Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Assets
Total investments	$ 10,221,704	$ 9,503,439
Cash and cash equivalents	647,973	1,361,592	$ 454,087	$ 421,157
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,684,630	1,304,622
Prepaid reinsurance premiums	794,921	533,546
Reinsurance recoverable	1,572,321	1,586,630	325,819
Accrued investment income	43,069	42,235
Deferred acquisition costs	477,010	426,551
Receivable for investments sold	111,431	103,145
Other assets	127,571	121,226
Goodwill and other intangible assets	241,572	243,145
Total assets	15,922,202	15,226,131
Liabilities
Reserve for claims and claim expenses	4,912,727	5,080,408	2,934,688
Unearned premiums	1,961,746	1,477,609
Debt	989,995	989,623
Amounts due to subsidiaries and affiliates	0	0
Reinsurance balances payable	1,758,948	989,090
Payable for investments purchased	306,664	208,749
Other liabilities	130,505	792,771
Total liabilities	10,060,585	9,538,250
Redeemable noncontrolling interests	1,425,364	1,296,506
Shareholders’ Equity
Total shareholders’ equity	4,436,253	4,391,375	4,860,837
Total liabilities, noncontrolling interests and shareholders’ equity	15,922,202	15,226,131
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Assets
Total investments	112,716	129,732
Cash and cash equivalents	97	139	164	162
Investments in subsidiaries	53,476	36,140
Due from subsidiaries and affiliates	91,891	91,891
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	223	428
Deferred acquisition costs	0	0
Receivable for investments sold	0	51
Other assets	21,340	21,342
Goodwill and other intangible assets	0	0
Total assets	279,743	279,723
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	0	0
Amounts due to subsidiaries and affiliates	61	54
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	793	1,053
Total liabilities	854	1,107
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	278,889	278,616
Total liabilities, noncontrolling interests and shareholders’ equity	279,743	279,723
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Assets
Total investments	22,433	31,255
Cash and cash equivalents	1,175	1,469	6,080	9,397
Investments in subsidiaries	1,137,922	1,141,733
Due from subsidiaries and affiliates	0	0
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	46	82
Deferred acquisition costs	0	0
Receivable for investments sold	6	8
Other assets	433,056	430,481
Goodwill and other intangible assets	0	0
Total assets	1,594,638	1,605,028
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	842,188	841,892
Amounts due to subsidiaries and affiliates	106,900	92,794
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	9,457	14,117
Total liabilities	958,545	948,803
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	636,093	656,225
Total liabilities, noncontrolling interests and shareholders’ equity	1,594,638	1,605,028
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Assets
Total investments	70,641	225,266
Cash and cash equivalents	8,150	14,656	4,177	7,067
Investments in subsidiaries	4,090,065	4,105,760
Due from subsidiaries and affiliates	137,639	4,602
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	16	405
Deferred acquisition costs	0	0
Receivable for investments sold	48	135
Other assets	439,667	433,468
Goodwill and other intangible assets	123,728	124,960
Total assets	4,869,954	4,909,252
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	417,000	417,000
Amounts due to subsidiaries and affiliates	9,639	82,579
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	7,062	18,298
Total liabilities	433,701	517,877
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	4,436,253	4,391,375
Total liabilities, noncontrolling interests and shareholders’ equity	4,869,954	4,909,252
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Assets
Total investments	10,015,914	9,117,186
Cash and cash equivalents	638,551	1,345,328	$ 439,502	$ 397,860
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,684,630	1,304,622
Prepaid reinsurance premiums	794,921	533,546
Reinsurance recoverable	1,572,321	1,586,630
Accrued investment income	42,784	41,320
Deferred acquisition costs	477,010	426,551
Receivable for investments sold	111,377	102,951
Other assets	82,133	76,703
Goodwill and other intangible assets	117,844	118,185
Total assets	15,537,485	14,653,022
Liabilities
Reserve for claims and claim expenses	4,912,727	5,080,408
Unearned premiums	1,961,746	1,477,609
Debt	147,807	147,731
Amounts due to subsidiaries and affiliates	0	0
Reinsurance balances payable	1,758,948	989,090
Payable for investments purchased	306,664	208,749
Other liabilities	119,676	764,432
Total liabilities	9,207,568	8,668,019
Redeemable noncontrolling interests	1,425,364	1,296,506
Shareholders’ Equity
Total shareholders’ equity	4,904,553	4,688,497
Total liabilities, noncontrolling interests and shareholders’ equity	15,537,485	14,653,022
Consolidating Adjustments
Assets
Total investments	0	0
Cash and cash equivalents	0	0
Investments in subsidiaries	(5,281,463)	(5,283,633)
Due from subsidiaries and affiliates	(229,530)	(96,493)
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	(848,625)	(840,768)
Goodwill and other intangible assets	0	0
Total assets	(6,359,618)	(6,220,894)
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	(417,000)	(417,000)
Amounts due to subsidiaries and affiliates	(116,600)	(175,427)
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	(6,483)	(5,129)
Total liabilities	(540,083)	(597,556)
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	(5,819,535)	(5,623,338)
Total liabilities, noncontrolling interests and shareholders’ equity	$ (6,359,618)	$ (6,220,894)