Annual report pursuant to Section 13 and 15(d)

Schedule of Unrealized Loss on Investments (Details)

v2.4.0.6
Schedule of Unrealized Loss on Investments (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Available-for-Sale Securities, Number of Positions 1,493 854
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Number of Positions 250 264
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Positions 47 20
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value $ 2,548,995 $ 1,277,120
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses (18,610) (175,348)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 52,689 15,608
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses (9,628) (4,113)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value 2,601,684 1,292,728
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses $ (28,238) $ (179,461)