RenaissanceRe (RNR) 10-Q 31 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 26, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	RENAISSANCERE HOLDINGS LTD.
Trading Symbol	RNR
Entity Central Index Key	913,144
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding (in shares)		40,265,961

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Fixed maturity investments trading, at fair value – amortized cost $7,901,884 at September 30, 2018 (December 31, 2017 – $7,434,870)	$ 7,814,779	$ 7,426,555
Short term investments, at fair value	2,461,415	991,863
Equity investments trading, at fair value	413,271	388,254
Other investments, at fair value	738,919	594,793
Investments in other ventures, under equity method	117,307	101,974
Total investments	11,545,691	9,503,439
Cash and cash equivalents	453,041	1,361,592
Premiums receivable	1,787,095	1,304,622
Prepaid reinsurance premiums	795,496	533,546
Reinsurance recoverable	1,204,059	1,586,630
Accrued investment income	46,690	42,235
Deferred acquisition costs	497,733	426,551
Receivable for investments sold	406,062	103,145
Other assets	121,724	121,226
Goodwill and other intangible assets	238,803	243,145
Total assets	17,096,394	15,226,131
Liabilities
Reserve for claims and claim expenses	4,952,498	5,080,408
Unearned premiums	2,058,851	1,477,609
Debt	990,749	989,623
Reinsurance balances payable	1,970,913	989,090
Payable for investments purchased	555,556	208,749
Other liabilities	147,328	792,771
Total liabilities	10,675,895	9,538,250
Commitments and Contingencies
Redeemable noncontrolling interests	1,533,978	1,296,506
Shareholders’ Equity
Preference shares: $1.00 par value – 16,010,000 shares issued and outstanding at September 30, 2018 (December 31, 2017 – 16,000,000)	650,000	400,000
Common shares: $1.00 par value – 40,265,961 shares issued and outstanding at September 30, 2018 (December 31, 2017 – 40,023,789)	40,266	40,024
Additional paid-in capital	42,395	37,355
Accumulated other comprehensive (loss) income	(1,483)	224
Retained earnings	4,155,343	3,913,772
Total shareholders’ equity attributable to RenaissanceRe	4,886,521	4,391,375
Total liabilities, noncontrolling interests and shareholders’ equity	$ 17,096,394	$ 15,226,131

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturity investments trading, amortized cost	$ 7,901,884	$ 7,434,870
Preference shares, par value (In dollars per share)	$ 1	$ 1
Preference shares, shares issued (In shares)	16,010,000	16,000,000
Preference shares, shares outstanding (In shares)	16,010,000	16,000,000
Common shares, par value (In dollars per share)	$ 1	$ 1
Common shares, Shares issued (In shares)	40,265,961	40,023,789
Common shares, shares outstanding (In shares)	40,265,961	40,023,789

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Gross premiums written	$ 625,677	$ 640,269	$ 2,762,672	$ 2,389,774
Net premiums written	453,255	483,221	1,720,808	1,583,102
Decrease (increase) in unearned premiums	78,594	64,571	(319,292)	(287,000)
Net premiums earned	531,849	547,792	1,401,516	1,296,102
Net investment income	80,696	40,257	208,528	148,745
Net foreign exchange (losses) gains	(4,566)	(156)	(11,496)	11,118
Equity in earnings of other ventures	7,648	1,794	14,331	5,830
Other income	497	2,996	480	7,053
Net realized and unrealized gains (losses) on investments	13,630	42,052	(86,415)	143,538
Total revenues	629,754	634,735	1,526,944	1,612,386
Expenses
Net claims and claim expenses incurred	410,510	1,221,696	642,380	1,557,364
Acquisition expenses	109,761	76,761	312,524	248,294
Operational expenses	40,593	42,537	119,408	131,586
Corporate expenses	6,841	4,413	21,875	14,335
Interest expense	11,769	11,799	35,304	32,416
Total expenses	579,474	1,357,206	1,131,491	1,983,995
Income (loss) before taxes	50,280	(722,471)	395,453	(371,609)
Income tax (expense) benefit	(1,451)	18,977	(2,550)	14,739
Net income (loss)	48,829	(703,494)	392,903	(356,870)
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Net income (loss) attributable to RenaissanceRe	42,389	(499,217)	302,081	(224,532)
Dividends on preference shares	(9,708)	(5,595)	(20,899)	(16,786)
Net income (loss) available (attributable) to RenaissanceRe common shareholders	$ 32,681	$ (504,812)	$ 281,182	$ (241,318)
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – basic (in dollars per share)	$ 0.82	$ (12.75)	$ 7.02	$ (6.04)
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – diluted (in dollars per share)	0.82	(12.75)	7.02	(6.04)
Dividends per common share	$ 0.33	$ 0.32	$ 0.99	$ 0.96

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Comprehensive income (loss)
Net income (loss)	$ 48,829	$ (703,494)	$ 392,903	$ (356,870)
Change in net unrealized gains on investments	(382)	300	(1,707)	(972)
Comprehensive income (loss)	48,447	(703,194)	391,196	(357,842)
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Comprehensive (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Comprehensive income (loss) attributable to RenaissanceRe	$ 42,007	$ (498,917)	$ 300,374	$ (225,504)

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Preference shares	Common shares	Additional paid-in capital	Accumulated other comprehensive (loss) income	Retained earnings
Beginning balance - January 1 at Dec. 31, 2016		$ 400,000	$ 41,187	$ 216,558	$ 1,133	$ 4,207,699
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares		0
Repurchase of shares			(1,322)	(187,269)
Offering expenses				0
Exercise of options and issuance of restricted stock awards			164	3,870
Change in redeemable noncontrolling interests				(307)
Change in net unrealized gains on investments					(972)
Cumulative effect of adoption of ASU 2016-09 (Note 2)						2,213
Net income (loss)	$ (224,532)					(356,870)
Net (income) loss attributable to redeemable noncontrolling interests	132,338					132,338
Dividends on common shares						(38,624)
Dividends on preference shares	(16,786)					(16,786)
Ending balance - September 30 at Sep. 30, 2017	4,403,012	400,000	40,029	32,852	161	3,929,970
Beginning balance - January 1 at Dec. 31, 2017	4,391,375	400,000	40,024	37,355	224	3,913,772
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares		250,000
Repurchase of shares			0	0
Offering expenses				(7,883)
Exercise of options and issuance of restricted stock awards			242	12,583
Change in redeemable noncontrolling interests				340
Change in net unrealized gains on investments					(1,707)
Cumulative effect of adoption of ASU 2016-09 (Note 2)						0
Net income (loss)	302,081					392,903
Net (income) loss attributable to redeemable noncontrolling interests	(90,822)					(90,822)
Dividends on common shares						(39,611)
Dividends on preference shares	(20,899)					(20,899)
Ending balance - September 30 at Sep. 30, 2018	$ 4,886,521	$ 650,000	$ 40,266	$ 42,395	$ (1,483)	$ 4,155,343

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows provided by operating activities
Net income (loss)	$ 392,903	$ (356,870)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Amortization, accretion and depreciation	30,936	18,586
Equity in undistributed earnings of other ventures	(13,016)	19,559
Net realized and unrealized losses (gains) on investments	86,415	(143,538)
Net unrealized gains included in net investment income	(17,778)	(2,686)
Change in:
Premiums receivable	(482,473)	(533,943)
Prepaid reinsurance premiums	(261,950)	(194,496)
Reinsurance recoverable	382,571	(1,308,740)
Deferred acquisition costs	(71,182)	(99,589)
Reserve for claims and claim expenses	(127,910)	2,344,019
Unearned premiums	581,242	481,496
Reinsurance balances payable	981,823	360,471
Other	(593,055)	17,433
Net cash provided by operating activities	888,526	601,702
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading	8,221,481	7,663,002
Purchases of fixed maturity investments trading	(8,692,688)	(7,798,285)
Net sales of equity investments trading	15,490	61,571
Net purchases of short term investments	(1,465,451)	(146,326)
Net (purchases) sales of other investments	(130,649)	5,181
Net purchases of investments in other ventures	(20,952)	0
Return of investment from investment in other ventures	8,464	20,000
Net cash used in investing activities	(2,064,305)	(194,857)
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	(39,611)	(38,624)
Dividends paid – preference shares	(20,899)	(16,786)
RenaissanceRe common share repurchases	0	(188,591)
Issuance of debt, net of expenses	0	295,866
Repayment of debt	0	(250,000)
Issuance of preference shares, net of expenses	242,371	0
Net third party redeemable noncontrolling interest share transactions	96,021	(44,193)
Taxes paid on withholding shares	(7,079)	(13,694)
Net cash provided by (used in) financing activities	270,803	(256,022)
Effect of exchange rate changes on foreign currency cash	(3,575)	9,596
Net (decrease) increase in cash and cash equivalents	(908,551)	160,419
Cash and cash equivalents, beginning of period	1,361,592	421,157
Cash and cash equivalents, end of period	$ 453,041	$ 581,576

Organization

Organization	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	ORGANIZATION This report on Form 10-Q should be read in conjunction with the RenaissanceRe’s Annual Report on Form 10-K (“Form 10-K”) for the fiscal year ended December 31, 2017 . RenaissanceRe was formed under the laws of Bermuda on June 7, 1993. Together with its wholly owned and majority-owned subsidiaries and DaVinciRe (as defined below), the Company provides property, casualty and specialty reinsurance and certain insurance solutions to its customers. • Renaissance Reinsurance, a Bermuda-domiciled reinsurance company, is the Company’s principal reinsurance subsidiary and provides property, casualty and specialty reinsurance coverages to insurers and reinsurers on a worldwide basis. • Renaissance Reinsurance U.S. Inc. (“Renaissance Reinsurance U.S.”) is a reinsurance company domiciled in the state of Maryland that provides property, casualty and specialty reinsurance coverages to insurers and reinsurers, primarily in the Americas. • RenaissanceRe Underwriting Managers U.S. LLC, a specialty reinsurance agency domiciled in the state of Connecticut, provides specialty treaty reinsurance solutions on both a quota share and excess of loss basis; and writes business on behalf of RenaissanceRe Specialty U.S. Ltd. (“RenaissanceRe Specialty U.S.”), a Bermuda-domiciled reinsurer, which operates subject to U.S. federal income tax, and RenaissanceRe Syndicate 1458 (“Syndicate 1458”). • Syndicate 1458 is the Company’s Lloyd’s syndicate. RenaissanceRe Corporate Capital (UK) Limited (“RenaissanceRe CCL”), a wholly owned subsidiary of RenaissanceRe, is Syndicate 1458’s sole corporate member and RenaissanceRe Syndicate Management Ltd. (“RSML”), a wholly owned subsidiary of RenaissanceRe, is the managing agent for Syndicate 1458. • The Company also manages property, casualty and specialty reinsurance business written on behalf of joint ventures, which principally include Top Layer Reinsurance Ltd. (“Top Layer Re”), recorded under the equity method of accounting, and DaVinci Reinsurance Ltd. (“DaVinci”). Because the Company owns a noncontrolling equity interest in, but controls a majority of the outstanding voting power of DaVinci’s parent, DaVinciRe Holdings Ltd. (“DaVinciRe”), the results of DaVinci and DaVinciRe are consolidated in the Company’s financial statements and all significant intercompany transactions have been eliminated. Redeemable noncontrolling interest - DaVinciRe represents the interests of external parties with respect to the net income and shareholders’ equity of DaVinciRe. Renaissance Underwriting Managers, Ltd. (“RUM”), a wholly owned subsidiary of RenaissanceRe, acts as exclusive underwriting manager for these joint ventures in return for fee-based income and profit participation. • RenaissanceRe Medici Fund Ltd. (“Medici”) is an exempted fund, incorporated under the laws of Bermuda. Medici’s objective is to seek to invest substantially all of its assets in various insurance based investment instruments that have returns primarily tied to property catastrophe risk. Third-party investors have subscribed for a portion of the participating, non-voting common shares of Medici. Because the Company owns a noncontrolling equity interest in, but controls a majority of the outstanding voting power of Medici’s parent, RenaissanceRe Fund Holdings Ltd. (“Fund Holdings”), the results of Medici and Fund Holdings are consolidated in the Company’s financial statements and all significant inter-company transactions have been eliminated. Redeemable noncontrolling interest - Medici represents the interests of external parties with respect to the net income and shareholders’ equity of Medici. • Upsilon RFO Re Ltd., formerly known as Upsilon Reinsurance II Ltd. (“Upsilon RFO”), a Bermuda domiciled special purpose insurer (“SPI”), is a managed joint venture formed by the Company primarily to provide additional capacity to the worldwide aggregate and per-occurrence primary and retrocessional property catastrophe excess of loss market. Upsilon RFO is considered a variable interest entity (“VIE”) and the Company is considered the primary beneficiary. As a result, Upsilon RFO is consolidated by the Company and all significant inter-company transactions have been eliminated. • RenaissanceRe Upsilon Fund Ltd. (“Upsilon Fund”), an exempted Bermuda segregated accounts company, was formed by the Company to provide a fund structure through which third-party investors can invest in reinsurance risk managed by the Company. As a segregated accounts company, Upsilon Fund is permitted to establish segregated accounts to invest in and hold identified pools of assets and liabilities. Each pool of assets and liabilities in each segregated account is structured to be ring-fenced from any claims from the creditors of Upsilon Fund’s general account and from the creditors of other segregated accounts within Upsilon Fund. Third-party investors purchase redeemable, non-voting preference shares linked to specific segregated accounts of Upsilon Fund and own 100% of these shares. Upsilon Fund is an investment company and is considered a VIE. The Company is not considered the primary beneficiary of Upsilon Fund and, as a result, the Company does not consolidate the financial position and results of operations of Upsilon Fund. • Effective November 7, 2016, Fibonacci Reinsurance Ltd. ("Fibonacci Re"), a Bermuda-domiciled SPI, was formed to provide collateralized capacity to Renaissance Reinsurance and its affiliates. Fibonacci Re raises capital from third-party investors and the Company, via private placements of participating notes which are listed on the Bermuda Stock Exchange. Fibonacci Re is considered a VIE. The Company is not considered the primary beneficiary of Fibonacci Re and, as a result, the Company does not consolidate the financial position and results of operations of Fibonacci Re. • Effective December 22, 2017, the Company and Reinsurance Group of America, Incorporated closed an initiative (“Langhorne”) to source third party capital to support reinsurers targeting large in-force life and annuity blocks. Langhorne Holdings LLC (“Langhorne Holdings”) is a company that owns and manages certain reinsurance entities within Langhorne. Langhorne Partners LLC (“Langhorne Partners”) is the general partner for Langhorne and the entity which manages the third-party investors investing into Langhorne Holdings. The Company concluded that Langhorne Holdings meets the definition of a VIE. The Company is not the primary beneficiary of Langhorne Holdings and as a result, the Company does not consolidate the financial position or results of operations of Langhorne Holdings. The Company concluded that Langhorne Partners is not a VIE. The Company will account for its investments in Langhorne Holdings and Langhorne Partners under the equity method of accounting, one quarter in arrears.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES There have been no material changes to the Company’s significant accounting policies as described in its Form 10-K for the year ended December 31, 2017 , except as noted below. BASIS OF PRESENTATION These consolidated financial statements have been prepared on the basis of accounting principles generally accepted in the United States (“GAAP”) for interim financial information and in conformity with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, these unaudited consolidated financial statements reflect all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the Company’s financial position and results of operations as at the end of and for the periods presented. All significant intercompany accounts and transactions have been eliminated from these statements. Certain comparative information has been reclassified to conform to the current presentation. Because of the seasonality of the Company’s business, the results of operations and cash flows for any interim period will not necessarily be indicative of the results of operations and cash flows for the full fiscal year or subsequent quarters. USE OF ESTIMATES IN FINANCIAL STATEMENTS The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ materially from those estimates. The major estimates reflected in the Company’s consolidated financial statements include, but are not limited to, the reserve for claims and claim expenses; reinsurance recoverables, including allowances for reinsurance recoverables deemed uncollectible; estimates of written and earned premiums; fair value, including the fair value of investments, financial instruments and derivatives; impairment charges; and the Company’s deferred tax valuation allowance. RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS Revenue from Contracts with Customers In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). ASU 2014-09 provides comprehensive guidance on the recognition of revenue from customers arising from the transfer of goods and services. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also provides guidance on accounting for certain contract costs and will also require new disclosures. ASU 2014-09 was to be effective for public business entities in annual and interim periods beginning after December 15, 2016, however in July 2015, the FASB decided to defer by one year the effective dates of ASU 2014-09, and as a result, ASU 2014-09 is effective for public business entities in annual and interim periods beginning after December 15, 2017. ASU 2014-09 notably excludes the accounting for insurance contracts, leases, financial instruments and guarantees. As a result, the Company’s implementation efforts primarily focused on other income and operational expenses on its consolidated statements of operations. The adoption of ASU 2014-09 did not have a material impact on the Company’s consolidated statements of operations and financial position. Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). ASU 2016-01 requires equity investments (except those accounted for under the equity method of accounting or those that result in the consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income, simplifies the impairment assessment of equity investments without readily determinable values by requiring a qualitative assessment to identify impairment, eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, requires the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes, requires separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liabilities in accordance with the fair value option, requires the separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and clarifies that the reporting organization should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the organization’s other deferred tax assets. ASU 2016-01 is effective for public business entities in annual and interim periods beginning after December 15, 2017. The adoption of ASU 2016-01 did not have a material impact on the Company’s consolidated statements of operations and financial position. Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 clarifies the classification of receipts and payments in the statement of cash flows. ASU 2016-15 provides guidance related to (1) settlement and payment of zero coupon debt instruments, (2) contingent consideration, (3) proceeds from settlement of insurance claims, (4) proceeds from settlement of corporate and bank owned life insurance policies, (5) distributions from equity method investees, (6) cash receipts from beneficial interests obtained by a transferor, and (7) general guidelines for cash receipts and payments that have more than one aspect of classification. ASU 2016-15 is effective for public business entities for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. The adoption of ASU 2016-15 resulted in the reclassification of $20.0 million of cash inflows from cash flows provided by operating activities, to cash flows used in investing activities for the nine months ended September 30, 2017 . This amount related to a return of investment associated with the Company’s investment in Top Layer Reinsurance Ltd, recorded under the equity method of accounting. Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”). ASU 2016-09 was issued to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and the classification of taxes paid on the statements of cash flows. ASU 2016-09 became effective for the Company in annual and interim periods beginning after December 15, 2016. The cumulative effect of the adoption of ASU 2016-09 was a $2.2 million increase to opening retained earnings as of January 1, 2017. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 requires lessees to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous guidance. ASU 2016-02 is effective for public business entities for annual and interim periods beginning after December 15, 2018. Early application is permitted. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position. Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 modifies the recognition of credit losses by replacing the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is applicable to financial assets such as loans, debt securities, trade receivables, off-balance sheet credit exposures, reinsurance receivables, and other financial assets that have the contractual right to receive cash. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The Company's invested assets are measured at fair value through net income, and therefore those invested assets would not be impacted by the adoption of ASU 2016-13. The Company has other financial assets, such as reinsurance recoverables, that could be impacted by the adoption of ASU 2016-13. ASU 2016-13 is effective for public business entities that are SEC filers for annual and interim periods beginning after December 15, 2019. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position. Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). ASU 2016-16 requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory when the transfers occur; this is a change from current guidance which prohibits the recognition of current and deferred income taxes until the underlying assets have been sold to outside entities. ASU 2016-16 is effective for public business entities for annual and interim periods beginning after December 15, 2018. Early adoption is permitted. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position. Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). Among other things, ASU 2017-04 requires the following: (1) the elimination of step two of the goodwill impairment test; entities will no longer utilize the implied fair value of their assets and liabilities for purposes of testing goodwill for impairment, (2) the quantitative portion of the goodwill impairment test will be performed by comparing the fair value of a reporting unit with its carrying amount; an impairment charge is to be recognized for the excess of carrying amount over fair value, but only to the extent of the amount of goodwill allocated to that reporting unit, and (3) foreign currency translation adjustments are not to be allocated to a reporting unit from an entity’s accumulated other comprehensive income; the reporting unit’s carrying amount should include only the currently translated balances of the assets and liabilities assigned to the reporting unit. ASU 2017-04 is effective for public business entities that are SEC filers for annual periods, or any interim goodwill impairment tests in annual periods, beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Investments [Abstract]
Investments	INVESTMENTS Fixed Maturity Investments Trading The following table summarizes the fair value of fixed maturity investments trading: September 30, December 31, U.S. treasuries $ 3,117,911 $ 3,168,763 Agencies 143,980 47,646 Municipal 7,061 509,802 Non-U.S. government (Sovereign debt) 254,169 287,660 Non-U.S. government-backed corporate 137,512 163,651 Corporate 2,448,795 2,063,459 Agency mortgage-backed 836,376 500,456 Non-agency mortgage-backed 289,649 300,331 Commercial mortgage-backed 257,434 202,062 Asset-backed 321,892 182,725 Total fixed maturity investments trading $ 7,814,779 $ 7,426,555 Contractual maturities of fixed maturity investments trading are described in the following table. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2018 Amortized Cost Fair Value Due in less than one year $ 303,364 $ 301,817 Due after one through five years 4,759,113 4,694,059 Due after five through ten years 1,029,502 1,020,157 Due after ten years 96,311 93,395 Mortgage-backed 1,390,933 1,383,459 Asset-backed 322,661 321,892 Total $ 7,901,884 $ 7,814,779 Equity Investments Trading The following table summarizes the fair value of equity investments trading: September 30, December 31, Financials $ 262,173 $ 253,543 Communications and technology 60,235 49,526 Industrial, utilities and energy 34,755 34,325 Consumer 26,649 24,779 Healthcare 25,250 21,364 Basic materials 4,209 4,717 Total $ 413,271 $ 388,254 Pledged Investments At September 30, 2018 , $5.1 billion of cash and investments at fair value were on deposit with, or in trust accounts for the benefit of, various counterparties, including with respect to the Company’s letter of credit facilities ( December 31, 2017 - $4.4 billion ). Of this amount, $1.9 billion is on deposit with, or in trust accounts for the benefit of, U.S. state regulatory authorities ( December 31, 2017 - $1.7 billion ). Reverse Repurchase Agreements At September 30, 2018 , the Company held $92.0 million ( December 31, 2017 - $30.0 million ) of reverse repurchase agreements. These loans are fully collateralized, are generally outstanding for a short period of time and are presented on a gross basis as part of short term investments on the Company’s consolidated balance sheets. The required collateral for these loans typically includes high-quality, readily marketable instruments at a minimum amount of 102% of the loan principal. Upon maturity, the Company receives principal and interest income. Net Investment Income The components of net investment income are as follows: Three months ended Nine months ended September 30, September 30, September 30, September 30, Fixed maturity investments $ 55,725 $ 45,305 $ 151,784 $ 133,080 Short term investments 9,403 2,771 22,340 7,476 Equity investments 903 930 3,091 2,630 Other investments Private equity investments 8,723 6,371 12,149 20,784 Other 8,665 (11,491 ) 27,346 (4,520 ) Cash and cash equivalents 1,104 352 2,708 836 84,523 44,238 219,418 160,286 Investment expenses (3,827 ) (3,981 ) (10,890 ) (11,541 ) Net investment income $ 80,696 $ 40,257 $ 208,528 $ 148,745 Net Realized and Unrealized Gains (Losses) on Investments Net realized and unrealized gains (losses) on investments are as follows: Three months ended Nine months ended September 30, September 30, September 30, September 30, Gross realized gains $ 5,229 $ 16,343 $ 14,945 $ 43,053 Gross realized losses (15,327 ) (6,126 ) (67,699 ) (29,902 ) Net realized (losses) gains on fixed maturity investments (10,098 ) 10,217 (52,754 ) 13,151 Net unrealized (losses) gains on fixed maturity investments trading (8,730 ) 5,545 (73,522 ) 48,940 Net realized and unrealized gains (losses) on investments-related derivatives 2,563 (4,020 ) (763 ) (4,344 ) Net realized gains on equity investments trading sold during the period 21,259 13,675 21,841 49,736 Net unrealized gains on equity investments trading still held at reporting date 8,636 16,635 18,783 36,055 Net realized and unrealized gains on equity investments trading 29,895 30,310 40,624 85,791 Net realized and unrealized gains (losses) on investments $ 13,630 $ 42,052 $ (86,415 ) $ 143,538

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The use of fair value to measure certain assets and liabilities with resulting unrealized gains or losses is pervasive within the Company’s consolidated financial statements. Fair value is defined under accounting guidance currently applicable to the Company to be the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between open market participants at the measurement date. The Company recognizes the change in unrealized gains and losses arising from changes in fair value in its consolidated statements of operations. FASB ASC Topic Fair Value Measurements and Disclosures prescribes a fair value hierarchy that prioritizes the inputs to the respective valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to valuation techniques that use at least one significant input that is unobservable (Level 3). The three levels of the fair value hierarchy are described below: • Fair values determined by Level 1 inputs utilize unadjusted quoted prices obtained from active markets for identical assets or liabilities for which the Company has access. The fair value is determined by multiplying the quoted price by the quantity held by the Company; • Fair values determined by Level 2 inputs utilize inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals, broker quotes and certain pricing indices; and • Level 3 inputs are based all or in part on significant unobservable inputs for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. In these cases, significant management assumptions can be used to establish management’s best estimate of the assumptions used by other market participants in determining the fair value of the asset or liability. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement of the asset or liability. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and the Company considers factors specific to the asset or liability. In order to determine if a market is active or inactive for a security, the Company considers a number of factors, including, but not limited to, the spread between what a seller is asking for a security and what a buyer is bidding for the same security, the volume of trading activity for the security in question, the price of the security compared to its par value (for fixed maturity investments), and other factors that may be indicative of market activity. There have been no material changes in the Company’s valuation techniques, nor have there been any transfers between Level 1 and Level 2, or Level 2 and Level 3 during the period represented by these consolidated financial statements. Below is a summary of the assets and liabilities that are measured at fair value on a recurring basis and also represents the carrying amount on the Company’s consolidated balance sheets: At September 30, 2018 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fixed maturity investments U.S. treasuries $ 3,117,911 $ 3,117,911 $ — $ — Agencies 143,980 — 143,980 — Municipal 7,061 — 7,061 — Non-U.S. government (Sovereign debt) 254,169 — 254,169 — Non-U.S. government-backed corporate 137,512 — 137,512 — Corporate 2,448,795 — 2,448,795 — Agency mortgage-backed 836,376 — 836,376 — Non-agency mortgage-backed 289,649 — 289,649 — Commercial mortgage-backed 257,434 — 257,434 — Asset-backed 321,892 — 321,892 — Total fixed maturity investments 7,814,779 3,117,911 4,696,868 — Short term investments 2,461,415 — 2,461,415 — Equity investments trading 413,271 413,271 — — Other investments Catastrophe bonds 525,126 — 525,126 — Private equity partnerships (1) 185,121 — — — Senior secured bank loan funds (1) 17,057 — — — Hedge funds (1) 11,615 — — — Total other investments 738,919 — 525,126 — Other assets and (liabilities) Assumed and ceded (re)insurance contracts (2) (8,949 ) — — (8,949 ) Derivatives (3) 1,594 249 1,345 — Total other assets and (liabilities) (7,355 ) 249 1,345 (8,949 ) $ 11,421,029 $ 3,531,431 $ 7,684,754 $ (8,949 ) (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheet. (2) Included in assumed and ceded (re)insurance contracts at September 30, 2018 was $5.3 million and $14.2 million of other assets and other liabilities, respectively. (3) See “Note 13 . Derivative Instruments” for additional information related to the fair value by type of contract, of derivatives entered into by the Company. At December 31, 2017 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fixed maturity investments U.S. treasuries $ 3,168,763 $ 3,168,763 $ — $ — Agencies 47,646 — 47,646 — Municipal 509,802 — 509,802 — Non-U.S. government (Sovereign debt) 287,660 — 287,660 — Non-U.S. government-backed corporate 163,651 — 163,651 — Corporate 2,063,459 — 2,063,459 — Agency mortgage-backed 500,456 — 500,456 — Non-agency mortgage-backed 300,331 — 300,331 — Commercial mortgage-backed 202,062 — 202,062 — Asset-backed 182,725 — 182,725 — Total fixed maturity investments 7,426,555 3,168,763 4,257,792 — Short term investments 991,863 — 991,863 — Equity investments trading 388,254 388,254 — — Other investments Catastrophe bonds 380,475 — 380,475 — Private equity partnerships (1) 196,220 — — — Senior secured bank loan funds (1) 17,574 — — — Hedge funds (1) 524 — — — Total other investments 594,793 — 380,475 — Other assets and (liabilities) Assumed and ceded (re)insurance contracts (2) (2,952 ) — — (2,952 ) Derivatives (3) 4,636 (45 ) 4,681 — Total other assets and (liabilities) 1,684 (45 ) 4,681 (2,952 ) $ 9,403,149 $ 3,556,972 $ 5,634,811 $ (2,952 ) (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheet. (2) Included in assumed and ceded (re)insurance contracts at December 31, 2017 was $2.5 million and $5.5 million of other assets and other liabilities, respectively. (3) See “Note 13 . Derivative Instruments” for additional information related to the fair value by type of contract, of derivatives entered into by the Company. Level 1 and Level 2 Assets and Liabilities Measured at Fair Value Fixed Maturity Investments Fixed maturity investments included in Level 1 consist of the Company’s investments in U.S. treasuries. Fixed maturity investments included in Level 2 are agencies, municipal, non-U.S. government, non-U.S. government-backed corporate, corporate, agency mortgage-backed, non-agency mortgage-backed, commercial mortgage-backed and asset-backed. The Company’s fixed maturity investments are primarily priced using pricing services, such as index providers and pricing vendors, as well as broker quotations. In general, the pricing vendors provide pricing for a high volume of liquid securities that are actively traded. For securities that do not trade on an exchange, the pricing services generally utilize market data and other observable inputs in matrix pricing models to determine month end prices. Observable inputs include benchmark yields, reported trades, broker-dealer quotes, issuer spreads, bids, offers, reference data and industry and economic events. Index pricing generally relies on market traders as the primary source for pricing; however, models are also utilized to provide prices for all index eligible securities. The models use a variety of observable inputs such as benchmark yields, transactional data, dealer runs, broker-dealer quotes and corporate actions. Prices are generally verified using third-party data. Securities which are priced by an index provider are generally included in the index. In general, broker-dealers value securities through their trading desks based on observable inputs. The methodologies include mapping securities based on trade data, bids or offers, observed spreads, and performance on newly issued securities. Broker-dealers also determine valuations by observing secondary trading of similar securities. Prices obtained from broker quotations are considered non-binding, however they are based on observable inputs and by observing secondary trading of similar securities obtained from active, non-distressed markets. The Company considers these broker quotations to be Level 2 inputs as they are corroborated with other market observable inputs. The techniques generally used to determine the fair value of the Company’s fixed maturity investments are detailed below by asset class. U.S. treasuries Level 1 - At September 30, 2018 , the Company’s U.S. treasuries fixed maturity investments were primarily priced by pricing services and had a weighted average yield to maturity of 2.8% and a weighted average credit quality of AA ( December 31, 2017 - 1.9% and AA, respectively). When pricing these securities, the pricing services utilize daily data from many real time market sources, including active broker dealers. Certain data sources are regularly reviewed for accuracy to attempt to ensure the most reliable price source is used for each issue and maturity date. Agencies Level 2 - At September 30, 2018 , the Company’s agency fixed maturity investments had a weighted average yield to maturity of 3.1% and a weighted average credit quality of AA ( December 31, 2017 - 2.1% and AA, respectively). The issuers of the Company’s agency fixed maturity investments primarily consist of the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and other agencies. Fixed maturity investments included in agencies are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources and integrate other observations from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The fair value of each security is individually computed using analytical models which incorporate option adjusted spreads and other daily interest rate data. Municipal Level 2 - At September 30, 2018 , the Company’s municipal fixed maturity investments had a weighted average yield to maturity of 4.0% and a weighted average credit quality of BBB ( December 31, 2017 - 2.2% and AA, respectively). The Company’s municipal fixed maturity investments are primarily priced by pricing services. When evaluating these securities, the pricing services gather information regarding the security from third-party sources such as trustees, paying agents or issuers. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The pricing services also consider the specific terms and conditions of the securities, including any specific features which may influence risk. In certain instances, securities are individually evaluated using a spread over widely accepted market benchmarks. Non-U.S. government (Sovereign debt) Level 2 - At September 30, 2018 , the Company’s non-U.S. government fixed maturity investments had a weighted average yield to maturity of 2.9% and a weighted average credit quality of AAA ( December 31, 2017 - 2.0% and AAA, respectively). The issuers of securities in this sector are non-U.S. governments and their respective agencies as well as supranational organizations. Securities held in these sectors are primarily priced by pricing services that employ proprietary discounted cash flow models to value the securities. Key quantitative inputs for these models are daily observed benchmark curves for treasury, swap and high issuance credits. The pricing services then apply a credit spread for each security which is developed by in-depth and real time market analysis. For securities in which trade volume is low, the pricing services utilize data from more frequently traded securities with similar attributes. These models may also be supplemented by daily market and credit research for international markets. Non-U.S. government-backed corporate Level 2 - At September 30, 2018 , the Company’s non-U.S. government-backed corporate fixed maturity investments had a weighted average yield to maturity of 3.2% and a weighted average credit quality of AA ( December 31, 2017 - 2.3% and AA, respectively). Non-U.S. government-backed fixed maturity investments are primarily priced by pricing services that employ proprietary discounted cash flow models to value the securities. Key quantitative inputs for these models are daily observed benchmark curves for treasury, swap and high issuance credits. The pricing services then apply a credit spread to the respective curve for each security which is developed by in-depth and real time market analysis. For securities in which trade volume is low, the pricing services utilize data from more frequently traded securities with similar attributes. These models may also be supplemented by daily market and credit research for international markets. Corporate Level 2 - At September 30, 2018 , the Company’s corporate fixed maturity investments principally consisted of U.S. and international corporations and had a weighted average yield to maturity of 4.3% and a weighted average credit quality of BBB ( December 31, 2017 - 3.8% and BBB, respectively). The Company’s corporate fixed maturity investments are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources regarding the issuer of the security and obtain credit data, as well as other observations, from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The pricing services also consider the specific terms and conditions of the securities, including any specific features which may influence risk. In certain instances, securities are individually evaluated using a spread which is added to the U.S. treasury curve or a security specific swap curve as appropriate. Agency mortgage-backed Level 2 - At September 30, 2018 , the Company’s agency mortgage-backed fixed maturity investments included agency residential mortgage-backed securities with a weighted average yield to maturity of 3.7% , a weighted average credit quality of AA and a weighted average life of 8.2 years ( December 31, 2017 - 3.0% , AA and 6.4 years, respectively). The Company’s agency mortgage-backed fixed maturity investments are primarily priced by pricing services using a mortgage pool specific model which utilizes daily inputs from the active to be announced market which is very liquid, as well as the U.S. treasury market. The model also utilizes additional information, such as the weighted average maturity, weighted average coupon and other available pool level data which is provided by the sponsoring agency. Valuations are also corroborated with daily active market quotes. Non-agency mortgage-backed Level 2 - The Company’s non-agency mortgage-backed fixed maturity investments include non-agency prime, non-agency Alt-A and other non-agency residential mortgage-backed securities. At September 30, 2018 , the Company’s non-agency prime residential mortgage-backed fixed maturity investments had a weighted average yield to maturity of 4.2% , a weighted average credit quality of non-investment grade, and a weighted average life of 5.5 years ( December 31, 2017 - 3.7% , BBB and 5.1 years, respectively). The Company’s non-agency Alt-A fixed maturity investments held at September 30, 2018 had a weighted average yield to maturity of 4.1% , a weighted average credit quality of non-investment grade and a weighted average life of 6.3 years ( December 31, 2017 - 3.7% , non-investment grade and 6.2 years, respectively). Securities held in these sectors are primarily priced by pricing services using an option adjusted spread model or other relevant models, which principally utilize inputs including benchmark yields, available trade information or broker quotes, and issuer spreads. The pricing services also review collateral prepayment speeds, loss severity and delinquencies among other collateral performance indicators for the securities valuation, when applicable. Commercial mortgage-backed Level 2 - At September 30, 2018 , the Company’s commercial mortgage-backed fixed maturity investments had a weighted average yield to maturity of 3.6% , a weighted average credit quality of AAA, and a weighted average life of 5.0 years ( December 31, 2017 - 2.9% , AAA and 4.5 years, respectively). Securities held in these sectors are primarily priced by pricing services. The pricing services apply dealer quotes and other available trade information such as bids and offers, prepayment speeds which may be adjusted for the underlying collateral or current price data, the U.S. treasury curve and swap curve as well as cash settlement. The pricing services discount the expected cash flows for each security held in this sector using a spread adjusted benchmark yield based on the characteristics of the security. Asset-backed Level 2 - At September 30, 2018 , the Company’s asset-backed fixed maturity investments had a weighted average yield to maturity of 3.7% , a weighted average credit quality of AAA and a weighted average life of 3.3 years ( December 31, 2017 - 2.8% , AAA and 3.0 years, respectively). The underlying collateral for the Company’s asset-backed fixed maturity investments primarily consists of bank loans, student loans, credit card receivables, auto loans and other receivables. Securities held in these sectors are primarily priced by pricing services. The pricing services apply dealer quotes and other available trade information such as bids and offers, prepayment speeds which may be adjusted for the underlying collateral or current price data, the U.S. treasury curve and swap curve as well as cash settlement. The pricing services determine the expected cash flows for each security held in this sector using historical prepayment and default projections for the underlying collateral and current market data. In addition, a spread is applied to the relevant benchmark and used to discount the cash flows noted above to determine the fair value of the securities held in this sector. Short Term Investments Level 2 - At September 30, 2018 , the Company’s short term investments had a weighted average yield to maturity of 1.8% and a weighted average credit quality of AAA ( December 31, 2017 - 1.4% and AAA, respectively). The fair value of the Company’s portfolio of short term investments is generally determined using amortized cost which approximates fair value and, in certain cases, in a manner similar to the Company’s fixed maturity investments noted above. Equity Investments, Classified as Trading Level 1 - The fair value of the Company’s portfolio of equity investments, classified as trading is primarily priced by pricing services, reflecting the closing price quoted for the final trading day of the period. When pricing these securities, the pricing services utilize daily data from many real time market sources, including applicable securities exchanges. All data sources are regularly reviewed for accuracy to attempt to ensure the most reliable price source was used for each security. Other investments Catastrophe bonds Level 2 - The Company’s other investments include investments in catastrophe bonds which are recorded at fair value based on broker or underwriter bid indications. Other assets and liabilities Derivatives Level 1 and Level 2 - Other assets and liabilities include certain derivatives entered into by the Company. The fair value of these transactions includes certain exchange traded futures contracts which are considered Level 1, and foreign currency contracts and certain credit derivatives, determined using standard industry valuation models and considered Level 2, as the inputs to the valuation model are based on observable market inputs. For credit derivatives, these inputs include credit spreads, credit ratings of the underlying referenced security, the risk free rate and the contract term. For foreign currency contracts, these inputs include spot rates and interest rate curves. Level 3 Assets and Liabilities Measured at Fair Value Below is a summary of quantitative information regarding the significant observable and unobservable inputs (Level 3) used in determining the fair value of assets and liabilities measured at fair value on a recurring basis: At September 30, 2018 Fair Value (Level 3) Valuation Technique Unobservable (U) and Observable (O) Inputs Low High Weighted Average or Actual Other assets and (liabilities) Assumed and ceded (re)insurance contracts $ 994 Internal valuation model Bond price (O) $ 101.31 $ 111.12 $ 106.80 Liquidity discount (U) n/a n/a 1.3 % Assumed and ceded (re)insurance contracts (9,943 ) Internal valuation model Net undiscounted cash flows (U) n/a n/a $ 10,180 Expected loss ratio (U) n/a n/a 38.2 % Net acquisition expense ratio (O) n/a n/a 4.9 % Contract period (O) 2.0 years 5.0 years 4.7 years Discount rate (U) n/a n/a 3.0 % Total other assets and (liabilities) $ (8,949 ) Below is a reconciliation of the beginning and ending balances, for the periods shown, of assets and liabilities measured at fair value on a recurring basis using Level 3 inputs. Interest and dividend income are included in net investment income and are excluded from the reconciliation. Other assets and (liabilities) Balance - January 1, 2018 $ (2,952 ) Total realized and unrealized gains Included in other income 2,399 Purchases (9,379 ) Settlements 983 Balance - September 30, 2018 $ (8,949 ) Other assets and (liabilities) Balance - January 1, 2017 $ (13,004 ) Total realized and unrealized gains Included in other income 3,525 Purchases 49 Settlements 5,937 Balance - September 30, 2017 $ (3,493 ) Other assets and liabilities Assumed and ceded (re)insurance contracts Level 3 - At September 30, 2018 , the Company had a $1.0 million net asset related to an assumed reinsurance contract accounted for at fair value, with the fair value obtained through the use of an internal valuation model. The inputs to the internal valuation model are principally based on indicative pricing obtained from independent brokers and pricing vendors for similarly structured marketable securities. The most significant unobservable inputs include prices for similar marketable securities and a liquidity premium. The Company considers the prices for similar securities to be unobservable, as there is little, if any market activity for these similar assets. In addition, the Company has estimated a liquidity premium that would be required if the Company attempted to effectively exit its position by executing a short sale of these securities. Generally, an increase in the prices for similar marketable securities or a decrease in the liquidity premium would result in an increase in the expected profit and ultimate fair value of this assumed reinsurance contract. Level 3 - At September 30, 2018 , the Company had a $9.9 million net liability related to assumed and ceded (re)insurance contracts accounted for at fair value, with the fair value obtained through the use of an internal valuation model. The inputs to the internal valuation model are principally based on proprietary data as observable market inputs are generally not available. The most significant unobservable inputs include the assumed and ceded expected net cash flows related to the contracts, including the expected premium, acquisition expenses and losses; the expected loss ratio and the relevant discount rate used to present value the net cash flows. The contract period and acquisition expense ratio are considered an observable input as each is defined in the contract. Generally, an increase in the net expected cash flows and expected term of the contract and a decrease in the discount rate, expected loss ratio or acquisition expense ratio, would result in an increase in the expected profit and ultimate fair value of these assumed and ceded (re)insurance contracts. Financial Instruments Disclosed, But Not Carried, at Fair Value The Company uses various financial instruments in the normal course of its business. The Company’s insurance contracts are excluded from the fair value of financial instruments accounting guidance, unless the Company elects the fair value option, and therefore, are not included in the amounts discussed herein. The carrying values of cash and cash equivalents, accrued investment income, receivables for investments sold, certain other assets, payables for investments purchased, certain other liabilities, and other financial instruments not included herein approximated their fair values. Debt Included on the Company’s consolidated balance sheet at September 30, 2018 were debt obligations of $990.7 million ( December 31, 2017 - $989.6 million ). At September 30, 2018 , the fair value of the Company’s debt obligations was $980.3 million ( December 31, 2017 – $1,018.2 million ). The fair value of the Company’s debt obligations is determined using indicative market pricing obtained from third-party service providers, which the Company considers Level 2 in the fair value hierarchy. There have been no changes during the period in the Company’s valuation technique used to determine the fair value of the Company’s debt obligations. The Fair Value Option for Financial Assets and Financial Liabilities The Company has elected to account for certain financial assets and financial liabilities at fair value using the guidance under FASB ASC Topic Financial Instruments as the Company believes it represents the most meaningful measurement basis for these assets and liabilities. Below is a summary of the balances the Company has elected to account for at fair value: September 30, December 31, Other investments $ 738,919 $ 594,793 Other assets $ 5,259 $ 2,542 Other liabilities $ 14,208 $ 5,494 Included in net investment income for the three and nine months ended September 30, 2018 were net unrealized gains of $9.1 million and $17.8 million , respectively, related to the changes in fair value of other investments ( 2017 – gains of $9.8 million and $2.7 million , respectively). Included in other income for the three and nine months ended September 30, 2018 were net unrealized gains of $Nil and $Nil , respectively, related to the changes in the fair value of other assets and liabilities ( 2017 - $Nil and $Nil , respectively). Measuring the Fair Value of Other Investments Using Net Asset Valuations The table below shows the Company’s portfolio of other investments measured using net asset valuations as a practical expedient: At September 30, 2018 Fair Value Unfunded Redemption Frequency Redemption Redemption Private equity partnerships $ 185,121 $ 416,847 See below See below See below Senior secured bank loan funds 17,057 20,262 See below See below See below Hedge funds 11,615 — See below See below See below Total other investments measured using net asset valuations $ 213,793 $ 437,109 Private equity partnerships – The Company’s investments in private equity partnerships included alternative asset limited partnerships (or similar corporate structures) that invest in certain private equity asset classes, including U.S. and global leveraged buyouts, mezzanine investments, distressed securities, real estate, and oil, gas and power. The Company generally has no right to redeem its interest in any of these private equity partnerships in advance of dissolution of the applicable private equity partnership. Instead, the nature of these investments is that distributions are received by the Company in connection with the liquidation of the underlying assets of the respective private equity partnership. It is estimated that the majority of the underlying assets of the limited partnerships would liquidate over 7 to 10 years from inception of the respective limited partnership. Senior secured bank loan funds – At September 30, 2018 , the Company had $17.1 million invested in closed end funds which invest primarily in loans. The Company has no right to redeem its investment in these funds. It is estimated that the majority of the underlying assets in these closed end funds would begin to liquidate over 4 to 5 years from inception of the applicable fund. Hedge funds – The Company invests in hedge funds that pursue multiple strategies. At September 30, 2018 , the Company had $11.6 million of investments in hedge funds that pursue multiple strategies. This included an investment of $11.3 million in a fund primarily focused on global credit opportunities which is redeemable at the option of the shareholder. The remainder of the Company’s hedge fund investments consisted of so called “side pocket” investments which are not redeemable at the option of the shareholder.

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Reinsurance	REINSURANCE The Company purchases reinsurance and other protection to manage its risk portfolio and to reduce its exposure to large losses. The Company currently has in place contracts that provide for recovery of a portion of certain claims and claim expenses, generally in excess of various retentions or on a proportional basis. In addition to loss recoveries, certain of the Company’s ceded reinsurance contracts provide for payments of additional premiums, for reinstatement premiums and for lost no-claims bonuses, which are incurred when losses are ceded to the respective reinsurance contracts. The Company remains liable to the extent that any reinsurer fails to meet its obligations. The following table sets forth the effect of reinsurance and retrocessional activity on premiums written and earned and on net claims and claim expenses incurred: Three months ended Nine months ended September 30, September 30, September 30, September 30, Premiums written Direct $ 74,635 $ 64,040 $ 250,375 $ 205,253 Assumed 551,042 576,229 2,512,297 2,184,521 Ceded (172,422 ) (157,048 ) (1,041,864 ) (806,672 ) Net premiums written $ 453,255 $ 483,221 $ 1,720,808 $ 1,583,102 Premiums earned Direct $ 73,356 $ 61,908 $ 213,292 $ 176,433 Assumed 760,920 712,499 1,968,138 1,731,845 Ceded (302,427 ) (226,615 ) (779,914 ) (612,176 ) Net premiums earned $ 531,849 $ 547,792 $ 1,401,516 $ 1,296,102 Claims and claim expenses Gross claims and claim expenses incurred $ 514,873 $ 2,482,510 $ 817,560 $ 2,924,217 Claims and claim expenses recovered (104,363 ) (1,260,814 ) (175,180 ) (1,366,853 ) Net claims and claim expenses incurred $ 410,510 $ 1,221,696 $ 642,380 $ 1,557,364 At September 30, 2018 , the Company’s reinsurance recoverable balance was $1.2 billion ( December 31, 2017 - $1.6 billion ). Of this amount, 52.5% is fully collateralized by our reinsurers, 46.4% is recoverable from reinsurers rated A- or higher by major rating agencies and 1.1% is recoverable from reinsurers rated lower than A- by major rating agencies ( December 31, 2017 - 54.5% , 44.5% and 1.0% , respectively). The reinsurers with the three largest balances accounted for 12.2% , 12.0% and 9.2% , respectively, of the Company’s reinsurance recoverable balance at September 30, 2018 ( December 31, 2017 - 10.4% , 7.5% and 7.3% , respectively). The valuation allowance recorded against reinsurance recoverable was $6.3 million at September 30, 2018 ( December 31, 2017 - $7.0 million ). The three largest company-specific components of the valuation allowance represented 19.9% , 19.8% and 18.0% , respectively, of the Company’s total valuation allowance at September 30, 2018 ( December 31, 2017 - 11.1% , 9.2% and 8.4% , respectively).

Reserve for Claims and Claim Ex

Reserve for Claims and Claim Expenses	9 Months Ended
	Sep. 30, 2018
Insurance Loss Reserves [Abstract]
Reserve for Claims and Claim Expenses	RESERVE FOR CLAIMS AND CLAIM EXPENSES The Company believes the most significant accounting judgment made by management is its estimate of claims and claim expense reserves. Claims and claim expense reserves represent estimates, including actuarial and statistical projections at a given point in time, of the ultimate settlement and administration costs for unpaid claims and claim expenses arising from the insurance and reinsurance contracts the Company sells. The Company establishes its claims and claim expense reserves by taking claims reported to the Company by insureds and ceding companies, but which have not yet been paid (“case reserves”), adding estimates for the anticipated cost of claims incurred but not yet reported to the Company, or incurred but not enough reported to the Company (collectively referred to as “IBNR”) and, if deemed necessary, adding costs for additional case reserves which represent the Company’s estimates for claims related to specific contracts previously reported to the Company which it believes may not be adequately estimated by the client as of that date, or adequately covered in the application of IBNR. The following table summarizes the Company’s claims and claim expense reserves by segment, allocated between case reserves, additional case reserves and IBNR: At September 30, 2018 Case Reserves Additional Case Reserves IBNR Total Property $ 610,932 $ 744,391 $ 774,220 $ 2,129,543 Casualty and Specialty 773,732 102,631 1,940,244 2,816,607 Other 3,240 — 3,108 6,348 Total $ 1,387,904 $ 847,022 $ 2,717,572 $ 4,952,498 At December 31, 2017 Property $ 696,285 $ 896,522 $ 893,583 $ 2,486,390 Casualty and Specialty 689,962 124,923 1,760,607 2,575,492 Other 6,605 — 11,921 18,526 Total $ 1,392,852 $ 1,021,445 $ 2,666,111 $ 5,080,408 Activity in the liability for unpaid claims and claim expenses is summarized as follows: Nine months ended September 30, 2018 2017 Net reserves as of January 1 $ 3,493,778 $ 2,568,730 Net incurred related to: Current year 839,360 1,561,027 Prior years (196,980 ) (3,663 ) Total net incurred 642,380 1,557,364 Net paid related to: Current year 48,075 158,685 Prior years 326,692 396,411 Total net paid 374,767 555,096 Foreign exchange (12,952 ) 33,011 Net reserves as of September 30 3,748,439 3,604,009 Reinsurance recoverable as of September 30 1,204,059 1,588,304 Gross reserves as of September 30 $ 4,952,498 $ 5,192,313 Prior Year Development of the Reserve for Net Claims and Claim Expenses The Company’s estimates of claims and claim expense reserves are not precise in that, among other things, they are based on predictions of future developments and estimates of future trends and other variable factors. Some, but not all, of the Company’s reserves are further subject to the uncertainty inherent in actuarial methodologies and estimates. Because a reserve estimate is simply an insurer’s estimate at a point in time of its ultimate liability, and because there are numerous factors that affect reserves and claims payments that cannot be determined with certainty in advance, the Company’s ultimate payments will vary, perhaps materially, from its estimates of reserves. If the Company determines in a subsequent period that adjustments to its previously established reserves are appropriate, such adjustments are recorded in the period in which they are identified. On a net basis, the Company’s cumulative favorable or unfavorable development is generally reduced by offsetting changes in its reinsurance recoverables, as well as changes to loss related premiums such as reinstatement premiums and redeemable noncontrolling interest for changes in claims and claim expenses that impact DaVinciRe, all of which generally move in the opposite direction to changes in the Company’s ultimate claims and claim expenses. The following table details the Company’s prior year development by segment of its liability for unpaid claims and claim expenses: Nine months ended September 30, 2018 2017 (Favorable) adverse development (Favorable) adverse development Property $ (172,872 ) $ (16,968 ) Casualty and Specialty (24,020 ) 14,015 Other (88 ) (710 ) Total favorable development of prior accident years net claims and claim expenses $ (196,980 ) $ (3,663 ) Changes to prior year estimated claims reserves increased the Company’s net income by $197.0 million during the nine months ended September 30, 2018 , ( 2017 - decreased the Company’s net loss by $3.7 million ), excluding the consideration of changes in reinstatement, adjustment or other premium changes, profit commissions, redeemable noncontrolling interest - DaVinciRe and income tax. Property Segment The following tables detail the development of the Company’s liability for unpaid claims and claim expenses for its Property segment, allocated between large and small catastrophe net claims and claim expenses and attritional net claims and claim expenses, included in the other line item: Nine months ended September 30, 2018 (Favorable) adverse development Catastrophe net claims and claim expenses Large catastrophe events 2017 Catastrophe Events $ (151,155 ) Other (7,313 ) Total large catastrophe events (158,468 ) Small catastrophe events and attritional loss movements Other small catastrophe events and attritional loss movements (8,722 ) Total small catastrophe events and attritional loss movements (8,722 ) Total catastrophe and attritional net claims and claim expenses (167,190 ) Actuarial assumption changes (5,682 ) Total net favorable development of prior accident years net claims and claim expenses $ (172,872 ) The net favorable development of prior accident years net claims and claim expenses within the Company’s Property segment in the nine months ended September 30, 2018 of $172.9 million was comprised of net favorable development of $158.5 million related to large catastrophe events, net favorable development of $8.7 million related to small catastrophe events and attritional loss movements and $5.7 million of net favorable development associated with actuarial assumption changes. Included in net favorable development of prior accident years net claims and claim expenses from large events was $151.2 million of net decreases in the estimated ultimate losses associated with Hurricanes Harvey, Irma and Maria, the Mexico City Earthquake, the wildfires in California during the fourth quarter of 2017 and certain losses associated with aggregate loss contracts (collectively, the “2017 Catastrophe Events”). The Company’s Property segment also experienced net favorable development of $8.7 million associated with a number of other small catastrophe events as well as attritional loss movements related to lines of business where the Company principally estimates net claims and claim expenses using traditional actuarial methods. Nine months ended September 30, 2017 (Favorable) adverse development Catastrophe net claims and claim expenses Large catastrophe events New Zealand Earthquake (2011) $ 5,807 New Zealand Earthquake (2010) 5,001 April and May U.S. Tornadoes (2011) (4,163 ) Other (3,881 ) Total large catastrophe events 2,764 Small catastrophe events and attritional loss movements Fort McMurray Wildfire (2016) (6,386 ) Tianjin Explosion (2015) (4,896 ) Other small catastrophe events and attritional loss movements (9,293 ) Total small catastrophe events and attritional loss movements (20,575 ) Total catastrophe and attritional net claims and claim expenses (17,811 ) Actuarial assumption changes 843 Total net favorable development of prior accident years net claims and claim expenses $ (16,968 ) The net favorable development of prior accident years net claims and claim expenses within the Company’s Property segment in the nine months ended September 30, 2017 of $17.0 million was principally comprised of net adverse development of $2.8 million related to large catastrophe events, net favorable development of $20.6 million related to small catastrophe events and attritional loss movements and $0.8 million of net adverse development associated with actuarial assumption changes. Included in net adverse development of prior accident years net claims and claim expenses from large events was adverse development of $5.8 million related to the 2011 New Zealand Earthquake and $5.0 million related to the 2010 New Zealand Earthquake due to increases in the estimated expected losses associated with these events. Partially offsetting these events was favorable development of $4.2 million and $3.9 million related to the 2011 April and May U.S. Tornadoes and a number of other events, respectively, due to reductions in the estimated ultimate losses associated with these events. Included in net favorable development of prior accident years net claims and claims expenses from small events was a reduction in the estimated ultimate losses associated with the 2016 Fort McMurray Wildfire of $6.4 million and the 2015 Tianjin Explosion of $4.9 million . In addition, the Company’s Property segment experienced net favorable development of $9.3 million associated with a number of other small catastrophe events and attritional loss movements related to lines of business where the Company principally estimates net claims and claim expenses using traditional actuarial methods. Casualty and Specialty Segment The following table details the development of the Company’s liability for unpaid claims and claim expenses for its Casualty and Specialty segment: Nine months ended September 30, 2018 2017 (Favorable) adverse development (Favorable) adverse development Actuarial methods $ (16,234 ) $ (17,004 ) Ogden Rate change — 33,481 Actuarial assumption changes (7,786 ) (2,462 ) Total (favorable) adverse development of prior accident years net claims and claim expenses $ (24,020 ) $ 14,015 The net favorable development of prior accident years net claims and claim expenses within the Company’s Casualty and Specialty segment in the nine months ended September 30, 2018 of $24.0 million was driven by reported losses generally coming in lower than expected on attritional net claims and claim expenses and certain assumption changes across a number of lines of business. The net adverse development of prior accident years net claims and claim expenses within the Company’s Casualty and Specialty segment in the nine months ended September 30, 2017 of $14.0 million was driven by $33.5 million of adverse development associated with the change in the discount rate used to calculate lump sum awards in U.K. bodily injury cases (the “Ogden Rate”), from 2.5% , to minus 0.75% . Notwithstanding the impact of the Ogden Rate change, the Company experienced $17.0 million of net favorable development in the nine months ended September 30, 2017 related to actual reported losses coming in lower than expected on attritional net claims and claim expenses across a number of lines of business and $2.5 million of net favorable development associated with actuarial assumption changes.

Debt and Credit Facilities

Debt and Credit Facilities	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt and Credit Facilities	DEBT AND CREDIT FACILITIES Except as noted below, there have been no material changes to the Company’s debt obligations and credit facilities as described in its Form 10-K for the year ended December 31, 2017 . Debt Obligations A summary of the Company’s debt obligations on its consolidated balance sheets is set forth below: September 30, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value 3.450% Senior Notes due 2027 $ 282,585 $ 295,673 $ 294,654 $ 295,303 3.700% Senior Notes due 2025 293,559 297,594 302,781 297,318 5.750% Senior Notes due 2020 256,250 249,520 263,750 249,272 4.750% Senior Notes due 2025 (DaVinciRe) (1) 147,924 147,962 157,050 147,730 $ 980,318 $ 990,749 $ 1,018,235 $ 989,623 (1) RenaissanceRe owns a noncontrolling economic interest in its joint venture DaVinciRe. Because RenaissanceRe controls a majority of DaVinciRe’s outstanding voting rights, the consolidated financial statements of DaVinciRe are included in the consolidated financial statements of RenaissanceRe. However, RenaissanceRe does not guarantee or provide credit support for DaVinciRe and RenaissanceRe’s financial exposure to DaVinciRe is limited to its investment in DaVinciRe’s shares and counterparty credit risk arising from reinsurance transactions. Credit Facilities The outstanding amounts issued or drawn under each of the Company’s significant credit facilities is set forth below: At September 30, 2018 Issued or Drawn RenaissanceRe Revolving Credit Facility (1) $ — Uncommitted Standby Letter of Credit Facility with Wells Fargo 87,057 Bilateral Letter of Credit Facility with Citibank Europe 180,416 Renaissance Reinsurance FAL Facility 180,000 Total credit facilities in U.S. dollars $ 447,473 Specialty Risks FAL Facility (1) £ — Total credit facilities in pound sterling £ — (1) At September 30, 2018, no amounts were issued or drawn under these facilities. National Australia Bank Limited Standby Letter of Credit Agreement Effective as of March 23, 2018, the Company terminated the Standby Letter of Credit Agreement, dated as of May 19, 2015, among National Australia Bank Limited (“NAB”) and Renaissance Reinsurance, RenaissanceRe Specialty Risks Ltd., DaVinci and Platinum Underwriters Bermuda, Ltd. (collectively, the “NAB Facility Applicants”) (the “NAB Standby Letter of Credit Agreement”). The NAB Standby Letter of Credit Agreement provided for a secured, uncommitted facility under which letters of credit were issued from time to time for the respective accounts of the NAB Facility Applicants in multiple currencies. RenaissanceRe unconditionally guaranteed the payment obligations of the NAB Facility Applicants, other than DaVinci.

Noncontrolling Interests

Noncontrolling Interests	9 Months Ended
	Sep. 30, 2018
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest [Abstract]
Noncontrolling Interests	NONCONTROLLING INTERESTS A summary of the Company’s redeemable noncontrolling interests on its consolidated balance sheets is set forth below: September 30, December 31, 2017 Redeemable noncontrolling interest - DaVinciRe $ 1,085,985 $ 1,011,659 Redeemable noncontrolling interest - Medici 447,993 284,847 Redeemable noncontrolling interests $ 1,533,978 $ 1,296,506 A summary of the Company’s redeemable noncontrolling interests on its consolidated statements of operations is set forth below: Three months ended Nine months ended September 30, September 30, September 30, September 30, Redeemable noncontrolling interest - DaVinciRe $ 3,730 $ (195,508 ) $ 74,935 $ (127,167 ) Redeemable noncontrolling interest - Medici 2,710 (8,769 ) 15,887 (5,171 ) Net income (loss) attributable to redeemable noncontrolling interests $ 6,440 $ (204,277 ) $ 90,822 $ (132,338 ) Redeemable Noncontrolling Interest – DaVinciRe RenaissanceRe owns a noncontrolling economic interest in DaVinciRe; however, because RenaissanceRe controls a majority of DaVinciRe’s outstanding voting rights, the consolidated financial statements of DaVinciRe are included in the consolidated financial statements of the Company. The portion of DaVinciRe’s earnings owned by third parties is recorded in the consolidated statements of operations as net income attributable to redeemable noncontrolling interests. The Company’s noncontrolling economic ownership in DaVinciRe was 22.1% at September 30, 2018 ( December 31, 2017 - 22.1% ). DaVinciRe shareholders are party to a shareholders agreement which provides DaVinciRe shareholders, excluding RenaissanceRe, with certain redemption rights that enable each shareholder to notify DaVinciRe of such shareholder’s desire for DaVinciRe to repurchase up to half of such shareholder’s initial aggregate number of shares held, subject to certain limitations, such as limiting the aggregate of all share repurchase requests to 25% of DaVinciRe’s capital in any given year and satisfying all applicable regulatory requirements. If total shareholder requests exceed 25% of DaVinciRe’s capital, the number of shares repurchased will be reduced among the requesting shareholders pro-rata, based on the amounts desired to be repurchased. Shareholders desiring to have DaVinci repurchase their shares must notify DaVinciRe before March 1 of each year. The repurchase price will be based on GAAP book value as of the end of the year in which the shareholder notice is given, and the repurchase will be effective as of January 1 of the following year. The repurchase price is generally subject to a true-up for potential development on outstanding loss reserves after settlement of all claims relating to the applicable years. 2017 During January 2017, DaVinciRe redeemed $75.0 million of its outstanding shares from certain existing DaVinciRe shareholders, including RenaissanceRe. In connection with the redemption, DaVinciRe retained a $7.5 million holdback. In addition, RenaissanceRe sold an aggregate of $24.0 million of its shares in DaVinciRe to an existing shareholder and a new shareholder. The Company’s noncontrolling economic ownership in DaVinciRe subsequent to these transactions was 22.6% , effective January 1, 2017. During July 2017, RenaissanceRe purchased $12.0 million of DaVinciRe’s outstanding shares from an existing third-party shareholder. The Company’s noncontrolling economic ownership in DaVinciRe subsequent to these transactions was 23.5% , effective July 1, 2017. Effective October 1, 2017, DaVinciRe completed an equity capital raise of $248.6 million from third-party investors and RenaissanceRe. In addition, RenaissanceRe sold an aggregate of $49.7 million of its shares in DaVinciRe to third-party investors. The Company’s noncontrolling economic ownership in DaVinciRe subsequent to these transactions was 22.1% , effective October 1, 2017. The Company expects its noncontrolling economic ownership in DaVinciRe to fluctuate over time. The activity in redeemable noncontrolling interest – DaVinciRe is detailed in the table below: Three months ended Nine months ended September 30, September 30, September 30, September 30, Beginning balance $ 1,082,425 $ 1,019,918 $ 1,011,659 $ 994,458 Redemption of shares from redeemable noncontrolling interest, net of adjustments (170 ) (12,068 ) (609 ) (78,870 ) Sale of shares to redeemable noncontrolling interests — — — 23,921 Net income (loss) attributable to redeemable noncontrolling interest 3,730 (195,508 ) 74,935 (127,167 ) Ending balance $ 1,085,985 $ 812,342 $ 1,085,985 $ 812,342 Redeemable Noncontrolling Interest - RenaissanceRe Medici Fund Ltd. (“Medici”) Medici is an exempted company incorporated under the laws of Bermuda and its objective is to seek to invest substantially all of its assets in various insurance-based investment instruments that have returns primarily tied to property catastrophe risk. RenaissanceRe owns a noncontrolling economic interest in Medici; however, because RenaissanceRe controls all of Medici’s outstanding voting rights, the financial statements of Medici are included in the consolidated financial statements of the Company. The portion of Medici’s earnings owned by third parties is recorded in the consolidated statements of operations as net income attributable to redeemable noncontrolling interests. Any shareholder may redeem all or any portion of its shares as of the last day of any calendar month, upon at least 30 calendar days’ prior irrevocable written notice to Medici. 2017 During 2017, third-party investors subscribed for $149.2 million and redeemed $48.0 million of the participating, non-voting common shares of Medici. As a result of these net subscriptions, the Company’s noncontrolling economic ownership in Medici was 26.8% , effective at December 31, 2017. 2018 During the nine months ended September 30, 2018 , third-party investors subscribed for $199.5 million and redeemed $52.2 million of the participating, non-voting common shares of Medici. As a result of these net subscriptions, the Company’s noncontrolling economic ownership in Medici was 15.8% at September 30, 2018 . The Company expects its noncontrolling economic ownership in Medici to fluctuate over time. The activity in redeemable noncontrolling interest – Medici is detailed in the table below: Three months ended Nine months ended September 30, September 30, September 30, September 30, Beginning balance $ 411,003 $ 222,165 $ 284,847 $ 181,136 Redemption of shares from redeemable noncontrolling interest, net of adjustments (8,720 ) (1,400 ) (52,223 ) (27,310 ) Sale of shares to redeemable noncontrolling interests 43,000 9,391 199,482 72,732 Net income (loss) attributable to redeemable noncontrolling interest 2,710 (8,769 ) 15,887 (5,171 ) Ending balance $ 447,993 $ 221,387 $ 447,993 $ 221,387

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	VARIABLE INTEREST ENTITIES Upsilon RFO Upsilon RFO is a managed joint venture and a Bermuda domiciled SPI that was formed by the Company primarily to provide additional capacity to the worldwide aggregate and per-occurrence retrocessional property catastrophe excess of loss market. The shareholders (other than the Class A shareholder) participate in substantially all of the profits or losses of Upsilon RFO while their shares remain outstanding. The shareholders (other than the Class A shareholder) indemnify Upsilon RFO against losses relating to insurance risk and therefore these shares have been accounted for as prospective reinsurance under FASB ASC Topic Financial Services - Insurance . Upsilon RFO is considered a VIE as it has insufficient equity capital to finance its activities without additional financial support. The Company is the primary beneficiary of Upsilon RFO as it has the power over the activities that most significantly impact the economic performance of Upsilon RFO and has the obligation to absorb expected losses and the right to receive expected benefits that could be significant to Upsilon RFO, in accordance with the accounting guidance. As a result, the Company consolidates Upsilon RFO and all significant inter-company transactions have been eliminated. Other than its equity investment in Upsilon RFO, the Company has not provided financial or other support to Upsilon RFO that it was not contractually required to provide. 2017 During 2017, Upsilon RFO returned $84.3 million of capital to its investors, including $33.0 million to the Company. In addition, during 2017, $180.6 million of Upsilon RFO non-voting preference shares were issued to existing investors therein, including $27.2 million to the Company, and an existing third-party investor purchased $7.5 million of Upsilon RFO non-voting preference shares from the Company. At December 31, 2017, the Company’s participation in the risks assumed by Upsilon RFO was 20.8% . 2018 During the nine months ended September 30, 2018 , $856.7 million of Upsilon RFO non-voting preference shares were issued to existing investors, including $109.8 million to the Company. At September 30, 2018 , the Company’s participation in the risks assumed by Upsilon RFO was 14.0% . Amounts received by the Company prior to December 31, 2017 were included in other liabilities on the Company’s consolidated balance sheet at December 31, 2017, and were also included in other operating cash flows on the Company’s consolidated statements of cash flows for the year ended December 31, 2017. During the nine months ended September 30, 2018 , in connection with the issuance of the non-voting preference shares of Upsilon RFO, other liabilities were reduced by this amount, and reinsurance balances payable were increased by an offsetting amount, with corresponding impacts to other operating cash flows and the change in reinsurance balances payable on the Company consolidated statements of cash flows for the nine months ended September 30, 2018 . At September 30, 2018 , the Company’s consolidated balance sheet included total assets and total liabilities of Upsilon RFO of $1.6 billion and $1.6 billion , respectively ( December 31, 2017 - $1.2 billion and $1.2 billion , respectively). Mona Lisa Re Ltd. (“Mona Lisa Re”) Mona Lisa Re is licensed as a Bermuda domiciled special purpose insurer to provide reinsurance capacity to subsidiaries of RenaissanceRe, namely Renaissance Reinsurance and DaVinci, through reinsurance agreements which will be collateralized and funded by Mona Lisa Re through the issuance of one or more series of principal-at-risk variable rate notes to third-party investors. Upon issuance of a series of notes by Mona Lisa Re, all of the proceeds from the issuance were deposited into collateral accounts, separated by series, to fund any potential obligation under the reinsurance agreements entered into with Renaissance Reinsurance and/or DaVinci underlying such series of notes. The outstanding principal amount of each series of notes generally will be returned to holders of such notes upon the expiration of the risk period underlying such notes, unless an event occurs which causes a loss under the applicable series of notes, in which case the amount returned will be reduced by such noteholder’s pro rata share of such loss, as specified in the applicable governing documents of such notes. In addition, holders of such notes are generally entitled to interest payments, payable quarterly, as determined by the applicable governing documents of each series of notes. The Company concluded that Mona Lisa Re meets the definition of a VIE as it does not have sufficient equity capital to finance its activities. The Company evaluated its relationship with Mona Lisa Re and concluded it does not have a variable interest in Mona Lisa Re. As a result, the financial position and results of operations of Mona Lisa Re are not consolidated by the Company. The Company has not provided financial or other support to Mona Lisa Re that it was not contractually required to provide. At September 30, 2018 , the total assets and total liabilities of Mona Lisa Re were $0.1 million and $0.1 million , respectively ( December 31, 2017 - $25.9 million and $25.9 million , respectively). On July 6, 2018 , all remaining outstanding series of notes issued by Mona Lisa Re were redeemed and the proceeds were returned to the holders of such notes. The only transactions related to Mona Lisa Re that are recorded in the Company’s consolidated financial statements are the ceded reinsurance agreements entered into by Renaissance Reinsurance and DaVinci which are accounted for as prospective reinsurance under FASB ASC Topic Financial Services - Insurance. Renaissance Reinsurance and DaVinci have together entered into ceded reinsurance contracts with Mona Lisa Re with gross premiums ceded of $0.2 million and $0.2 million , respectively, during the nine months ended September 30, 2018 ( 2017 - $0.2 million and $0.2 million , respectively). In addition, Renaissance Reinsurance and DaVinci recognized ceded premiums earned related to the ceded reinsurance contracts with Mona Lisa Re of $0.2 million and $0.2 million , respectively, during the nine months ended September 30, 2018 ( 2017 - $4.0 million and $2.8 million , respectively). Fibonacci Re Effective November 7, 2016 , Fibonacci Re, a Bermuda-domiciled SPI, was formed to provide collateralized capacity to Renaissance Reinsurance and its affiliates. Upon issuance of a series of notes by Fibonacci Re, all of the proceeds from the issuance are deposited into collateral accounts, separated by series, to fund any potential obligation under the reinsurance agreements entered into with Renaissance Reinsurance underlying such series of notes. The outstanding principal amount of each series of notes generally is expected to be returned to holders of such notes upon the expiration of the risk period underlying such notes, unless an event occurs which causes a loss under the applicable series of notes, in which case the amount returned is expected to be reduced by such noteholder’s pro rata share of such loss, as specified in the applicable governing documents of such notes. In addition, holders of such notes are generally entitled to interest payments, payable quarterly, as determined by the applicable governing documents of each series of notes. RUM receives an origination and structuring fee in connection with the formation and operation of Fibonacci Re. The Company concluded that Fibonacci Re meets the definition of a VIE as it does not have sufficient equity capital to finance its activities. The Company evaluated its relationship with Fibonacci Re and concluded it is not the primary beneficiary of Fibonacci Re as it does not have power over the activities that most significantly impact the economic performance of Fibonacci Re. As a result, the Company does not consolidate the financial position or results of operations of Fibonacci Re. The only transactions related to Fibonacci Re that will be recorded in the Company’s consolidated financial statements will be the ceded reinsurance agreements entered into by Renaissance Reinsurance that are accounted for as prospective reinsurance under FASB ASC Topic Financial Services - Insurance, and the fair value of the participating notes owned by the Company. Other than its investment in the participating notes of Fibonacci Re, the Company has not provided financial or other support to Fibonacci Re that it was not contractually required to provide. The fair value of the Company’s investment in the participating notes of Fibonacci Re is included in other investments. Net of third-party investors, the fair value of the Company’s investment in Fibonacci Re was $8.5 million at September 30, 2018 ( December 31, 2017 - $14.1 million ). Renaissance Reinsurance entered into ceded reinsurance contracts with Fibonacci Re with ceded premiums of $9.1 million and ceded premiums earned of $6.8 million during the nine months ended September 30, 2018 ( 2017 - $9.4 million and $6.2 million , respectively). Langhorne Effective December 22, 2017, the Company and Reinsurance Group of America, Incorporated closed Langhorne, an initiative to source third party capital to support reinsurers targeting large in-force life and annuity blocks. In connection with Langhorne, as of September 30, 2018 the Company had invested $1.3 million in Langhorne Holdings ( December 31, 2017 - $0.6 million ), a company that owns and manages certain reinsurance entities within Langhorne. In addition, as of September 30, 2018 the Company had invested $0.1 million in Langhorne Partners ( December 31, 2017 - $Nil ), the general partner for Langhorne and the entity which manages the third-party investors investing into Langhorne Holdings. The Company concluded that Langhorne Holdings meets the definition of a VIE as the voting rights are not proportional with the obligations to absorb losses and rights to receive residual returns. The Company evaluated its relationship with Langhorne Holdings and concluded it is not the primary beneficiary of Langhorne Holdings, as it does not have power over the activities that most significantly impact the economic performance of Langhorne Holdings. As a result, the Company does not consolidate the financial position or results of operations of Langhorne Holdings. The Company separately evaluated Langhorne Partners and concluded that it was not a VIE. The Company accounts for its investments in Langhorne Holdings and Langhorne Partners under the equity method of accounting, one quarter in arrears. The Company anticipates that its absolute investment in Langhorne will increase, perhaps materially, as in-force life and annuity blocks of businesses are written. The Company expects its absolute and relative ownership in Langhorne Partners to remain stable. Other than its current and committed future equity investment in Langhorne, the Company has not provided financial or other support to Langhorne that it was not contractually required to provide.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2018
Stockholders' Equity Note [Abstract]
Shareholders' Equity	SHAREHOLDERS’ EQUITY Dividends The Board of Directors of RenaissanceRe declared dividends, payable to common shareholders of record on each of March 15, 2018, June 15, 2018 and September 14, 2018, of $0.33 per common share, and the Company paid the dividends on March 29, 2018, June 29, 2018 and September 28, 2018, respectively. The Board of Directors approved the payment of quarterly dividends on the Series C 6.08% Preference Shares, Series E 5.375% Preference Shares and 5.750% Series F Preference Shares to preference shareholders of record in the amounts and on the quarterly record dates and dividend payment dates set forth in the prospectus supplement and Certificate of Designation for the applicable series of preference shares, unless and until further action is taken by the Board of Directors. The dividend payment dates for the preference shares will be the first day of March, June, September and December of each year (or if this date is not a business day, on the business day immediately following this date). The record dates for the preference share dividends are one day prior to the dividend payment dates. The amount of the dividend on the Series C 6.08% Preference Shares is an amount per share equal to 6.08% of the liquidation preference per annum (the equivalent to $1.52 per share per annum, or $0.38 per share per quarter). The amount of the dividend on the Series E 5.375% Preference Shares is an amount per share equal to 5.375% of the liquidation preference per annum (the equivalent to $1.34375 per share per annum, or $0.3359375 per share per quarter). The amount of the dividend on the 5.750% Series F Preference Shares is an amount per share equal to 5.750% of the liquidation preference per annum (the equivalent to $1,437.50 per 5.750% Series F Preference Share per annum, or $359.375 per 5.750% Series F Preference Share per quarter, or $1.4375 per Depositary Share per annum, or $0.359375 per Depositary Share per quarter). During the nine months ended September 30, 2018 , the Company paid $20.9 million in preference share dividends ( 2017 - $16.8 million ) and $39.6 million in common share dividends ( 2017 - $38.6 million ). Preference Shares In June 2018, the Company issued 10,000 shares of its 5.750% Series F Preference Shares, $1.00 par value and liquidation preference $25,000 per share (equivalent to 10,000,000 Depositary Shares, each of which represents a 1/1,000th interest in a 5.750% Series F Preference Share). The 5.750% Series F Preference Shares have no stated maturity date and may be redeemed at a redemption price of $25,000 per share (equivalent to $25.00 per Depositary Share), plus declared and unpaid dividends, at RenaissanceRe’s option on or after June 30, 2023, provided that no redemption may occur prior to June 30, 2028 unless certain redemption requirements are met. In certain circumstances, such as a change in tax law or a capital disqualification event, the Company may redeem the 5.750% Series F Preference Shares prior to June 30, 2023. In addition, the Company may redeem the 5.750% Series F Preference Shares prior to June 30, 2023 at a redemption price of $26,000 per share (equivalent to $26.00 per Depositary Share), plus accrued and unpaid dividends, in certain circumstances where the 5.750% Series F Preference Shares are entitled to vote on an amalgamation, consolidation, merger or other similar corporate transaction, or change in Bermuda law. Dividends on the 5.750% Series F Preference Shares are payable on a non-cumulative basis, only when, as and if declared by the Board of Directors, at an annual rate of 5.750% of the liquidation preference per annum (the equivalent to $1,437.50 per 5.750% Series F Preference Share per annum, or $359.375 per 5.750% Series F Preference Share per quarter, or $1.4375 per Depositary Share per annum, or $0.359375 per Depositary Share per quarter). Unless certain dividend payments are made on the 5.750% Series F Preference Shares, RenaissanceRe will be restricted from paying any dividends on and repurchasing its common shares. Share Repurchases The Company’s share repurchase program may be effected from time to time, depending on market conditions and other factors, through open market purchases and privately negotiated transactions. On November 10, 2017 , RenaissanceRe’s Board of Directors approved a renewal of its authorized share repurchase program for an aggregate amount of up to $500.0 million . Unless terminated earlier by RenaissanceRe’s Board of Directors, the program will expire when the Company has repurchased the full value of the common shares authorized. The Company’s decision to repurchase common shares will depend on, among other matters, the market price of the common shares and the capital requirements of the Company. During the nine months ended September 30, 2018 , the Company did no t repurchase any of its common shares. At September 30, 2018 , $500.0 million remained available for repurchase under the share repurchase program.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE The following table sets forth the computation of basic and diluted earnings per common share: Three months ended Nine months ended (common shares in thousands) September 30, September 30, September 30, September 30, Numerator: Net income (loss) available (attributable) to RenaissanceRe common shareholders $ 32,681 $ (504,812 ) $ 281,182 $ (241,318 ) Amount allocated to participating common shareholders (1) (294 ) (116 ) (2,977 ) (344 ) Net income (loss) allocated to RenaissanceRe common shareholders $ 32,387 $ (504,928 ) $ 278,205 $ (241,662 ) Denominator: Denominator for basic income per RenaissanceRe common share - weighted average common shares 39,624 39,591 39,606 39,979 Per common share equivalents of employee stock options and restricted shares 13 — 21 — Denominator for diluted income per RenaissanceRe common share - adjusted weighted average common shares and assumed conversions 39,637 39,591 39,627 39,979 Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – basic $ 0.82 $ (12.75 ) $ 7.02 $ (6.04 ) Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – diluted $ 0.82 $ (12.75 ) $ 7.02 $ (6.04 ) (1) Represents earnings attributable to holders of unvested restricted shares issued pursuant to the Company’s 2001 Stock Incentive Plan, 2010 Performance-Based Equity Incentive Plan, 2016 Long-Term Incentive Plan and to the Company’s non-employee directors.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2018
Segment Reporting, Measurement Disclosures [Abstract]
Segment Reporting	SEGMENT REPORTING The Company’s reportable segments are defined as follows: (1) Property, which is comprised of catastrophe and other property reinsurance and insurance written on behalf of the Company’s operating subsidiaries and certain joint ventures managed by the Company’s ventures unit, and (2) Casualty and Specialty, which is comprised of casualty and specialty reinsurance and insurance written on behalf of the Company’s operating subsidiaries and certain joint ventures managed by the Company’s ventures unit. In addition to its reportable segments, the Company has an Other category, which primarily includes its strategic investments, investments unit, corporate expenses, capital servicing costs, noncontrolling interests and the remnants of its former Bermuda-based insurance operations. The Company’s Property segment is managed by the Chief Underwriting Officer - Property and the Casualty and Specialty segment is managed by the Chief Underwriting Officer - Casualty and Specialty, each of whom operate under the direction of the Company’s Group Chief Underwriting Officer, who in turn reports to the Company’s President and Chief Executive Officer. The Company does not manage its assets by segment; accordingly, net investment income and total assets are not allocated to the segments. A summary of the significant components of the Company’s revenues and expenses by segment is as follows: Three months ended September 30, 2018 Property Casualty and Specialty Other Total Gross premiums written $ 301,413 $ 324,264 $ — $ 625,677 Net premiums written $ 232,632 $ 220,623 $ — $ 453,255 Net premiums earned $ 293,059 $ 238,791 $ (1 ) $ 531,849 Net claims and claim expenses incurred 265,857 144,671 (18 ) 410,510 Acquisition expenses 45,524 64,238 (1 ) 109,761 Operational expenses 25,577 14,976 40 40,593 Underwriting (loss) income $ (43,899 ) $ 14,906 $ (22 ) (29,015 ) Net investment income 80,696 80,696 Net foreign exchange losses (4,566 ) (4,566 ) Equity in earnings of other ventures 7,648 7,648 Other income 497 497 Net realized and unrealized gains on investments 13,630 13,630 Corporate expenses (6,841 ) (6,841 ) Interest expense (11,769 ) (11,769 ) Income before taxes and redeemable noncontrolling interests 50,280 Income tax expense (1,451 ) (1,451 ) Net income attributable to redeemable noncontrolling interests (6,440 ) (6,440 ) Dividends on preference shares (9,708 ) (9,708 ) Net income available to RenaissanceRe common shareholders $ 32,681 Net claims and claim expenses incurred – current accident year $ 268,022 $ 151,904 $ — $ 419,926 Net claims and claim expenses incurred – prior accident years (2,165 ) (7,233 ) (18 ) (9,416 ) Net claims and claim expenses incurred – total $ 265,857 $ 144,671 $ (18 ) $ 410,510 Net claims and claim expense ratio – current accident year 91.5 % 63.6 % 79.0 % Net claims and claim expense ratio – prior accident years (0.8 )% (3.0 )% (1.8 )% Net claims and claim expense ratio – calendar year 90.7 % 60.6 % 77.2 % Underwriting expense ratio 24.3 % 33.2 % 28.3 % Combined ratio 115.0 % 93.8 % 105.5 % Nine months ended September 30, 2018 Property Casualty and Specialty Other Total Gross premiums written $ 1,561,008 $ 1,201,664 $ — $ 2,762,672 Net premiums written $ 884,541 $ 836,267 $ — $ 1,720,808 Net premiums earned $ 722,246 $ 679,271 $ (1 ) $ 1,401,516 Net claims and claim expenses incurred 222,195 420,273 (88 ) 642,380 Acquisition expenses 127,095 185,429 — 312,524 Operational expenses 75,933 43,121 354 119,408 Underwriting income (loss) $ 297,023 $ 30,448 $ (267 ) 327,204 Net investment income 208,528 208,528 Net foreign exchange losses (11,496 ) (11,496 ) Equity in earnings of other ventures 14,331 14,331 Other income 480 480 Net realized and unrealized losses on investments (86,415 ) (86,415 ) Corporate expenses (21,875 ) (21,875 ) Interest expense (35,304 ) (35,304 ) Income before taxes and redeemable noncontrolling interests 395,453 Income tax expense (2,550 ) (2,550 ) Net income attributable to redeemable noncontrolling interests (90,822 ) (90,822 ) Dividends on preference shares (20,899 ) (20,899 ) Net income available to RenaissanceRe common shareholders $ 281,182 Net claims and claim expenses incurred – current accident year $ 395,067 $ 444,293 $ — $ 839,360 Net claims and claim expenses incurred – prior accident years (172,872 ) (24,020 ) (88 ) (196,980 ) Net claims and claim expenses incurred – total $ 222,195 $ 420,273 $ (88 ) $ 642,380 Net claims and claim expense ratio – current accident year 54.7 % 65.4 % 59.9 % Net claims and claim expense ratio – prior accident years (23.9 )% (3.5 )% (14.1 )% Net claims and claim expense ratio – calendar year 30.8 % 61.9 % 45.8 % Underwriting expense ratio 28.1 % 33.6 % 30.9 % Combined ratio 58.9 % 95.5 % 76.7 % Three months ended September 30, 2017 Property Casualty and Specialty Other Total Gross premiums written $ 325,395 $ 314,881 $ (7 ) $ 640,269 Net premiums written $ 269,393 $ 213,835 $ (7 ) $ 483,221 Net premiums earned $ 336,838 $ 210,961 $ (7 ) $ 547,792 Net claims and claim expenses incurred 1,044,418 177,433 (155 ) 1,221,696 Acquisition expenses 17,514 59,248 (1 ) 76,761 Operational expenses 25,123 17,389 25 42,537 Underwriting (loss) income $ (750,217 ) $ (43,109 ) $ 124 (793,202 ) Net investment income 40,257 40,257 Net foreign exchange losses (156 ) (156 ) Equity in earnings of other ventures 1,794 1,794 Other income 2,996 2,996 Net realized and unrealized gains on investments 42,052 42,052 Corporate expenses (4,413 ) (4,413 ) Interest expense (11,799 ) (11,799 ) Loss before taxes and redeemable noncontrolling interests (722,471 ) Income tax benefit 18,977 18,977 Net loss attributable to redeemable noncontrolling interests 204,277 204,277 Dividends on preference shares (5,595 ) (5,595 ) Net loss attributable to RenaissanceRe common shareholders $ (504,812 ) Net claims and claim expenses incurred – current accident year $ 1,036,586 $ 172,675 $ — $ 1,209,261 Net claims and claim expenses incurred – prior accident years 7,832 4,758 (155 ) 12,435 Net claims and claim expenses incurred – total $ 1,044,418 $ 177,433 $ (155 ) $ 1,221,696 Net claims and claim expense ratio – current accident year 307.7 % 81.9 % 220.8 % Net claims and claim expense ratio – prior accident years 2.4 % 2.2 % 2.2 % Net claims and claim expense ratio – calendar year 310.1 % 84.1 % 223.0 % Underwriting expense ratio 12.6 % 36.3 % 21.8 % Combined ratio 322.7 % 120.4 % 244.8 % Nine months ended September 30, 2017 Property Casualty and Specialty Other Total Gross premiums written $ 1,345,271 $ 1,044,510 $ (7 ) $ 2,389,774 Net premiums written $ 895,728 $ 687,381 $ (7 ) $ 1,583,102 Net premiums earned $ 716,024 $ 580,085 $ (7 ) $ 1,296,102 Net claims and claim expenses incurred 1,116,273 441,801 (710 ) 1,557,364 Acquisition expenses 75,117 173,179 (2 ) 248,294 Operational expenses 76,841 54,708 37 131,586 Underwriting (loss) income $ (552,207 ) $ (89,603 ) $ 668 (641,142 ) Net investment income 148,745 148,745 Net foreign exchange gains 11,118 11,118 Equity in earnings of other ventures 5,830 5,830 Other income 7,053 7,053 Net realized and unrealized gains on investments 143,538 143,538 Corporate expenses (14,335 ) (14,335 ) Interest expense (32,416 ) (32,416 ) Loss before taxes and redeemable noncontrolling interests (371,609 ) Income tax benefit 14,739 14,739 Net loss attributable to RenaissanceRe common shareholders 132,338 132,338 Dividends on preference shares (16,786 ) (16,786 ) Net loss attributable to RenaissanceRe common shareholders $ (241,318 ) Net claims and claim expenses incurred – current accident year $ 1,133,241 $ 427,786 $ — $ 1,561,027 Net claims and claim expenses incurred – prior accident years (16,968 ) 14,015 (710 ) (3,663 ) Net claims and claim expenses incurred – total $ 1,116,273 $ 441,801 $ (710 ) $ 1,557,364 Net claims and claim expense ratio – current accident year 158.3 % 73.7 % 120.4 % Net claims and claim expense ratio – prior accident years (2.4 )% 2.5 % (0.2 )% Net claims and claim expense ratio – calendar year 155.9 % 76.2 % 120.2 % Underwriting expense ratio 21.2 % 39.2 % 29.3 % Combined ratio 177.1 % 115.4 % 149.5 %

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Summary of Derivative Instruments [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS From time to time, the Company may enter into derivative instruments such as futures, options, swaps, forward contracts and other derivative contracts primarily to manage its foreign currency exposure, obtain exposure to a particular financial market, for yield enhancement, or for trading and speculation. The Company’s derivative instruments can be exchange traded or over-the-counter, with over-the-counter derivatives generally traded under International Swaps and Derivatives Association master agreements, which establish the terms of the transactions entered into with the Company’s derivative counterparties. In the event a party becomes insolvent or otherwise defaults on its obligations, a master agreement generally permits the non-defaulting party to accelerate and terminate all outstanding transactions and net the transactions’ marked-to-market values so that a single sum in a single currency will be owed by, or owed to, the non-defaulting party. Effectively, this contractual close-out netting reduces credit exposure from gross to net exposure. Where the Company has entered into master netting agreements with counterparties, or the Company has the legal and contractual right to offset positions, the derivative positions are generally netted by counterparty and are reported accordingly in other assets and other liabilities. The tables below show the gross and net amounts of recognized derivative assets and liabilities at fair value, including the location on the consolidated balance sheets of the Company’s principal derivative instruments: Derivative Assets At September 30, 2018 Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Assets Presented in the Balance Sheet Balance Sheet Location Collateral Net Amount Interest rate futures $ 438 184 $ 254 Other assets $ — $ 254 Interest rate swaps 782 — 782 Other assets — 782 Foreign currency forward contracts (1) 6,547 — 6,547 Other assets — 6,547 Foreign currency forward contracts (2) 1,416 40 1,376 Other assets — 1,376 Credit default swaps 277 — 277 Other assets — 277 Total $ 9,460 $ 224 $ 9,236 $ — $ 9,236 Derivative Liabilities At September 30, 2018 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amounts of Liabilities Presented in the Balance Sheet Balance Sheet Location Collateral Pledged Net Amount Interest rate futures $ 189 184 $ 5 Other liabilities $ 5 $ — Interest rate swaps 232 — 232 Other liabilities 232 — Foreign currency forward contracts (1) 7,272 504 6,768 Other liabilities — 6,768 Foreign currency forward contracts (2) 663 40 623 Other liabilities — 623 Credit default swaps 14 — 14 Other liabilities — 14 Total $ 8,370 $ 728 $ 7,642 $ 237 $ 7,405 (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. (2) Contracts used to manage foreign currency risks in investment operations. Derivative Assets At December 31, 2017 Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Assets Presented in the Balance Sheet Balance Sheet Location Collateral Net Amount Interest rate futures $ 684 524 $ 160 Other assets $ — $ 160 Interest rate swaps 424 — 424 Other assets — 424 Foreign currency forward contracts (1) 3,865 358 3,507 Other assets — 3,507 Foreign currency forward contracts (2) 39 11 28 Other assets — 28 Credit default swaps 1,518 — 1,518 Other assets — 1,518 Total $ 6,530 $ 893 $ 5,637 $ — $ 5,637 Derivative Liabilities At December 31, 2017 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amounts of Liabilities Presented in the Balance Sheet Balance Sheet Location Collateral Pledged Net Amount Interest rate futures $ 729 524 $ 205 Other liabilities $ 205 $ — Foreign currency forward contracts (1) 670 — 670 Other liabilities — 670 Foreign currency forward contracts (2) 115 11 104 Other liabilities — 104 Credit default swaps 22 — 22 Other liabilities 22 — Total $ 1,536 $ 535 $ 1,001 $ 227 $ 774 (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. (2) Contracts used to manage foreign currency risks in investment operations. Refer to “Note 3 . Investments” for information on reverse repurchase agreements. The location and amount of the gain (loss) recognized in the Company’s consolidated statements of operations related to its principal derivative instruments are shown in the following table: Location of gain (loss) recognized on derivatives Amount of gain (loss) recognized on derivatives Three months ended September 30, 2018 2017 Interest rate futures Net realized and unrealized gains (losses) on investments $ 2,760 $ (3,016 ) Interest rate swaps Net realized and unrealized gains (losses) on investments (6 ) 271 Foreign currency forward contracts (1) Net foreign exchange (losses) gains (2,596 ) 2,056 Foreign currency forward contracts (2) Net foreign exchange (losses) gains 650 (40 ) Credit default swaps Net realized and unrealized gains (losses) on investments (191 ) (1,275 ) Total $ 617 $ (2,004 ) Location of gain (loss) recognized on derivatives Amount of gain (loss) recognized on derivatives Nine months ended September 30, 2018 2017 Interest rate futures Net realized and unrealized gains (losses) on investments $ 336 $ (4,064 ) Interest rate swaps Net realized and unrealized gains (losses) on investments 129 271 Foreign currency forward contracts (1) Net foreign exchange (losses) gains (2,227 ) 8,339 Foreign currency forward contracts (2) Net foreign exchange (losses) gains 1,302 (940 ) Credit default swaps Net realized and unrealized gains (losses) on investments (1,228 ) (551 ) Total $ (1,688 ) $ 3,055 (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. (2) Contracts used to manage foreign currency risks in investment operations. The Company is not aware of the existence of any credit-risk related contingent features that it believes would be triggered in its derivative instruments that are in a net liability position at September 30, 2018 . Interest Rate Derivatives The Company uses interest rate futures and swaps within its portfolio of fixed maturity investments to manage its exposure to interest rate risk, which may result in increasing or decreasing its exposure to this risk. Interest Rate Futures The fair value of interest rate futures is determined using exchange traded prices. At September 30, 2018 , the Company had $1.6 billion of notional long positions and $699.0 million of notional short positions of primarily Eurodollar, U.S. treasury and non-U.S. dollar futures contracts ( December 31, 2017 - $1.5 billion and $801.1 million , respectively). Interest Rate Swaps The fair value of interest rate swaps is determined using the relevant exchange traded price where available or a discounted cash flow model based on the terms of the contract and inputs, including, where applicable, observable yield curves. At September 30, 2018 , the Company had $62.6 million of notional positions paying a fixed rate and $29.5 million receiving a fixed rate denominated in U.S. dollars ( December 31, 2017 - $40.3 million and $Nil , respectively). Foreign Currency Derivatives The Company’s functional currency is the U.S. dollar. The Company writes a portion of its business in currencies other than U.S. dollars and may, from time to time, experience foreign exchange gains and losses in the Company’s consolidated financial statements. All changes in exchange rates, with the exception of non-monetary assets and liabilities, are recognized in the Company’s consolidated statements of operations. Underwriting Operations Related Foreign Currency Contracts The Company’s foreign currency policy with regard to its underwriting operations is generally to hold foreign currency assets, including cash, investments and receivables that approximate the foreign currency liabilities, including claims and claim expense reserves and reinsurance balances payable. When necessary, the Company may use foreign currency forward and option contracts to minimize the effect of fluctuating foreign currencies on the value of non-U.S. dollar denominated assets and liabilities associated with its underwriting operations. The fair value of the Company’s underwriting operations related foreign currency contracts is determined using indicative pricing obtained from counterparties or broker quotes. At September 30, 2018 , the Company had outstanding underwriting related foreign currency contracts of $354.4 million in notional long positions and $536.4 million in notional short positions, denominated in U.S. dollars ( December 31, 2017 - $215.4 million and $44.2 million , respectively). Investment Portfolio Related Foreign Currency Forward Contracts The Company’s investment operations are exposed to currency fluctuations through its investments in non-U.S. dollar fixed maturity investments, short term investments and other investments. From time to time, the Company may employ foreign currency forward contracts in its investment portfolio to either assume foreign currency risk or to economically hedge its exposure to currency fluctuations from these investments. The fair value of the Company’s investment portfolio related foreign currency forward contracts is determined using an interpolated rate based on closing forward market rates. At September 30, 2018 , the Company had outstanding investment portfolio related foreign currency contracts of $109.0 million in notional long positions and $62.4 million in notional short positions, denominated in U.S. dollars ( December 31, 2017 - $16.6 million and $5.1 million , respectively). Credit Derivatives The Company’s exposure to credit risk is primarily due to its fixed maturity investments, short term investments, premiums receivable and reinsurance recoverable. From time to time, the Company may purchase credit derivatives to hedge its exposures in the insurance industry, and to assist in managing the credit risk associated with ceded reinsurance. The Company also employs credit derivatives in its investment portfolio to either assume credit risk or hedge its credit exposure. The fair value of credit derivatives is determined using industry valuation models, broker bid indications or internal pricing valuation techniques. The fair value of these credit derivatives can change based on a variety of factors including changes in credit spreads, default rates and recovery rates, the correlation of credit risk between the referenced credit and the counterparty, and market rate inputs such as interest rates. At September 30, 2018 , the Company had outstanding credit derivatives of $1.0 million in notional positions to hedge credit risk and $109.7 million in notional positions to assume credit risk, denominated in U.S. dollars ( December 31, 2017 - $1.0 million and $18.8 million , respectively).

Commitments, Contingencies and

Commitments, Contingencies and Other Items	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Other Items	COMMITMENTS, CONTINGENCIES AND OTHER ITEMS There are no material changes from the commitments and contingencies previously disclosed in the Company’s Form 10-K for the year ended December 31, 2017 . Legal Proceedings The Company and its subsidiaries are subject to lawsuits and regulatory actions in the normal course of business that do not arise from or directly relate to claims on reinsurance treaties or contracts or direct surplus lines insurance policies. In the Company’s industry, business litigation may involve allegations of underwriting or claims-handling errors or misconduct, disputes relating to the scope of, or compliance with, the terms of delegated underwriting agreements, employment claims, regulatory actions or disputes arising from the Company’s business ventures. The Company’s operating subsidiaries are subject to claims litigation involving, among other things, disputed interpretations of policy coverages. Generally, the Company’s direct surplus lines insurance operations are subject to greater frequency and diversity of claims and claims-related litigation than its reinsurance operations and, in some jurisdictions, may be subject to direct actions by allegedly injured persons or entities seeking damages from policyholders. These lawsuits, involving or arising out of claims on policies issued by the Company’s subsidiaries which are typical to the insurance industry in general and in the normal course of business, are considered in its loss and loss expense reserves. In addition, the Company may from time to time engage in litigation or arbitration related to its claims for payment in respect of ceded reinsurance, including disputes that challenge the Company’s ability to enforce its underwriting intent. Such matters could result, directly or indirectly, in providers of protection not meeting their obligations to the Company or not doing so on a timely basis. The Company may also be subject to other disputes from time to time, relating to operational or other matters distinct from insurance or reinsurance claims. Any litigation or arbitration, or regulatory process, contains an element of uncertainty, and the value of an exposure or a gain contingency related to a dispute is difficult to estimate accordingly. Currently, the Company believes that no individual litigation or arbitration to which it is presently a party is likely to have a material adverse effect on its financial condition, business or operations.

Condensed Consolidating Financi

Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries	9 Months Ended
	Sep. 30, 2018
Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries [Abstract]
Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries	CONDENSED CONSOLIDATING FINANCIAL INFORMATION PROVIDED IN CONNECTION WITH OUTSTANDING DEBT OF SUBSIDIARIES The following tables present condensed consolidating balance sheets at September 30, 2018 and December 31, 2017 , condensed consolidating statements of operations and condensed consolidating statements of comprehensive income for the three and nine months ended September 30, 2018 and 2017 , and condensed consolidating statements of cash flows for the nine months ended September 30, 2018 . Each of RenRe North America Holdings Inc. and RenaissanceRe Finance, Inc. is a 100% owned subsidiary of RenaissanceRe. On June 1, 2017, the notes issued by Platinum Underwriters Finance, Inc. (“Platinum Finance”) matured and the Company repaid the aggregate principal amount plus applicable accrued interest in full. Platinum Finance was subsequently dissolved on November 30, 2017. Prior to the liquidation of Platinum Finance, it was a 100% owned subsidiary of RenaissanceRe. For additional information related to the terms of the Company’s outstanding debt securities, see “Note 9. Debt and Credit Facilities” in the “Notes to Consolidated Financial Statements” in the Company’s Form 10-K for the year ended December 31, 2017 and “Note 7 . Debt and Credit Facilities” in the “Notes to Consolidated Financial Statements” included herein. Condensed Consolidating Balance Sheet at September 30, 2018 RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Assets Total investments $ 36,092 $ 110,117 $ 15,504 $ 11,383,978 $ — $ 11,545,691 Cash and cash equivalents 3,734 56 4,372 444,879 — 453,041 Investments in subsidiaries 4,544,513 57,082 1,235,547 — (5,837,142 ) — Due from subsidiaries and affiliates 101,372 101,579 — — (202,951 ) — Premiums receivable — — — 1,787,095 — 1,787,095 Prepaid reinsurance premiums — — — 795,496 — 795,496 Reinsurance recoverable — — — 1,204,059 — 1,204,059 Accrued investment income — 241 20 46,429 — 46,690 Deferred acquisition costs — — — 497,733 — 497,733 Receivable for investments sold 30 1 6 406,025 — 406,062 Other assets 450,161 19,771 367,408 84,974 (800,590 ) 121,724 Goodwill and other intangible assets 121,560 — — 117,243 — 238,803 Total assets $ 5,257,462 $ 288,847 $ 1,622,857 $ 16,767,911 $ (6,840,683 ) $ 17,096,394 Liabilities, Noncontrolling Interests and Shareholders’ Equity Liabilities Reserve for claims and claim expenses $ — $ — $ — $ 4,952,498 $ — $ 4,952,498 Unearned premiums — — — 2,058,851 — 2,058,851 Debt 352,000 — 842,786 147,963 (352,000 ) 990,749 Amounts due to subsidiaries and affiliates 6,132 144 129,056 — (135,332 ) — Reinsurance balances payable — — — 1,970,913 — 1,970,913 Payable for investments purchased — 17 — 555,539 — 555,556 Other liabilities 12,809 773 9,179 134,181 (9,614 ) 147,328 Total liabilities 370,941 934 981,021 9,819,945 (496,946 ) 10,675,895 Redeemable noncontrolling interests — — — 1,533,978 — 1,533,978 Shareholders’ Equity Total shareholders’ equity 4,886,521 287,913 641,836 5,413,988 (6,343,737 ) 4,886,521 Total liabilities, noncontrolling interests and shareholders’ equity $ 5,257,462 $ 288,847 $ 1,622,857 $ 16,767,911 $ (6,840,683 ) $ 17,096,394 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor, Subsidiary Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Balance Sheet at December 31, 2017 RenaissanceRe Holdings Ltd. (Parent Guarantor) RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other RenaissanceRe Holdings Ltd. Subsidiaries and Eliminations (Non-guarantor Subsidiaries) (1) Consolidating Adjustments (2) RenaissanceRe Consolidated Assets Total investments $ 225,266 $ 129,732 $ 31,255 $ 9,117,186 $ — $ 9,503,439 Cash and cash equivalents 14,656 139 1,469 1,345,328 — 1,361,592 Investments in subsidiaries 4,105,760 36,140 1,141,733 — (5,283,633 ) — Due from subsidiaries and affiliates 4,602 91,891 — — (96,493 ) — Premiums receivable — — — 1,304,622 — 1,304,622 Prepaid reinsurance premiums — — — 533,546 — 533,546 Reinsurance recoverable — — — 1,586,630 — 1,586,630 Accrued investment income 405 428 82 41,320 — 42,235 Deferred acquisition costs — — — 426,551 — 426,551 Receivable for investments sold 135 51 8 102,951 — 103,145 Other assets 433,468 21,342 430,481 76,703 (840,768 ) 121,226 Goodwill and other intangible assets 124,960 — — 118,185 — 243,145 Total assets $ 4,909,252 $ 279,723 $ 1,605,028 $ 14,653,022 $ (6,220,894 ) $ 15,226,131 Liabilities, Redeemable Noncontrolling Interest and Shareholders’ Equity Liabilities Reserve for claims and claim expenses $ — $ — $ — $ 5,080,408 $ — $ 5,080,408 Unearned premiums — — — 1,477,609 — 1,477,609 Debt 417,000 — 841,892 147,731 (417,000 ) 989,623 Amounts due to subsidiaries and affiliates 82,579 54 92,794 — (175,427 ) — Reinsurance balances payable — — — 989,090 — 989,090 Payable for investments purchased — — — 208,749 — 208,749 Other liabilities 18,298 1,053 14,117 764,432 (5,129 ) 792,771 Total liabilities 517,877 1,107 948,803 8,668,019 (597,556 ) 9,538,250 Redeemable noncontrolling interests — — — 1,296,506 — 1,296,506 Shareholders’ Equity Total shareholders’ equity 4,391,375 278,616 656,225 4,688,497 (5,623,338 ) 4,391,375 Total liabilities, redeemable noncontrolling interest and shareholders’ equity $ 4,909,252 $ 279,723 $ 1,605,028 $ 14,653,022 $ (6,220,894 ) $ 15,226,131 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Operations for RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Revenues Net premiums earned $ — $ — $ — $ 531,849 $ — $ 531,849 Net investment income 6,542 539 1,541 80,472 (8,398 ) 80,696 Net foreign exchange gains (losses) 3 — — (4,569 ) — (4,566 ) Equity in earnings of other ventures — — 290 7,358 — 7,648 Other income — — — 497 — 497 Net realized and unrealized (losses) gains on investments (176 ) 4,479 (73 ) 9,400 — 13,630 Total revenues 6,369 5,018 1,758 625,007 (8,398 ) 629,754 Expenses Net claims and claim expenses incurred — — — 410,510 — 410,510 Acquisition expenses — — — 109,761 — 109,761 Operational expenses 3,570 29 7,493 42,682 (13,181 ) 40,593 Corporate expenses 3,778 — — 3,063 — 6,841 Interest expense 1,478 — 9,257 2,512 (1,478 ) 11,769 Total expenses 8,826 29 16,750 568,528 (14,659 ) 579,474 (Loss) income before equity in net income of subsidiaries and taxes (2,457 ) 4,989 (14,992 ) 56,479 6,261 50,280 Equity in net income of subsidiaries 45,130 2,735 11,666 — (59,531 ) — Income (loss) before taxes 42,673 7,724 (3,326 ) 56,479 (53,270 ) 50,280 Income tax (expense) benefit (284 ) (1,026 ) 1,840 (1,981 ) — (1,451 ) Net income (loss) 42,389 6,698 (1,486 ) 54,498 (53,270 ) 48,829 Net income attributable to redeemable noncontrolling interests — — — (6,440 ) — (6,440 ) Net income (loss) attributable to RenaissanceRe 42,389 6,698 (1,486 ) 48,058 (53,270 ) 42,389 Dividends on preference shares (9,708 ) — — — — (9,708 ) Net income (loss) available (attributable) to RenaissanceRe common shareholders $ 32,681 $ 6,698 $ (1,486 ) $ 48,058 $ (53,270 ) $ 32,681 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Comprehensive Income (Loss) for the three months ended September 30, 2018 RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Comprehensive income (loss) Net income (loss) $ 42,389 $ 6,698 $ (1,486 ) $ 54,498 $ (53,270 ) $ 48,829 Change in net unrealized gains on investments — — — (382 ) — (382 ) Comprehensive income (loss) 42,389 6,698 (1,486 ) 54,116 (53,270 ) 48,447 Net income attributable to redeemable noncontrolling interests — — — (6,440 ) — (6,440 ) Comprehensive income attributable to redeemable noncontrolling interests — — — (6,440 ) — (6,440 ) Comprehensive income (loss) attributable to RenaissanceRe $ 42,389 $ 6,698 $ (1,486 ) $ 47,676 $ (53,270 ) $ 42,007 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Operations for RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Revenues Net premiums earned $ — $ — $ — $ 1,401,516 $ — $ 1,401,516 Net investment income 18,504 1,629 3,981 208,034 (23,620 ) 208,528 Net foreign exchange losses (1 ) — — (11,495 ) — (11,496 ) Equity in earnings of other ventures — — 2,045 12,286 — 14,331 Other income — — — 480 — 480 Net realized and unrealized (losses) gains on investments (821 ) 4,906 (399 ) (90,101 ) — (86,415 ) Total revenues 17,682 6,535 5,627 1,520,720 (23,620 ) 1,526,944 Expenses Net claims and claim expenses incurred — — — 642,380 — 642,380 Acquisition expenses — — — 312,524 — 312,524 Operational expenses 7,551 60 26,737 113,721 (28,661 ) 119,408 Corporate expenses 12,498 — 7 9,370 — 21,875 Interest expense 3,694 — 27,763 7,541 (3,694 ) 35,304 Total expenses 23,743 60 54,507 1,085,536 (32,355 ) 1,131,491 (Loss) income before equity in net income of subsidiaries and taxes (6,061 ) 6,475 (48,880 ) 435,184 8,735 395,453 Equity in net income of subsidiaries 310,081 4,285 29,005 — (343,371 ) — Income (loss) before taxes 304,020 10,760 (19,875 ) 435,184 (334,636 ) 395,453 Income tax (expense) benefit (1,939 ) (1,273 ) 5,677 (5,015 ) — (2,550 ) Net income (loss) 302,081 9,487 (14,198 ) 430,169 (334,636 ) 392,903 Net income attributable to redeemable noncontrolling interests — — — (90,822 ) — (90,822 ) Net income (loss) attributable to RenaissanceRe 302,081 9,487 (14,198 ) 339,347 (334,636 ) 302,081 Dividends on preference shares (20,899 ) — — — — (20,899 ) Net income (loss) available (attributable) to RenaissanceRe common shareholders $ 281,182 $ 9,487 $ (14,198 ) $ 339,347 $ (334,636 ) $ 281,182 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor, Subsidiary Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Comprehensive Income (Loss) for the nine months ended September 30, 2018 RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Comprehensive income (loss) Net income (loss) $ 302,081 $ 9,487 $ (14,198 ) $ 430,169 $ (334,636 ) $ 392,903 Change in net unrealized gains on investments — — — (1,707 ) — (1,707 ) Comprehensive income (loss) 302,081 9,487 (14,198 ) 428,462 (334,636 ) 391,196 Net income attributable to redeemable noncontrolling interests — — — (90,822 ) — (90,822 ) Comprehensive income attributable to noncontrolling interests — — — (90,822 ) — (90,822 ) Comprehensive income (loss) attributable to RenaissanceRe $ 302,081 $ 9,487 $ (14,198 ) $ 337,640 $ (334,636 ) $ 300,374 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor, Subsidiary Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Operations for RenaissanceRe RenRe North Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Revenues Net premiums earned $ — $ — $ — $ — $ 547,792 $ — $ 547,792 Net investment income (loss) 5,725 544 (3 ) 1,335 39,342 (6,686 ) 40,257 Net foreign exchange losses — — — — (156 ) — (156 ) Equity in earnings of other ventures — — — 38 1,756 — 1,794 Other income 1 — — — 2,995 — 2,996 Net realized and unrealized gains on investments 110 2,186 — 51 39,705 — 42,052 Total revenues 5,836 2,730 (3 ) 1,424 631,434 (6,686 ) 634,735 Expenses Net claims and claim expenses incurred — — — — 1,221,696 — 1,221,696 Acquisition expenses — — — — 76,761 — 76,761 Operational expenses 2,910 17 1 6,266 37,752 (4,409 ) 42,537 Corporate expenses 4,634 — — — (221 ) — 4,413 Interest expense 183 — — 9,258 2,541 (183 ) 11,799 Total expenses 7,727 17 1 15,524 1,338,529 (4,592 ) 1,357,206 (Loss) income before equity in net (loss) income of subsidiaries and taxes (1,891 ) 2,713 (4 ) (14,100 ) (707,095 ) (2,094 ) (722,471 ) (Loss) equity in net (loss) income of subsidiaries (499,408 ) 928 — (16,352 ) — 514,832 — (Loss) income before taxes (501,299 ) 3,641 (4 ) (30,452 ) (707,095 ) 512,738 (722,471 ) Income tax benefit (expense) 2,082 (890 ) 29 3,307 14,449 — 18,977 Net (loss) income (499,217 ) 2,751 25 (27,145 ) (692,646 ) 512,738 (703,494 ) Net loss attributable to redeemable noncontrolling interests — — — — 204,277 — 204,277 Net (loss) income attributable to RenaissanceRe (499,217 ) 2,751 25 (27,145 ) (488,369 ) 512,738 (499,217 ) Dividends on preference shares (5,595 ) — — — — — (5,595 ) Net (loss) income (attributable) available attributable to RenaissanceRe common shareholders $ (504,812 ) $ 2,751 $ 25 $ (27,145 ) $ (488,369 ) $ 512,738 $ (504,812 ) (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Comprehensive (Loss) Income for the three months ended September 30, 2017 RenaissanceRe RenRe North Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Comprehensive (loss) income Net (loss) income $ (499,217 ) $ 2,751 $ 25 $ (27,145 ) $ (692,646 ) $ 512,738 $ (703,494 ) Change in net unrealized gains on investments — — — — 300 — 300 Comprehensive (loss) income (499,217 ) 2,751 25 (27,145 ) (692,346 ) 512,738 (703,194 ) Net loss attributable to redeemable noncontrolling interests — — — — 204,277 — 204,277 Comprehensive loss attributable to redeemable noncontrolling interests — — — — 204,277 — 204,277 Comprehensive (loss) income attributable to RenaissanceRe $ (499,217 ) $ 2,751 $ 25 $ (27,145 ) $ (488,069 ) $ 512,738 $ (498,917 ) (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Operations for the nine months ended September 30, 2017 RenaissanceRe RenRe North Inc. Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Revenues Net premiums earned $ — $ — $ — $ — $ 1,296,102 $ — $ 1,296,102 Net investment income 16,466 1,436 1,373 1,843 146,816 (19,189 ) 148,745 Net foreign exchange (losses) gains (1 ) — — — 11,119 — 11,118 Equity in (losses) earnings of other ventures — — — (412 ) 6,242 — 5,830 Other income — — — — 7,053 — 7,053 Net realized and unrealized gains (losses) on investments 155 6,528 4,916 (217 ) 132,156 — 143,538 Total revenues 16,620 7,964 6,289 1,214 1,599,488 (19,189 ) 1,612,386 Expenses Net claims and claim expenses incurred — — — — 1,557,364 — 1,557,364 Acquisition expenses — — — — 248,294 — 248,294 Operational expenses 9,398 57 86 20,892 116,212 (15,059 ) 131,586 Corporate expenses 14,640 — — — (305 ) — 14,335 Interest expense 464 — 2,461 22,401 7,554 (464 ) 32,416 Total expenses 24,502 57 2,547 43,293 1,929,119 (15,523 ) 1,983,995 (Loss) income before equity in net (loss) income of subsidiaries and taxes (7,882 ) 7,907 3,742 (42,079 ) (329,631 ) (3,666 ) (371,609 ) Equity in net (loss) income of subsidiaries (219,309 ) 3,234 28,028 20,584 — 167,463 — (Loss) income before taxes (227,191 ) 11,141 31,770 (21,495 ) (329,631 ) 163,797 (371,609 ) Income tax benefit (expense) 2,659 (2,572 ) (1,175 ) 9,281 6,546 — 14,739 Net (loss) income (224,532 ) 8,569 30,595 (12,214 ) (323,085 ) 163,797 (356,870 ) Net loss attributable to redeemable noncontrolling interests — — — — 132,338 — 132,338 Net (loss) income attributable to RenaissanceRe (224,532 ) 8,569 30,595 (12,214 ) (190,747 ) 163,797 (224,532 ) Dividends on preference shares (16,786 ) — — — — — (16,786 ) Net (loss) income (attributable) available to RenaissanceRe common shareholders $ (241,318 ) $ 8,569 $ 30,595 $ (12,214 ) $ (190,747 ) $ 163,797 $ (241,318 ) (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Comprehensive (Loss) Income for the nine months ended September 30, 2017 RenaissanceRe RenRe North Inc. Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Comprehensive (loss) income Net (loss) income $ (224,532 ) $ 8,569 $ 30,595 $ (12,214 ) $ (323,085 ) $ 163,797 $ (356,870 ) Change in net unrealized gains on investments — — — — (972 ) — (972 ) Comprehensive (loss) income (224,532 ) 8,569 30,595 (12,214 ) (324,057 ) 163,797 (357,842 ) Net loss attributable to redeemable noncontrolling interests — — — — 132,338 — 132,338 Comprehensive loss attributable to noncontrolling interests — — — — 132,338 — 132,338 Comprehensive (loss) income attributable to RenaissanceRe $ (224,532 ) $ 8,569 $ 30,595 $ (12,214 ) $ (191,719 ) $ 163,797 $ (225,504 ) (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Cash Flows for the nine months ended September 30, 2018 RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other RenaissanceRe Consolidated Cash flows (used in) provided by operating activities Net cash (used in) provided by operating activities $ (5,869 ) $ 1,496 $ 16,194 $ 876,705 $ 888,526 Cash flows used in investing activities Proceeds from sales and maturities of fixed maturity investments trading 384,818 91,118 45,459 7,700,086 8,221,481 Purchases of fixed maturity investments trading (281,994 ) (65,988 ) (20,806 ) (8,323,900 ) (8,692,688 ) Net (purchases) sales of equity investments trading — (624 ) — 16,114 15,490 Net sales (purchases) of short term investments 85,598 360 (9,206 ) (1,542,203 ) (1,465,451 ) Net purchases of other investments — — — (130,649 ) (130,649 ) Net purchases of investments in other ventures — — — (20,952 ) (20,952 ) Return of investment from investments in other ventures — — — 8,464 8,464 Dividends and return of capital from subsidiaries 511,098 — — (511,098 ) — Contributions to subsidiaries (686,106 ) (16,847 ) (65,000 ) 767,953 — Due (from) to subsidiary (193,249 ) (9,598 ) 36,262 166,585 — Net cash used in investing activities (179,835 ) (1,579 ) (13,291 ) (1,869,600 ) (2,064,305 ) Cash flows provided by financing activities Dividends paid – RenaissanceRe common shares (39,611 ) — — — (39,611 ) Dividends paid – preference shares (20,899 ) — — — (20,899 ) Issuance of preference shares, net of expenses 242,371 — — — 242,371 Net third party redeemable noncontrolling interest share transactions — — — 96,021 96,021 Taxes paid on withholding shares (7,079 ) — — — (7,079 ) Net cash provided by financing activities 174,782 — — 96,021 270,803 Effect of exchange rate changes on foreign currency cash — — — (3,575 ) (3,575 ) Net (decrease) increase in cash and cash equivalents (10,922 ) (83 ) 2,903 (900,449 ) (908,551 ) Cash and cash equivalents, beginning of period 14,656 139 1,469 1,345,328 1,361,592 Cash and cash equivalents, end of period $ 3,734 $ 56 $ 4,372 $ 444,879 $ 453,041 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. Condensed Consolidating Statement of Cash Flows for the nine months ended September 30, 2017 RenaissanceRe RenRe North Inc. Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other RenaissanceRe Holdings Ltd. Subsidiaries and Eliminations (Non-guarantor Subsidiaries) (1) RenaissanceRe Consolidated Cash flows (used in) provided by operating activities Net cash (used in) provided by operating activities $ (6,870 ) $ (8,209 ) $ (2,262 ) $ (343,093 ) $ 962,136 $ 601,702 Cash flows provided by (used in) investing activities Proceeds from sales and maturities of fixed maturity investments trading 106,761 74,455 289,741 279,830 6,912,215 7,663,002 Purchases of fixed maturity investments trading (118,402 ) (69,168 ) (143,991 ) (270,785 ) (7,195,939 ) (7,798,285 ) Net (purchases) sales of equity investments trading — (1,708 ) 85,324 — (22,045 ) 61,571 Net sales (purchases) of short term investments 205,864 (4,495 ) 41,299 (305 ) (388,689 ) (146,326 ) Net sales of other investments — — — — 5,181 5,181 Return of investment from investment in other ventures — — — — 20,000 20,000 Dividends and return of capital from subsidiaries 285,515 9,175 — 41,866 (336,556 ) — Contributions to subsidiaries (500,000 ) — (26,649 ) (9,175 ) 535,824 — Due (from) to subsidiaries 290,130 14 (123 ) 4,062 (294,083 ) — Net cash provided by (used in) investing activities 269,868 8,273 245,601 45,493 (764,092 ) (194,857 ) Cash flows (used in) provided by financing activities Dividends paid – RenaissanceRe common shares (38,624 ) — — — — (38,624 ) Dividends paid – preference shares (16,786 ) — — — — (16,786 ) RenaissanceRe common share repurchases (188,591 ) — — — — (188,591 ) Repayment of debt — — (250,000 ) — — (250,000 ) Issuance of debt, net of expenses — — — 295,866 — 295,866 Net third party redeemable noncontrolling interest share transactions — — — — (44,193 ) (44,193 ) Taxes paid on withholding shares (13,694 ) — — — — (13,694 ) Net cash (used in) provided by financing activities (257,695 ) — (250,000 ) 295,866 (44,193 ) (256,022 ) Effect of exchange rate changes on foreign currency cash — — — — 9,596 9,596 Net increase (decrease) in cash and cash equivalents 5,303 64 (6,661 ) (1,734 ) 163,447 160,419 Cash and cash equivalents, beginning of period 7,067 162 6,671 9,397 397,860 421,157 Cash and cash equivalents, end of period $ 12,370 $ 226 $ 10 $ 7,663 $ 561,307 $ 581,576 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Acquisition of Tokio Millennium Re On October 30, 2018, the Company announced it had entered into a Stock Purchase Agreement by and among the Company, Tokio Marine & Nichido Fire Insurance Co. Ltd. and, with respect to certain sections only, Tokio Marine Holdings, Inc. (the “TMR Stock Purchase Agreement”), pursuant to which the Company has agreed, subject to the terms and conditions therein, to cause its wholly owned subsidiary RenaissanceRe Specialty Holdings (UK) Limited to purchase all of the share capital of Tokio Millennium Re AG and Tokio Millennium Re (UK) Limited, together with their respective subsidiaries (the “TMR Group Entities”). This transaction is expected to close in the first half of 2019, subject to the closing conditions set forth in the TMR Stock Purchase Agreement, including receipt of required regulatory approvals. State Farm Stock Purchase On October 30, 2018, the Company also announced entry into an Investment Agreement by and between the Company and State Farm Mutual Automobile Insurance Company (“State Farm”), pursuant to which State Farm has agreed, subject to the terms and conditions therein, to purchase 1,947,496 Common Shares of the Company in exchange for $250.0 million in a private placement. This transaction is expected to close in the fourth quarter of 2018, subject to the expiration of the waiting period under the Hart-Scott-Rodino Act. Investment in Catalina Holdings (Bermuda) Ltd (“Catalina”) In January 2018, the Company announced it had signed a definitive agreement to acquire a minority shareholding in Catalina, subject to regulatory approval and other closing conditions. On October 10, 2018, the Company closed on its investment and became a minority shareholder alongside Catalina’s management. Hurricane Michael The Company currently estimates, on a preliminary basis, that losses from Hurricane Michael will have an estimated net negative impact on net income (loss) available (attributable) to RenaissanceRe common shareholders of approximately $100.0 million on its fourth quarter 2018 results of operations. Net negative impact includes the sum of estimates of net claims and claim expenses incurred, earned reinstatement premiums assumed and ceded, lost profit commissions and redeemable noncontrolling interest. The Company’s estimate of Hurricane Michael’s impact on the financial results is based on a review of its potential exposures, preliminary discussions with certain counterparties and catastrophe modeling techniques. Meaningful uncertainty regarding the estimates and the nature and extent of the losses from the Hurricane Michael remains, driven by the magnitude and recent occurrence, relatively limited claims data received to date, the contingent nature of business interruption and other exposures, potential uncertainties relating to reinsurance recoveries and other factors inherent in loss estimation, among other things. Accordingly, the Company’s actual net negative impact from this event may vary from these preliminary estimates, perhaps materially. Updated estimates related to this event will be reflected in RenaissanceRe’s fourth quarter 2018 results of operations, when reported, and changes in these estimates will be recorded in the period in which they occur.

Significant Accounting Polici_2

Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION These consolidated financial statements have been prepared on the basis of accounting principles generally accepted in the United States (“GAAP”) for interim financial information and in conformity with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, these unaudited consolidated financial statements reflect all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the Company’s financial position and results of operations as at the end of and for the periods presented. All significant intercompany accounts and transactions have been eliminated from these statements. Certain comparative information has been reclassified to conform to the current presentation. Because of the seasonality of the Company’s business, the results of operations and cash flows for any interim period will not necessarily be indicative of the results of operations and cash flows for the full fiscal year or subsequent quarters.
Use of Estimates in Financial Statements	USE OF ESTIMATES IN FINANCIAL STATEMENTS The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ materially from those estimates. The major estimates reflected in the Company’s consolidated financial statements include, but are not limited to, the reserve for claims and claim expenses; reinsurance recoverables, including allowances for reinsurance recoverables deemed uncollectible; estimates of written and earned premiums; fair value, including the fair value of investments, financial instruments and derivatives; impairment charges; and the Company’s deferred tax valuation allowance.
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements Not Yet Adopted	RECENTLY ADOPTED ACCOUNTING PRONOUNCEMENTS Revenue from Contracts with Customers In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). ASU 2014-09 provides comprehensive guidance on the recognition of revenue from customers arising from the transfer of goods and services. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also provides guidance on accounting for certain contract costs and will also require new disclosures. ASU 2014-09 was to be effective for public business entities in annual and interim periods beginning after December 15, 2016, however in July 2015, the FASB decided to defer by one year the effective dates of ASU 2014-09, and as a result, ASU 2014-09 is effective for public business entities in annual and interim periods beginning after December 15, 2017. ASU 2014-09 notably excludes the accounting for insurance contracts, leases, financial instruments and guarantees. As a result, the Company’s implementation efforts primarily focused on other income and operational expenses on its consolidated statements of operations. The adoption of ASU 2014-09 did not have a material impact on the Company’s consolidated statements of operations and financial position. Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). ASU 2016-01 requires equity investments (except those accounted for under the equity method of accounting or those that result in the consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income, simplifies the impairment assessment of equity investments without readily determinable values by requiring a qualitative assessment to identify impairment, eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, requires the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes, requires separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liabilities in accordance with the fair value option, requires the separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and clarifies that the reporting organization should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the organization’s other deferred tax assets. ASU 2016-01 is effective for public business entities in annual and interim periods beginning after December 15, 2017. The adoption of ASU 2016-01 did not have a material impact on the Company’s consolidated statements of operations and financial position. Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 clarifies the classification of receipts and payments in the statement of cash flows. ASU 2016-15 provides guidance related to (1) settlement and payment of zero coupon debt instruments, (2) contingent consideration, (3) proceeds from settlement of insurance claims, (4) proceeds from settlement of corporate and bank owned life insurance policies, (5) distributions from equity method investees, (6) cash receipts from beneficial interests obtained by a transferor, and (7) general guidelines for cash receipts and payments that have more than one aspect of classification. ASU 2016-15 is effective for public business entities for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. The adoption of ASU 2016-15 resulted in the reclassification of $20.0 million of cash inflows from cash flows provided by operating activities, to cash flows used in investing activities for the nine months ended September 30, 2017 . This amount related to a return of investment associated with the Company’s investment in Top Layer Reinsurance Ltd, recorded under the equity method of accounting. Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”). ASU 2016-09 was issued to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and the classification of taxes paid on the statements of cash flows. ASU 2016-09 became effective for the Company in annual and interim periods beginning after December 15, 2016. The cumulative effect of the adoption of ASU 2016-09 was a $2.2 million increase to opening retained earnings as of January 1, 2017. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 requires lessees to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous guidance. ASU 2016-02 is effective for public business entities for annual and interim periods beginning after December 15, 2018. Early application is permitted. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position. Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 modifies the recognition of credit losses by replacing the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is applicable to financial assets such as loans, debt securities, trade receivables, off-balance sheet credit exposures, reinsurance receivables, and other financial assets that have the contractual right to receive cash. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The Company's invested assets are measured at fair value through net income, and therefore those invested assets would not be impacted by the adoption of ASU 2016-13. The Company has other financial assets, such as reinsurance recoverables, that could be impacted by the adoption of ASU 2016-13. ASU 2016-13 is effective for public business entities that are SEC filers for annual and interim periods beginning after December 15, 2019. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position. Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). ASU 2016-16 requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory when the transfers occur; this is a change from current guidance which prohibits the recognition of current and deferred income taxes until the underlying assets have been sold to outside entities. ASU 2016-16 is effective for public business entities for annual and interim periods beginning after December 15, 2018. Early adoption is permitted. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position. Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). Among other things, ASU 2017-04 requires the following: (1) the elimination of step two of the goodwill impairment test; entities will no longer utilize the implied fair value of their assets and liabilities for purposes of testing goodwill for impairment, (2) the quantitative portion of the goodwill impairment test will be performed by comparing the fair value of a reporting unit with its carrying amount; an impairment charge is to be recognized for the excess of carrying amount over fair value, but only to the extent of the amount of goodwill allocated to that reporting unit, and (3) foreign currency translation adjustments are not to be allocated to a reporting unit from an entity’s accumulated other comprehensive income; the reporting unit’s carrying amount should include only the currently translated balances of the assets and liabilities assigned to the reporting unit. ASU 2017-04 is effective for public business entities that are SEC filers for annual periods, or any interim goodwill impairment tests in annual periods, beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company’s consolidated statements of operations and financial position.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments [Abstract]
Schedule of Fair Value of Fixed Maturity Investments Trading	The following table summarizes the fair value of fixed maturity investments trading: September 30, December 31, U.S. treasuries $ 3,117,911 $ 3,168,763 Agencies 143,980 47,646 Municipal 7,061 509,802 Non-U.S. government (Sovereign debt) 254,169 287,660 Non-U.S. government-backed corporate 137,512 163,651 Corporate 2,448,795 2,063,459 Agency mortgage-backed 836,376 500,456 Non-agency mortgage-backed 289,649 300,331 Commercial mortgage-backed 257,434 202,062 Asset-backed 321,892 182,725 Total fixed maturity investments trading $ 7,814,779 $ 7,426,555
Schedule of Contractual Maturities of Fixed Maturity Investments	Contractual maturities of fixed maturity investments trading are described in the following table. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2018 Amortized Cost Fair Value Due in less than one year $ 303,364 $ 301,817 Due after one through five years 4,759,113 4,694,059 Due after five through ten years 1,029,502 1,020,157 Due after ten years 96,311 93,395 Mortgage-backed 1,390,933 1,383,459 Asset-backed 322,661 321,892 Total $ 7,901,884 $ 7,814,779
Schedule of Fair Value of Equity Investments Trading	The following table summarizes the fair value of equity investments trading: September 30, December 31, Financials $ 262,173 $ 253,543 Communications and technology 60,235 49,526 Industrial, utilities and energy 34,755 34,325 Consumer 26,649 24,779 Healthcare 25,250 21,364 Basic materials 4,209 4,717 Total $ 413,271 $ 388,254
Schedule of Net Investment Income	The components of net investment income are as follows: Three months ended Nine months ended September 30, September 30, September 30, September 30, Fixed maturity investments $ 55,725 $ 45,305 $ 151,784 $ 133,080 Short term investments 9,403 2,771 22,340 7,476 Equity investments 903 930 3,091 2,630 Other investments Private equity investments 8,723 6,371 12,149 20,784 Other 8,665 (11,491 ) 27,346 (4,520 ) Cash and cash equivalents 1,104 352 2,708 836 84,523 44,238 219,418 160,286 Investment expenses (3,827 ) (3,981 ) (10,890 ) (11,541 ) Net investment income $ 80,696 $ 40,257 $ 208,528 $ 148,745
Schedule of Net Realized and Unrealized Gains (Losses)	Net realized and unrealized gains (losses) on investments are as follows: Three months ended Nine months ended September 30, September 30, September 30, September 30, Gross realized gains $ 5,229 $ 16,343 $ 14,945 $ 43,053 Gross realized losses (15,327 ) (6,126 ) (67,699 ) (29,902 ) Net realized (losses) gains on fixed maturity investments (10,098 ) 10,217 (52,754 ) 13,151 Net unrealized (losses) gains on fixed maturity investments trading (8,730 ) 5,545 (73,522 ) 48,940 Net realized and unrealized gains (losses) on investments-related derivatives 2,563 (4,020 ) (763 ) (4,344 ) Net realized gains on equity investments trading sold during the period 21,259 13,675 21,841 49,736 Net unrealized gains on equity investments trading still held at reporting date 8,636 16,635 18,783 36,055 Net realized and unrealized gains on equity investments trading 29,895 30,310 40,624 85,791 Net realized and unrealized gains (losses) on investments $ 13,630 $ 42,052 $ (86,415 ) $ 143,538

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	Below is a summary of the assets and liabilities that are measured at fair value on a recurring basis and also represents the carrying amount on the Company’s consolidated balance sheets: At September 30, 2018 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fixed maturity investments U.S. treasuries $ 3,117,911 $ 3,117,911 $ — $ — Agencies 143,980 — 143,980 — Municipal 7,061 — 7,061 — Non-U.S. government (Sovereign debt) 254,169 — 254,169 — Non-U.S. government-backed corporate 137,512 — 137,512 — Corporate 2,448,795 — 2,448,795 — Agency mortgage-backed 836,376 — 836,376 — Non-agency mortgage-backed 289,649 — 289,649 — Commercial mortgage-backed 257,434 — 257,434 — Asset-backed 321,892 — 321,892 — Total fixed maturity investments 7,814,779 3,117,911 4,696,868 — Short term investments 2,461,415 — 2,461,415 — Equity investments trading 413,271 413,271 — — Other investments Catastrophe bonds 525,126 — 525,126 — Private equity partnerships (1) 185,121 — — — Senior secured bank loan funds (1) 17,057 — — — Hedge funds (1) 11,615 — — — Total other investments 738,919 — 525,126 — Other assets and (liabilities) Assumed and ceded (re)insurance contracts (2) (8,949 ) — — (8,949 ) Derivatives (3) 1,594 249 1,345 — Total other assets and (liabilities) (7,355 ) 249 1,345 (8,949 ) $ 11,421,029 $ 3,531,431 $ 7,684,754 $ (8,949 ) (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheet. (2) Included in assumed and ceded (re)insurance contracts at September 30, 2018 was $5.3 million and $14.2 million of other assets and other liabilities, respectively. (3) See “Note 13 . Derivative Instruments” for additional information related to the fair value by type of contract, of derivatives entered into by the Company. At December 31, 2017 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fixed maturity investments U.S. treasuries $ 3,168,763 $ 3,168,763 $ — $ — Agencies 47,646 — 47,646 — Municipal 509,802 — 509,802 — Non-U.S. government (Sovereign debt) 287,660 — 287,660 — Non-U.S. government-backed corporate 163,651 — 163,651 — Corporate 2,063,459 — 2,063,459 — Agency mortgage-backed 500,456 — 500,456 — Non-agency mortgage-backed 300,331 — 300,331 — Commercial mortgage-backed 202,062 — 202,062 — Asset-backed 182,725 — 182,725 — Total fixed maturity investments 7,426,555 3,168,763 4,257,792 — Short term investments 991,863 — 991,863 — Equity investments trading 388,254 388,254 — — Other investments Catastrophe bonds 380,475 — 380,475 — Private equity partnerships (1) 196,220 — — — Senior secured bank loan funds (1) 17,574 — — — Hedge funds (1) 524 — — — Total other investments 594,793 — 380,475 — Other assets and (liabilities) Assumed and ceded (re)insurance contracts (2) (2,952 ) — — (2,952 ) Derivatives (3) 4,636 (45 ) 4,681 — Total other assets and (liabilities) 1,684 (45 ) 4,681 (2,952 ) $ 9,403,149 $ 3,556,972 $ 5,634,811 $ (2,952 ) (1) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheet. (2) Included in assumed and ceded (re)insurance contracts at December 31, 2017 was $2.5 million and $5.5 million of other assets and other liabilities, respectively. (3) See “Note 13 . Derivative Instruments” for additional information related to the fair value by type of contract, of derivatives entered into by the Company.
Schedule of Quantitative Information Used as Level 3 Inputs	Below is a summary of quantitative information regarding the significant observable and unobservable inputs (Level 3) used in determining the fair value of assets and liabilities measured at fair value on a recurring basis: At September 30, 2018 Fair Value (Level 3) Valuation Technique Unobservable (U) and Observable (O) Inputs Low High Weighted Average or Actual Other assets and (liabilities) Assumed and ceded (re)insurance contracts $ 994 Internal valuation model Bond price (O) $ 101.31 $ 111.12 $ 106.80 Liquidity discount (U) n/a n/a 1.3 % Assumed and ceded (re)insurance contracts (9,943 ) Internal valuation model Net undiscounted cash flows (U) n/a n/a $ 10,180 Expected loss ratio (U) n/a n/a 38.2 % Net acquisition expense ratio (O) n/a n/a 4.9 % Contract period (O) 2.0 years 5.0 years 4.7 years Discount rate (U) n/a n/a 3.0 % Total other assets and (liabilities) $ (8,949 )
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs	Below is a reconciliation of the beginning and ending balances, for the periods shown, of assets and liabilities measured at fair value on a recurring basis using Level 3 inputs. Interest and dividend income are included in net investment income and are excluded from the reconciliation. Other assets and (liabilities) Balance - January 1, 2018 $ (2,952 ) Total realized and unrealized gains Included in other income 2,399 Purchases (9,379 ) Settlements 983 Balance - September 30, 2018 $ (8,949 ) Other assets and (liabilities) Balance - January 1, 2017 $ (13,004 ) Total realized and unrealized gains Included in other income 3,525 Purchases 49 Settlements 5,937 Balance - September 30, 2017 $ (3,493 )
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs	Below is a reconciliation of the beginning and ending balances, for the periods shown, of assets and liabilities measured at fair value on a recurring basis using Level 3 inputs. Interest and dividend income are included in net investment income and are excluded from the reconciliation. Other assets and (liabilities) Balance - January 1, 2018 $ (2,952 ) Total realized and unrealized gains Included in other income 2,399 Purchases (9,379 ) Settlements 983 Balance - September 30, 2018 $ (8,949 ) Other assets and (liabilities) Balance - January 1, 2017 $ (13,004 ) Total realized and unrealized gains Included in other income 3,525 Purchases 49 Settlements 5,937 Balance - September 30, 2017 $ (3,493 )
Schedule of Balances Elected to Account for at Fair Value	Below is a summary of the balances the Company has elected to account for at fair value: September 30, December 31, Other investments $ 738,919 $ 594,793 Other assets $ 5,259 $ 2,542 Other liabilities $ 14,208 $ 5,494
Schedule of Other Investments Measured Using Net Asset Valuations	The table below shows the Company’s portfolio of other investments measured using net asset valuations as a practical expedient: At September 30, 2018 Fair Value Unfunded Redemption Frequency Redemption Redemption Private equity partnerships $ 185,121 $ 416,847 See below See below See below Senior secured bank loan funds 17,057 20,262 See below See below See below Hedge funds 11,615 — See below See below See below Total other investments measured using net asset valuations $ 213,793 $ 437,109

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Effect of Reinsurance and Retrocessional Activity on Premiums Written and Earned and on Net Claims and Claim Expenses Incurred	The following table sets forth the effect of reinsurance and retrocessional activity on premiums written and earned and on net claims and claim expenses incurred: Three months ended Nine months ended September 30, September 30, September 30, September 30, Premiums written Direct $ 74,635 $ 64,040 $ 250,375 $ 205,253 Assumed 551,042 576,229 2,512,297 2,184,521 Ceded (172,422 ) (157,048 ) (1,041,864 ) (806,672 ) Net premiums written $ 453,255 $ 483,221 $ 1,720,808 $ 1,583,102 Premiums earned Direct $ 73,356 $ 61,908 $ 213,292 $ 176,433 Assumed 760,920 712,499 1,968,138 1,731,845 Ceded (302,427 ) (226,615 ) (779,914 ) (612,176 ) Net premiums earned $ 531,849 $ 547,792 $ 1,401,516 $ 1,296,102 Claims and claim expenses Gross claims and claim expenses incurred $ 514,873 $ 2,482,510 $ 817,560 $ 2,924,217 Claims and claim expenses recovered (104,363 ) (1,260,814 ) (175,180 ) (1,366,853 ) Net claims and claim expenses incurred $ 410,510 $ 1,221,696 $ 642,380 $ 1,557,364

Reserve for Claims and Claim _2

Reserve for Claims and Claim Expenses (Tables)	9 Months Ended
	Sep. 30, 2018
Insurance Loss Reserves [Abstract]
Schedule of Liability for Unpaid Claims and Claim Expenses	The following table details the Company’s prior year development by segment of its liability for unpaid claims and claim expenses: Nine months ended September 30, 2018 2017 (Favorable) adverse development (Favorable) adverse development Property $ (172,872 ) $ (16,968 ) Casualty and Specialty (24,020 ) 14,015 Other (88 ) (710 ) Total favorable development of prior accident years net claims and claim expenses $ (196,980 ) $ (3,663 ) The following table details the development of the Company’s liability for unpaid claims and claim expenses for its Casualty and Specialty segment: Nine months ended September 30, 2018 2017 (Favorable) adverse development (Favorable) adverse development Actuarial methods $ (16,234 ) $ (17,004 ) Ogden Rate change — 33,481 Actuarial assumption changes (7,786 ) (2,462 ) Total (favorable) adverse development of prior accident years net claims and claim expenses $ (24,020 ) $ 14,015 The following tables detail the development of the Company’s liability for unpaid claims and claim expenses for its Property segment, allocated between large and small catastrophe net claims and claim expenses and attritional net claims and claim expenses, included in the other line item: Nine months ended September 30, 2018 (Favorable) adverse development Catastrophe net claims and claim expenses Large catastrophe events 2017 Catastrophe Events $ (151,155 ) Other (7,313 ) Total large catastrophe events (158,468 ) Small catastrophe events and attritional loss movements Other small catastrophe events and attritional loss movements (8,722 ) Total small catastrophe events and attritional loss movements (8,722 ) Total catastrophe and attritional net claims and claim expenses (167,190 ) Actuarial assumption changes (5,682 ) Total net favorable development of prior accident years net claims and claim expenses $ (172,872 ) Nine months ended September 30, 2017 (Favorable) adverse development Catastrophe net claims and claim expenses Large catastrophe events New Zealand Earthquake (2011) $ 5,807 New Zealand Earthquake (2010) 5,001 April and May U.S. Tornadoes (2011) (4,163 ) Other (3,881 ) Total large catastrophe events 2,764 Small catastrophe events and attritional loss movements Fort McMurray Wildfire (2016) (6,386 ) Tianjin Explosion (2015) (4,896 ) Other small catastrophe events and attritional loss movements (9,293 ) Total small catastrophe events and attritional loss movements (20,575 ) Total catastrophe and attritional net claims and claim expenses (17,811 ) Actuarial assumption changes 843 Total net favorable development of prior accident years net claims and claim expenses $ (16,968 ) The following table summarizes the Company’s claims and claim expense reserves by segment, allocated between case reserves, additional case reserves and IBNR: At September 30, 2018 Case Reserves Additional Case Reserves IBNR Total Property $ 610,932 $ 744,391 $ 774,220 $ 2,129,543 Casualty and Specialty 773,732 102,631 1,940,244 2,816,607 Other 3,240 — 3,108 6,348 Total $ 1,387,904 $ 847,022 $ 2,717,572 $ 4,952,498 At December 31, 2017 Property $ 696,285 $ 896,522 $ 893,583 $ 2,486,390 Casualty and Specialty 689,962 124,923 1,760,607 2,575,492 Other 6,605 — 11,921 18,526 Total $ 1,392,852 $ 1,021,445 $ 2,666,111 $ 5,080,408 Activity in the liability for unpaid claims and claim expenses is summarized as follows: Nine months ended September 30, 2018 2017 Net reserves as of January 1 $ 3,493,778 $ 2,568,730 Net incurred related to: Current year 839,360 1,561,027 Prior years (196,980 ) (3,663 ) Total net incurred 642,380 1,557,364 Net paid related to: Current year 48,075 158,685 Prior years 326,692 396,411 Total net paid 374,767 555,096 Foreign exchange (12,952 ) 33,011 Net reserves as of September 30 3,748,439 3,604,009 Reinsurance recoverable as of September 30 1,204,059 1,588,304 Gross reserves as of September 30 $ 4,952,498 $ 5,192,313

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	A summary of the Company’s debt obligations on its consolidated balance sheets is set forth below: September 30, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value 3.450% Senior Notes due 2027 $ 282,585 $ 295,673 $ 294,654 $ 295,303 3.700% Senior Notes due 2025 293,559 297,594 302,781 297,318 5.750% Senior Notes due 2020 256,250 249,520 263,750 249,272 4.750% Senior Notes due 2025 (DaVinciRe) (1) 147,924 147,962 157,050 147,730 $ 980,318 $ 990,749 $ 1,018,235 $ 989,623 (1) RenaissanceRe owns a noncontrolling economic interest in its joint venture DaVinciRe. Because RenaissanceRe controls a majority of DaVinciRe’s outstanding voting rights, the consolidated financial statements of DaVinciRe are included in the consolidated financial statements of RenaissanceRe. However, RenaissanceRe does not guarantee or provide credit support for DaVinciRe and RenaissanceRe’s financial exposure to DaVinciRe is limited to its investment in DaVinciRe’s shares and counterparty credit risk arising from reinsurance transactions.
Schedule of Line of Credit Facilities	The outstanding amounts issued or drawn under each of the Company’s significant credit facilities is set forth below: At September 30, 2018 Issued or Drawn RenaissanceRe Revolving Credit Facility (1) $ — Uncommitted Standby Letter of Credit Facility with Wells Fargo 87,057 Bilateral Letter of Credit Facility with Citibank Europe 180,416 Renaissance Reinsurance FAL Facility 180,000 Total credit facilities in U.S. dollars $ 447,473 Specialty Risks FAL Facility (1) £ — Total credit facilities in pound sterling £ — (1) At September 30, 2018, no amounts were issued or drawn under these facilities.

Noncontrolling Interests (Table

Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest [Abstract]
Schedule of Redeemable Noncontrolling Interest	The activity in redeemable noncontrolling interest – Medici is detailed in the table below: Three months ended Nine months ended September 30, September 30, September 30, September 30, Beginning balance $ 411,003 $ 222,165 $ 284,847 $ 181,136 Redemption of shares from redeemable noncontrolling interest, net of adjustments (8,720 ) (1,400 ) (52,223 ) (27,310 ) Sale of shares to redeemable noncontrolling interests 43,000 9,391 199,482 72,732 Net income (loss) attributable to redeemable noncontrolling interest 2,710 (8,769 ) 15,887 (5,171 ) Ending balance $ 447,993 $ 221,387 $ 447,993 $ 221,387 A summary of the Company’s redeemable noncontrolling interests on its consolidated balance sheets is set forth below: September 30, December 31, 2017 Redeemable noncontrolling interest - DaVinciRe $ 1,085,985 $ 1,011,659 Redeemable noncontrolling interest - Medici 447,993 284,847 Redeemable noncontrolling interests $ 1,533,978 $ 1,296,506 A summary of the Company’s redeemable noncontrolling interests on its consolidated statements of operations is set forth below: Three months ended Nine months ended September 30, September 30, September 30, September 30, Redeemable noncontrolling interest - DaVinciRe $ 3,730 $ (195,508 ) $ 74,935 $ (127,167 ) Redeemable noncontrolling interest - Medici 2,710 (8,769 ) 15,887 (5,171 ) Net income (loss) attributable to redeemable noncontrolling interests $ 6,440 $ (204,277 ) $ 90,822 $ (132,338 ) The activity in redeemable noncontrolling interest – DaVinciRe is detailed in the table below: Three months ended Nine months ended September 30, September 30, September 30, September 30, Beginning balance $ 1,082,425 $ 1,019,918 $ 1,011,659 $ 994,458 Redemption of shares from redeemable noncontrolling interest, net of adjustments (170 ) (12,068 ) (609 ) (78,870 ) Sale of shares to redeemable noncontrolling interests — — — 23,921 Net income (loss) attributable to redeemable noncontrolling interest 3,730 (195,508 ) 74,935 (127,167 ) Ending balance $ 1,085,985 $ 812,342 $ 1,085,985 $ 812,342

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings Per Common Share	The following table sets forth the computation of basic and diluted earnings per common share: Three months ended Nine months ended (common shares in thousands) September 30, September 30, September 30, September 30, Numerator: Net income (loss) available (attributable) to RenaissanceRe common shareholders $ 32,681 $ (504,812 ) $ 281,182 $ (241,318 ) Amount allocated to participating common shareholders (1) (294 ) (116 ) (2,977 ) (344 ) Net income (loss) allocated to RenaissanceRe common shareholders $ 32,387 $ (504,928 ) $ 278,205 $ (241,662 ) Denominator: Denominator for basic income per RenaissanceRe common share - weighted average common shares 39,624 39,591 39,606 39,979 Per common share equivalents of employee stock options and restricted shares 13 — 21 — Denominator for diluted income per RenaissanceRe common share - adjusted weighted average common shares and assumed conversions 39,637 39,591 39,627 39,979 Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – basic $ 0.82 $ (12.75 ) $ 7.02 $ (6.04 ) Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – diluted $ 0.82 $ (12.75 ) $ 7.02 $ (6.04 ) (1) Represents earnings attributable to holders of unvested restricted shares issued pursuant to the Company’s 2001 Stock Incentive Plan, 2010 Performance-Based Equity Incentive Plan, 2016 Long-Term Incentive Plan and to the Company’s non-employee directors.

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting, Measurement Disclosures [Abstract]
Schedule of Significant Components of the Company's Revenues and Expenses by Segment	A summary of the significant components of the Company’s revenues and expenses by segment is as follows: Three months ended September 30, 2018 Property Casualty and Specialty Other Total Gross premiums written $ 301,413 $ 324,264 $ — $ 625,677 Net premiums written $ 232,632 $ 220,623 $ — $ 453,255 Net premiums earned $ 293,059 $ 238,791 $ (1 ) $ 531,849 Net claims and claim expenses incurred 265,857 144,671 (18 ) 410,510 Acquisition expenses 45,524 64,238 (1 ) 109,761 Operational expenses 25,577 14,976 40 40,593 Underwriting (loss) income $ (43,899 ) $ 14,906 $ (22 ) (29,015 ) Net investment income 80,696 80,696 Net foreign exchange losses (4,566 ) (4,566 ) Equity in earnings of other ventures 7,648 7,648 Other income 497 497 Net realized and unrealized gains on investments 13,630 13,630 Corporate expenses (6,841 ) (6,841 ) Interest expense (11,769 ) (11,769 ) Income before taxes and redeemable noncontrolling interests 50,280 Income tax expense (1,451 ) (1,451 ) Net income attributable to redeemable noncontrolling interests (6,440 ) (6,440 ) Dividends on preference shares (9,708 ) (9,708 ) Net income available to RenaissanceRe common shareholders $ 32,681 Net claims and claim expenses incurred – current accident year $ 268,022 $ 151,904 $ — $ 419,926 Net claims and claim expenses incurred – prior accident years (2,165 ) (7,233 ) (18 ) (9,416 ) Net claims and claim expenses incurred – total $ 265,857 $ 144,671 $ (18 ) $ 410,510 Net claims and claim expense ratio – current accident year 91.5 % 63.6 % 79.0 % Net claims and claim expense ratio – prior accident years (0.8 )% (3.0 )% (1.8 )% Net claims and claim expense ratio – calendar year 90.7 % 60.6 % 77.2 % Underwriting expense ratio 24.3 % 33.2 % 28.3 % Combined ratio 115.0 % 93.8 % 105.5 % Nine months ended September 30, 2018 Property Casualty and Specialty Other Total Gross premiums written $ 1,561,008 $ 1,201,664 $ — $ 2,762,672 Net premiums written $ 884,541 $ 836,267 $ — $ 1,720,808 Net premiums earned $ 722,246 $ 679,271 $ (1 ) $ 1,401,516 Net claims and claim expenses incurred 222,195 420,273 (88 ) 642,380 Acquisition expenses 127,095 185,429 — 312,524 Operational expenses 75,933 43,121 354 119,408 Underwriting income (loss) $ 297,023 $ 30,448 $ (267 ) 327,204 Net investment income 208,528 208,528 Net foreign exchange losses (11,496 ) (11,496 ) Equity in earnings of other ventures 14,331 14,331 Other income 480 480 Net realized and unrealized losses on investments (86,415 ) (86,415 ) Corporate expenses (21,875 ) (21,875 ) Interest expense (35,304 ) (35,304 ) Income before taxes and redeemable noncontrolling interests 395,453 Income tax expense (2,550 ) (2,550 ) Net income attributable to redeemable noncontrolling interests (90,822 ) (90,822 ) Dividends on preference shares (20,899 ) (20,899 ) Net income available to RenaissanceRe common shareholders $ 281,182 Net claims and claim expenses incurred – current accident year $ 395,067 $ 444,293 $ — $ 839,360 Net claims and claim expenses incurred – prior accident years (172,872 ) (24,020 ) (88 ) (196,980 ) Net claims and claim expenses incurred – total $ 222,195 $ 420,273 $ (88 ) $ 642,380 Net claims and claim expense ratio – current accident year 54.7 % 65.4 % 59.9 % Net claims and claim expense ratio – prior accident years (23.9 )% (3.5 )% (14.1 )% Net claims and claim expense ratio – calendar year 30.8 % 61.9 % 45.8 % Underwriting expense ratio 28.1 % 33.6 % 30.9 % Combined ratio 58.9 % 95.5 % 76.7 % Three months ended September 30, 2017 Property Casualty and Specialty Other Total Gross premiums written $ 325,395 $ 314,881 $ (7 ) $ 640,269 Net premiums written $ 269,393 $ 213,835 $ (7 ) $ 483,221 Net premiums earned $ 336,838 $ 210,961 $ (7 ) $ 547,792 Net claims and claim expenses incurred 1,044,418 177,433 (155 ) 1,221,696 Acquisition expenses 17,514 59,248 (1 ) 76,761 Operational expenses 25,123 17,389 25 42,537 Underwriting (loss) income $ (750,217 ) $ (43,109 ) $ 124 (793,202 ) Net investment income 40,257 40,257 Net foreign exchange losses (156 ) (156 ) Equity in earnings of other ventures 1,794 1,794 Other income 2,996 2,996 Net realized and unrealized gains on investments 42,052 42,052 Corporate expenses (4,413 ) (4,413 ) Interest expense (11,799 ) (11,799 ) Loss before taxes and redeemable noncontrolling interests (722,471 ) Income tax benefit 18,977 18,977 Net loss attributable to redeemable noncontrolling interests 204,277 204,277 Dividends on preference shares (5,595 ) (5,595 ) Net loss attributable to RenaissanceRe common shareholders $ (504,812 ) Net claims and claim expenses incurred – current accident year $ 1,036,586 $ 172,675 $ — $ 1,209,261 Net claims and claim expenses incurred – prior accident years 7,832 4,758 (155 ) 12,435 Net claims and claim expenses incurred – total $ 1,044,418 $ 177,433 $ (155 ) $ 1,221,696 Net claims and claim expense ratio – current accident year 307.7 % 81.9 % 220.8 % Net claims and claim expense ratio – prior accident years 2.4 % 2.2 % 2.2 % Net claims and claim expense ratio – calendar year 310.1 % 84.1 % 223.0 % Underwriting expense ratio 12.6 % 36.3 % 21.8 % Combined ratio 322.7 % 120.4 % 244.8 % Nine months ended September 30, 2017 Property Casualty and Specialty Other Total Gross premiums written $ 1,345,271 $ 1,044,510 $ (7 ) $ 2,389,774 Net premiums written $ 895,728 $ 687,381 $ (7 ) $ 1,583,102 Net premiums earned $ 716,024 $ 580,085 $ (7 ) $ 1,296,102 Net claims and claim expenses incurred 1,116,273 441,801 (710 ) 1,557,364 Acquisition expenses 75,117 173,179 (2 ) 248,294 Operational expenses 76,841 54,708 37 131,586 Underwriting (loss) income $ (552,207 ) $ (89,603 ) $ 668 (641,142 ) Net investment income 148,745 148,745 Net foreign exchange gains 11,118 11,118 Equity in earnings of other ventures 5,830 5,830 Other income 7,053 7,053 Net realized and unrealized gains on investments 143,538 143,538 Corporate expenses (14,335 ) (14,335 ) Interest expense (32,416 ) (32,416 ) Loss before taxes and redeemable noncontrolling interests (371,609 ) Income tax benefit 14,739 14,739 Net loss attributable to RenaissanceRe common shareholders 132,338 132,338 Dividends on preference shares (16,786 ) (16,786 ) Net loss attributable to RenaissanceRe common shareholders $ (241,318 ) Net claims and claim expenses incurred – current accident year $ 1,133,241 $ 427,786 $ — $ 1,561,027 Net claims and claim expenses incurred – prior accident years (16,968 ) 14,015 (710 ) (3,663 ) Net claims and claim expenses incurred – total $ 1,116,273 $ 441,801 $ (710 ) $ 1,557,364 Net claims and claim expense ratio – current accident year 158.3 % 73.7 % 120.4 % Net claims and claim expense ratio – prior accident years (2.4 )% 2.5 % (0.2 )% Net claims and claim expense ratio – calendar year 155.9 % 76.2 % 120.2 % Underwriting expense ratio 21.2 % 39.2 % 29.3 % Combined ratio 177.1 % 115.4 % 149.5 %

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Summary of Derivative Instruments [Abstract]
Schedule of Location on Consolidated Balance Sheets and Fair Value of Principal Derivative Instruments	The tables below show the gross and net amounts of recognized derivative assets and liabilities at fair value, including the location on the consolidated balance sheets of the Company’s principal derivative instruments: Derivative Assets At September 30, 2018 Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Assets Presented in the Balance Sheet Balance Sheet Location Collateral Net Amount Interest rate futures $ 438 184 $ 254 Other assets $ — $ 254 Interest rate swaps 782 — 782 Other assets — 782 Foreign currency forward contracts (1) 6,547 — 6,547 Other assets — 6,547 Foreign currency forward contracts (2) 1,416 40 1,376 Other assets — 1,376 Credit default swaps 277 — 277 Other assets — 277 Total $ 9,460 $ 224 $ 9,236 $ — $ 9,236 Derivative Liabilities At September 30, 2018 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amounts of Liabilities Presented in the Balance Sheet Balance Sheet Location Collateral Pledged Net Amount Interest rate futures $ 189 184 $ 5 Other liabilities $ 5 $ — Interest rate swaps 232 — 232 Other liabilities 232 — Foreign currency forward contracts (1) 7,272 504 6,768 Other liabilities — 6,768 Foreign currency forward contracts (2) 663 40 623 Other liabilities — 623 Credit default swaps 14 — 14 Other liabilities — 14 Total $ 8,370 $ 728 $ 7,642 $ 237 $ 7,405 (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. (2) Contracts used to manage foreign currency risks in investment operations. Derivative Assets At December 31, 2017 Gross Amounts of Recognized Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Assets Presented in the Balance Sheet Balance Sheet Location Collateral Net Amount Interest rate futures $ 684 524 $ 160 Other assets $ — $ 160 Interest rate swaps 424 — 424 Other assets — 424 Foreign currency forward contracts (1) 3,865 358 3,507 Other assets — 3,507 Foreign currency forward contracts (2) 39 11 28 Other assets — 28 Credit default swaps 1,518 — 1,518 Other assets — 1,518 Total $ 6,530 $ 893 $ 5,637 $ — $ 5,637 Derivative Liabilities At December 31, 2017 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Balance Sheet Net Amounts of Liabilities Presented in the Balance Sheet Balance Sheet Location Collateral Pledged Net Amount Interest rate futures $ 729 524 $ 205 Other liabilities $ 205 $ — Foreign currency forward contracts (1) 670 — 670 Other liabilities — 670 Foreign currency forward contracts (2) 115 11 104 Other liabilities — 104 Credit default swaps 22 — 22 Other liabilities 22 — Total $ 1,536 $ 535 $ 1,001 $ 227 $ 774 (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. (2) Contracts used to manage foreign currency risks in investment operations.
Schedule of Gain (Loss) Recognized in Consolidated Statements of Operations Related to Principal Derivative Instruments	The location and amount of the gain (loss) recognized in the Company’s consolidated statements of operations related to its principal derivative instruments are shown in the following table: Location of gain (loss) recognized on derivatives Amount of gain (loss) recognized on derivatives Three months ended September 30, 2018 2017 Interest rate futures Net realized and unrealized gains (losses) on investments $ 2,760 $ (3,016 ) Interest rate swaps Net realized and unrealized gains (losses) on investments (6 ) 271 Foreign currency forward contracts (1) Net foreign exchange (losses) gains (2,596 ) 2,056 Foreign currency forward contracts (2) Net foreign exchange (losses) gains 650 (40 ) Credit default swaps Net realized and unrealized gains (losses) on investments (191 ) (1,275 ) Total $ 617 $ (2,004 ) Location of gain (loss) recognized on derivatives Amount of gain (loss) recognized on derivatives Nine months ended September 30, 2018 2017 Interest rate futures Net realized and unrealized gains (losses) on investments $ 336 $ (4,064 ) Interest rate swaps Net realized and unrealized gains (losses) on investments 129 271 Foreign currency forward contracts (1) Net foreign exchange (losses) gains (2,227 ) 8,339 Foreign currency forward contracts (2) Net foreign exchange (losses) gains 1,302 (940 ) Credit default swaps Net realized and unrealized gains (losses) on investments (1,228 ) (551 ) Total $ (1,688 ) $ 3,055 (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. (2) Contracts used to manage foreign currency risks in investment operations.

Condensed Consolidating Finan_2

Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries (Tables)	9 Months Ended
	Sep. 30, 2018
Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries [Abstract]
Condensed Consolidating Balance Sheets	(1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor, Subsidiary Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Balance Sheet at December 31, 2017 RenaissanceRe Holdings Ltd. (Parent Guarantor) RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other RenaissanceRe Holdings Ltd. Subsidiaries and Eliminations (Non-guarantor Subsidiaries) (1) Consolidating Adjustments (2) RenaissanceRe Consolidated Assets Total investments $ 225,266 $ 129,732 $ 31,255 $ 9,117,186 $ — $ 9,503,439 Cash and cash equivalents 14,656 139 1,469 1,345,328 — 1,361,592 Investments in subsidiaries 4,105,760 36,140 1,141,733 — (5,283,633 ) — Due from subsidiaries and affiliates 4,602 91,891 — — (96,493 ) — Premiums receivable — — — 1,304,622 — 1,304,622 Prepaid reinsurance premiums — — — 533,546 — 533,546 Reinsurance recoverable — — — 1,586,630 — 1,586,630 Accrued investment income 405 428 82 41,320 — 42,235 Deferred acquisition costs — — — 426,551 — 426,551 Receivable for investments sold 135 51 8 102,951 — 103,145 Other assets 433,468 21,342 430,481 76,703 (840,768 ) 121,226 Goodwill and other intangible assets 124,960 — — 118,185 — 243,145 Total assets $ 4,909,252 $ 279,723 $ 1,605,028 $ 14,653,022 $ (6,220,894 ) $ 15,226,131 Liabilities, Redeemable Noncontrolling Interest and Shareholders’ Equity Liabilities Reserve for claims and claim expenses $ — $ — $ — $ 5,080,408 $ — $ 5,080,408 Unearned premiums — — — 1,477,609 — 1,477,609 Debt 417,000 — 841,892 147,731 (417,000 ) 989,623 Amounts due to subsidiaries and affiliates 82,579 54 92,794 — (175,427 ) — Reinsurance balances payable — — — 989,090 — 989,090 Payable for investments purchased — — — 208,749 — 208,749 Other liabilities 18,298 1,053 14,117 764,432 (5,129 ) 792,771 Total liabilities 517,877 1,107 948,803 8,668,019 (597,556 ) 9,538,250 Redeemable noncontrolling interests — — — 1,296,506 — 1,296,506 Shareholders’ Equity Total shareholders’ equity 4,391,375 278,616 656,225 4,688,497 (5,623,338 ) 4,391,375 Total liabilities, redeemable noncontrolling interest and shareholders’ equity $ 4,909,252 $ 279,723 $ 1,605,028 $ 14,653,022 $ (6,220,894 ) $ 15,226,131 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments.
Condensed Consolidating Statements of Operations	Condensed Consolidating Statement of Operations for the nine months ended September 30, 2017 RenaissanceRe RenRe North Inc. Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Revenues Net premiums earned $ — $ — $ — $ — $ 1,296,102 $ — $ 1,296,102 Net investment income 16,466 1,436 1,373 1,843 146,816 (19,189 ) 148,745 Net foreign exchange (losses) gains (1 ) — — — 11,119 — 11,118 Equity in (losses) earnings of other ventures — — — (412 ) 6,242 — 5,830 Other income — — — — 7,053 — 7,053 Net realized and unrealized gains (losses) on investments 155 6,528 4,916 (217 ) 132,156 — 143,538 Total revenues 16,620 7,964 6,289 1,214 1,599,488 (19,189 ) 1,612,386 Expenses Net claims and claim expenses incurred — — — — 1,557,364 — 1,557,364 Acquisition expenses — — — — 248,294 — 248,294 Operational expenses 9,398 57 86 20,892 116,212 (15,059 ) 131,586 Corporate expenses 14,640 — — — (305 ) — 14,335 Interest expense 464 — 2,461 22,401 7,554 (464 ) 32,416 Total expenses 24,502 57 2,547 43,293 1,929,119 (15,523 ) 1,983,995 (Loss) income before equity in net (loss) income of subsidiaries and taxes (7,882 ) 7,907 3,742 (42,079 ) (329,631 ) (3,666 ) (371,609 ) Equity in net (loss) income of subsidiaries (219,309 ) 3,234 28,028 20,584 — 167,463 — (Loss) income before taxes (227,191 ) 11,141 31,770 (21,495 ) (329,631 ) 163,797 (371,609 ) Income tax benefit (expense) 2,659 (2,572 ) (1,175 ) 9,281 6,546 — 14,739 Net (loss) income (224,532 ) 8,569 30,595 (12,214 ) (323,085 ) 163,797 (356,870 ) Net loss attributable to redeemable noncontrolling interests — — — — 132,338 — 132,338 Net (loss) income attributable to RenaissanceRe (224,532 ) 8,569 30,595 (12,214 ) (190,747 ) 163,797 (224,532 ) Dividends on preference shares (16,786 ) — — — — — (16,786 ) Net (loss) income (attributable) available to RenaissanceRe common shareholders $ (241,318 ) $ 8,569 $ 30,595 $ (12,214 ) $ (190,747 ) $ 163,797 $ (241,318 ) (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Operations for RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Revenues Net premiums earned $ — $ — $ — $ 1,401,516 $ — $ 1,401,516 Net investment income 18,504 1,629 3,981 208,034 (23,620 ) 208,528 Net foreign exchange losses (1 ) — — (11,495 ) — (11,496 ) Equity in earnings of other ventures — — 2,045 12,286 — 14,331 Other income — — — 480 — 480 Net realized and unrealized (losses) gains on investments (821 ) 4,906 (399 ) (90,101 ) — (86,415 ) Total revenues 17,682 6,535 5,627 1,520,720 (23,620 ) 1,526,944 Expenses Net claims and claim expenses incurred — — — 642,380 — 642,380 Acquisition expenses — — — 312,524 — 312,524 Operational expenses 7,551 60 26,737 113,721 (28,661 ) 119,408 Corporate expenses 12,498 — 7 9,370 — 21,875 Interest expense 3,694 — 27,763 7,541 (3,694 ) 35,304 Total expenses 23,743 60 54,507 1,085,536 (32,355 ) 1,131,491 (Loss) income before equity in net income of subsidiaries and taxes (6,061 ) 6,475 (48,880 ) 435,184 8,735 395,453 Equity in net income of subsidiaries 310,081 4,285 29,005 — (343,371 ) — Income (loss) before taxes 304,020 10,760 (19,875 ) 435,184 (334,636 ) 395,453 Income tax (expense) benefit (1,939 ) (1,273 ) 5,677 (5,015 ) — (2,550 ) Net income (loss) 302,081 9,487 (14,198 ) 430,169 (334,636 ) 392,903 Net income attributable to redeemable noncontrolling interests — — — (90,822 ) — (90,822 ) Net income (loss) attributable to RenaissanceRe 302,081 9,487 (14,198 ) 339,347 (334,636 ) 302,081 Dividends on preference shares (20,899 ) — — — — (20,899 ) Net income (loss) available (attributable) to RenaissanceRe common shareholders $ 281,182 $ 9,487 $ (14,198 ) $ 339,347 $ (334,636 ) $ 281,182 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor, Subsidiary Guarantor and Subsidiary Issuer consolidating adjustments.
Condensed Consolidating Statement of Comprehensive Income (Loss)	Condensed Consolidating Statement of Comprehensive (Loss) Income for the nine months ended September 30, 2017 RenaissanceRe RenRe North Inc. Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Comprehensive (loss) income Net (loss) income $ (224,532 ) $ 8,569 $ 30,595 $ (12,214 ) $ (323,085 ) $ 163,797 $ (356,870 ) Change in net unrealized gains on investments — — — — (972 ) — (972 ) Comprehensive (loss) income (224,532 ) 8,569 30,595 (12,214 ) (324,057 ) 163,797 (357,842 ) Net loss attributable to redeemable noncontrolling interests — — — — 132,338 — 132,338 Comprehensive loss attributable to noncontrolling interests — — — — 132,338 — 132,338 Comprehensive (loss) income attributable to RenaissanceRe $ (224,532 ) $ 8,569 $ 30,595 $ (12,214 ) $ (191,719 ) $ 163,797 $ (225,504 ) (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor and Subsidiary Issuer consolidating adjustments. Condensed Consolidating Statement of Comprehensive Income (Loss) for the nine months ended September 30, 2018 RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other Consolidating RenaissanceRe Comprehensive income (loss) Net income (loss) $ 302,081 $ 9,487 $ (14,198 ) $ 430,169 $ (334,636 ) $ 392,903 Change in net unrealized gains on investments — — — (1,707 ) — (1,707 ) Comprehensive income (loss) 302,081 9,487 (14,198 ) 428,462 (334,636 ) 391,196 Net income attributable to redeemable noncontrolling interests — — — (90,822 ) — (90,822 ) Comprehensive income attributable to noncontrolling interests — — — (90,822 ) — (90,822 ) Comprehensive income (loss) attributable to RenaissanceRe $ 302,081 $ 9,487 $ (14,198 ) $ 337,640 $ (334,636 ) $ 300,374 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. (2) Includes Parent Guarantor, Subsidiary Guarantor and Subsidiary Issuer consolidating adjustments.
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statement of Cash Flows for the nine months ended September 30, 2018 RenaissanceRe RenRe North RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other RenaissanceRe Consolidated Cash flows (used in) provided by operating activities Net cash (used in) provided by operating activities $ (5,869 ) $ 1,496 $ 16,194 $ 876,705 $ 888,526 Cash flows used in investing activities Proceeds from sales and maturities of fixed maturity investments trading 384,818 91,118 45,459 7,700,086 8,221,481 Purchases of fixed maturity investments trading (281,994 ) (65,988 ) (20,806 ) (8,323,900 ) (8,692,688 ) Net (purchases) sales of equity investments trading — (624 ) — 16,114 15,490 Net sales (purchases) of short term investments 85,598 360 (9,206 ) (1,542,203 ) (1,465,451 ) Net purchases of other investments — — — (130,649 ) (130,649 ) Net purchases of investments in other ventures — — — (20,952 ) (20,952 ) Return of investment from investments in other ventures — — — 8,464 8,464 Dividends and return of capital from subsidiaries 511,098 — — (511,098 ) — Contributions to subsidiaries (686,106 ) (16,847 ) (65,000 ) 767,953 — Due (from) to subsidiary (193,249 ) (9,598 ) 36,262 166,585 — Net cash used in investing activities (179,835 ) (1,579 ) (13,291 ) (1,869,600 ) (2,064,305 ) Cash flows provided by financing activities Dividends paid – RenaissanceRe common shares (39,611 ) — — — (39,611 ) Dividends paid – preference shares (20,899 ) — — — (20,899 ) Issuance of preference shares, net of expenses 242,371 — — — 242,371 Net third party redeemable noncontrolling interest share transactions — — — 96,021 96,021 Taxes paid on withholding shares (7,079 ) — — — (7,079 ) Net cash provided by financing activities 174,782 — — 96,021 270,803 Effect of exchange rate changes on foreign currency cash — — — (3,575 ) (3,575 ) Net (decrease) increase in cash and cash equivalents (10,922 ) (83 ) 2,903 (900,449 ) (908,551 ) Cash and cash equivalents, beginning of period 14,656 139 1,469 1,345,328 1,361,592 Cash and cash equivalents, end of period $ 3,734 $ 56 $ 4,372 $ 444,879 $ 453,041 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations. Condensed Consolidating Statement of Cash Flows for the nine months ended September 30, 2017 RenaissanceRe RenRe North Inc. Platinum Underwriters Finance, Inc. (Subsidiary Issuer) RenaissanceRe Finance, Inc. (Subsidiary Issuer) Other RenaissanceRe Holdings Ltd. Subsidiaries and Eliminations (Non-guarantor Subsidiaries) (1) RenaissanceRe Consolidated Cash flows (used in) provided by operating activities Net cash (used in) provided by operating activities $ (6,870 ) $ (8,209 ) $ (2,262 ) $ (343,093 ) $ 962,136 $ 601,702 Cash flows provided by (used in) investing activities Proceeds from sales and maturities of fixed maturity investments trading 106,761 74,455 289,741 279,830 6,912,215 7,663,002 Purchases of fixed maturity investments trading (118,402 ) (69,168 ) (143,991 ) (270,785 ) (7,195,939 ) (7,798,285 ) Net (purchases) sales of equity investments trading — (1,708 ) 85,324 — (22,045 ) 61,571 Net sales (purchases) of short term investments 205,864 (4,495 ) 41,299 (305 ) (388,689 ) (146,326 ) Net sales of other investments — — — — 5,181 5,181 Return of investment from investment in other ventures — — — — 20,000 20,000 Dividends and return of capital from subsidiaries 285,515 9,175 — 41,866 (336,556 ) — Contributions to subsidiaries (500,000 ) — (26,649 ) (9,175 ) 535,824 — Due (from) to subsidiaries 290,130 14 (123 ) 4,062 (294,083 ) — Net cash provided by (used in) investing activities 269,868 8,273 245,601 45,493 (764,092 ) (194,857 ) Cash flows (used in) provided by financing activities Dividends paid – RenaissanceRe common shares (38,624 ) — — — — (38,624 ) Dividends paid – preference shares (16,786 ) — — — — (16,786 ) RenaissanceRe common share repurchases (188,591 ) — — — — (188,591 ) Repayment of debt — — (250,000 ) — — (250,000 ) Issuance of debt, net of expenses — — — 295,866 — 295,866 Net third party redeemable noncontrolling interest share transactions — — — — (44,193 ) (44,193 ) Taxes paid on withholding shares (13,694 ) — — — — (13,694 ) Net cash (used in) provided by financing activities (257,695 ) — (250,000 ) 295,866 (44,193 ) (256,022 ) Effect of exchange rate changes on foreign currency cash — — — — 9,596 9,596 Net increase (decrease) in cash and cash equivalents 5,303 64 (6,661 ) (1,734 ) 163,447 160,419 Cash and cash equivalents, beginning of period 7,067 162 6,671 9,397 397,860 421,157 Cash and cash equivalents, end of period $ 12,370 $ 226 $ 10 $ 7,663 $ 561,307 $ 581,576 (1) Includes all other subsidiaries of RenaissanceRe Holdings Ltd. and eliminations.

Organization (Details)

Organization (Details)	9 Months Ended
	Sep. 30, 2018
RenaissanceRe Upsilon Fund Ltd. | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Percent of segregated funds owned by third party investors	100.00%

Significant Accounting Polici_3

Significant Accounting Policies (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in cash inflows from cash flows provided by operating activities	$ (888,526)	$ (601,702)
Increase in cash flows used in investing activities	$ 2,064,305	194,857
Reclassification effect of adoption of ASU 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in cash inflows from cash flows provided by operating activities		20,000
Increase in cash flows used in investing activities		$ 20,000
Cumulative effect of adoption of ASU 2016-09 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption			$ 2,200

Investments (Schedule of Fair V

Investments (Schedule of Fair Value of Fixed Maturity Investments Trading) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment [Line Items]
Total fixed maturity investments trading	$ 7,814,779	$ 7,426,555
U.S. treasuries
Investment [Line Items]
Total fixed maturity investments trading	3,117,911	3,168,763
Agencies
Investment [Line Items]
Total fixed maturity investments trading	143,980	47,646
Municipal
Investment [Line Items]
Total fixed maturity investments trading	7,061	509,802
Non-U.S. government (Sovereign debt)
Investment [Line Items]
Total fixed maturity investments trading	254,169	287,660
Non-U.S. government-backed corporate
Investment [Line Items]
Total fixed maturity investments trading	137,512	163,651
Corporate
Investment [Line Items]
Total fixed maturity investments trading	2,448,795	2,063,459
Agency mortgage-backed
Investment [Line Items]
Total fixed maturity investments trading	836,376	500,456
Non-agency mortgage-backed
Investment [Line Items]
Total fixed maturity investments trading	289,649	300,331
Commercial mortgage-backed
Investment [Line Items]
Total fixed maturity investments trading	257,434	202,062
Asset-backed
Investment [Line Items]
Total fixed maturity investments trading	$ 321,892	$ 182,725

Investments (Schedule of Contra

Investments (Schedule of Contractual Maturities of Fixed Maturity Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Trading Securities
Amortized Cost, Due in less than one year	$ 303,364
Amortized Cost, Due after one through five years	4,759,113
Amortized Cost, Due after five through ten years	1,029,502
Amortized Cost, Due after ten years	96,311
Amortized Cost	7,901,884	$ 7,434,870
Fair Value, Due in less than one year	301,817
Fair Value, Due after one through five years	4,694,059
Fair Value, Due after five through ten years	1,020,157
Fair Value, Due after ten years	93,395
Fair Value	7,814,779	7,426,555
Mortgage-backed
Trading Securities
Amortized Cost	1,390,933
Fair Value	1,383,459
Asset-backed
Trading Securities
Amortized Cost	322,661
Fair Value	$ 321,892	$ 182,725

Investments (Schedule of Fair_2

Investments (Schedule of Fair Value of Equity Investments Trading) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	$ 413,271	$ 388,254
Financials
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	262,173	253,543
Communications and technology
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	60,235	49,526
Industrial, utilities and energy
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	34,755	34,325
Consumer
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	26,649	24,779
Healthcare
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	25,250	21,364
Basic materials
Debt and Equity Securities, FV-NI [Line Items]
Equity investments trading	$ 4,209	$ 4,717

Investments (Pledged Investment

Investments (Pledged Investments) (Details) - USD ($) $ in Billions	Sep. 30, 2018	Dec. 31, 2017
Investments [Abstract]
Cash and investments at fair value on deposit with, or in trust accounts for the benefit of various counterparties	$ 5.1	$ 4.4
Cash and investments at fair value on deposit with, or in trust accounts for the benefit of U.S. state regulatory authorities	$ 1.9	$ 1.7

Investments (Reverse Purchase A

Investments (Reverse Purchase Agreements) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Value of reverse repurchase agreements	$ 92	$ 30
Minimum required collateral for reverse repurchase agreements, expressed as a percentage of loan principal	102.00%

Investments (Schedule of Net In

Investments (Schedule of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	$ 84,523	$ 44,238	$ 219,418	$ 160,286
Investment expenses	(3,827)	(3,981)	(10,890)	(11,541)
Net investment income	80,696	40,257	208,528	148,745
Fixed maturity investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	55,725	45,305	151,784	133,080
Short term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	9,403	2,771	22,340	7,476
Equity investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	903	930	3,091	2,630
Private equity investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	8,723	6,371	12,149	20,784
Other
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	8,665	(11,491)	27,346	(4,520)
Cash and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income before investment expenses	$ 1,104	$ 352	$ 2,708	$ 836

Investments (Schedule of Net Re

Investments (Schedule of Net Realized and Unrealized (Losses) Gains on Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains (losses) on investments	$ 13,630	$ 42,052	$ (86,415)	$ 143,538
Fixed maturity investments
Gain (Loss) on Securities [Line Items]
Gross realized gains	5,229	16,343	14,945	43,053
Gross realized losses	(15,327)	(6,126)	(67,699)	(29,902)
Net realized (losses) gains on fixed maturity investments	(10,098)	10,217	(52,754)	13,151
Net unrealized (losses) gains on fixed maturity investments trading	(8,730)	5,545	(73,522)	48,940
Derivatives
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains (losses) on investments-related derivatives	2,563	(4,020)	(763)	(4,344)
Equity investments
Gain (Loss) on Securities [Line Items]
Net realized gains on equity investments trading sold during the period	21,259	13,675	21,841	49,736
Net unrealized gains on equity investments trading still held at reporting date	8,636	16,635	18,783	36,055
Net realized and unrealized gains on equity investments trading	$ 29,895	$ 30,310	$ 40,624	$ 85,791

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	$ 7,814,779	$ 7,426,555
Equity investments trading	413,271	388,254
Other investments	738,919	594,793
Other assets	5,259	2,542
Other liabilities	(14,208)	(5,494)
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	7,814,779	7,426,555
Short term investments	2,461,415	991,863
Equity investments trading	413,271	388,254
Other investments	738,919	594,793
Other assets		1,684
Other liabilities	(7,355)
Total assets and liabilities measured on recurring basis	11,421,029	9,403,149
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	3,117,911	3,168,763
Short term investments	0	0
Equity investments trading	413,271	388,254
Other investments	0	0
Other assets	249
Other liabilities		(45)
Total assets and liabilities measured on recurring basis	3,531,431	3,556,972
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	4,696,868	4,257,792
Short term investments	2,461,415	991,863
Equity investments trading	0	0
Other investments	525,126	380,475
Other assets	1,345	4,681
Total assets and liabilities measured on recurring basis	7,684,754	5,634,811
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Short term investments	0	0
Equity investments trading	0	0
Other investments	0	0
Other liabilities	(8,949)	(2,952)
Total assets and liabilities measured on recurring basis	(8,949)	(2,952)
Fair Value, Measurements, Recurring | U.S. treasuries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	3,117,911	3,168,763
Fair Value, Measurements, Recurring | U.S. treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	3,117,911	3,168,763
Fair Value, Measurements, Recurring | U.S. treasuries | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | U.S. treasuries | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	143,980	47,646
Fair Value, Measurements, Recurring | Agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Agencies | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	143,980	47,646
Fair Value, Measurements, Recurring | Agencies | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	7,061	509,802
Fair Value, Measurements, Recurring | Municipal | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Municipal | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	7,061	509,802
Fair Value, Measurements, Recurring | Municipal | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Non-U.S. government (Sovereign debt)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	254,169	287,660
Fair Value, Measurements, Recurring | Non-U.S. government (Sovereign debt) | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Non-U.S. government (Sovereign debt) | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	254,169	287,660
Fair Value, Measurements, Recurring | Non-U.S. government (Sovereign debt) | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Non-U.S. government-backed corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	137,512	163,651
Fair Value, Measurements, Recurring | Non-U.S. government-backed corporate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Non-U.S. government-backed corporate | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	137,512	163,651
Fair Value, Measurements, Recurring | Non-U.S. government-backed corporate | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	2,448,795	2,063,459
Fair Value, Measurements, Recurring | Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Corporate | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	2,448,795	2,063,459
Fair Value, Measurements, Recurring | Corporate | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Agency mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	836,376	500,456
Fair Value, Measurements, Recurring | Agency mortgage-backed | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Agency mortgage-backed | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	836,376	500,456
Fair Value, Measurements, Recurring | Agency mortgage-backed | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Non-agency mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	289,649	300,331
Fair Value, Measurements, Recurring | Non-agency mortgage-backed | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Non-agency mortgage-backed | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	289,649	300,331
Fair Value, Measurements, Recurring | Non-agency mortgage-backed | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	257,434	202,062
Fair Value, Measurements, Recurring | Commercial mortgage-backed | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Commercial mortgage-backed | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	257,434	202,062
Fair Value, Measurements, Recurring | Commercial mortgage-backed | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	321,892	182,725
Fair Value, Measurements, Recurring | Asset-backed | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Asset-backed | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	321,892	182,725
Fair Value, Measurements, Recurring | Asset-backed | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Fair Value, Measurements, Recurring | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	525,126	380,475
Fair Value, Measurements, Recurring | Catastrophe bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Catastrophe bonds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	525,126	380,475
Fair Value, Measurements, Recurring | Catastrophe bonds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Private equity partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	185,121	196,220
Fair Value, Measurements, Recurring | Private equity partnerships | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Private equity partnerships | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Private equity partnerships | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Senior secured bank loan funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	17,057	17,574
Fair Value, Measurements, Recurring | Senior secured bank loan funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Senior secured bank loan funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Senior secured bank loan funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	11,615	524
Fair Value, Measurements, Recurring | Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Hedge funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Hedge funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	(8,949)	(2,952)
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0
Other liabilities		0
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0
Other liabilities		0
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	(8,949)	(2,952)
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts | Significant Unobservable Inputs (Level 3) | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	5,300	2,500
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts | Significant Unobservable Inputs (Level 3) | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	(14,200)	(5,500)
Fair Value, Measurements, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	1,594	4,636
Fair Value, Measurements, Recurring | Derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	249
Other liabilities		(45)
Fair Value, Measurements, Recurring | Derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	1,345	4,681
Fair Value, Measurements, Recurring | Derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	$ 0
Other liabilities		$ 0

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	$ 5,259,000		$ 5,259,000		$ 2,542,000
Other liabilities	14,208,000		14,208,000		5,494,000
Debt	990,749,000		990,749,000		989,623,000
Long-term debt, fair value	980,300,000		980,300,000		1,018,200,000
Net unrealized gains recognized in earnings			17,778,000	$ 2,686,000
Net investment income | Other Investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net unrealized gains recognized in earnings	9,100,000	$ 9,800,000	17,800,000	2,700,000
Other income (loss) | Other assets and (liabilities)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net unrealized gains recognized in earnings	0	$ 0	0	$ 0
Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	990,749,000		990,749,000		989,623,000
Long-term debt, fair value	980,318,000		980,318,000		1,018,235,000
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets					1,684,000
Other liabilities	7,355,000		7,355,000
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities	8,949,000		8,949,000		$ 2,952,000
Significant Unobservable Inputs (Level 3) | Internal valuation model | Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities	8,949,000		8,949,000
Significant Unobservable Inputs (Level 3) | Internal valuation model | Fair Value, Measurements, Recurring | Assumed reinsurance contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	994,000		994,000
Significant Unobservable Inputs (Level 3) | Internal valuation model | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities	9,943,000		9,943,000
Fair Value Measured at Net Asset Value Per Share
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 213,793,000		$ 213,793,000
U.S. treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	2.80%		2.80%		1.90%
Agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	3.10%		3.10%		2.10%
Municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	4.00%		4.00%		2.20%
Non-U.S. government (Sovereign debt)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	2.90%		2.90%		2.00%
Non-U.S. government-backed corporate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	3.20%		3.20%		2.30%
Corporate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	4.30%		4.30%		3.80%
Agency mortgage-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	3.70%		3.70%		3.00%
Weighted average life			8 years 2 months 12 days		6 years 4 months 24 days
Non-agency prime residential mortgage-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	4.20%		4.20%		3.70%
Weighted average life			5 years 6 months		5 years 1 month 6 days
Alt-A non-agency mortgage-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	4.10%		4.10%		3.70%
Weighted average life			6 years 3 months 18 days		6 years 2 months 12 days
Commercial mortgage-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	3.60%		3.60%		2.90%
Weighted average life			5 years		4 years 6 months
Asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	3.70%		3.70%		2.80%
Weighted average life			3 years 3 months 18 days		3 years
Short term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield	1.80%		1.80%		1.40%
Private equity partnerships | Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liquidation period for fund assets			7 years
Private equity partnerships | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liquidation period for fund assets			10 years
Private equity partnerships | Fair Value Measured at Net Asset Value Per Share
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 185,121,000		$ 185,121,000
Senior secured bank loan funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment in closed end fund	17,100,000		$ 17,100,000
Senior secured bank loan funds | Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liquidation period for fund assets			4 years
Senior secured bank loan funds | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liquidation period for fund assets			5 years
Senior secured bank loan funds | Fair Value Measured at Net Asset Value Per Share
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	17,057,000		$ 17,057,000
Hedge funds | Fair Value Measured at Net Asset Value Per Share
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	11,615,000		11,615,000
Hedge funds redeemable at option of shareholder | Fair Value Measured at Net Asset Value Per Share
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 11,300,000		$ 11,300,000

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Information Used as Level 3 Inputs) (Details) $ in Thousands	Sep. 30, 2018USD ($)year$ / shares	Dec. 31, 2017USD ($)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	$ (14,208)	$ (5,494)
Total other assets and (liabilities)	5,259	2,542
Fair Value, Measurements, Recurring
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	(7,355)
Total other assets and (liabilities)		1,684
Fair Value, Measurements, Recurring | Fair Value (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	(8,949)	$ (2,952)
Fair Value, Measurements, Recurring | Internal valuation model | Fair Value (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	(8,949)
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group one | Internal valuation model | Fair Value (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Total other assets and (liabilities)	994
Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Other assets (liabilities)	$ (9,943)
Bond price | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group one | Internal valuation model | Fair Value (Level 3) | Low
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs | $ / shares	101.31
Bond price | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group one | Internal valuation model | Fair Value (Level 3) | High
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs | $ / shares	111.12
Bond price | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group one | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs | $ / shares	106.80
Liquidity discount | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group one | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs	0.013
Net undiscounted cash flows | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs	(10,180,000)
Expected loss ratio | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs	0.382
Net acquisition expense ratio | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs	(0.049)
Contract period | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | Low
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs | year	2
Contract period | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | High
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs | year	5
Contract period | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs | year	4.7
Discount rate | Fair Value, Measurements, Recurring | Assumed and ceded (re)insurance contracts, group two | Internal valuation model | Fair Value (Level 3) | Weighted Average or Actual
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Significant observable and unobservable inputs	0.030

Fair Value Measurements (Asse_2

Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Level 3 Inputs) (Details) - Other assets and (liabilities) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of the period	$ (2,952)	$ (13,004)
Total realized and unrealized gains
Purchases	(9,379)	49
Settlements	983	5,937
Balance at end of the period	(8,949)	(3,493)
Other income (loss)
Total realized and unrealized gains
Included in other income	$ 2,399	$ 3,525

Fair Value Measurements (Summar

Fair Value Measurements (Summary of the Balances Company Has Elected to Account For at Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Other investments	$ 738,919	$ 594,793
Other assets	5,259	2,542
Other liabilities	$ 14,208	$ 5,494

Fair Value Measurements (Compan

Fair Value Measurements (Company's Portfolio of Other Investments Measured Using Net Asset Valuations) (Details) - Fair Value Measured at Net Asset Value Per Share $ in Thousands	Sep. 30, 2018USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 213,793
Unfunded Commitments	437,109
Private equity partnerships
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	185,121
Unfunded Commitments	416,847
Senior secured bank loan funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	17,057
Unfunded Commitments	20,262
Hedge funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	11,615
Unfunded Commitments	$ 0

Reinsurance (Effect of Reinsura

Reinsurance (Effect of Reinsurance and Retrocessional Activity on Premiums Written and Earned and on Net Claims and Claim Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Premiums written
Direct	$ 74,635	$ 64,040	$ 250,375	$ 205,253
Assumed	551,042	576,229	2,512,297	2,184,521
Ceded	(172,422)	(157,048)	(1,041,864)	(806,672)
Net premiums written	453,255	483,221	1,720,808	1,583,102
Premiums earned
Direct	73,356	61,908	213,292	176,433
Assumed	760,920	712,499	1,968,138	1,731,845
Ceded	(302,427)	(226,615)	(779,914)	(612,176)
Net premiums earned	531,849	547,792	1,401,516	1,296,102
Claims and claim expenses
Gross claims and claim expenses incurred	514,873	2,482,510	817,560	2,924,217
Claims and claim expenses recovered	(104,363)	(1,260,814)	(175,180)	(1,366,853)
Net claims and claim expenses incurred	$ 410,510	$ 1,221,696	$ 642,380	$ 1,557,364

Reinsurance (Narrative) (Detail

Reinsurance (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Reinsurance recoverable	$ 1,204,059	$ 1,588,304	$ 1,586,630
Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Valuation allowances and reserves balance	$ 6,300		$ 7,000
Customer Concentration Risk, Customer One | Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	12.20%	10.40%
Customer Concentration Risk, Customer One | Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	19.90%	11.10%
Customer Concentration Risk, Customer Two | Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	12.00%	7.50%
Customer Concentration Risk, Customer Two | Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	19.80%	9.20%
Customer Concentration Risk, Customer Three | Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	9.20%	7.30%
Customer Concentration Risk, Customer Three | Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	18.00%	8.40%
Ceded Credit Risk, Secured | Reinsurer Concentration Risk | Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	52.50%	54.50%
Ceded Credit Risk, Unsecured | Reinsurer Concentration Risk | Reinsurance recoverable | Standard & Poor's, A- Rating
Ceded Credit Risk [Line Items]
Concentration risk, percentage	46.40%	44.50%
Ceded Credit Risk, Unsecured | Reinsurer Concentration Risk | Reinsurance recoverable | Standard & Poor's, BBB Rating
Ceded Credit Risk [Line Items]
Concentration risk, percentage	1.10%	1.00%

Reserve for Claims and Claim _3

Reserve for Claims and Claim Expenses (Claims and Claim Expense Reserves by Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Case Reserves	$ 1,387,904	$ 1,392,852
Additional Case Reserves	847,022	1,021,445
IBNR	2,717,572	2,666,111
Gross reserve for claims and claim expenses	4,952,498	5,080,408	$ 5,192,313
Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Case Reserves	3,240	6,605
Additional Case Reserves	0	0
IBNR	3,108	11,921
Gross reserve for claims and claim expenses	6,348	18,526
Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Case Reserves	610,932	696,285
Additional Case Reserves	744,391	896,522
IBNR	774,220	893,583
Gross reserve for claims and claim expenses	2,129,543	2,486,390
Casualty and Specialty
Liability for Claims and Claims Adjustment Expense [Line Items]
Case Reserves	773,732	689,962
Additional Case Reserves	102,631	124,923
IBNR	1,940,244	1,760,607
Gross reserve for claims and claim expenses	$ 2,816,607	$ 2,575,492

Reserve for Claims and Claim _4

Reserve for Claims and Claim Expenses (Schedule of Liability for Unpaid Claims and Claims Adjustment Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves as of January 1			$ 3,493,778	$ 2,568,730
Net incurred related to:
Current year	$ 419,926	$ 1,209,261	839,360	1,561,027
Prior years	(9,416)	12,435	(196,980)	(3,663)
Total net incurred	410,510	1,221,696	642,380	1,557,364
Net paid related to:
Current year			48,075	158,685
Prior years			326,692	396,411
Total net paid			374,767	555,096
Foreign exchange			(12,952)	33,011
Net reserves as of September 30	3,748,439	3,604,009	3,748,439	3,604,009
Reinsurance recoverable as of September 30	1,204,059	1,588,304	1,204,059	1,588,304
Gross reserves as of September 30	$ 4,952,498	$ 5,192,313	$ 4,952,498	$ 5,192,313

Reserve for Claims and Claim _5

Reserve for Claims and Claim Expenses (Prior Year Development of the Reserve for Net Claims and Claim Expenses) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years	$ (9,416)	$ 12,435	$ (196,980)	$ (3,663)
Ogden Rate | Discount rate
Liability for Catastrophe Claims [Line Items]
Cash surrender value, measurement input	(0.0075)		(0.0075)		0.025
Other
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years	$ (18)	$ (155)	$ (88)	(710)
Property
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(172,872)	(16,968)
Property | Actuarial assumption changes
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(5,682)	843
Property | Large and Small Catastrophe Events
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(167,190)	(17,811)
Property | Large catastrophe events
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(158,468)	2,764
Property | 2017 Catastrophe Events
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(151,155)
Property | Other
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(7,313)	(3,881)
Property | New Zealand Earthquake (2011)
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years				5,807
Property | New Zealand Earthquake (2010)
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years				5,001
Property | April and May U.S. Tornadoes (2011)
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years				(4,163)
Property | Small catastrophe events and attritional loss movements
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(8,722)	(20,575)
Property | Other small catastrophe events and attritional loss movements
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(8,722)	(9,293)
Property | Fort McMurray Wildfire (2016)
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years				(6,386)
Property | Tianjin Explosion (2015)
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years				(4,896)
Casualty and Specialty
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(24,020)	14,015
Casualty and Specialty | Actuarial methods
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(16,234)	(17,004)
Casualty and Specialty | Actuarial assumption changes
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			(7,786)	(2,462)
Casualty and Specialty | Ogden Rate change
Liability for Catastrophe Claims [Line Items]
Net claims and claim expenses incurred – prior accident years			$ 0	$ 33,481

Debt and Credit Facilities (Sum

Debt and Credit Facilities (Summary of Debt Obligations) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Fair Value	$ 980,300	$ 1,018,200
Carrying Value	$ 990,749	989,623
3.450% Senior Notes due 2027
Debt Instrument [Line Items]
Debt instrument, Interest rate	3.45%
3.700% Senior Notes due 2025
Debt Instrument [Line Items]
Debt instrument, Interest rate	3.70%
5.750% Senior Notes due 2020
Debt Instrument [Line Items]
Debt instrument, Interest rate	5.75%
4.750% Senior Notes due 2025 (DaVinciRe)
Debt Instrument [Line Items]
Debt instrument, Interest rate	4.75%
Senior Notes
Debt Instrument [Line Items]
Fair Value	$ 980,318	1,018,235
Carrying Value	990,749	989,623
Senior Notes | 3.450% Senior Notes due 2027 | RenaissanceRe Finance, Inc.
Debt Instrument [Line Items]
Fair Value	282,585	294,654
Carrying Value	295,673	295,303
Senior Notes | 3.700% Senior Notes due 2025
Debt Instrument [Line Items]
Fair Value	293,559	302,781
Carrying Value	297,594	297,318
Senior Notes | 5.750% Senior Notes due 2020
Debt Instrument [Line Items]
Fair Value	256,250	263,750
Carrying Value	249,520	249,272
Senior Notes | 4.750% Senior Notes due 2025 (DaVinciRe) | DaVinciRe Holdings Ltd.
Debt Instrument [Line Items]
Fair Value	147,924	157,050
Carrying Value	$ 147,962	$ 147,730

Debt and Credit Facilities (Sch

Debt and Credit Facilities (Schedule of Credit Facilities) (Details) - Sep. 30, 2018 £ in Thousands, $ in Thousands	USD ($)	GBP (£)
Line of Credit Facility [Line Items]
Credit facilities outstanding	$ 447,473	£ 0
Renaissance Reinsurance FAL Facility | Line of Credit
Line of Credit Facility [Line Items]
Credit facilities outstanding	180,000
Specialty Risks FAL Facility | Line of Credit
Line of Credit Facility [Line Items]
Credit facilities outstanding | £		£ 0
Wells Fargo | Uncommitted Standby Letter of Credit Facility | Letter of Credit
Line of Credit Facility [Line Items]
Credit facilities outstanding	87,057
Citibank Europe PLC | Bilateral Facility | Letter of Credit
Line of Credit Facility [Line Items]
Credit facilities outstanding	180,416
Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Credit facilities outstanding	$ 0

Noncontrolling Interests (Detai

Noncontrolling Interests (Details) - USD ($) $ in Thousands	Oct. 01, 2017	Jul. 31, 2017	Jan. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2017	Jan. 01, 2017	Dec. 31, 2016
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests				$ 1,533,978		$ 1,533,978		$ 1,296,506
Net income (loss) attributable to redeemable noncontrolling interests				$ 6,440	$ (204,277)	$ 90,822	$ (132,338)
DaVinci Reinsurance Ltd.
Redeemable Noncontrolling Interest [Line Items]
Parent company ownership in redeemable noncontrolling interest	22.10%			22.10%		22.10%		22.10%		23.50%		22.60%
RenaissanceRe Medici Fund Ltd.
Redeemable Noncontrolling Interest [Line Items]
Parent company ownership in redeemable noncontrolling interest				15.80%		15.80%		26.80%
DaVinciRe Holdings Ltd.
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests				$ 1,085,985	812,342	$ 1,085,985	812,342	$ 1,011,659	$ 1,082,425		$ 1,019,918		$ 994,458
Net income (loss) attributable to redeemable noncontrolling interests				3,730	(195,508)	74,935	(127,167)
Redeemable noncontrolling interest, net redemptions			$ 75,000
Redeemable noncontrolling interest, reserve holdback			7,500
Noncontrolling interest, change from purchase or sale of interests	$ 49,700	$ 12,000	$ 24,000
Issuance of equity to third party investors	$ 248,600
Sale of shares to redeemable noncontrolling interest				0	0	0	23,921
Redemption of shares from redeemable noncontrolling interest				$ 170	12,068	$ 609	78,870
DaVinciRe Holdings Ltd. | Maximum
Redeemable Noncontrolling Interest [Line Items]
Share repurchase requests, limit				25.00%		25.00%
RenaissanceRe Medici Fund Ltd.
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests				$ 447,993	221,387	$ 447,993	221,387	284,847	$ 411,003		$ 222,165		$ 181,136
Net income (loss) attributable to redeemable noncontrolling interests				2,710	(8,769)	$ 15,887	(5,171)
Redemption provision, notice period						30 days
Sale of shares to redeemable noncontrolling interest				43,000	9,391	$ 199,482	72,732	149,200
Redemption of shares from redeemable noncontrolling interest				$ 8,720	$ 1,400	$ 52,223	$ 27,310	$ 48,000

Noncontrolling Interests (Sched

Noncontrolling Interests (Schedule of Redeemable Noncontrolling Interest) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Activity in redeemable noncontrolling interest
Beginning balance			$ 1,296,506
Net income (loss) attributable to redeemable noncontrolling interest	$ 6,440	$ (204,277)	90,822	$ (132,338)
Ending balance	1,533,978		1,533,978		$ 1,296,506
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	1,082,425	1,019,918	1,011,659	994,458	994,458
Redemption of shares from redeemable noncontrolling interest, net of adjustments	(170)	(12,068)	(609)	(78,870)
Sale of shares to redeemable noncontrolling interests	0	0	0	23,921
Net income (loss) attributable to redeemable noncontrolling interest	3,730	(195,508)	74,935	(127,167)
Ending balance	1,085,985	812,342	1,085,985	812,342	1,011,659
RenaissanceRe Medici Fund Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	411,003	222,165	284,847	181,136	181,136
Redemption of shares from redeemable noncontrolling interest, net of adjustments	(8,720)	(1,400)	(52,223)	(27,310)	(48,000)
Sale of shares to redeemable noncontrolling interests	43,000	9,391	199,482	72,732	149,200
Net income (loss) attributable to redeemable noncontrolling interest	2,710	(8,769)	15,887	(5,171)
Ending balance	$ 447,993	$ 221,387	$ 447,993	$ 221,387	$ 284,847

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Variable Interest Entity [Line Items]
Assets	$ 17,096,394,000		$ 17,096,394,000		$ 15,226,131,000
Liabilities	10,675,895,000		10,675,895,000		9,538,250,000
Ceded premiums written	172,422,000	$ 157,048,000	1,041,864,000	$ 806,672,000
Ceded premiums earned	302,427,000	$ 226,615,000	779,914,000	612,176,000
Investments in other ventures, under equity method	117,307,000		117,307,000		101,974,000
Upsilon RFO Re Ltd. | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Return of capital					84,300,000
Assets	1,600,000,000		1,600,000,000		1,200,000,000
Liabilities	1,600,000,000		1,600,000,000		1,200,000,000
Upsilon RFO Re Ltd. | Variable Interest Entity, Primary Beneficiary | Non-Voting Preference Shares
Variable Interest Entity [Line Items]
Issuance of equity to third party investors					180,600,000
Contributions to subsidiaries			$ 109,800,000		27,200,000
Upsilon RFO Re Ltd. | Variable Interest Entity, Primary Beneficiary | RenaissanceRe Holdings Ltd.
Variable Interest Entity [Line Items]
Return of capital					$ 33,000,000
Variable interest entity, ownership percentage			14.00%		20.80%
Upsilon RFO Re Ltd. | Variable Interest Entity, Primary Beneficiary | Third party investor | Non-Voting Preference Shares
Variable Interest Entity [Line Items]
Contributions to subsidiaries			$ 856,700,000		$ 7,500,000
Renaissance Reinsurance Ltd. | Variable Interest Entity, Primary Beneficiary | Fibonacci Reinsurance Ltd.
Variable Interest Entity [Line Items]
Ceded premiums written			9,100,000	9,400,000
Ceded premiums earned			6,800,000	6,200,000
Mona Lisa Re Ltd | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	100,000		100,000		25,900,000
Liabilities	100,000		100,000		25,900,000
Mona Lisa Re Ltd | Variable Interest Entity, Not Primary Beneficiary | Renaissance Reinsurance Ltd.
Variable Interest Entity [Line Items]
Ceded premiums written			200,000	200,000
Ceded premiums earned			200,000	4,000,000
Mona Lisa Re Ltd | Variable Interest Entity, Not Primary Beneficiary | DaVinci Reinsurance Ltd.
Variable Interest Entity [Line Items]
Ceded premiums written			200,000	200,000
Ceded premiums earned			200,000	$ 2,800,000
Fibonacci Reinsurance Ltd. | Variable Interest Entity, Primary Beneficiary | Other Investments
Variable Interest Entity [Line Items]
Investment in participating notes	8,500,000		8,500,000		14,100,000
Langhorne Holdings LLC | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investments in other ventures, under equity method	1,300,000		1,300,000		600,000
Langhorne Partners
Variable Interest Entity [Line Items]
Investments in other ventures, under equity method	$ 100,000		$ 100,000
Langhorne Partners | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investments in other ventures, under equity method					$ 0

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($)	Sep. 28, 2018	Sep. 14, 2018	Jun. 29, 2018	Jun. 15, 2018	Mar. 29, 2018	Mar. 15, 2018	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Nov. 10, 2017
Class of Stock [Line Items]
Dividends per common share		$ 0.33		$ 0.33				$ 0.33	$ 0.32	$ 0.99	$ 0.96
Dividends paid per common share (in dollars per share)	$ 0.33		$ 0.33		$ 0.33
Dividends declared and paid, preference shares								$ 9,708,000	$ 5,595,000	$ 20,899,000	$ 16,786,000
Shares issued (In shares)								16,010,000		16,010,000		16,000,000
Par value (In dollars per share)								$ 1		$ 1		$ 1
Retained Earnings
Class of Stock [Line Items]
Dividends declared and paid, preference shares										$ 20,899,000	16,786,000
Dividends declared and paid, common shares										$ 39,611,000	$ 38,624,000
Common Shares
Class of Stock [Line Items]
Dividends per common share						$ 0.33
Share repurchase program, authorized amount													$ 500,000,000
Share repurchase program, shares repurchased (in shares)										0
Share repurchase program, remaining authorized aggregate amount								$ 500,000,000		$ 500,000,000
Series C Preference Shares
Class of Stock [Line Items]
Dividend rate, percentage										6.08%
Liquidation preference per annum (in dollars per share)								$ 1.52		$ 1.52
Liquidation preference quarterly (in dollars per share)								0.38		$ 0.38
Series E Preference Shares
Class of Stock [Line Items]
Dividend rate, percentage										5.375%
Liquidation preference per annum (in dollars per share)								1.34375		$ 1.34375
Liquidation preference quarterly (in dollars per share)								$ 0.3359375		$ 0.3359375
Series F Preference Shares
Class of Stock [Line Items]
Dividend rate, percentage							5.75%
Liquidation preference per annum (in dollars per share)							$ 1,437.50
Liquidation preference quarterly (in dollars per share)							$ 359.375
Shares issued (In shares)							10,000
Par value (In dollars per share)							$ 1
Liquidation preference (in dollars per share)							25,000
Redemption price per share (in dollars per share)							25,000
Series F Preference Shares | Prior To June 30, 2023
Class of Stock [Line Items]
Redemption price per share (in dollars per share)							26,000
Depositary Shares
Class of Stock [Line Items]
Liquidation preference per annum (in dollars per share)							1.4375
Liquidation preference quarterly (in dollars per share)							$ 0.359375
Shares issued (In shares)							10,000,000
Percentage interest in underlying shares								0.10%		0.10%
Redemption price per share (in dollars per share)							$ 25
Depositary Shares | Prior To June 30, 2023
Class of Stock [Line Items]
Redemption price per share (in dollars per share)							$ 26

Earnings Per Share (Computation

Earnings Per Share (Computation of Basic and Diluted Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income (loss) available (attributable) to RenaissanceRe common shareholders	$ 32,681	$ (504,812)	$ 281,182	$ (241,318)
Amount allocated to participating common shareholders	(294)	(116)	(2,977)	(344)
Net income (loss) allocated to RenaissanceRe common shareholders	$ 32,387	$ (504,928)	$ 278,205	$ (241,662)
Denominator:
Denominator for basic income per RenaissanceRe common share - weighted average common shares (in shares)	39,624	39,591	39,606	39,979
Per common share equivalents of employee stock options and restricted shares (in shares)	13	0	21	0
Denominator for diluted income per RenaissanceRe common share - adjusted weighted average common shares and assumed conversions (in shares)	39,637	39,591	39,627	39,979
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – basic (in dollars per share)	$ 0.82	$ (12.75)	$ 7.02	$ (6.04)
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – diluted (in dollars per share)	$ 0.82	$ (12.75)	$ 7.02	$ (6.04)

Segment Reporting (Schedule of

Segment Reporting (Schedule of Significant Components of the Company's Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Gross premiums written	$ 625,677	$ 640,269	$ 2,762,672	$ 2,389,774
Net premiums written	453,255	483,221	1,720,808	1,583,102
Net premiums earned	531,849	547,792	1,401,516	1,296,102
Net claims and claim expenses incurred	410,510	1,221,696	642,380	1,557,364
Acquisition expenses	109,761	76,761	312,524	248,294
Operational expenses	40,593	42,537	119,408	131,586
Underwriting income (loss)	(29,015)	(793,202)	327,204	(641,142)
Net investment income	80,696	40,257	208,528	148,745
Net foreign exchange (losses) gains	(4,566)	(156)	(11,496)	11,118
Equity in earnings of other ventures	7,648	1,794	14,331	5,830
Other income	497	2,996	480	7,053
Net realized and unrealized gains (losses) on investments	13,630	42,052	(86,415)	143,538
Corporate expenses	(6,841)	(4,413)	(21,875)	(14,335)
Interest expense	(11,769)	(11,799)	(35,304)	(32,416)
Income (loss) before taxes	50,280	(722,471)	395,453	(371,609)
Income tax (expense) benefit	(1,451)	18,977	(2,550)	14,739
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Dividends on preference shares	(9,708)	(5,595)	(20,899)	(16,786)
Net income (loss) available (attributable) to RenaissanceRe common shareholders	32,681	(504,812)	281,182	(241,318)
Net claims and claim expenses incurred – current accident year	419,926	1,209,261	839,360	1,561,027
Net claims and claim expenses incurred – prior accident years	(9,416)	12,435	(196,980)	(3,663)
Total net incurred	$ 410,510	$ 1,221,696	$ 642,380	$ 1,557,364
Net claims and claim expense ratio – current accident year	79.00%	220.80%	59.90%	120.40%
Net claims and claim expense ratio – prior accident years	(1.80%)	2.20%	(14.10%)	(0.20%)
Net claims and claim expense ratio – calendar year	77.20%	223.00%	45.80%	120.20%
Underwriting expense ratio	28.30%	21.80%	30.90%	29.30%
Combined ratio	105.50%	244.80%	76.70%	149.50%
Other
Segment Reporting Information [Line Items]
Gross premiums written	$ 0	$ (7)	$ 0	$ (7)
Net premiums written	0	(7)	0	(7)
Net premiums earned	(1)	(7)	(1)	(7)
Net claims and claim expenses incurred	(18)	(155)	(88)	(710)
Acquisition expenses	(1)	(1)	0	(2)
Operational expenses	40	25	354	37
Underwriting income (loss)	(22)	124	(267)	668
Net investment income	80,696	40,257	208,528	148,745
Net foreign exchange (losses) gains	(4,566)	(156)	(11,496)	11,118
Equity in earnings of other ventures	7,648	1,794	14,331	5,830
Other income	497	2,996	480	7,053
Net realized and unrealized gains (losses) on investments	13,630	42,052	(86,415)	143,538
Corporate expenses	(6,841)	(4,413)	(21,875)	(14,335)
Interest expense	(11,769)	(11,799)	(35,304)	(32,416)
Income tax (expense) benefit	(1,451)	18,977	(2,550)	14,739
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Dividends on preference shares	(9,708)	(5,595)	(20,899)	(16,786)
Net claims and claim expenses incurred – current accident year	0	0	0	0
Net claims and claim expenses incurred – prior accident years	(18)	(155)	(88)	(710)
Total net incurred	(18)	(155)	(88)	(710)
Property
Segment Reporting Information [Line Items]
Net claims and claim expenses incurred – prior accident years			(172,872)	(16,968)
Property | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	301,413	325,395	1,561,008	1,345,271
Net premiums written	232,632	269,393	884,541	895,728
Net premiums earned	293,059	336,838	722,246	716,024
Net claims and claim expenses incurred	265,857	1,044,418	222,195	1,116,273
Acquisition expenses	45,524	17,514	127,095	75,117
Operational expenses	25,577	25,123	75,933	76,841
Underwriting income (loss)	(43,899)	(750,217)	297,023	(552,207)
Net claims and claim expenses incurred – current accident year	268,022	1,036,586	395,067	1,133,241
Net claims and claim expenses incurred – prior accident years	(2,165)	7,832	(172,872)	(16,968)
Total net incurred	$ 265,857	$ 1,044,418	$ 222,195	$ 1,116,273
Net claims and claim expense ratio – current accident year	91.50%	307.70%	54.70%	158.30%
Net claims and claim expense ratio – prior accident years	(0.80%)	2.40%	(23.90%)	(2.40%)
Net claims and claim expense ratio – calendar year	90.70%	310.10%	30.80%	155.90%
Underwriting expense ratio	24.30%	12.60%	28.10%	21.20%
Combined ratio	115.00%	322.70%	58.90%	177.10%
Casualty and Specialty
Segment Reporting Information [Line Items]
Net claims and claim expenses incurred – prior accident years			$ (24,020)	$ 14,015
Casualty and Specialty | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 324,264	$ 314,881	1,201,664	1,044,510
Net premiums written	220,623	213,835	836,267	687,381
Net premiums earned	238,791	210,961	679,271	580,085
Net claims and claim expenses incurred	144,671	177,433	420,273	441,801
Acquisition expenses	64,238	59,248	185,429	173,179
Operational expenses	14,976	17,389	43,121	54,708
Underwriting income (loss)	14,906	(43,109)	30,448	(89,603)
Net claims and claim expenses incurred – current accident year	151,904	172,675	444,293	427,786
Net claims and claim expenses incurred – prior accident years	(7,233)	4,758	(24,020)	14,015
Total net incurred	$ 144,671	$ 177,433	$ 420,273	$ 441,801
Net claims and claim expense ratio – current accident year	63.60%	81.90%	65.40%	73.70%
Net claims and claim expense ratio – prior accident years	(3.00%)	2.20%	(3.50%)	2.50%
Net claims and claim expense ratio – calendar year	60.60%	84.10%	61.90%	76.20%
Underwriting expense ratio	33.20%	36.30%	33.60%	39.20%
Combined ratio	93.80%	120.40%	95.50%	115.40%

Derivative Instruments (Consoli

Derivative Instruments (Consolidated Balance Sheets and Fair Value of the Principal Derivative Instruments) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other assets
Derivative Assets
Gross Amounts of Recognized Assets	$ 9,460	$ 6,530
Gross Amounts Offset in the Balance Sheet	224	893
Net Amounts of Assets Presented in the Balance Sheet	9,236	5,637
Collateral	0	0
Net Amount	9,236	5,637
Other assets | Interest rate futures
Derivative Assets
Gross Amounts of Recognized Assets	438	684
Gross Amounts Offset in the Balance Sheet	184	524
Net Amounts of Assets Presented in the Balance Sheet	254	160
Collateral	0	0
Net Amount	254	160
Other assets | Interest rate swaps
Derivative Assets
Gross Amounts of Recognized Assets	782	424
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	782	424
Collateral	0	0
Net Amount	782	424
Other assets | Foreign currency forward contracts, underwriting and non-investment operations
Derivative Assets
Gross Amounts of Recognized Assets	6,547	3,865
Gross Amounts Offset in the Balance Sheet	0	358
Net Amounts of Assets Presented in the Balance Sheet	6,547	3,507
Collateral	0	0
Net Amount	6,547	3,507
Other assets | Foreign currency forward contracts, investment operations
Derivative Assets
Gross Amounts of Recognized Assets	1,416	39
Gross Amounts Offset in the Balance Sheet	40	11
Net Amounts of Assets Presented in the Balance Sheet	1,376	28
Collateral	0	0
Net Amount	1,376	28
Other assets | Credit default swaps
Derivative Assets
Gross Amounts of Recognized Assets	277	1,518
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	277	1,518
Collateral	0	0
Net Amount	277	1,518
Other liabilities
Derivative Liabilities
Gross Amounts of Recognized Liabilities	8,370	1,536
Gross Amounts Offset in the Balance Sheet	728	535
Net Amounts of Liabilities Presented in the Balance Sheet	7,642	1,001
Collateral Pledged	237	227
Net Amount	7,405	774
Other liabilities | Interest rate futures
Derivative Liabilities
Gross Amounts of Recognized Liabilities	189	729
Gross Amounts Offset in the Balance Sheet	184	524
Net Amounts of Liabilities Presented in the Balance Sheet	5	205
Collateral Pledged	5	205
Net Amount	0	0
Other liabilities | Interest rate swaps
Derivative Liabilities
Gross Amounts of Recognized Liabilities	232
Gross Amounts Offset in the Balance Sheet	0
Net Amounts of Liabilities Presented in the Balance Sheet	232
Collateral Pledged	232
Net Amount	0
Other liabilities | Foreign currency forward contracts, underwriting and non-investment operations
Derivative Liabilities
Gross Amounts of Recognized Liabilities	7,272	670
Gross Amounts Offset in the Balance Sheet	504	0
Net Amounts of Liabilities Presented in the Balance Sheet	6,768	670
Collateral Pledged	0	0
Net Amount	6,768	670
Other liabilities | Foreign currency forward contracts, investment operations
Derivative Liabilities
Gross Amounts of Recognized Liabilities	663	115
Gross Amounts Offset in the Balance Sheet	40	11
Net Amounts of Liabilities Presented in the Balance Sheet	623	104
Collateral Pledged	0	0
Net Amount	623	104
Other liabilities | Credit default swaps
Derivative Liabilities
Gross Amounts of Recognized Liabilities	14	22
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	14	22
Collateral Pledged	0	22
Net Amount	$ 14	$ 0

Derivative Instruments (Gain (L

Derivative Instruments (Gain (Loss) Recognized in the Consolidated Statements of Operations Related to its Derivative Instruments) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	$ 617	$ (2,004)	$ (1,688)	$ 3,055
Net realized and unrealized gains (losses) on investments | Interest rate futures
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	2,760	(3,016)	336	(4,064)
Net realized and unrealized gains (losses) on investments | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	(6)	271	129	271
Net realized and unrealized gains (losses) on investments | Credit default swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	(191)	(1,275)	(1,228)	(551)
Net foreign exchange (losses) gains | Foreign currency forward contracts, underwriting and non-investment operations
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	(2,596)	2,056	(2,227)	8,339
Net foreign exchange (losses) gains | Foreign currency forward contracts, investment operations
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	$ 650	$ (40)	$ 1,302	$ (940)

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Details) - Not Designated as Hedging Instrument - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Interest rate futures | Long
Derivative [Line Items]
Notional amount	$ 1,600,000,000	$ 1,500,000,000
Interest rate futures | Short
Derivative [Line Items]
Notional amount	699,000,000	801,100,000
Interest rate swaps | US Dollars | Paying a Fixed Rate
Derivative [Line Items]
Notional amount	62,600,000	40,300,000
Interest rate swaps | US Dollars | Receiving a Fixed Rate
Derivative [Line Items]
Notional amount	29,500,000	0
Foreign currency forward contracts, underwriting and non-investment operations | Long
Derivative [Line Items]
Notional amount	354,400,000	215,400,000
Foreign currency forward contracts, underwriting and non-investment operations | Short
Derivative [Line Items]
Notional amount	536,400,000	44,200,000
Foreign currency forward contracts, investment operations | Long
Derivative [Line Items]
Notional amount	109,000,000	16,600,000
Foreign currency forward contracts, investment operations | Short
Derivative [Line Items]
Notional amount	62,400,000	5,100,000
Credit default swaps | Long
Derivative [Line Items]
Notional amount	1,000,000	1,000,000
Credit default swaps | Short
Derivative [Line Items]
Notional amount	$ 109,700,000	$ 18,800,000

Condensed Consolidating Finan_3

Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Total investments	$ 11,545,691	$ 9,503,439
Cash and cash equivalents	453,041	1,361,592	$ 581,576	$ 421,157
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,787,095	1,304,622
Prepaid reinsurance premiums	795,496	533,546
Reinsurance recoverable	1,204,059	1,586,630	1,588,304
Accrued investment income	46,690	42,235
Deferred acquisition costs	497,733	426,551
Receivable for investments sold	406,062	103,145
Other assets	121,724	121,226
Goodwill and other intangible assets	238,803	243,145
Total assets	17,096,394	15,226,131
Liabilities
Reserve for claims and claim expenses	4,952,498	5,080,408	5,192,313
Unearned premiums	2,058,851	1,477,609
Debt	990,749	989,623
Amounts due to subsidiaries and affiliates	0	0
Reinsurance balances payable	1,970,913	989,090
Payable for investments purchased	555,556	208,749
Other liabilities	147,328	792,771
Total liabilities	10,675,895	9,538,250
Redeemable noncontrolling interests	1,533,978	1,296,506
Shareholders’ Equity
Total shareholders’ equity	4,886,521	4,391,375	4,403,012
Total liabilities, noncontrolling interests and shareholders’ equity	17,096,394	15,226,131
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Assets
Total investments	110,117	129,732
Cash and cash equivalents	56	139	226	162
Investments in subsidiaries	57,082	36,140
Due from subsidiaries and affiliates	101,579	91,891
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	241	428
Deferred acquisition costs	0	0
Receivable for investments sold	1	51
Other assets	19,771	21,342
Goodwill and other intangible assets	0	0
Total assets	288,847	279,723
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	0	0
Amounts due to subsidiaries and affiliates	144	54
Reinsurance balances payable	0	0
Payable for investments purchased	17	0
Other liabilities	773	1,053
Total liabilities	934	1,107
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	287,913	278,616
Total liabilities, noncontrolling interests and shareholders’ equity	288,847	279,723
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Assets
Total investments	15,504	31,255
Cash and cash equivalents	4,372	1,469	7,663	9,397
Investments in subsidiaries	1,235,547	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	20	82
Deferred acquisition costs	0	0
Receivable for investments sold	6	8
Other assets	367,408	430,481
Goodwill and other intangible assets	0	0
Total assets	1,622,857	1,605,028
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	842,786	841,892
Amounts due to subsidiaries and affiliates	129,056	92,794
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	9,179	14,117
Total liabilities	981,021	948,803
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	641,836	656,225
Total liabilities, noncontrolling interests and shareholders’ equity	1,622,857	1,605,028
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Assets
Total investments	36,092	225,266
Cash and cash equivalents	3,734	14,656	12,370	7,067
Investments in subsidiaries	4,544,513	4,105,760
Due from subsidiaries and affiliates	101,372	4,602
Premiums receivable	0	0
Prepaid reinsurance premiums	0	0
Reinsurance recoverable	0	0
Accrued investment income	0	405
Deferred acquisition costs	0	0
Receivable for investments sold	30	135
Other assets	450,161	433,468
Goodwill and other intangible assets	121,560	124,960
Total assets	5,257,462	4,909,252
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	352,000	417,000
Amounts due to subsidiaries and affiliates	6,132	82,579
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	12,809	18,298
Total liabilities	370,941	517,877
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	4,886,521	4,391,375
Total liabilities, noncontrolling interests and shareholders’ equity	5,257,462	4,909,252
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Assets
Total investments	11,383,978	9,117,186
Cash and cash equivalents	444,879	1,345,328	$ 561,307	$ 397,860
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,787,095	1,304,622
Prepaid reinsurance premiums	795,496	533,546
Reinsurance recoverable	1,204,059	1,586,630
Accrued investment income	46,429	41,320
Deferred acquisition costs	497,733	426,551
Receivable for investments sold	406,025	102,951
Other assets	84,974	76,703
Goodwill and other intangible assets	117,243	118,185
Total assets	16,767,911	14,653,022
Liabilities
Reserve for claims and claim expenses	4,952,498	5,080,408
Unearned premiums	2,058,851	1,477,609
Debt	147,963	147,731
Amounts due to subsidiaries and affiliates	0	0
Reinsurance balances payable	1,970,913	989,090
Payable for investments purchased	555,539	208,749
Other liabilities	134,181	764,432
Total liabilities	9,819,945	8,668,019
Redeemable noncontrolling interests	1,533,978	1,296,506
Shareholders’ Equity
Total shareholders’ equity	5,413,988	4,688,497
Total liabilities, noncontrolling interests and shareholders’ equity	16,767,911	14,653,022
Consolidating Adjustments
Assets
Total investments	0	0
Cash and cash equivalents	0	0
Investments in subsidiaries	(5,837,142)	(5,283,633)
Due from subsidiaries and affiliates	(202,951)	(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	(800,590)	(840,768)
Goodwill and other intangible assets	0	0
Total assets	(6,840,683)	(6,220,894)
Liabilities
Reserve for claims and claim expenses	0	0
Unearned premiums	0	0
Debt	(352,000)	(417,000)
Amounts due to subsidiaries and affiliates	(135,332)	(175,427)
Reinsurance balances payable	0	0
Payable for investments purchased	0	0
Other liabilities	(9,614)	(5,129)
Total liabilities	(496,946)	(597,556)
Redeemable noncontrolling interests	0	0
Shareholders’ Equity
Total shareholders’ equity	(6,343,737)	(5,623,338)
Total liabilities, noncontrolling interests and shareholders’ equity	$ (6,840,683)	$ (6,220,894)

Condensed Consolidating Finan_4

Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries (Condensed Consolidating Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Net premiums earned	$ 531,849	$ 547,792	$ 1,401,516	$ 1,296,102
Net investment income	80,696	40,257	208,528	148,745
Net foreign exchange (losses) gains	(4,566)	(156)	(11,496)	11,118
Equity in earnings of other ventures	7,648	1,794	14,331	5,830
Other income	497	2,996	480	7,053
Net realized and unrealized gains (losses) on investments	13,630	42,052	(86,415)	143,538
Total revenues	629,754	634,735	1,526,944	1,612,386
Expenses
Net claims and claim expenses incurred	410,510	1,221,696	642,380	1,557,364
Acquisition expenses	109,761	76,761	312,524	248,294
Operational expenses	40,593	42,537	119,408	131,586
Corporate expenses	6,841	4,413	21,875	14,335
Interest expense	11,769	11,799	35,304	32,416
Total expenses	579,474	1,357,206	1,131,491	1,983,995
Income (loss) before equity in net income (loss) of subsidiaries and taxes	50,280	(722,471)	395,453	(371,609)
Equity in net income (loss) of subsidiaries	0	0	0	0
Income (loss) before taxes	50,280	(722,471)	395,453	(371,609)
Income tax (expense) benefit	(1,451)	18,977	(2,550)	14,739
Net income (loss)	48,829	(703,494)	392,903	(356,870)
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Net income (loss) attributable to RenaissanceRe	42,389	(499,217)	302,081	(224,532)
Dividends on preference shares	(9,708)	(5,595)	(20,899)	(16,786)
Net income (loss) available (attributable) to RenaissanceRe common shareholders	32,681	(504,812)	281,182	(241,318)
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Revenues
Net premiums earned	0	0	0	0
Net investment income	539	544	1,629	1,436
Net foreign exchange (losses) gains	0	0	0	0
Equity in earnings of other ventures	0	0	0	0
Other income	0	0	0	0
Net realized and unrealized gains (losses) on investments	4,479	2,186	4,906	6,528
Total revenues	5,018	2,730	6,535	7,964
Expenses
Net claims and claim expenses incurred	0	0	0	0
Acquisition expenses	0	0	0	0
Operational expenses	29	17	60	57
Corporate expenses	0	0	0	0
Interest expense	0	0	0	0
Total expenses	29	17	60	57
Income (loss) before equity in net income (loss) of subsidiaries and taxes	4,989	2,713	6,475	7,907
Equity in net income (loss) of subsidiaries	2,735	928	4,285	3,234
Income (loss) before taxes	7,724	3,641	10,760	11,141
Income tax (expense) benefit	(1,026)	(890)	(1,273)	(2,572)
Net income (loss)	6,698	2,751	9,487	8,569
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Net income (loss) attributable to RenaissanceRe	6,698	2,751	9,487	8,569
Dividends on preference shares	0	0	0	0
Net income (loss) available (attributable) to RenaissanceRe common shareholders	6,698	2,751	9,487	8,569
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Revenues
Net premiums earned		0		0
Net investment income		(3)		1,373
Net foreign exchange (losses) gains		0		0
Equity in earnings of other ventures		0		0
Other income		0		0
Net realized and unrealized gains (losses) on investments		0		4,916
Total revenues		(3)		6,289
Expenses
Net claims and claim expenses incurred		0		0
Acquisition expenses		0		0
Operational expenses		1		86
Corporate expenses		0		0
Interest expense		0		2,461
Total expenses		1		2,547
Income (loss) before equity in net income (loss) of subsidiaries and taxes		(4)		3,742
Equity in net income (loss) of subsidiaries		0		28,028
Income (loss) before taxes		(4)		31,770
Income tax (expense) benefit		29		(1,175)
Net income (loss)		25		30,595
Net (income) loss attributable to redeemable noncontrolling interests		0		0
Net income (loss) attributable to RenaissanceRe		25		30,595
Dividends on preference shares		0		0
Net income (loss) available (attributable) to RenaissanceRe common shareholders		25		30,595
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Revenues
Net premiums earned	0	0	0	0
Net investment income	1,541	1,335	3,981	1,843
Net foreign exchange (losses) gains	0	0	0	0
Equity in earnings of other ventures	290	38	2,045	(412)
Other income	0	0	0	0
Net realized and unrealized gains (losses) on investments	(73)	51	(399)	(217)
Total revenues	1,758	1,424	5,627	1,214
Expenses
Net claims and claim expenses incurred	0	0	0	0
Acquisition expenses	0	0	0	0
Operational expenses	7,493	6,266	26,737	20,892
Corporate expenses	0	0	7	0
Interest expense	9,257	9,258	27,763	22,401
Total expenses	16,750	15,524	54,507	43,293
Income (loss) before equity in net income (loss) of subsidiaries and taxes	(14,992)	(14,100)	(48,880)	(42,079)
Equity in net income (loss) of subsidiaries	11,666	(16,352)	29,005	20,584
Income (loss) before taxes	(3,326)	(30,452)	(19,875)	(21,495)
Income tax (expense) benefit	1,840	3,307	5,677	9,281
Net income (loss)	(1,486)	(27,145)	(14,198)	(12,214)
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Net income (loss) attributable to RenaissanceRe	(1,486)	(27,145)	(14,198)	(12,214)
Dividends on preference shares	0	0	0	0
Net income (loss) available (attributable) to RenaissanceRe common shareholders	(1,486)	(27,145)	(14,198)	(12,214)
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Revenues
Net premiums earned	0	0	0	0
Net investment income	6,542	5,725	18,504	16,466
Net foreign exchange (losses) gains	3	0	(1)	(1)
Equity in earnings of other ventures	0	0	0	0
Other income	0	1	0	0
Net realized and unrealized gains (losses) on investments	(176)	110	(821)	155
Total revenues	6,369	5,836	17,682	16,620
Expenses
Net claims and claim expenses incurred	0	0	0	0
Acquisition expenses	0	0	0	0
Operational expenses	3,570	2,910	7,551	9,398
Corporate expenses	3,778	4,634	12,498	14,640
Interest expense	1,478	183	3,694	464
Total expenses	8,826	7,727	23,743	24,502
Income (loss) before equity in net income (loss) of subsidiaries and taxes	(2,457)	(1,891)	(6,061)	(7,882)
Equity in net income (loss) of subsidiaries	45,130	(499,408)	310,081	(219,309)
Income (loss) before taxes	42,673	(501,299)	304,020	(227,191)
Income tax (expense) benefit	(284)	2,082	(1,939)	2,659
Net income (loss)	42,389	(499,217)	302,081	(224,532)
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Net income (loss) attributable to RenaissanceRe	42,389	(499,217)	302,081	(224,532)
Dividends on preference shares	(9,708)	(5,595)	(20,899)	(16,786)
Net income (loss) available (attributable) to RenaissanceRe common shareholders	32,681	(504,812)	281,182	(241,318)
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Revenues
Net premiums earned	531,849	547,792	1,401,516	1,296,102
Net investment income	80,472	39,342	208,034	146,816
Net foreign exchange (losses) gains	(4,569)	(156)	(11,495)	11,119
Equity in earnings of other ventures	7,358	1,756	12,286	6,242
Other income	497	2,995	480	7,053
Net realized and unrealized gains (losses) on investments	9,400	39,705	(90,101)	132,156
Total revenues	625,007	631,434	1,520,720	1,599,488
Expenses
Net claims and claim expenses incurred	410,510	1,221,696	642,380	1,557,364
Acquisition expenses	109,761	76,761	312,524	248,294
Operational expenses	42,682	37,752	113,721	116,212
Corporate expenses	3,063	(221)	9,370	(305)
Interest expense	2,512	2,541	7,541	7,554
Total expenses	568,528	1,338,529	1,085,536	1,929,119
Income (loss) before equity in net income (loss) of subsidiaries and taxes	56,479	(707,095)	435,184	(329,631)
Equity in net income (loss) of subsidiaries	0	0	0	0
Income (loss) before taxes	56,479	(707,095)	435,184	(329,631)
Income tax (expense) benefit	(1,981)	14,449	(5,015)	6,546
Net income (loss)	54,498	(692,646)	430,169	(323,085)
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Net income (loss) attributable to RenaissanceRe	48,058	(488,369)	339,347	(190,747)
Dividends on preference shares	0	0	0	0
Net income (loss) available (attributable) to RenaissanceRe common shareholders	48,058	(488,369)	339,347	(190,747)
Consolidating Adjustments
Revenues
Net premiums earned	0	0	0	0
Net investment income	(8,398)	(6,686)	(23,620)	(19,189)
Net foreign exchange (losses) gains	0	0	0	0
Equity in earnings of other ventures	0	0	0	0
Other income	0	0	0	0
Net realized and unrealized gains (losses) on investments	0	0	0	0
Total revenues	(8,398)	(6,686)	(23,620)	(19,189)
Expenses
Net claims and claim expenses incurred	0	0	0	0
Acquisition expenses	0	0	0	0
Operational expenses	(13,181)	(4,409)	(28,661)	(15,059)
Corporate expenses	0	0	0	0
Interest expense	(1,478)	(183)	(3,694)	(464)
Total expenses	(14,659)	(4,592)	(32,355)	(15,523)
Income (loss) before equity in net income (loss) of subsidiaries and taxes	6,261	(2,094)	8,735	(3,666)
Equity in net income (loss) of subsidiaries	(59,531)	514,832	(343,371)	167,463
Income (loss) before taxes	(53,270)	512,738	(334,636)	163,797
Income tax (expense) benefit	0	0	0	0
Net income (loss)	(53,270)	512,738	(334,636)	163,797
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Net income (loss) attributable to RenaissanceRe	(53,270)	512,738	(334,636)	163,797
Dividends on preference shares	0	0	0	0
Net income (loss) available (attributable) to RenaissanceRe common shareholders	$ (53,270)	$ 512,738	$ (334,636)	$ 163,797

Condensed Consolidating Finan_5

Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries (Condensed Consolidating Statement of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 48,829	$ (703,494)	$ 392,903	$ (356,870)
Change in net unrealized gains on investments	(382)	300	(1,707)	(972)
Comprehensive income (loss)	48,447	(703,194)	391,196	(357,842)
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Comprehensive (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Comprehensive income (loss) attributable to RenaissanceRe	42,007	(498,917)	300,374	(225,504)
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	6,698	2,751	9,487	8,569
Change in net unrealized gains on investments	0	0	0	0
Comprehensive income (loss)	6,698	2,751	9,487	8,569
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to RenaissanceRe	6,698	2,751	9,487	8,569
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income (loss)		25		30,595
Change in net unrealized gains on investments		0		0
Comprehensive income (loss)		25		30,595
Net (income) loss attributable to redeemable noncontrolling interests		0		0
Comprehensive (income) loss attributable to redeemable noncontrolling interests		0		0
Comprehensive income (loss) attributable to RenaissanceRe		25		30,595
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(1,486)	(27,145)	(14,198)	(12,214)
Change in net unrealized gains on investments	0	0	0	0
Comprehensive income (loss)	(1,486)	(27,145)	(14,198)	(12,214)
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to RenaissanceRe	(1,486)	(27,145)	(14,198)	(12,214)
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	42,389	(499,217)	302,081	(224,532)
Change in net unrealized gains on investments	0	0	0	0
Comprehensive income (loss)	42,389	(499,217)	302,081	(224,532)
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to RenaissanceRe	42,389	(499,217)	302,081	(224,532)
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	54,498	(692,646)	430,169	(323,085)
Change in net unrealized gains on investments	(382)	300	(1,707)	(972)
Comprehensive income (loss)	54,116	(692,346)	428,462	(324,057)
Net (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Comprehensive (income) loss attributable to redeemable noncontrolling interests	(6,440)	204,277	(90,822)	132,338
Comprehensive income (loss) attributable to RenaissanceRe	47,676	(488,069)	337,640	(191,719)
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(53,270)	512,738	(334,636)	163,797
Change in net unrealized gains on investments	0	0	0	0
Comprehensive income (loss)	(53,270)	512,738	(334,636)	163,797
Net (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive (income) loss attributable to redeemable noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to RenaissanceRe	$ (53,270)	$ 512,738	$ (334,636)	$ 163,797

Condensed Consolidating Finan_6

Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	$ 888,526	$ 601,702
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading	8,221,481	7,663,002
Purchases of fixed maturity investments trading	(8,692,688)	(7,798,285)
Net (purchases) sales of equity investments trading	15,490	61,571
Net purchases of short term investments	(1,465,451)	(146,326)
Net purchases of other investments	(130,649)	5,181
Net purchases of investments in other ventures	(20,952)	0
Return of investment from investment in other ventures	8,464	20,000
Dividends and return of capital from subsidiaries	0	0
Contributions to subsidiaries	0	0
Due (from) to subsidiary	0	0
Net cash used in investing activities	(2,064,305)	(194,857)
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	(39,611)	(38,624)
Dividends paid – preference shares	(20,899)	(16,786)
Issuance of preference shares, net of expenses	242,371	0
RenaissanceRe common share repurchases	0	(188,591)
Repayment of debt		(250,000)
Issuance of debt, net of expenses	0	295,866
Net third party redeemable noncontrolling interest share transactions	96,021	(44,193)
Taxes paid on withholding shares	(7,079)	(13,694)
Net cash provided by (used in) financing activities	270,803	(256,022)
Effect of exchange rate changes on foreign currency cash	(3,575)	9,596
Net (decrease) increase in cash and cash equivalents	(908,551)	160,419
Cash and cash equivalents, beginning of period	1,361,592	421,157
Cash and cash equivalents, end of period	453,041	581,576
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	1,496	(8,209)
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading	91,118	74,455
Purchases of fixed maturity investments trading	(65,988)	(69,168)
Net (purchases) sales of equity investments trading	(624)	(1,708)
Net purchases of short term investments	360	(4,495)
Net purchases of other investments	0	0
Net purchases of investments in other ventures	0
Return of investment from investment in other ventures	0	0
Dividends and return of capital from subsidiaries	0	9,175
Contributions to subsidiaries	(16,847)	0
Due (from) to subsidiary	(9,598)	14
Net cash used in investing activities	(1,579)	8,273
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
Issuance of preference shares, net of expenses	0
RenaissanceRe common share repurchases		0
Repayment of debt		0
Issuance of debt, net of expenses		0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash provided by (used in) financing activities	0	0
Effect of exchange rate changes on foreign currency cash	0	0
Net (decrease) increase in cash and cash equivalents	(83)	64
Cash and cash equivalents, beginning of period	139	162
Cash and cash equivalents, end of period	56	226
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities		(2,262)
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading		289,741
Purchases of fixed maturity investments trading		(143,991)
Net (purchases) sales of equity investments trading		85,324
Net purchases of short term investments		41,299
Net purchases of other investments		0
Return of investment from investment in other ventures		0
Dividends and return of capital from subsidiaries		0
Contributions to subsidiaries		(26,649)
Due (from) to subsidiary		(123)
Net cash used in investing activities		245,601
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares		0
Dividends paid – preference shares		0
RenaissanceRe common share repurchases		0
Repayment of debt		(250,000)
Issuance of debt, net of expenses		0
Net third party redeemable noncontrolling interest share transactions		0
Taxes paid on withholding shares		0
Net cash provided by (used in) financing activities		(250,000)
Effect of exchange rate changes on foreign currency cash		0
Net (decrease) increase in cash and cash equivalents		(6,661)
Cash and cash equivalents, beginning of period		6,671
Cash and cash equivalents, end of period		10
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	16,194	(343,093)
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading	45,459	279,830
Purchases of fixed maturity investments trading	(20,806)	(270,785)
Net (purchases) sales of equity investments trading	0	0
Net purchases of short term investments	(9,206)	(305)
Net purchases of other investments	0	0
Net purchases of investments in other ventures	0
Return of investment from investment in other ventures	0	0
Dividends and return of capital from subsidiaries	0	41,866
Contributions to subsidiaries	(65,000)	(9,175)
Due (from) to subsidiary	36,262	4,062
Net cash used in investing activities	(13,291)	45,493
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
Issuance of preference shares, net of expenses	0
RenaissanceRe common share repurchases		0
Repayment of debt		0
Issuance of debt, net of expenses		295,866
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash provided by (used in) financing activities	0	295,866
Effect of exchange rate changes on foreign currency cash	0	0
Net (decrease) increase in cash and cash equivalents	2,903	(1,734)
Cash and cash equivalents, beginning of period	1,469	9,397
Cash and cash equivalents, end of period	4,372	7,663
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(5,869)	(6,870)
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading	384,818	106,761
Purchases of fixed maturity investments trading	(281,994)	(118,402)
Net (purchases) sales of equity investments trading	0	0
Net purchases of short term investments	85,598	205,864
Net purchases of other investments	0	0
Net purchases of investments in other ventures	0
Return of investment from investment in other ventures	0	0
Dividends and return of capital from subsidiaries	511,098	285,515
Contributions to subsidiaries	(686,106)	(500,000)
Due (from) to subsidiary	(193,249)	290,130
Net cash used in investing activities	(179,835)	269,868
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	(39,611)	(38,624)
Dividends paid – preference shares	(20,899)	(16,786)
Issuance of preference shares, net of expenses	242,371
RenaissanceRe common share repurchases		(188,591)
Repayment of debt		0
Issuance of debt, net of expenses		0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	(7,079)	(13,694)
Net cash provided by (used in) financing activities	174,782	(257,695)
Effect of exchange rate changes on foreign currency cash	0	0
Net (decrease) increase in cash and cash equivalents	(10,922)	5,303
Cash and cash equivalents, beginning of period	14,656	7,067
Cash and cash equivalents, end of period	3,734	12,370
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	876,705	962,136
Cash flows used in investing activities
Proceeds from sales and maturities of fixed maturity investments trading	7,700,086	6,912,215
Purchases of fixed maturity investments trading	(8,323,900)	(7,195,939)
Net (purchases) sales of equity investments trading	16,114	(22,045)
Net purchases of short term investments	(1,542,203)	(388,689)
Net purchases of other investments	(130,649)	5,181
Net purchases of investments in other ventures	(20,952)
Return of investment from investment in other ventures	8,464	20,000
Dividends and return of capital from subsidiaries	(511,098)	(336,556)
Contributions to subsidiaries	767,953	535,824
Due (from) to subsidiary	166,585	(294,083)
Net cash used in investing activities	(1,869,600)	(764,092)
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
Issuance of preference shares, net of expenses	0
RenaissanceRe common share repurchases		0
Repayment of debt		0
Issuance of debt, net of expenses		0
Net third party redeemable noncontrolling interest share transactions	96,021	(44,193)
Taxes paid on withholding shares	0	0
Net cash provided by (used in) financing activities	96,021	(44,193)
Effect of exchange rate changes on foreign currency cash	(3,575)	9,596
Net (decrease) increase in cash and cash equivalents	(900,449)	163,447
Cash and cash equivalents, beginning of period	1,345,328	397,860
Cash and cash equivalents, end of period	$ 444,879	$ 561,307

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Oct. 30, 2018	Dec. 31, 2018
Hurricane Michael 2018 | Scenario, Forecast
Subsequent Event [Line Items]
Estimate of possible loss		$ 100,000,000
State Farm Mutual Automobile Insurance Company | Subsequent Event | Private Placement
Subsequent Event [Line Items]
Investment Agreement, number of shares issued in transaction (in shares)	1,947,496
Investment Agreement, consideration received per transaction	$ 250,000,000