Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Total temporarily impaired securities, Less than 12 Months Fair Value	$ 187,737	$ 111,328
Total Temporarily Impaired Securities, 12 months or longer, Fair Value	221,954	138,610
Total Temporarily Impaired Securities Continuous Unrealized Losses Position Less than 12 Months Unrealized Losses	1,550	2,490
Total Temporarily Impaired Securities Continuous Unrealized Losses Position Twelve Months or Longer Unrealized Losses	691	1,486
Total Temporarily Impaired Securities Continuous Unrealized Losses Position Unrealized Losses	(2,241)	(3,976)
Twelve Months or Longer, Fair Value		0
12 Months or Longer, Aggregate Losses		0
Securities with unrealized losses,12 months or longer, Fair Value	34,217	27,282
Mortgage-backed securities of U.S Government Sponsored Entities [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Twelve Months or Longer, Fair Value	0
12 Months or Longer, Aggregate Losses	0
Less than Twelve Months, Fair Value	45,484	18,800
Less than 12 Months, Aggregate Losses	(343)	(37)
Aggregate Losses	(343)	(37)
Fair Value, Total	45,484	18,800
Collateralized mortgage obligations of U.S. Government Sponsored Entities [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Securities with unrealized losses,12 months or longer, Fair Value	132,055	59,913
Twelve Months or Longer, Fair Value	0
12 Months or Longer, Aggregate Losses	0
Less than Twelve Months, Fair Value	132,055
Securities with unrealized losses, Less than 12 months, Fair Value		59,913
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Losses	(1,038)	(452)
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Less than 12 Months Aggregate Losses	1,038	452
Private collateralized mortgage obligations [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Total Temporarily Impaired Securities Continuous Unrealized Losses Position Unrealized Losses	(2,200)
Twelve Months or Longer, Fair Value	34,217	27,282
12 Months or Longer, Aggregate Losses	(691)	(1,486)
Less than Twelve Months, Fair Value	9,768	32,615
Less than 12 Months, Aggregate Losses	(166)	(2,001)
Aggregate Losses	(857)	(3,487)
Fair Value, Total	43,985	59,897
Obligations of state and political subdivisions [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Twelve Months or Longer, Fair Value	0
12 Months or Longer, Aggregate Losses	0
Less than Twelve Months, Fair Value	430
Less than 12 Months, Aggregate Losses	(3)
Aggregate Losses	(3)
Fair Value, Total	$ 430