Investments - Analysis of net realized gains (losses) and the change in unrealized (losses) gains on investments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net realized gains (losses):
OTTI on investments, net of amounts transferred to other comprehensive income	$ (35,700)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	107,462us-gaap_MarketableSecuritiesGainLoss	87,777us-gaap_MarketableSecuritiesGainLoss	14,098us-gaap_MarketableSecuritiesGainLoss
Net realized and unrealized (losses) on investment related derivative instruments	20,121	6,367	(1,228)
Net realized (losses) on investments and net realized and unrealized (losses) on investment related derivative instruments	127,583	94,144	12,870
Net change in unrealized gains (losses) on investments	970,715	(957,192)	1,196,430
Total net realized (losses) on investments, net realized and unrealized (losses) on investment related derivative instruments, and net change in unrealized gains (losses) on investments	1,098,298	(863,048)	1,209,300
Fixed maturities \| HTM
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	(272,540)	(175,817)	221,647
Equity securities
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	(32,577)	105,163	44,361
Affiliates and other investments
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	35,143	26,636	46,163
Exclude Life Funds Withheld Assets [Member]
Net realized gains (losses):
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	122,991	87,777	14,098
Exclude Life Funds Withheld Assets [Member] \| Fixed maturities, short term investments and cash equivalents
Net realized gains (losses):
Gross realized gains	119,817	129,479	163,328
Gross realized losses on investments sold	(66,892)	(84,703)	(107,033)
OTTI on investments, net of amounts transferred to other comprehensive income	(12,341)	(16,282)	(74,245)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	40,584	28,494	(17,950)
Exclude Life Funds Withheld Assets [Member] \| Fixed maturities \| AFS
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	360,463	(913,174)	884,259
Exclude Life Funds Withheld Assets [Member] \| Equity securities
Net realized gains (losses):
Gross realized gains	96,260	29,402	42,009
Gross realized losses on investments sold	(12,270)	(3,185)	(7,121)
OTTI on investments, net of amounts transferred to other comprehensive income	(10,944)	(17)	(3,746)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	73,046	26,200	31,142
Exclude Life Funds Withheld Assets [Member] \| Other investments
Net realized gains (losses):
Gross realized gains	31,830	46,934	11,610
Gross realized losses on investments sold	(10,011)	(13,851)	(7,983)
OTTI on investments, net of amounts transferred to other comprehensive income	(12,458)	0	(2,721)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	9,361	33,083	906
Life Funds Withheld Assets [Member]
Net realized gains (losses):
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(9)	0	0
Life Funds Withheld Assets [Member] \| Fixed maturities, short term investments and cash equivalents
Net realized gains (losses):
Gross realized gains	7,926	0	0
Gross realized losses on investments sold	(2,859)	0	0
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(9)	0	0
OTTI on investments, net of amounts transferred to other comprehensive income	(20,587)	0	0
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	(15,529)	0	0
Life Funds Withheld Assets [Member] \| Fixed maturities \| AFS
Net realized gains (losses):
Net change in unrealized gains (losses) on investments	$ 880,226	$ 0	$ 0

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities and excluding other than temporary impairments (OTTI), if any, recognized elsewhere.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

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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

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-Publisher FASB

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Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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The aggregate net change in the difference between the fair value and the carrying value, or in the comparative fair values, of marketable securities categorized as trading held at each balance sheet date, that was included in earnings for the period, which may have arisen from (a) securities classified as trading, (b) the unrealized holding gain (loss) on held-to-maturity securities transferred to the trading security category, and (c) the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) on available-for-sale securities transferred to trading securities during the period and/or any unrealized gains or losses on investments that are separately or otherwise not categorized as trading or available-for-sale.

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Net realized gains or losses on investments and realized and unrealized gains or losses on investment related derivative instruments.

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Net realized gains or losses on investments and realized and unrealized gains or losses on investment related derivative instruments.

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