Segment information (Segment reporting by segment - Corporate and investments) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Segment Reporting Information [Line Items]
Net investment income		$ 57,560	$ 44,241	$ 109,632		$ 84,455
Net realized gains (losses) on investments		(7,394)	2,274	(5,194)		1,110
Change in net unrealized (losses) gains on investments		(10,730)	16,321	(68,111)		29,669
Income from investment affiliates		2,178	9,466	15,246		14,654
Managed investment return		41,614	72,302	51,573	[1]	129,888	[1]
General and administrative expenses		120,862	96,349	235,588		184,273
Share compensation expenses		16,040	11,146	25,769		20,637
Finance expenses		14,310	14,209	28,573		28,152
Dividends on preferred shares		5,828	2,203	11,656		4,406
Tax (benefit)		(7,151)	(987)	(13,984)		(4,536)
Foreign exchange losses		(526)	(7,329)	(1)		(5,760)
Transaction expenses		(3,837)	(4,427)	(11,593)		(4,427)
Net (loss) income (attributable) available to Validus common shareholders		(52,898)	101,095	(56,976)		195,656
Corporate & Investments
Segment Reporting Information [Line Items]
Net investment income	[2]	42,752	38,063	82,543		74,255
Net realized gains (losses) on investments	[2]	(7,432)	2,269	(6,290)		(623)
Change in net unrealized (losses) gains on investments	[2]	(11,392)	15,942	(68,169)		30,291
Income from investment affiliates		2,178	9,466	15,246		14,654
Managed investment return	[1]	26,106	65,740	23,330		118,577
General and administrative expenses		13,523	16,219	25,832		34,180
Share compensation expenses		7,796	4,636	11,832		8,049
Finance expenses	[2]	14,249	14,149	28,339		28,013
Dividends on preferred shares		5,828	2,203	11,656		4,406
Tax (benefit)	[2]	(7,153)	(1,122)	(13,979)		(4,670)
Total expenses		34,243	36,085	63,680		69,978
Foreign exchange losses	[2]	(1,652)	(7,323)	(1,655)		(6,220)
Other income		538	174	582		268
Transaction expenses		(3,837)	(4,427)	(11,593)		(4,427)
Total other items		(4,951)	(11,576)	(12,666)		(10,379)
Net (loss) income (attributable) available to Validus common shareholders		$ (13,088)	$ 18,079	$ (53,016)		$ 38,220

[1] Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates.

[2] These items exclude the components which are included in the Asset Management segment income (loss) and amounts which are consolidated from VIEs.