Variable Interest Entities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Investment in variable interest entity	$ 0	$ 0	$ 0
Total assets	12,352,082	11,555,287
Total liabilities	6,309,911	5,777,139
Other assets	175,382	181,011
Ceded premiums written	839,264	595,127	482,336
Ceded premiums earned	628,675	466,719	$ 453,658
Upsilon RFO Re Ltd. | Primary Beneficiary
Variable Interest Entity [Line Items]
Return of capital	242,500	420,200
Total assets	193,000	250,600
Total liabilities	$ 193,000	250,500
Other assets		$ 135,700
Upsilon RFO Re Ltd. | Primary Beneficiary | RenaissanceRe Holdings Ltd.
Variable Interest Entity [Line Items]
Variable interest entity, ownership percentage	28.80%	21.70%
Return of capital	$ 59,800	$ 132,300
Upsilon RFO Re Ltd. | Primary Beneficiary | Non-voting preference shares
Variable Interest Entity [Line Items]
Non-voting preference shares issued to third parties	166,600	153,700
Investment in variable interest entity	55,200	42,500
Mona Lisa Re Ltd. | Renaissance Reinsurance Ltd.
Variable Interest Entity [Line Items]
Ceded premiums written	7,400	7,300
Ceded premiums earned	7,300	7,300
Mona Lisa Re Ltd. | DaVinci Reinsurance Ltd.
Variable Interest Entity [Line Items]
Ceded premiums written	5,100	5,000
Ceded premiums earned	5,000	5,000
Mona Lisa Re Ltd. | Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets	184,200	184,000
Total liabilities	$ 184,200	$ 184,000