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 [Line Items]
Deferred Acquisition Costs	$ 466,987	$ 456,122	$ 389,248
Reserve for Losses and Loss Expenses	9,596,797	9,582,140	9,058,731
Unearned Premiums	2,735,376	2,683,849	2,454,692
Net Premiums Earned	3,870,999	3,707,065	3,415,463
Net Investment Income	342,766	409,312	380,957
Losses and Loss Expenses	2,186,722	2,134,195	2,096,028
Amortization of Deferred Acquisition Costs	737,197	664,191	627,653
Other Operating Expenses	621,876	575,390	560,981
Net Premiums Written	3,906,975	3,928,200	3,337,456
Insurance [Member]
Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	135,111	150,109	128,311
Reserve for Losses and Loss Expenses	5,063,147	4,873,184	4,492,553
Unearned Premiums	1,506,925	1,548,653	1,456,318
Net Premiums Earned	1,830,544	1,722,762	1,558,058
Net Investment Income	0	0	0
Losses and Loss Expenses	1,131,880	1,050,402	953,564
Amortization of Deferred Acquisition Costs	278,804	242,363	226,859
Other Operating Expenses	341,214	347,684	314,834
Net Premiums Written	1,779,501	1,813,538	1,522,245
Reinsurance [Member]
Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	331,876	306,013	260,937
Reserve for Losses and Loss Expenses	4,533,650	4,708,956	4,566,178
Unearned Premiums	1,228,451	1,135,196	998,374
Net Premiums Earned	2,040,455	1,984,303	1,857,405
Net Investment Income	0	0	0
Losses and Loss Expenses	1,054,842	1,083,793	1,142,464
Amortization of Deferred Acquisition Costs	458,393	421,828	400,794
Other Operating Expenses	144,987	137,450	116,487
Net Premiums Written	2,127,474	2,114,662	1,815,211
Corporate, Non-Segment [Member]
Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	0	0	0
Reserve for Losses and Loss Expenses	0	0	0
Unearned Premiums	0	0	0
Net Premiums Earned	0	0	0
Net Investment Income	342,766	409,312	380,957
Losses and Loss Expenses	0	0	0
Amortization of Deferred Acquisition Costs	0	0	0
Other Operating Expenses	135,675	90,256	129,660
Net Premiums Written	$ 0	$ 0	$ 0

Amount of amortization of deferred policy acquisition costs recognized.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-16)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915

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Amount of insurance benefits, claims, losses and settlement expenses incurred.

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Net amount of deferred policy acquisition costs capitalized on contracts remaining in force on the balance sheet date.

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Amount of reserves for future policy claims payable and loss expenses to be incurred.

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Amount of premium revenue earned.

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Amount of actual written premiums, including, as applicable, premiums from reinsurance assumed and net of premiums on reinsurance ceded.

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