v2.4.0.8

Investments - Credit Ratings (Details) (USD $) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2014 | Mar. 31, 2013 | Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
OTTI | $ 0 |  | $ 0 |  |
Amortized cost | 3,096,675,000 |  |  | 3,127,792,000 |
Fair value | 3,168,819,000 |  |  | 3,162,067,000 |
% of Total fair value | 100.00% |  |  | 100.00% |
U.S. treasury bonds [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 16,616,000 | [1] |  | 16,622,000 | [1]
Fair value | 17,135,000 | [1] |  | 17,209,000 | [1]
% of Total fair value | 0.50% | [1] |  | 0.50% | [1]
U.S. agency bonds [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 1,264,253,000 | [1] |  | 1,299,239,000 | [1]
Fair value | 1,243,666,000 | [1] |  | 1,270,763,000 | [1]
% of Total fair value | 39.20% | [1] |  | 40.20% | [1]
AAA [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 216,123,000 | [1] |  | 210,872,000 | [1]
Fair value | 231,871,000 | [1] |  | 222,417,000 | [1]
% of Total fair value | 7.30% | [1] |  | 7.00% | [1]
AA Plus, AA, AA Minus [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 138,743,000 | [1] |  | 236,424,000 | [1]
Fair value | 147,363,000 | [1] |  | 242,986,000 | [1]
% of Total fair value | 4.70% | [1] |  | 7.70% | [1]
A Plus, A, A Minus [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 688,926,000 | [1] |  | 619,148,000 | [1]
Fair value | 729,160,000 | [1] |  | 651,248,000 | [1]
% of Total fair value | 23.00% | [1] |  | 20.60% | [1]
BBB Plus, BBB, BBB Minus [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 716,179,000 | [1] |  | 689,532,000 | [1]
Fair value | 742,241,000 | [1] |  | 701,529,000 | [1]
% of Total fair value | 23.50% | [1] |  | 22.20% | [1]
BB Plus or Lower [Member] |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized cost | 55,835,000 | [1] |  | 55,955,000 | [1]
Fair value | $ 57,383,000 | [1] |  | $ 55,915,000 | [1]
% of Total fair value | 1.80% | [1] |  | 1.80% | [1]
[1] | Ratings as assigned by Standard & Poor’s ("S&P")

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- Definition This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition Amount of debt securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -Subparagraph (b)-(g) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803 + Details
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- Definition The change during the reporting period in the cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27340-111563 + Details
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