Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

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The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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The fair value, as of the date of each statement of financial position presented, of other securities, classified as available for sale or held for investment, which are owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The number of investment positions held before consideration of those determined to be temporarily impaired.

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- Definition

Percentage of Fixed Income Investment portfolio at fair value invested in below investment grade or not rated as at the balance sheet date.

+ References

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Percentage of Gross Unrealized losses in Fixed income securities portfolio as at the balance sheet date related to securities that were below investment grade or not rated.

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Investments - Narrative (Details) $ in Thousands	3 Months Ended
Investments - Narrative (Details) $ in Thousands	Mar. 31, 2017 USD ($) positions	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Percentage of Fixed Income Investment portfolio invested in below investment grade or not rated	2.70%		2.50%
Percentage of Gross Unrealized losses in Fixed income securities portfolio related to securities below investment grade or not rated	4.40%		4.10%
Pledged Assets Separately Reported, Other Debt Securities Available-for-sale or Held-for-investment	$ 17,600,000		$ 17,100,000
Available for sale securities, Gross unrealized losses	$ 311,674		370,017
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions \| positions	2,848
Available-for-sale Securities, Qualitative Disclosure, Number of Positions \| positions	8,324
Excluding Life Funds Withheld Assets
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Gross unrealized losses	$ 311,674		$ 370,017
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	6,874	$ 19,580
Excluding Life Funds Withheld Assets \| Structured securities
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	100	900
Excluding Life Funds Withheld Assets \| Other investments
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	5,000	0
Excluding Life Funds Withheld Assets \| Foreign exchange losses
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	1,700	1,900
No Longer Intend To Hold For A Period Sufficient To Recover Fair Value To Cost [Member] \| Excluding Life Funds Withheld Assets
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	100	9,800
In A Loss Position For More Than 11 Months Or Greater Than Fifty Percent Of Amortized Cost [Member] \| Excluding Life Funds Withheld Assets
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	$ 0	$ 7,000