Investments Schedule of Available-for-sale and Held-to-Maturity Securities (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 681,070		$ 694,832
Available-for-sale Securities, Gross Unrealized Gains	6,623		4,535
Available-for-sale Securities, Gross Unrealized Losses	(4,103)		(7,638)
Available-for-sale securities at fair value	683,590		691,729
Held-to-maturity Securities	138,380		112,014
Held-to-maturity Securities, Unrecognized Holding Gain	1,299		15
Held-to-maturity Securities, Unrecognized Holding Loss	0		(1,112)
Held-to-maturity Securities, Fair Value	139,679		110,917
US Government and Government Agencies and Authorities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	12,139		2,300
Available-for-sale Securities, Gross Unrealized Gains	9		15
Available-for-sale Securities, Gross Unrealized Losses	(69)		(27)
Available-for-sale securities at fair value	12,079		2,288
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	239,406		228,670
Available-for-sale Securities, Gross Unrealized Gains	1,030		301
Available-for-sale Securities, Gross Unrealized Losses	(208)		(1,031)
Available-for-sale securities at fair value	240,228		227,940
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	218,027		218,900
Available-for-sale Securities, Gross Unrealized Gains	2,850		1,431
Available-for-sale Securities, Gross Unrealized Losses	(516)		(1,898)
Available-for-sale securities at fair value	220,361		218,433
Mortgage Backed Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	194,008	[1]	229,609	[1]
Available-for-sale Securities, Gross Unrealized Gains	2,427	[1]	2,513	[1]
Available-for-sale Securities, Gross Unrealized Losses	(3,303)	[1]	(4,678)	[1]
Available-for-sale securities at fair value	193,132	[1]	227,444	[1]
Held-to-maturity Securities	138,380	[1]	112,014	[1]
Held-to-maturity Securities, Unrecognized Holding Gain	1,299	[1]	15	[1]
Held-to-maturity Securities, Unrecognized Holding Loss	0	[1]	(1,112)	[1]
Held-to-maturity Securities, Fair Value	139,679	[1]	110,917	[1]
Other Aggregated Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	17,490		15,353
Available-for-sale Securities, Gross Unrealized Gains	307		275
Available-for-sale Securities, Gross Unrealized Losses	(7)		(4)
Available-for-sale securities at fair value	$ 17,790		$ 15,624

[1] All mortgage-backed securities are guaranteed by U.S. government agencies or government-sponsored entities.