SCHEDULE III - Supplementary Insurance Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	$ 661,186		$ 644,952		$ 568,391
Gross Reserves	9,745,806		10,646,318		10,709,371
Unearned Premiums	1,750,607		1,723,767		1,534,625
Other Benefits Payable	2,050,107		1,974,133		1,813,244
Premium Revenue	5,609,195		5,198,210		4,485,939
Net Investment Income(1)	479,696	[1]	484,367	[1]	571,338	[1]
Losses Incurred	3,462,770		3,157,808		2,804,610
Amortization of DAC	1,213,822		1,077,628		936,909
Other Expenses(2)	449,688	[2]	500,466	[2]	411,374	[2]
Premiums Written	4,765,907		4,556,765		3,774,474
Non Life [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	463,958		434,109		363,174
Gross Reserves	9,745,806		10,646,318		10,709,371
Unearned Premiums	1,731,212		1,699,393		1,517,217
Other Benefits Payable	0		0		0
Premium Revenue	4,387,406		4,234,850		3,684,069
Losses Incurred	2,462,568		2,399,867		2,155,147
Amortization of DAC	1,065,117		952,570		820,464
Other Expenses(2)	252,322	[2]	258,997	[2]	257,256	[2]
Premiums Written	4,500,214		4,426,719		3,768,111
Life and Health [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	197,228		210,841		205,203
Gross Reserves	0		0		0
Unearned Premiums	19,395		24,337		17,267
Other Benefits Payable	2,050,107		1,974,133		1,813,244
Premium Revenue	1,221,751		957,146		794,598
Net Investment Income(1)	60,369	[1]	60,897	[1]	64,223	[1]
Losses Incurred	1,000,202		760,552		646,981
Amortization of DAC	148,689		124,631		115,887
Other Expenses(2)	67,811	[2]	71,092	[2]	52,352	[2]
Premiums Written	265,693		123,936
Corporate and Other [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	0		2		14
Gross Reserves	0		0		0
Unearned Premiums	0		37		141
Other Benefits Payable	0		0		0
Premium Revenue	38		6,214		7,272
Net Investment Income(1)	419,327	[1]	423,470	[1]	507,115	[1]
Losses Incurred	0		(2,611)		2,482
Amortization of DAC	16		427		558
Other Expenses(2)	129,555	[2]	170,377	[2]	101,766	[2]
Premiums Written	$ 0		$ 6,110		$ 6,363

[1] Because the Company does not manage its assets by segment, net investment income is not allocated to the Non-life segment of the reinsurance operations. However, because of the interest-sensitive nature of some of the Company’s Life products, net investment income is considered in Management’s assessment of the profitability of the Life and Health segment.

[2] Other expenses are a component of underwriting result for the Non-life and Life and Health segments. Other expenses included in Corporate and Other represent corporate expenses and other expenses related to the Company’s principal finance transactions, insurance-linked securities and strategic investments.