Securities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	$ 681,174	$ 637,940
Gross Unrealized Gains, Securities Available for Sale	3,625	7,011
Gross Unrealized Losses, Securities Available for Sale	(11,990)	(1,901)
Fair Value, Securities Available for Sale	672,809	643,050
Gross Amortized Cost, Securities Held for Investment		13,818
Gross Unrealized Gains, Securities Held for Investment		819
Gross Unrealized Losses, Securities Held for Investment		(95)
Fair value, Securities Held for Investment		14,542
U.S. Treasury securities and obligations of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	101	1,700
Gross Unrealized Gains, Securities Available for Sale	0	7
Gross Unrealized Losses, Securities Available for Sale	0	0
Fair Value, Securities Available for Sale	101	1,707
Mortgage-backed securities of U.S Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	145,485	186,404
Gross Unrealized Gains, Securities Available for Sale	1,446	3,320
Gross Unrealized Losses, Securities Available for Sale	(3,866)	(469)
Fair Value, Securities Available for Sale	143,065	189,255
Collateralized mortgage obligations of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	406,894	352,731
Gross Unrealized Gains, Securities Available for Sale	1,084	2,430
Gross Unrealized Losses, Securities Available for Sale	(7,005)	(902)
Fair Value, Securities Available for Sale	400,973	354,259
Gross Amortized Cost, Securities Held for Investment		4,687
Gross Unrealized Gains, Securities Held for Investment		0
Gross Unrealized Losses, Securities Held for Investment		(92)
Fair value, Securities Held for Investment		4,595
Private collateralized mortgage obligations [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	87,571	96,258
Gross Unrealized Gains, Securities Available for Sale	692	1,203
Gross Unrealized Losses, Securities Available for Sale	(1,073)	(530)
Fair Value, Securities Available for Sale	87,190	96,931
Gross Amortized Cost, Securities Held for Investment		1,278
Gross Unrealized Gains, Securities Held for Investment		33
Gross Unrealized Losses, Securities Held for Investment		0
Fair value, Securities Held for Investment		1,311
Collateralized loan obligations [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	32,530
Gross Unrealized Gains, Securities Available for Sale	20
Gross Unrealized Losses, Securities Available for Sale	(23)
Fair Value, Securities Available for Sale	32,527
Obligations of state and political subdivisions [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	7,093	847
Gross Unrealized Gains, Securities Available for Sale	380	51
Gross Unrealized Losses, Securities Available for Sale	(8)	0
Fair Value, Securities Available for Sale	7,465	898
Gross Amortized Cost, Securities Held for Investment		6,353
Gross Unrealized Gains, Securities Held for Investment		737
Gross Unrealized Losses, Securities Held for Investment		(3)
Fair value, Securities Held for Investment		7,087
Other [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Securities Available for Sale	1,500
Gross Unrealized Gains, Securities Available for Sale	3
Gross Unrealized Losses, Securities Available for Sale	(15)
Fair Value, Securities Available for Sale	1,488
Gross Amortized Cost, Securities Held for Investment		1,500
Gross Unrealized Gains, Securities Held for Investment		49
Gross Unrealized Losses, Securities Held for Investment		0
Fair value, Securities Held for Investment		$ 1,549