gross Unrealized Losses, Total	478	431
Fair Value of Investment with unrealized Losses, 12 Months or Greater
Gross Unrealized Losses, 12 Months or Greater
Total available-for-sale securities [Member] | Corporate bonds [Member]
Investment securities continuous unrealized loss position
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	21,648	14,301
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	76	233
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	21,648	14,301
Available-for Sale, Gross Unrealized Losses, Total	76	233
Fair Value of Investment with unrealized Losses, 12 Months or Greater
Gross Unrealized Losses, 12 Months or Greater
Total available-for-sale securities [Member] | States and political subdivision [Member]
Investment securities continuous unrealized loss position
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	6,453	222
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	28	1
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	6,453	222
Available-for Sale, Gross Unrealized Losses, Total	28	1
Fair Value of Investment with unrealized Losses, 12 Months or Greater
Gross Unrealized Losses, 12 Months or Greater
Total available-for-sale securities [Member] | U.S. agency-based mortgage-backed securities [Member]
Investment securities continuous unrealized loss position
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	991
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	14
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	991
Available-for Sale, Gross Unrealized Losses, Total	14
Gross Unrealized Losses, 12 Months or Greater
Total available-for-sale securities [Member] | Equity Securities [Member]
Investment securities continuous unrealized loss position
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	4,439	2,789
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	360	197
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	4,439	2,789
Available-for Sale, Gross Unrealized Losses, Total	360	197
Fair Value of Investment with unrealized Losses, 12 Months or Greater
Gross Unrealized Losses, 12 Months or Greater