Fair Value Measurements - Schedule of assets and liabilities that were accounted for at fair value (Details) - USD ($) $ in Thousands		Dec. 31, 2016		Dec. 31, 2015
ASSETS
Fixed maturities, AFS, at fair value		$ 30,256,602		$ 32,257,589
Equity securities, AFS, at fair value		1,037,331		878,919
Short-term investments, at fair value		625,193		617,390
Total investments available for sale		31,919,126		33,753,898
Fixed maturities, trading, at fair value		1,617,014		1,235,699
Short-term investments, at fair value		9,563		60,330
Total investments trading		1,626,577		1,296,029
Collateral and counterparty netting, asset	[1]	(17,947)		(3,087)
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2016 - $3,072,615; 2015 - $3,719,131)		998,968		914,629
Collateral and counterparty netting, liability	[1]	(17,947)		(3,087)
Recurring
ASSETS
Total investments available for sale		31,919,126		33,753,898
Cash equivalents	[2]	1,669,652		1,268,666
Other investments		699,402	[3]	773,608
Other assets	[1]	89,549		86,227
Total assets accounted for at fair value		36,077,104		37,279,702
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2016 - $3,072,615; 2015 - $3,719,131)	[4]	937,721		463,915
Financial instruments sold, but not yet purchased	[5]			347
Other liabilities	[1]	46,757		42,408
Total liabilities accounted for at fair value		984,478		506,670
Recurring | Quoted prices in active markets for identical assets (Level 1)
ASSETS
Total investments available for sale		898,664		528,581
Cash equivalents	[2]	573,398		437,742
Other investments			[3]	0
Other assets	[1]	0		0
Total assets accounted for at fair value		1,472,062		966,840
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2016 - $3,072,615; 2015 - $3,719,131)	[4]	0		0
Financial instruments sold, but not yet purchased	[5]			347
Other liabilities	[1]	0		0
Total liabilities accounted for at fair value		0		347
Recurring | Significant other observable inputs (Level 2)
ASSETS
Total investments available for sale		30,974,396		33,073,039
Cash equivalents	[2]	1,096,254		830,924
Other investments		493,874	[3]	490,058
Other assets	[1]	87,655		69,914
Total assets accounted for at fair value		34,351,554		35,860,721
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2016 - $3,072,615; 2015 - $3,719,131)	[4]	937,721		463,915
Financial instruments sold, but not yet purchased	[5]			0
Other liabilities	[1]	44,865		16,304
Total liabilities accounted for at fair value		982,586		480,219
Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Total investments available for sale		46,066		152,278
Cash equivalents	[2]	0		0
Other investments		205,528	[3]	283,550
Other assets	[1]	19,841		19,400
Total assets accounted for at fair value		271,435		455,228
Liabilities:
Funds withheld on GreyCastle life retrocession arrangements (net of future policy benefit reserves recoverable: 2016 - $3,072,615; 2015 - $3,719,131)	[4]	0		0
Financial instruments sold, but not yet purchased	[5]			0
Other liabilities	[1]	19,839		29,191
Total liabilities accounted for at fair value		19,839		29,191
Exclude Life Funds Withheld Assets
ASSETS
Fixed maturities, AFS, at fair value		27,948,560		29,104,486
Equity securities, AFS, at fair value		1,037,331		878,919
Short-term investments, at fair value		625,193		617,390
Total investments available for sale		29,611,084		30,600,795
Exclude Life Funds Withheld Assets | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		3,894,388		5,065,637
Exclude Life Funds Withheld Assets | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		4,218,367		3,757,971
Exclude Life Funds Withheld Assets | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		274,258		328,540
Exclude Life Funds Withheld Assets | CMBS
ASSETS
Fixed maturities, AFS, at fair value		665,186		405,316
Exclude Life Funds Withheld Assets | Collateralized debt obligations ('CDO')
ASSETS
Fixed maturities, AFS, at fair value		377,491		32,410
Exclude Life Funds Withheld Assets | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		875,897		1,168,572
Exclude Life Funds Withheld Assets | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, AFS, at fair value		2,478,112		2,632,070
Exclude Life Funds Withheld Assets | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		5,030,132		5,251,614
Exclude Life Funds Withheld Assets | Recurring
ASSETS
Fixed maturities, AFS, at fair value		27,948,560		29,104,486
Equity securities, AFS, at fair value		1,037,331		878,919
Short-term investments, at fair value	[6]	625,193		617,390
Total investments available for sale		29,611,084		30,600,795
Exclude Life Funds Withheld Assets | Recurring | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		3,894,388		5,065,637
Exclude Life Funds Withheld Assets | Recurring | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		4,218,367		3,757,971
Exclude Life Funds Withheld Assets | Recurring | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		274,258		328,540
Exclude Life Funds Withheld Assets | Recurring | CMBS
ASSETS
Fixed maturities, AFS, at fair value		665,186		405,316
Exclude Life Funds Withheld Assets | Recurring | Collateralized debt obligations ('CDO')
ASSETS
Fixed maturities, AFS, at fair value		377,491		32,410
Exclude Life Funds Withheld Assets | Recurring | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		875,897		1,168,572
Exclude Life Funds Withheld Assets | Recurring | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, AFS, at fair value		2,478,112		2,632,070
Exclude Life Funds Withheld Assets | Recurring | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		5,030,132		5,251,614
Exclude Life Funds Withheld Assets | 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		898,664		528,581
Short-term investments, at fair value		0		0	[6]
Total investments available for sale		898,664		528,581
Exclude Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets | 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 | 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 | 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 | Recurring | Quoted prices in active markets for identical assets (Level 1) | Collateralized debt obligations ('CDO')
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets | 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 | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2)
ASSETS
Fixed maturities, AFS, at fair value		27,902,494		28,952,208
Equity securities, AFS, at fair value		138,667		350,338
Short-term investments, at fair value	[6]	625,193		617,390
Total investments available for sale		28,666,354		29,919,936
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		3,869,637		5,020,574
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		4,218,367		3,754,894
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		274,258		328,540
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		665,087		405,316
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Collateralized debt obligations ('CDO')
ASSETS
Fixed maturities, AFS, at fair value		377,490		2
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		874,767		1,150,715
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, AFS, at fair value		2,478,112		2,632,070
Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		5,030,132		5,251,614
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3)
ASSETS
Fixed maturities, AFS, at fair value		46,066		152,278
Equity securities, AFS, at fair value		0		0
Short-term investments, at fair value		0		0	[6]
Total investments available for sale		46,066		152,278
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		24,751		45,063
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		0		3,077
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		99		0
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | Collateralized debt obligations ('CDO')
ASSETS
Fixed maturities, AFS, at fair value		1		32,408
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		1,130		17,857
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, AFS, at fair value		0		0
Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		0		0
Life Funds Withheld Assets
ASSETS
Fixed maturities, AFS, at fair value		2,308,042		3,153,103
Fixed maturities, trading, at fair value		1,617,014		1,235,699
Short-term investments, at fair value		9,563		60,330
Total investments trading		1,626,577		1,296,029
Life Funds Withheld Assets | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		10,577		12,742
Fixed maturities, trading, at fair value		14,708		4,990
Life Funds Withheld Assets | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		613		752
Fixed maturities, trading, at fair value		852		368
Life Funds Withheld Assets | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		21,767		26,953
Fixed maturities, trading, at fair value		109
Life Funds Withheld Assets | CMBS
ASSETS
Fixed maturities, AFS, at fair value		94,240		122,481
Fixed maturities, trading, at fair value		5,526		4,803
Life Funds Withheld Assets | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		101,560		149,795
Fixed maturities, trading, at fair value		39,446		25,700
Life Funds Withheld Assets | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, trading, at fair value		224
Life Funds Withheld Assets | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		624,677		933,516
Fixed maturities, trading, at fair value		444,944		370,261
Life Funds Withheld Assets | Recurring
ASSETS
Fixed maturities, AFS, at fair value		2,308,042		3,153,103
Fixed maturities, trading, at fair value		1,617,014		1,235,699
Short-term investments, at fair value		9,563		60,330
Total investments trading		1,626,577		1,296,029
Cash equivalents		72,798		101,274	[2]
Life Funds Withheld Assets | Recurring | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		10,577		12,742
Fixed maturities, trading, at fair value		14,708		4,990
Life Funds Withheld Assets | Recurring | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		613		752
Fixed maturities, trading, at fair value		852		368
Life Funds Withheld Assets | Recurring | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		21,767		26,953
Fixed maturities, trading, at fair value		109
Life Funds Withheld Assets | Recurring | CMBS
ASSETS
Fixed maturities, AFS, at fair value		94,240		122,481
Fixed maturities, trading, at fair value		5,526		4,803
Life Funds Withheld Assets | Recurring | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		101,560		149,795
Fixed maturities, trading, at fair value		39,446		25,700
Life Funds Withheld Assets | Recurring | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, trading, at fair value		224
Life Funds Withheld Assets | Recurring | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		624,677		933,516
Fixed maturities, trading, at fair value		444,944		370,261
Life Funds Withheld Assets | 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		0
Total investments trading		0		0
Cash equivalents		0		517	[2]
Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Life Funds Withheld Assets | 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		0
Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets | 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		0
Life Funds Withheld Assets | 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		0
Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2)
ASSETS
Fixed maturities, AFS, at fair value		2,308,042		3,153,103
Fixed maturities, trading, at fair value		1,617,014		1,235,699
Short-term investments, at fair value		9,563		60,330
Total investments trading		1,626,577		1,296,029
Cash equivalents		72,798		100,757	[2]
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		10,577		12,742
Fixed maturities, trading, at fair value		14,708		4,990
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | RMBS - Agency
ASSETS
Fixed maturities, AFS, at fair value		613		752
Fixed maturities, trading, at fair value		852		368
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		21,767		26,953
Fixed maturities, trading, at fair value		109
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		94,240		122,481
Fixed maturities, trading, at fair value		5,526		4,803
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Other asset-backed securities
ASSETS
Fixed maturities, AFS, at fair value		101,560		149,795
Fixed maturities, trading, at fair value		39,446		25,700
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, trading, at fair value		224
Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		624,677		933,516
Fixed maturities, trading, at fair value		444,944		370,261
Life Funds Withheld Assets | 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		0
Total investments trading		0		0
Cash equivalents		0		0	[2]
Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | U.S. Government and Government - Related/Supported
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Life Funds Withheld Assets | 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		0
Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | RMBS - Non-Agency
ASSETS
Fixed maturities, AFS, at fair value		0		0	[5]
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | CMBS
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Life Funds Withheld Assets | 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		0
Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | U.S. States and political subdivisions of the States
ASSETS
Fixed maturities, trading, at fair value		0
Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | Non-U.S. Government
ASSETS
Fixed maturities, AFS, at fair value		0		0
Fixed maturities, trading, at fair value		0		0
Financial Services Sector | Exclude Life Funds Withheld Assets | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,622,290		3,561,909
Financial Services Sector | Exclude Life Funds Withheld Assets | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,622,290		3,561,909
Financial Services Sector | Exclude Life Funds Withheld Assets | Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		0		0
Financial Services Sector | Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		3,612,006		3,508,224
Financial Services Sector | Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		10,284		53,685
Financial Services Sector | Life Funds Withheld Assets | Corporate
ASSETS
Fixed maturities, AFS, at fair value		439,267		598,236
Fixed maturities, trading, at fair value		468,175		335,956
Financial Services Sector | Life Funds Withheld Assets | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		439,267		598,236
Fixed maturities, trading, at fair value		468,175		335,956
Financial Services Sector | Life Funds Withheld Assets | 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
Financial Services Sector | Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		439,267		598,236
Fixed maturities, trading, at fair value		468,175		335,956
Financial Services Sector | Life Funds Withheld Assets | 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
Non-Financial Services Sector | Exclude Life Funds Withheld Assets | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,512,439		6,900,447
Non-Financial Services Sector | Exclude Life Funds Withheld Assets | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,512,439		6,900,447
Non-Financial Services Sector | Exclude Life Funds Withheld Assets | 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 | Exclude Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		6,502,638		6,900,259
Non-Financial Services Sector | Exclude Life Funds Withheld Assets | Recurring | Significant other unobservable inputs (Level 3) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		9,801		188
Non-Financial Services Sector | Life Funds Withheld Assets | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,015,341		1,308,628
Fixed maturities, trading, at fair value		643,030		493,621
Non-Financial Services Sector | Life Funds Withheld Assets | Recurring | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,015,341		1,308,628
Fixed maturities, trading, at fair value		643,030		493,621
Non-Financial Services Sector | Life Funds Withheld Assets | 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 | Life Funds Withheld Assets | Recurring | Significant other observable inputs (Level 2) | Corporate
ASSETS
Fixed maturities, AFS, at fair value		1,015,341		1,308,628
Fixed maturities, trading, at fair value		643,030		493,621
Non-Financial Services Sector | Life Funds Withheld Assets | 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.

[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] Other Investments balance excludes $322.9 million and $518.1 million as of December 31, 2016 and December 31, 2015, respectively, measured using Net Asset Value, based on new accounting guidance. In addition, the Other investments balance excludes a certain payment obligation. These investments, which totaled $142.3 million at December 31, 2016 and $141.3 million at December 31, 2015, are carried at amortized cost.

[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 to the GreyCastle Life Retro Arrangements described in Note 2(g), "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.