Investment Securities (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012 securities	Dec. 31, 2011 securities	Sep. 30, 2011 securities
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	$ 124,987	$ 148,345	$ 52,717
Unrealized Losses, Less than 12 months	(400)	(506)	(167)
Number of Impaired Securities, Less than 12 months	16	26	22
Fair Value, 12 months or longer	49,090	44,385	47,009
Unrealized Losses, 12 months or longer	(14,038)	(17,256)	(15,312)
Number of Impaired Securities, 12 months or longer	11	10	11
Fair Value, Total	174,077	192,730	99,726
Unrealized Losses, Total	(14,438)	(17,762)	(15,479)
US Government Agencies Debt Securities [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	0		15,032
Unrealized Losses, Less than 12 months	0		20
Number of Impaired Securities, Less than 12 months	0		1
Fair Value, 12 months or longer	0		0
Unrealized Losses, 12 months or longer	0		0
Number of Impaired Securities, 12 months or longer	0		0
Fair Value, Total	0		15,032
Unrealized Losses, Total	0		20
US States and Political Subdivisions Debt Securities [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	3,560	5,249	16,180
Unrealized Losses, Less than 12 months	21	50	102
Number of Impaired Securities, Less than 12 months	8	0	18
Fair Value, 12 months or longer	0	0	648
Unrealized Losses, 12 months or longer	0	0	23
Number of Impaired Securities, 12 months or longer	0	0	1
Fair Value, Total	3,560	5,249	16,828
Unrealized Losses, Total	21	50	125
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	0	40,020	0
Unrealized Losses, Less than 12 months	0	129	0
Number of Impaired Securities, Less than 12 months	0	0	0
Fair Value, 12 months or longer	14	149	174
Unrealized Losses, 12 months or longer	0	2	2
Number of Impaired Securities, 12 months or longer	1	0	2
Fair Value, Total	14	40,169	174
Unrealized Losses, Total	0	131	2
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	0
Unrealized Losses, Less than 12 months	0
Number of Impaired Securities, Less than 12 months	0
Fair Value, 12 months or longer	0
Unrealized Losses, 12 months or longer	0
Number of Impaired Securities, 12 months or longer	0
Fair Value, Total	0
Unrealized Losses, Total	0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	121,427	48,003	21,505
Unrealized Losses, Less than 12 months	379	55	45
Number of Impaired Securities, Less than 12 months	8	0	3
Fair Value, 12 months or longer	1,581	0	0
Unrealized Losses, 12 months or longer	4	0	0
Number of Impaired Securities, 12 months or longer	1	0	0
Fair Value, Total	123,008	48,003	21,505
Unrealized Losses, Total	383	55	45
Non-agency [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	0	0
Unrealized Losses, Less than 12 months	0	0
Number of Impaired Securities, Less than 12 months	0	0
Fair Value, 12 months or longer	2	2
Unrealized Losses, 12 months or longer	0	0
Number of Impaired Securities, 12 months or longer	1	0
Fair Value, Total	2	2
Unrealized Losses, Total	0	0
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	0	30,227
Unrealized Losses, Less than 12 months	0	145
Number of Impaired Securities, Less than 12 months	0	0
Fair Value, 12 months or longer	0	0
Unrealized Losses, 12 months or longer	0	0
Number of Impaired Securities, 12 months or longer	0	0
Fair Value, Total	0	30,227
Unrealized Losses, Total	0	145
Corporate Debt Securities [Member]
Gross unrealized losses and fair value of securities
Fair Value, Less than 12 months	0	24,846	0
Unrealized Losses, Less than 12 months	0	127	0
Number of Impaired Securities, Less than 12 months	0	0	0
Fair Value, 12 months or longer	47,493	44,234	46,187
Unrealized Losses, 12 months or longer	14,034	17,254	15,287
Number of Impaired Securities, 12 months or longer	0	0	8
Fair Value, Total	47,493	69,080	46,187
Unrealized Losses, Total	$ 14,034	$ 17,381	$ 15,287