Securities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 903,678	$ 920,897
Unrealized Gains	25,075	20,347
Unrealized Losses	(16,258)	(26,684)
Fair Value	912,495	914,560
U.S. Government agencies
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	1,529	1,623
Unrealized Gains	22	10
Unrealized Losses	0	0
Fair Value	1,551	1,633
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	178,473	191,995
Unrealized Gains	8,125	7,761
Unrealized Losses	(879)	(1,992)
Fair Value	185,719	197,764
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	22	4,642
Unrealized Gains	1	1
Unrealized Losses	0	(252)
Fair Value	23	4,391
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	519,491	521,148
Unrealized Gains	2,190	1,492
Unrealized Losses	(12,931)	(15,899)
Fair Value	508,750	506,741
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	193,608	190,521
Unrealized Gains	8,702	6,388
Unrealized Losses	(479)	(1,922)
Fair Value	201,831	194,987
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	10,555	10,968
Unrealized Gains	6,035	4,695
Unrealized Losses	(1,969)	(6,619)
Fair Value	$ 14,621	$ 9,044