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Investment Securities (Details 3) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2014 | Dec. 31, 2013
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Available for sale: |  |
Fair value, less than 12 months | $ 1,078,371 | $ 2,534,354
Unrealized losses, less than 12 months | (24,016) | (101,585)
Fair value, 12 months or more | 1,774,278 | 434,554
Unrealized losses, 12 months or more | (78,912) | (31,534)
Fair value, total | 2,852,649 | 2,968,908
Unrealized losses, total | (102,928) | (133,119)
Residential mortgage-backed securities |  |
Available for sale: |  |
Fair value, less than 12 months | 1,028,459 | 2,459,565
Unrealized losses, less than 12 months | (22,666) | (98,022)
Fair value, 12 months or more | 1,747,859 | 420,262
Unrealized losses, 12 months or more | (73,131) | (26,552)
Fair value, total | 2,776,318 | 2,879,827
Unrealized losses, total | (95,797) | (124,574)
Obligations of states and political subdivisions |  |
Available for sale: |  |
Fair value, less than 12 months | 35,096 | 55,327
Unrealized losses, less than 12 months | (1,166) | (3,025)
Fair value, 12 months or more | 22,377 | 14,292
Unrealized losses, 12 months or more | (5,574) | (4,982)
Fair value, total | 57,473 | 69,619
Unrealized losses, total | (6,740) | (8,007)
Equity Securities |  |
Available for sale: |  |
Fair value, less than 12 months | 14,816 | 19,462
Unrealized losses, less than 12 months | (184) | (538)
Fair value, 12 months or more | 4,042 |
Unrealized losses, 12 months or more | (207) |
Fair value, total | 18,858 | 19,462
Unrealized losses, total | $ (391) | $ (538)

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- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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