Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Total temporarily impaired securities, Less than 12 Months, Fair Value	$ 436,327	$ 234,315
Total Temporarily Impaired Securities, Less than 12 Months, Unrealized Losses	(10,738)	(1,811)
Securities with unrealized losses,12 months or longer, Fair Value	62,858	13,939
Total Temporarily Impaired Securities, 12 months or longer, Unrealized Losses	(1,252)	(185)
Total Temporarily Impaired Securities, 12 months or longer, Fair Value	499,185	248,524
Total Temporarily Impaired Securities Continuous Unrealized Losses Position Unrealized Losses	(11,990)	(1,996)
Mortgage-backed securities of U.S Government Sponsored Entities [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Less than 12 Months, Fair Value	81,251	54,289
Less than 12 Months, Unrealized Losses	(3,472)	(469)
12 Months or Longer, Fair Value	15,736	0
12 Months or Longer, Unrealized Losses	(394)	0
Fair Value, Total	96,987	54,289
Aggregate Losses	(3,866)	(469)
Collateralized mortgage obligations of U.S. Government Sponsored Entities [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
12 Months or Longer, Fair Value	39,561	4,593
12 Months or Longer, Unrealized Losses	(714)	(93)
Securities with unrealized losses,12 months or longer, Fair Value	334,097	154,650
Securities with unrealized losses, Less than 12 months, Fair Value	294,536	150,057
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Losses	(7,005)	(994)
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Less than 12 Months Aggregate Losses	(6,291)	(901)
Private collateralized mortgage obligations [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Less than 12 Months, Fair Value	46,425	29,969
Less than 12 Months, Unrealized Losses	(931)	(441)
12 Months or Longer, Fair Value	7,436	9,221
12 Months or Longer, Unrealized Losses	(142)	(89)
Fair Value, Total	53,861	39,190
Aggregate Losses	(1,073)	(530)
Collateralized loan obligations [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Less than 12 Months, Fair Value	12,615
Less than 12 Months, Unrealized Losses	(23)
12 Months or Longer, Fair Value	0
12 Months or Longer, Unrealized Losses	0
Fair Value, Total	12,615
Aggregate Losses	(23)
Obligations of state and political subdivisions [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Less than 12 Months, Fair Value	1,015	0
Less than 12 Months, Unrealized Losses	(6)	0
12 Months or Longer, Fair Value	125	125
12 Months or Longer, Unrealized Losses	(2)	(3)
Fair Value, Total	1,140	125
Aggregate Losses	(8)	(3)
Other [Member]
Available for sale securities continuous unrealized loss position fair value and unrealized losses
Less than 12 Months, Fair Value	485
Less than 12 Months, Unrealized Losses	(15)
12 Months or Longer, Fair Value	0
12 Months or Longer, Unrealized Losses	0
Fair Value, Total	485
Aggregate Losses	$ (15)