Investment with an Unrealized Loss Position (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale, Fair Value
Less than 12 Months	$ 404,596	$ 358,126
12 Months or More	149,357	202,027
Total	553,953	560,153
Available-for-sale, Unrealized Loss
Less than 12 Months	(3,717)	(2,746)
12 Months or More	(3,954)	(5,061)
Total	(7,671)	(7,807)
Held-to-maturity, Fair Value
Less than 12 Months	65,748	18,643
12 Months or More	66,621	76,761
Total	132,369	95,404
Held-to-maturity, Unrealized Loss
Less than 12 Months	(1,379)	(624)
12 Months or More	(2,503)	(2,352)
Total	(3,882)	(2,976)
U.S. government and federal agency
Available-for-sale, Fair Value
Less than 12 Months	34,013	0
12 Months or More	3	3
Total	34,016	3
Available-for-sale, Unrealized Loss
Less than 12 Months	(279)	0
12 Months or More	0	0
Total	(279)	0
U.S. government sponsored enterprises
Available-for-sale, Fair Value
Less than 12 Months	26,722	13,793
12 Months or More	0	0
Total	26,722	13,793
Available-for-sale, Unrealized Loss
Less than 12 Months	(44)	(2)
12 Months or More	0	0
Total	(44)	(2)
State and local governments
Available-for-sale, Fair Value
Less than 12 Months	143,300	91,082
12 Months or More	95,229	115,927
Total	238,529	207,009
Available-for-sale, Unrealized Loss
Less than 12 Months	(2,157)	(1,273)
12 Months or More	(2,963)	(3,296)
Total	(5,120)	(4,569)
Held-to-maturity, Fair Value
Less than 12 Months	65,748	18,643
12 Months or More	66,621	76,761
Total	132,369	95,404
Held-to-maturity, Unrealized Loss
Less than 12 Months	(1,379)	(624)
12 Months or More	(2,503)	(2,352)
Total	(3,882)	(2,976)
Corporate bonds
Available-for-sale, Fair Value
Less than 12 Months	79,816	60,289
12 Months or More	7,087	7,874
Total	86,903	68,163
Available-for-sale, Unrealized Loss
Less than 12 Months	(503)	(545)
12 Months or More	(65)	(205)
Total	(568)	(750)
Residential mortgage-backed securities
Available-for-sale, Fair Value
Less than 12 Months	120,745	192,962
12 Months or More	47,038	78,223
Total	167,783	271,185
Available-for-sale, Unrealized Loss
Less than 12 Months	(734)	(926)
12 Months or More	(926)	(1,560)
Total	$ (1,660)	$ (2,486)

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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