Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 874,954	$ 668,615
Unrealized Gains	21,345	30,619
Unrealized Losses	(23,624)	(8,234)
Fair Value	872,675	691,000
U.S. Government agencies
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	1,625	1,807
Unrealized Gains	6	79
Unrealized Losses	0	0
Fair Value	1,631	1,886
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	203,624	231,316
Unrealized Gains	8,386	13,373
Unrealized Losses	(1,783)	(13)
Fair Value	210,227	244,676
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	4,768	5,146
Unrealized Gains	1	1
Unrealized Losses	(246)	(16)
Fair Value	4,523	5,131
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	466,978	230,739
Unrealized Gains	1,918	2,827
Unrealized Losses	(12,784)	(246)
Fair Value	456,112	233,320
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	186,632	187,044
Unrealized Gains	7,011	12,518
Unrealized Losses	(1,647)	(77)
Fair Value	191,996	199,485
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	11,007	12,243
Unrealized Gains	3,681	1,761
Unrealized Losses	(7,164)	(7,882)
Fair Value	7,524	6,122
Equity Securities
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	320	320
Unrealized Gains	342	60
Unrealized Losses	0	0
Fair Value	$ 662	$ 380