Segment Reporting (Schedule of Significant Components of the Company's Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Gross premiums written	$ 2,025,721	$ 1,564,295
Net premiums written	1,269,808	929,031
Net premiums earned	913,098	550,028
Net claims and claim expenses incurred	570,954	227,035
Acquisition expenses	210,604	123,951
Operational expenses	67,461	44,933
Underwriting income (loss)	64,079	154,109
Net investment income	99,473	82,094
Net foreign exchange losses	(5,728)	(2,846)
Equity in earnings of other ventures	4,564	4,661
Other loss	(4,436)	3,171
Net realized and unrealized (losses) gains on investments	(110,707)	170,013
Corporate expenses	(15,991)	(38,789)
Interest expense	(14,927)	(11,754)
Income before taxes	16,327	360,659
Income tax benefit (expense)	8,846	(7,531)
Net income attributable to redeemable noncontrolling interests	(98,091)	(70,222)
Dividends on preference shares	(9,056)	(9,189)
Net (loss) income (attributable) available to RenaissanceRe common shareholders	(81,974)	273,717
Net claims and claim expenses incurred – current accident year	557,054	231,341
Net claims and claim expenses incurred – prior accident years	13,900	(4,306)
Total net incurred	$ 570,954	$ 227,035
Net claims and claim expense ratio – current accident year	61.00%	42.10%
Net claims and claim expense ratio – prior accident years	1.50%	(0.80%)
Net claims and claim expense ratio – calendar year	62.50%	41.30%
Underwriting expense ratio	30.50%	30.70%
Combined ratio	93.00%	72.00%
Other
Segment Reporting Information [Line Items]
Gross premiums written	$ 0	$ 0
Net premiums written	0	0
Net premiums earned	0	0
Net claims and claim expenses incurred	(107)	19
Acquisition expenses	0	0
Operational expenses	0	0
Underwriting income (loss)	107	(19)
Net investment income	99,473	82,094
Net foreign exchange losses	(5,728)	(2,846)
Equity in earnings of other ventures	4,564	4,661
Other loss	(4,436)	3,171
Net realized and unrealized (losses) gains on investments	(110,707)	170,013
Corporate expenses	(15,991)	(38,789)
Interest expense	(14,927)	(11,754)
Income tax benefit (expense)	8,846	(7,531)
Net income attributable to redeemable noncontrolling interests	(98,091)	(70,222)
Dividends on preference shares	(9,056)	(9,189)
Net claims and claim expenses incurred – current accident year	0	0
Net claims and claim expenses incurred – prior accident years	(107)	19
Total net incurred	(107)	19
Property
Segment Reporting Information [Line Items]
Net claims and claim expenses incurred – prior accident years	14,008	1,877
Property | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	1,220,526	1,032,384
Net premiums written	674,581	564,230
Net premiums earned	421,335	290,745
Net claims and claim expenses incurred	144,852	56,083
Acquisition expenses	85,351	53,739
Operational expenses	44,007	28,544
Underwriting income (loss)	147,125	152,379
Net claims and claim expenses incurred – current accident year	130,844	54,206
Net claims and claim expenses incurred – prior accident years	14,008	1,877
Total net incurred	$ 144,852	$ 56,083
Net claims and claim expense ratio – current accident year	31.10%	18.60%
Net claims and claim expense ratio – prior accident years	3.30%	0.70%
Net claims and claim expense ratio – calendar year	34.40%	19.30%
Underwriting expense ratio	30.70%	28.30%
Combined ratio	65.10%	47.60%
Casualty and Specialty
Segment Reporting Information [Line Items]
Net claims and claim expenses incurred – prior accident years	$ (1)	$ (6,202)
Casualty and Specialty | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	805,195	531,911
Net premiums written	595,227	364,801
Net premiums earned	491,763	259,283
Net claims and claim expenses incurred	426,209	170,933
Acquisition expenses	125,253	70,212
Operational expenses	23,454	16,389
Underwriting income (loss)	(83,153)	1,749
Net claims and claim expenses incurred – current accident year	426,210	177,135
Net claims and claim expenses incurred – prior accident years	(1)	(6,202)
Total net incurred	$ 426,209	$ 170,933
Net claims and claim expense ratio – current accident year	86.70%	68.30%
Net claims and claim expense ratio – prior accident years	0.00%	(2.40%)
Net claims and claim expense ratio – calendar year	86.70%	65.90%
Underwriting expense ratio	30.20%	33.40%
Combined ratio	116.90%	99.30%