Securities (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 835,536	$ 668,615
Unrealized Gains	21,885	30,619
Unrealized Losses	20,374	(8,234)
Fair Value	837,047	691,000
U.S. Government agencies
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	1,719	1,807
Unrealized Gains	36	79
Unrealized Losses	0	0
Fair Value	1,755	1,886
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	220,988	231,316
Unrealized Gains	8,589	13,373
Unrealized Losses	(1,887)	(13)
Fair Value	227,690	244,676
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	4,905	5,146
Unrealized Gains	1	1
Unrealized Losses	(268)	(16)
Fair Value	4,638	5,131
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	410,427	230,739
Unrealized Gains	1,728	2,827
Unrealized Losses	(9,158)	(246)
Fair Value	402,997	233,320
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	185,821	187,044
Unrealized Gains	7,257	12,518
Unrealized Losses	(1,757)	(77)
Fair Value	191,321	199,485
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	11,356	12,243
Unrealized Gains	4,124	1,761
Unrealized Losses	(7,304)	(7,882)
Fair Value	8,176	6,122
Equity Securities
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	320	320
Unrealized Gains	150	60
Unrealized Losses	0	0
Fair Value	$ 470	$ 380