Fair Value Measurements - Schedule of assets and liabilities that were accounted for at fair value (Details) - USD ($) $ in Thousands		Dec. 31, 2015		Dec. 31, 2014
ASSETS
Fixed maturities, AFS, at fair value		$ 32,257,589		$ 29,359,034
Equity securities, AFS, at fair value		878,919		868,292
Short-term investments, at fair value		617,390		256,727
Total investments available for sale		33,753,898		30,484,053
Fixed maturities, trading, at fair value		1,235,699		1,171
Short-term investments, at fair value		60,330		0
Trading Securities		1,296,029		1,171
Collateral and counterparty netting, asset	[1]	(3,087)		(696)
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)		914,629		1,155,016
Collateral and counterparty netting, liability	[1]	(3,087)		(696)
Recurring
ASSETS
Total investments available for sale		33,753,898		30,484,053
Cash equivalents	[2]	1,268,666		1,501,832
Other investments		1,291,726	[3]	894,057
Other assets	[1]	86,227		135,963
Total assets accounted for at fair value		37,797,820		33,150,274
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	463,915		450,831
Financial instruments sold, but not yet purchased	[5]	347		30,406
Other liabilities	[1]	42,408		30,488
Total liabilities accounted for at fair value		506,670		511,725
Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Total investments available for sale		528,581		502,284
Cash equivalents	[2]	437,742		1,103,877
Other investments		0	[3]	0
Other assets	[1]	0		0
Total assets accounted for at fair value		966,840		1,606,621
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	0		0
Financial instruments sold, but not yet purchased	[5]	347		4,737
Other liabilities	[1]	0		0
Total liabilities accounted for at fair value		347		4,737
Recurring | Significant other observable inputs (Level 2)
ASSETS
Total investments available for sale		33,073,039		29,280,719
Cash equivalents	[2]	830,924		397,955
Other investments		1,008,176	[3]	708,974
Other assets	[1]	69,914		122,996
Total assets accounted for at fair value		36,378,839		30,644,553
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	463,915		450,831
Financial instruments sold, but not yet purchased	[5]	0		25,669
Other liabilities	[1]	16,304		7,757
Total liabilities accounted for at fair value		480,219		484,257
Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Total investments available for sale		152,278		701,050
Cash equivalents	[2]	0		0
Other investments		283,550	[3]	185,083
Other assets	[1]	19,400		13,663
Total assets accounted for at fair value		455,228		899,796
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2015, $3,719,131; 2014, $4,265,678)	[4]	0		0
Financial instruments sold, but not yet purchased	[5]	0		0
Other liabilities	[1]	29,191		23,427
Total liabilities accounted for at fair value		29,191		23,427
Exclude Life Funds Withheld Assets [Member]
ASSETS
Fixed maturities, AFS, at fair value		29,104,486		24,177,469
Equity securities, AFS, at fair value		878,919		868,292
Short-term investments, at fair value		617,390		256,727
Total investments available for sale		30,600,795		25,302,488
Exclude Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,065,637		2,171,953
Exclude Life Funds Withheld Assets [Member] | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,757,971		3,728,576
Exclude Life Funds Withheld Assets [Member] | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		328,540		427,351
Exclude Life Funds Withheld Assets [Member] | CMBS
ASSETS
Fixed maturities, AFS, at fair value		405,316		1,052,544
Exclude Life Funds Withheld Assets [Member] | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		32,410		692,034
Exclude Life Funds Withheld Assets [Member] | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,168,572		1,065,293
Exclude Life Funds Withheld Assets [Member] | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		2,632,070		2,021,272
Exclude Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,251,614		4,240,073
Exclude Life Funds Withheld Assets [Member] | Recurring
ASSETS
Fixed maturities, AFS, at fair value		29,104,486		24,177,469
Equity securities, AFS, at fair value		878,919		868,292
Short-term investments, at fair value	[6]	617,390		256,727
Total investments available for sale		30,600,795		25,302,488
Exclude Life Funds Withheld Assets [Member] | Recurring | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,065,637		2,171,953
Exclude Life Funds Withheld Assets [Member] | Recurring | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,757,971		3,728,576
Exclude Life Funds Withheld Assets [Member] | Recurring | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		328,540		427,351
Exclude Life Funds Withheld Assets [Member] | Recurring | CMBS
ASSETS
Fixed maturities, AFS, at fair value		405,316		1,052,544
Exclude Life Funds Withheld Assets [Member] | Recurring | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		32,410		692,034
Exclude Life Funds Withheld Assets [Member] | Recurring | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,168,572		1,065,293
Exclude Life Funds Withheld Assets [Member] | Recurring | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		2,632,070		2,021,272
Exclude Life Funds Withheld Assets [Member] | Recurring | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,251,614		4,240,073
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Fixed maturities, AFS, at fair value		0		0
Equity securities, AFS, at fair value		528,581		502,284
Short-term investments, at fair value		0		0	[6]
Total investments available for sale		528,581		502,284
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2)
ASSETS
Fixed maturities, AFS, at fair value		28,952,208		23,476,419
Equity securities, AFS, at fair value		350,338		366,008
Short-term investments, at fair value	[6]	617,390		256,727
Total investments available for sale		29,919,936		24,099,154
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,020,574		2,171,953
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,754,894		3,726,666
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		328,540		427,351
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		405,316		1,052,544
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		2		4,076
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,150,715		1,060,005
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		2,632,070		2,021,272
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		5,251,614		4,240,073
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Fixed maturities, AFS, at fair value		152,278		701,050
Equity securities, AFS, at fair value		0		0
Short-term investments, at fair value		0		0	[6]
Total investments available for sale		152,278		701,050
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		45,063		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		3,077		1,910
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Collateralized debt obligations ('CDO') [Member]
ASSETS
Fixed maturities, AFS, at fair value		32,408		687,958
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		17,857		5,288
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | U.S. States and political subdivisions of the States [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Life Funds Withheld Assets [Member]
ASSETS
Fixed maturities, AFS, at fair value		3,153,103		5,181,565
Fixed maturities, trading, at fair value		1,235,699
Short-term investments, at fair value		60,330
Trading Securities		1,296,029		1,171
Life Funds Withheld Assets [Member] | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		12,742		18,724
Fixed maturities, trading, at fair value		4,990
Life Funds Withheld Assets [Member] | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		752		3,782
Fixed maturities, trading, at fair value		368
Life Funds Withheld Assets [Member] | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		26,953		85,335
Life Funds Withheld Assets [Member] | CMBS
ASSETS
Fixed maturities, AFS, at fair value		122,481		193,167
Fixed maturities, trading, at fair value		4,803
Life Funds Withheld Assets [Member] | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		149,795		273,541
Fixed maturities, trading, at fair value		25,700
Life Funds Withheld Assets [Member] | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		933,516		1,789,036
Fixed maturities, trading, at fair value		370,261
Life Funds Withheld Assets [Member] | Recurring
ASSETS
Fixed maturities, AFS, at fair value		3,153,103		5,181,565
Fixed maturities, trading, at fair value		1,235,699		1,171
Short-term investments, at fair value		60,330
Trading Securities		1,296,029
Cash equivalents		101,274		133,198	[2]
Life Funds Withheld Assets [Member] | Recurring | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		12,742		18,724
Fixed maturities, trading, at fair value		4,990
Life Funds Withheld Assets [Member] | Recurring | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		752		3,782
Fixed maturities, trading, at fair value		368
Life Funds Withheld Assets [Member] | Recurring | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		26,953		85,335
Life Funds Withheld Assets [Member] | Recurring | CMBS
ASSETS
Fixed maturities, AFS, at fair value		122,481		193,167
Fixed maturities, trading, at fair value		4,803
Life Funds Withheld Assets [Member] | Recurring | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		149,795		273,541
Fixed maturities, trading, at fair value		25,700
Life Funds Withheld Assets [Member] | Recurring | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		933,516		1,789,036
Fixed maturities, trading, at fair value		370,261
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Short-term investments, at fair value		0
Trading Securities		0
Cash equivalents		517		460	[2]
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2)
ASSETS
Fixed maturities, AFS, at fair value		3,153,103		5,181,565
Fixed maturities, trading, at fair value		1,235,699		1,171
Short-term investments, at fair value		60,330
Trading Securities		1,296,029
Cash equivalents		100,757		132,738	[2]
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		12,742		18,724
Fixed maturities, trading, at fair value		4,990
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		752		3,782
Fixed maturities, trading, at fair value		368
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		26,953		85,335
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		122,481		193,167
Fixed maturities, trading, at fair value		4,803
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		149,795		273,541
Fixed maturities, trading, at fair value		25,700
Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		933,516		1,789,036
Fixed maturities, trading, at fair value		370,261
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Short-term investments, at fair value		0
Trading Securities		0
Cash equivalents		0		0	[2]
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | U.S. Government and Government - Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0	[5]
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Non-U.S. Sovereign Government, Provincial, Supranational, and Government-Related/Supported [Member]
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,561,909		2,761,916
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,561,909		2,761,916
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,508,224		2,761,916
Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		53,685		0
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		598,236		801,019
Fixed maturities, trading, at fair value		335,956
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		598,236		801,019
Fixed maturities, trading, at fair value		335,956
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		598,236		801,019
Fixed maturities, trading, at fair value		335,956
Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,900,447		6,016,457
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,900,447		6,016,457
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,900,259		6,010,563
Non-Financial Services Sector [Member] | Exclude Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		188		5,894
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,308,628		2,016,961
Fixed maturities, trading, at fair value		493,621		1,171
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,308,628		2,016,961
Fixed maturities, trading, at fair value		493,621		1,171
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,308,628		2,016,961
Fixed maturities, trading, at fair value		493,621		1,171
Non-Financial Services Sector [Member] | Life Funds Withheld Assets [Member] | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		$ 0		$ 0

[1] Other assets and other liabilities include derivative instruments. The derivative balances included in each category are reported on a gross basis by level with a netting adjustment presented separately in the Collateral and Counterparty Netting column. The fair values of the individual derivative contracts are reported gross in their respective levels based on the fair value hierarchy. For further details regarding derivative fair values and associated collateral received or paid see

[2] Cash equivalents balances subject to fair value measurement include certificates of deposit and money market funds. Operating cash balances are not subject to recurring fair value measurement guidance.

[3] The Other investments balance excludes certain structured transactions including certain investments in project finance transactions, a payment obligation and liquidity financing provided to a structured credit vehicle as a part of a third party medium term note facility. These investments, which totaled $141.3 million at December 31, 2015 and $354.4 million at December 31, 2014, are carried at amortized cost. For further information, see Note 8, "Other Investments.

[4] Funds withheld on life retrocession arrangements (net of future policy benefit reserves recoverable) include balances related to the life retrocession embedded derivative, under which all investment results associated with the Life Funds Withheld Assets related the GreyCastle Life Retro Arrangements described in Note 3(e), "Acquisitions and Disposals - Sale of Life Reinsurance Subsidiary", accrue to the benefit of GCLR.

[5] Financial instruments sold, but not yet purchased, represent "short sales" and are included within "Payable for investments purchased" on the balance sheets.

[6] Short-term investments consist primarily of Corporate securities and U.S. and Non-U.S. Government and Government-Related/ Supported securities.