XML 15 R25.htm IDEA: XBRL DOCUMENT v2.4.0.8
Investments - Gross Unrealized Gains and Losses and Amortized Cost and Fair Value of Investments Classified as Held-to-Maturity (Detail) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2014
Dec. 31, 2013
Investment [Line Items]    
Held-to-Maturity, Amortized Cost $ 599,087 $ 536,583
Held-to-Maturity, Gross Unrealized Gains 27,020 25,934
Held-to-Maturity, Gross Unrealized Losses (324) (1,338)
Held-to-Maturity, Fair Value 625,783 561,179
States and Political Subdivisions [Member]
    
Investment [Line Items]    
Held-to-Maturity, Amortized Cost 374,869 381,674
Held-to-Maturity, Gross Unrealized Gains 21,092 18,634
Held-to-Maturity, Gross Unrealized Losses (34) (1,153)
Held-to-Maturity, Fair Value 395,927 399,155
Corporate Bonds [Member]
    
Investment [Line Items]    
Held-to-Maturity, Amortized Cost 144,898 67,423
Held-to-Maturity, Gross Unrealized Gains 579 861
Held-to-Maturity, Gross Unrealized Losses (204) (41)
Held-to-Maturity, Fair Value 145,273 68,243
Commercial Mortgage-Backed Securities [Member]
    
Investment [Line Items]    
Held-to-Maturity, Amortized Cost 47,657 50,813
Held-to-Maturity, Gross Unrealized Gains 2,371 3,431
Held-to-Maturity, Fair Value 50,028 54,244
U.S. Agency-Based Mortgage-Backed Securities [Member]
    
Investment [Line Items]    
Held-to-Maturity, Amortized Cost 18,012 21,775
Held-to-Maturity, Gross Unrealized Gains 1,735 1,790
Held-to-Maturity, Fair Value 19,747 23,565
U.S. Treasury securities and obligations of U.S. Government agencies [Member]
    
Investment [Line Items]    
Held-to-Maturity, Amortized Cost 10,703 11,514
Held-to-Maturity, Gross Unrealized Gains 1,016 1,002
Held-to-Maturity, Gross Unrealized Losses (1)  
Held-to-Maturity, Fair Value 11,718 12,516
Asset-Backed Securities [Member]
    
Investment [Line Items]    
Held-to-Maturity, Amortized Cost 2,948 3,384
Held-to-Maturity, Gross Unrealized Gains 227 216
Held-to-Maturity, Gross Unrealized Losses (85) (144)
Held-to-Maturity, Fair Value $ 3,090 $ 3,456