v2.4.0.8
Investments - Fair Value and Unrealized Losses (Details) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2013
securities
Dec. 31, 2012
securities
Fair value    
Less than 12 months, Fair Value $ 1,011,713 $ 253,333
12 Months or More, Fair value 135,523 143,853
Total, Fair value 1,147,236 397,186
Unrealized losses    
Less than 12 months, Unrealized losses (41,631) (2,571)
12 Months or More, Unrealized losses (3,455) (5,445)
Total, Unrealized losses (45,086) (8,016)
Number of securities in loss position (in securities) 118 32
12 Months or More, number of securities (in securities) 9 9
U.S. agency bonds – mortgage-backed [Member]
    
Fair value    
Less than 12 Months, Fair value 627,532 158,591
12 Months or More, Fair value 9,104 0
Total, Fair value 636,636 158,591
Unrealized losses    
Less than 12 Months, Unrealized losses (19,210) (1,473)
12 Months or More, Unrealized losses (246) 0
Total, Unrealized losses (19,456) (1,473)
Non-U.S. government bonds [Member]
    
Fair value    
Less than 12 Months, Fair value 27,630  
12 Months or More, Fair value 0  
Total, Fair value 27,630  
Unrealized losses    
Less than 12 Months, Unrealized losses (918)  
12 Months or More, Unrealized losses 0  
Total, Unrealized losses (918)  
Corporate bonds [Member]
    
Fair value    
Less than 12 Months, Fair value 343,524 94,742
12 Months or More, Fair value 123,920 141,842
Total, Fair value 467,444 236,584
Unrealized losses    
Less than 12 Months, Unrealized losses (21,309) (1,098)
12 Months or More, Unrealized losses (3,196) (5,394)
Total, Unrealized losses (24,505) (6,492)
Other mortgage-backed bonds [Member]
    
Fair value    
Less than 12 Months, Fair value 13,027  
12 Months or More, Fair value 0  
Total, Fair value 13,027  
Unrealized losses    
Less than 12 Months, Unrealized losses (194)  
12 Months or More, Unrealized losses 0  
Total, Unrealized losses (194)  
Available-for-sale securities [Member]
    
Fair value    
Less than 12 Months, Fair value 1,011,713 253,333
12 Months or More, Fair value 133,024 141,842
Total, Fair value 1,144,737 395,175
Unrealized losses    
Less than 12 Months, Unrealized losses (41,631) (2,571)
12 Months or More, Unrealized losses (3,442) (5,394)
Total, Unrealized losses (45,073) (7,965)
Other investments [Member]
    
Fair value    
Less than 12 months, Fair Value 0 0
12 Months or More, Fair value 2,499 2,011
Total, Fair value 2,499 2,011
Unrealized losses    
Less than 12 months, Unrealized losses 0 0
12 Months or More, Unrealized losses (13) (51)
Total, Unrealized losses $ (13) $ (51)