Segment information (Summary of results of operating and other segments) (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segments	Jun. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segments				4
Underwriting revenues
Gross premiums written		$ 764,042	$ 726,168	$ 1,936,833	$ 1,845,392
Reinsurance premiums ceded		(36,229)	(55,418)	(204,064)	(246,743)
Net premiums written		727,813	670,750	1,732,769	1,598,649
Change in unearned premiums		(154,090)	(98,062)	(587,778)	(450,071)
Net premiums earned		573,723	572,688	1,144,991	1,148,578
Other insurance related income (loss)		745	708	1,481	1,648
Segmental revenues		574,468	573,396	1,146,472	1,150,226
Underwriting deductions
Losses and loss expenses	[1]	307,130	266,146	531,577	507,075
Policy acquisition costs		107,966	104,323	215,159	202,734
General and administrative expenses		89,688	84,025	175,896	168,260
Share compensation expenses		10,727	9,242	21,964	18,296
Total underwriting deductions		515,511	463,736	944,596	896,365
Segmental income		58,957	109,660	201,876	253,861
Other items	[2]	24,056	(54,920)	60,617	(38,561)
Dividends on preferred shares		0	0	0	0
Net investment income		39,257	33,611	68,718	64,640
(Income) attributable to AlphaCat investors		(6,114)	0	(10,714)	0
Net (income) attributable to noncontrolling interest		(21,193)	(22,561)	(58,724)	(40,739)
Finance expenses		14,166	18,682	29,369	39,649
Tax (benefit) expense		1,706	2,549	(412)	5,114
Net realized gains on investments		2,724	2,244	2,140	6,413
Change in net unrealized gains (losses) on investments (a)		31,428	(34,676)	78,872	(1,449)
(Loss) income from investment affiliate		(589)	284	(4,702)	3,060
Foreign exchange gains (losses)		(6,286)	2,671	(12,531)	6,936
Net income available to Validus		94,963	65,790	261,773	239,201
Selected ratios:
Net income available to Validus common shareholders		94,963	65,790	261,773	239,201
Corporate and investment
Underwriting deductions
General and administrative expenses		17,872	17,092	34,055	32,698
Share compensation expenses		4,007	3,178	8,099	6,071
Total underwriting deductions		21,879	20,270	42,154	38,769
Segmental income		(21,879)	(20,270)	(42,154)	(38,769)
Other items	[2]	22,998	(53,076)	59,405	(32,808)
Dividends on preferred shares		0	0	0	0
Net investment income	[3]	36,849	31,854	64,772	61,290
Finance expenses	[3]	13,979	15,144	28,320	30,480
Tax (benefit) expense		1,706	2,549	(412)	5,114
Total expenses		37,564	37,963	70,062	74,363
Validus share of segmental income		37,968	(41,492)	82,023	(10,287)
Net realized gains on investments	[3]	2,520	2,104	1,434	6,284
Change in net unrealized gains (losses) on investments (a)	[3]	30,052	(33,926)	77,130	743
(Loss) income from investment affiliate		(589)	284	(4,702)	3,060
Foreign exchange gains (losses)	[3]	(6,621)	3,237	(12,695)	6,693
Other income		79	(608)	756	(608)
Total other items		38,683	(35,383)	87,313	2,786
Operating Segments | Validus Re
Underwriting revenues
Gross premiums written		285,810	297,420	977,478	1,009,113
Reinsurance premiums ceded		(3,196)	(19,378)	(95,691)	(133,155)
Net premiums written		282,614	278,042	881,787	875,958
Change in unearned premiums		(35,492)	(13,492)	(390,834)	(358,320)
Net premiums earned		247,122	264,550	490,953	517,638
Other insurance related income (loss)		150	434	(165)	749
Segmental revenues		247,272	264,984	490,788	518,387
Underwriting deductions
Losses and loss expenses		132,139	123,405	215,007	236,533
Policy acquisition costs		42,564	43,826	84,823	85,920
General and administrative expenses		17,872	18,781	35,051	38,290
Share compensation expenses		2,775	2,396	5,676	4,974
Total underwriting deductions		195,350	188,408	340,557	365,717
Segmental income		51,922	76,576	150,231	152,670
Validus share of segmental income		$ 51,922	$ 76,576	$ 150,231	$ 152,670
Selected ratios:
Net premiums written / Gross premiums written		98.90%	93.50%	90.20%	86.80%
Losses and loss expenses		53.50%	46.60%	43.80%	45.70%
Policy acquisition costs		17.20%	16.60%	17.30%	16.60%
General and administrative expenses	[4]	8.40%	8.00%	8.30%	8.40%
Expense ratio		25.60%	24.60%	25.60%	25.00%
Combined ratio		79.10%	71.20%	69.40%	70.70%
Operating Segments | Talbot Segment
Underwriting revenues
Gross premiums written		$ 296,067	$ 293,046	$ 562,384	$ 563,123
Reinsurance premiums ceded		(27,161)	(37,246)	(114,619)	(128,321)
Net premiums written		268,906	255,800	447,765	434,802
Change in unearned premiums		(67,357)	(50,362)	(39,424)	(6,775)
Net premiums earned		201,549	205,438	408,341	428,027
Other insurance related income (loss)		279	40	290	94
Segmental revenues		201,828	205,478	408,631	428,121
Underwriting deductions
Losses and loss expenses		109,310	95,970	209,411	174,098
Policy acquisition costs		43,613	47,659	87,956	96,763
General and administrative expenses		39,061	35,555	77,596	72,049
Share compensation expenses		3,270	3,024	6,792	5,981
Total underwriting deductions		195,254	182,208	381,755	348,891
Segmental income		6,574	23,270	26,876	79,230
Validus share of segmental income		$ 6,574	$ 23,270	$ 26,876	$ 79,230
Selected ratios:
Net premiums written / Gross premiums written		90.80%	87.30%	79.60%	77.20%
Losses and loss expenses		54.20%	46.70%	51.30%	40.70%
Policy acquisition costs		21.60%	23.20%	21.50%	22.60%
General and administrative expenses	[4]	21.10%	18.80%	20.70%	18.20%
Expense ratio		42.70%	42.00%	42.20%	40.80%
Combined ratio		96.90%	88.70%	93.50%	81.50%
Operating Segments | Western World
Underwriting revenues
Gross premiums written		$ 86,971	$ 79,554	$ 150,930	$ 136,501
Reinsurance premiums ceded		(5,006)	(5,441)	(9,145)	(8,674)
Net premiums written		81,965	74,113	141,785	127,827
Change in unearned premiums		(16,309)	(8,995)	(14,630)	5,173
Net premiums earned		65,656	65,118	127,155	133,000
Other insurance related income (loss)		189	276	477	539
Segmental revenues		65,845	65,394	127,632	133,539
Underwriting deductions
Losses and loss expenses		44,229	46,771	83,875	97,288
Policy acquisition costs		15,410	9,617	29,610	13,896
General and administrative expenses		11,458	8,923	23,533	19,550
Share compensation expenses		542	494	1,123	971
Total underwriting deductions		71,639	65,805	138,141	131,705
Segmental income		(5,794)	(411)	(10,509)	1,834
Validus share of segmental income		$ (5,794)	$ (411)	$ (10,509)	$ 1,834
Selected ratios:
Net premiums written / Gross premiums written		94.20%	93.20%	93.90%	93.60%
Losses and loss expenses		67.40%	71.80%	66.00%	73.10%
Policy acquisition costs		23.50%	14.80%	23.30%	10.50%
General and administrative expenses	[4]	18.20%	14.50%	19.30%	15.40%
Expense ratio		41.70%	29.30%	42.60%	25.90%
Combined ratio		109.10%	101.10%	108.60%	99.00%
Operating Segments | AlphaCat
Underwriting revenues
Gross premiums written	[5]	$ 98,905	$ 62,795	$ 266,253	$ 164,600
Third party management fees	[5]	3,091	4,323	7,818	8,860
Related party management fees	[5]	328	1,134	1,219	2,320
Segmental revenues	[5]	3,419	5,457	9,037	11,180
Underwriting deductions
General and administrative expenses	[5]	2,751	2,330	4,233	4,759
Share compensation expenses	[5]	133	150	274	299
Total underwriting deductions	[5]	2,963	5,029	5,402	12,022
Segmental income	[5]	456	428	3,635	(842)
Net investment income	[5],[6]	4,421	7,341	10,028	16,378
Finance expenses	[5]	75	2,534	883	6,962
Foreign exchange gains (losses)	[5]	4	15	12	2
Operating Segments | AlphaCat | AlphaCat sidecars
Underwriting revenues
Gross premiums written	[5]	(14)	3,241	(66)	43,347
Underwriting deductions
Net investment income	[5],[6]	541	1,273	665	2,441
Operating Segments | AlphaCat | AlphaCat ILS funds - Lower Risk (a)
Underwriting revenues
Gross premiums written	[5],[7]	50,234	45,687	110,192	88,435
Underwriting deductions
Net investment income	[5],[6],[7]	2,075	1,894	4,582	3,180
Operating Segments | AlphaCat | AlphaCat ILS funds - Higher Risk (a)
Underwriting revenues
Gross premiums written	[5],[7]	42,010	13,867	138,330	32,818
Underwriting deductions
Net investment income	[5],[6],[7]	692	2,376	3,128	4,801
Operating Segments | AlphaCat | BetaCat ILS funds
Underwriting deductions
Net investment income	[5],[6]	1,113	60	1,676	234
Operating Segments | AlphaCat | PaCRe funds
Underwriting deductions
Net investment income	[5],[6]	0	1,738	(23)	5,722
Operating Segments | AlphaCat | AlphaCat direct
Underwriting revenues
Gross premiums written	[5],[8]	6,675	0	17,797	0
Operating Segments | AlphaCat And Consolidated Variable Interest Entities
Underwriting revenues
Gross premiums written		98,905	62,795	266,253	164,600
Reinsurance premiums ceded		(4,577)	0	(4,821)	(4,538)
Net premiums written		94,328	62,795	261,432	160,062
Change in unearned premiums		(34,932)	(25,213)	(142,890)	(90,149)
Net premiums earned		59,396	37,582	118,542	69,913
Other insurance related income (loss)		3,401	5,532	9,066	11,456
Segmental revenues		62,797	43,114	127,608	81,369
Underwriting deductions
Losses and loss expenses		21,452	0	23,284	(844)
Policy acquisition costs		6,530	3,742	12,687	7,177
General and administrative expenses		6,561	8,805	14,017	16,059
Share compensation expenses		133	150	274	299
Total underwriting deductions		34,676	12,697	50,262	22,691
Segmental income		28,121	30,417	77,346	58,678
Other items	[2]	1,058	(1,844)	1,212	(5,753)
Net investment income		3,005	1,757	4,543	3,350
(Income) attributable to AlphaCat investors		(6,114)	0	(10,714)
Net (income) attributable to noncontrolling interest		(21,193)	(22,561)	(58,724)	(40,739)
Validus share of segmental income	[5]	4,877	7,769	13,663	15,536
Eliminations
Underwriting revenues
Gross premiums written		(3,711)	(6,647)	(20,212)	(27,945)
Reinsurance premiums ceded		3,711	6,647	20,212	27,945
Other insurance related income (loss)		(3,274)	(5,574)	(8,187)	(11,190)
Segmental revenues		(3,274)	(5,574)	(8,187)	(11,190)
Underwriting deductions
Policy acquisition costs		(151)	(521)	83	(1,022)
General and administrative expenses		(3,136)	(5,131)	(8,356)	(10,386)
Total underwriting deductions		(3,287)	(5,652)	(8,273)	(11,408)
Segmental income		13	78	86	218
Net investment income		(597)		(597)
Validus share of segmental income		$ (584)	$ 78	$ (511)	$ 218

[1] Upon closing the acquisition of Western World, an adjustment of $15,586 was made to increase net reserves to reflect fair value. This adjustment was amortized to income through a reduction in losses and loss expenses of $2,892 and $6,115, respectively, during the three and six months ended June 30, 2015, benefiting the loss ratio by 4.4 and 4.6 percentage points, respectively. The remaining fair value adjustment of $4,864 was fully amortized during 2015.

[2] Other items includes finance expenses, tax expenses, foreign exchange gains (losses), net realized and change in net unrealized gains (losses) on investments, income from investment and operating affiliates and other income (loss).

[3] These items exclude the components which are included in Validus' share of AlphaCat and amounts which are consolidated from VIEs.

[4] The general and administrative expense ratio includes share compensation expenses.

[5] The results of AlphaCat are presented on an asset manager basis, which is non-GAAP. A reconciliation of segmental income to net income available to Validus is included in the tables below.

[6] The investment income from the AlphaCat funds and sidecars is based on equity accounting.

[7] Lower risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of less than 7%, whereas higher risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of greater than 7%. Expected loss represents the average annual loss over the set of simulation scenarios divided by the total limit.

[8] AlphaCat Direct includes direct investments from third party investors in AlphaCat Re.