Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Total investments	$ 9,503,439	$ 9,316,968
Cash and cash equivalents	1,361,592	421,157	$ 506,885	$ 525,584
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,304,622	987,323
Prepaid reinsurance premiums	533,546	441,260
Reinsurance recoverable	1,586,630	279,564	134,526
Accrued investment income	42,235	38,076
Deferred acquisition costs	426,551	335,325
Receivable for investments sold	103,145	105,841
Other assets	121,226	175,382
Goodwill and other intangible assets	243,145	251,186
Total assets	15,226,131	12,352,082
Liabilities
Reserve for claims and claim expenses (Note 8)	5,080,408	2,848,294	2,767,045
Unearned premiums	1,477,609	1,231,573
Debt (Note 9)	989,623	948,663
Amounts due to subsidiaries and affiliates	0	0
Reinsurance balances payable	989,090	673,983
Payable for investments purchased	208,749	305,714
Other liabilities	792,771	301,684
Total liabilities	9,538,250	6,309,911
Redeemable noncontrolling interests	1,296,506	1,175,594
Shareholders’ Equity
Total shareholders’ equity	4,391,375	4,866,577	4,732,184
Total liabilities, noncontrolling interests and shareholders’ equity	15,226,131	12,352,082
RenaissanceRe Holdings Ltd. (Parent Guarantor)
Assets
Cash and cash equivalents	14,656	7,067	10,185	5,986
Investments in subsidiaries	4,105,760	4,074,769
Accrued investment income	405	105
Receivable for investments sold	135	136
Other assets	433,468	410,757
Goodwill and other intangible assets	124,960	130,407
Total assets	4,909,252	5,017,928
Liabilities
Amounts due to subsidiaries and affiliates	82,579	14,644
Other liabilities	18,298	19,707
Total liabilities	517,877	151,351
Shareholders’ Equity
Total liabilities, noncontrolling interests and shareholders’ equity	4,909,252	5,017,928
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Assets
Total investments	225,266	387,274
Cash and cash equivalents	14,656	7,067	10,185	5,986
Investments in subsidiaries	4,105,760	4,074,769
Due from subsidiaries and affiliates	4,602	7,413
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	405	105
Deferred acquisition costs	0	0
Receivable for investments sold	135	136
Other assets	433,468	410,757
Goodwill and other intangible assets	124,960	130,407
Total assets	4,909,252	5,017,928
Liabilities
Reserve for claims and claim expenses (Note 8)	0	0
Unearned premiums	0	0
Debt (Note 9)	417,000	117,000
Amounts due to subsidiaries and affiliates	82,579	14,644
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	18,298	19,707
Total liabilities	517,877	151,351
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	4,391,375	4,866,577
Total liabilities, noncontrolling interests and shareholders’ equity	4,909,252	5,017,928
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Assets
Total investments	9,117,186	8,497,948
Cash and cash equivalents	1,345,328	397,860	483,012	518,565
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,304,622	987,323
Prepaid reinsurance premiums	533,546	441,260
Reinsurance recoverable	1,586,630	279,564
Accrued investment income	41,320	37,025
Deferred acquisition costs	426,551	335,325
Receivable for investments sold	102,951	105,559
Other assets	76,703	118,098
Goodwill and other intangible assets	118,185	120,779
Total assets	14,653,022	11,320,741
Liabilities
Reserve for claims and claim expenses (Note 8)	5,080,408	2,848,294
Unearned premiums	1,477,609	1,231,573
Debt (Note 9)	147,731	147,422
Amounts due to subsidiaries and affiliates	0	0
Reinsurance balances payable	989,090	673,983
Payable for investments purchased	208,749	305,714
Other liabilities	764,432	270,610
Total liabilities	8,668,019	5,477,596
Redeemable noncontrolling interests	1,296,506	1,175,594
Shareholders’ Equity
Total shareholders’ equity	4,688,497	4,667,551
Total liabilities, noncontrolling interests and shareholders’ equity	14,653,022	11,320,741
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Assets
Total investments	129,732	119,163
Cash and cash equivalents	139	162	5,908	1,033
Investments in subsidiaries	36,140	34,761
Due from subsidiaries and affiliates	91,891	91,892
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	428	289
Deferred acquisition costs	0	0
Receivable for investments sold	51	2
Other assets	21,342	37,204
Goodwill and other intangible assets	0	0
Total assets	279,723	283,473
Liabilities
Reserve for claims and claim expenses (Note 8)	0	0
Unearned premiums	0	0
Debt (Note 9)	0	0
Amounts due to subsidiaries and affiliates	54	42
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	1,053	10,544
Total liabilities	1,107	10,586
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	278,616	272,887
Total liabilities, noncontrolling interests and shareholders’ equity	279,723	283,473
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Assets
Total investments		267,556
Cash and cash equivalents	0	6,671	7,103	0
Investments in subsidiaries		843,089
Due from subsidiaries and affiliates		0
Premiums receivable		0
Prepaid reinsurance premiums		0
Reinsurance recoverable		0
Accrued investment income		551
Deferred acquisition costs		0
Receivable for investments sold		99
Other assets		4,689
Goodwill and other intangible assets		0
Total assets		1,122,655
Liabilities
Reserve for claims and claim expenses (Note 8)		0
Unearned premiums		0
Debt (Note 9)		255,352
Amounts due to subsidiaries and affiliates		123
Reinsurance balances payable		0
Payable for investments purchased		0
Other liabilities		0
Total liabilities		255,475
Redeemable noncontrolling interests		0
Shareholders’ Equity
Total shareholders’ equity		867,180
Total liabilities, noncontrolling interests and shareholders’ equity		1,122,655
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Assets
Total investments	31,255	45,027
Cash and cash equivalents	1,469	9,397	$ 677	$ 0
Investments in subsidiaries	1,141,733	1,165,413
Due from subsidiaries and affiliates	0	0
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	82	106
Deferred acquisition costs	0	0
Receivable for investments sold	8	45
Other assets	430,481	127,572
Goodwill and other intangible assets	0	0
Total assets	1,605,028	1,347,560
Liabilities
Reserve for claims and claim expenses (Note 8)	0	0
Unearned premiums	0	0
Debt (Note 9)	841,892	545,889
Amounts due to subsidiaries and affiliates	92,794	96,061
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	14,117	13,350
Total liabilities	948,803	655,300
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	656,225	692,260
Total liabilities, noncontrolling interests and shareholders’ equity	1,605,028	1,347,560
Consolidating Adjustments
Assets
Total investments	0	0
Cash and cash equivalents	0	0
Investments in subsidiaries	(5,283,633)	(6,118,032)
Due from subsidiaries and affiliates	(96,493)	(99,305)
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	0	0
Deferred acquisition costs	0	0
Receivable for investments sold	0	0
Other assets	(840,768)	(522,938)
Goodwill and other intangible assets	0	0
Total assets	(6,220,894)	(6,740,275)
Liabilities
Reserve for claims and claim expenses (Note 8)	0	0
Unearned premiums	0	0
Debt (Note 9)	(417,000)	(117,000)
Amounts due to subsidiaries and affiliates	(175,427)	(110,870)
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	(5,129)	(12,527)
Total liabilities	(597,556)	(240,397)
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	(5,623,338)	(6,499,878)
Total liabilities, noncontrolling interests and shareholders’ equity	$ (6,220,894)	$ (6,740,275)