Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair value measurement
Securities available-for-sale	$ 872,675	$ 691,000
U.S. Government agencies
Fair value measurement
Securities available-for-sale	1,631	1,886
Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	210,227	244,676
Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	4,523	5,131
Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	456,112	233,320
State and Municipal Obligations
Fair value measurement
Securities available-for-sale	191,996	199,485
Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	7,524	6,122
Equity Securities
Fair value measurement
Securities available-for-sale	662	380
Level 1
Fair value measurement
Securities available-for-sale	662	380
Level 1 | U.S. Government agencies
Fair value measurement
Securities available-for-sale	0	0
Level 1 | Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	0	0
Level 1 | Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	0	0
Level 1 | Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	0	0
Level 1 | State and Municipal Obligations
Fair value measurement
Securities available-for-sale	0	0
Level 1 | Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	0	0
Level 1 | Equity Securities
Fair value measurement
Securities available-for-sale	662	380
Level 2
Fair value measurement
Securities available-for-sale	859,965	674,587
Derivative Assets	1,381	2,053
Derivative Liability	(1,381)	(2,053)
Level 2 | U.S. Government agencies
Fair value measurement
Securities available-for-sale	1,631	1,886
Level 2 | Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	210,227	244,676
Level 2 | Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	4,523	5,131
Level 2 | Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	456,112	233,320
Level 2 | State and Municipal Obligations
Fair value measurement
Securities available-for-sale	187,472	189,574
Level 2 | Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	0	0
Level 2 | Equity Securities
Fair value measurement
Securities available-for-sale	0	0
Level 3
Fair value measurement
Securities available-for-sale	12,048	16,033
Level 3 | U.S. Government agencies
Fair value measurement
Securities available-for-sale	0	0
Level 3 | Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	0	0
Level 3 | Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	0	0
Level 3 | Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	0	0
Level 3 | State and Municipal Obligations
Fair value measurement
Securities available-for-sale	4,524	9,911
Level 3 | Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	7,524	6,122
Level 3 | Equity Securities
Fair value measurement
Securities available-for-sale	$ 0	$ 0