Investments - Analysis of net realized gains (losses) and the change in unrealized (losses) gains on investments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Realized investment gains (losses):
OTTI on investments, net of amounts transferred to other comprehensive income	$ (78,600)	$ (83,000)	$ (35,700)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading	372,138	202,178	107,462
Net realized and unrealized (losses) on investment related derivative instruments	2,521	(8,616)	20,121
Net realized (losses) on investments and net realized and unrealized (losses) on investment related derivative instruments	374,659	193,562	127,583
Net change in unrealized gains (losses) on investments	(137,692)	(956,986)	970,715
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	236,967	(763,424)	1,098,298
Fixed maturities \| HTM
Realized investment gains (losses):
Net change in unrealized gains (losses) on investments	0	0	(272,540)
Equity securities
Realized investment gains (losses):
Net change in unrealized gains (losses) on investments	(4,119)	(59,619)	(32,577)
Affiliates and other investments
Realized investment gains (losses):
Net change in unrealized gains (losses) on investments	(63,096)	(6,072)	35,143
Exclude Life Funds Withheld Assets
Realized investment gains (losses):
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading	112,689	19,997	122,991
Exclude Life Funds Withheld Assets \| Fixed maturities, short term investments and cash equivalents
Realized investment gains (losses):
Gross realized gains	192,119	187,523	119,817
Gross realized losses on investments sold	(151,013)	(134,441)	(66,892)
OTTI on investments, net of amounts transferred to other comprehensive income	(48,432)	(54,346)	(12,341)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading	(7,326)	(1,264)	40,584
Exclude Life Funds Withheld Assets \| Fixed maturities \| AFS
Realized investment gains (losses):
Net change in unrealized gains (losses) on investments	(84,721)	(486,140)	360,463
Exclude Life Funds Withheld Assets \| Equity securities
Realized investment gains (losses):
Gross realized gains	140,864	79,556	96,260
Gross realized losses on investments sold	(11,882)	(49,223)	(12,270)
OTTI on investments, net of amounts transferred to other comprehensive income	(30,126)	(15,954)	(10,944)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading	98,856	14,379	73,046
Exclude Life Funds Withheld Assets \| Other investments
Realized investment gains (losses):
Gross realized gains	37,596	39,198	31,830
Gross realized losses on investments sold	(16,437)	(19,656)	(10,011)
OTTI on investments, net of amounts transferred to other comprehensive income	0	(12,660)	(12,458)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading	21,159	6,882	9,361
Life Funds Withheld Assets
Realized investment gains (losses):
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	109,458	(27,734)	(9)
Life Funds Withheld Assets \| Fixed maturities, short term investments and cash equivalents
Realized investment gains (losses):
Gross realized gains	185,487	259,798	7,926
Gross realized losses on investments sold	(32,898)	(36,526)	(2,859)
Net unrealized gains (losses) on investments, Trading - Life Funds Withheld Assets	109,458	(27,734)	(9)
OTTI on investments, net of amounts transferred to other comprehensive income	(2,598)	(13,357)	(20,587)
Total net realized gains (losses) on investments, and net unrealized gains (losses) on investments, Trading	259,449	182,181	(15,529)
Life Funds Withheld Assets \| Fixed maturities \| AFS
Realized investment gains (losses):
Net change in unrealized gains (losses) on investments	$ 14,244	$ (405,155)	$ 880,226

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

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Amount of loss realized on the sale of debt or equity securities classified as available-for-sale. Excludes other than temporary impairments (OTTI).

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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
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(c)-(e)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(c))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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-Publisher FASB
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-Topic 320
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-Section 50
-Paragraph 10
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-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27405-111563

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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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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
-Glossary Trading Securities
-URI http://asc.fasb.org/extlink&oid=6526789

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(c))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
-Paragraph 9
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

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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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No definition available.

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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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No definition available.

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This item represents the total net realized losses on investments, net realized losses on investment related derivative instruments and the net change in unrealized gains (losses) on investments.

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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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