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Fair Value Measurements - Quantitative Information About Level 3 Fair Value Measurements (Detail) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2013
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Dec. 31, 2012
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Mar. 31, 2013
Debt securities
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Dec. 31, 2012
Debt securities
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Mar. 31, 2013
Level 3
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Dec. 31, 2012
Level 3
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Mar. 31, 2013
Level 3
Debt securities
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Mar. 31, 2013
Level 3
Minimum
Debt securities
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Mar. 31, 2013
Level 3
Maximum
Debt securities
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| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||||||||
| Fair Value of Fixed maturity securities | $ 2,789,733 | $ 2,808,202 | $ 2,764,263 | $ 2,788,141 | $ 44,273 | $ 47,388 | $ 44,273 | ||
| Fair Value of Fixed maturity securities on Valuation Technique | Market comparable | ||||||||
| Fair Value Measurements Unobservable Inputs | Spread adjustment | ||||||||
| Fair value inputs spread adjustment, range | 0.0069 | 0.0313 | |||||||
| Fair value input spread adjustment, weighted average | 0.0168 | ||||||||