Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period				$ 762,777
Amounts attributable to noncontrolling interests		$ 67,768	$ 136	(578)	$ 54,819
Other comprehensive (income) loss attributable to noncontrolling interests		10,820	(764)	(2,127)	6,266
Non-redeemable noncontrolling interests, end of period		757,920	854,924	757,920	854,924
Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period		679,089	855,347	762,777	791,560
Additional paid in capital attributable to noncontrolling interests		243	205	715	2,279
Repurchases attributable to non-redeemable noncontrolling interests	[1]			(2,867)	0
Amounts attributable to noncontrolling interests		67,768	136	(578)	54,819
Other comprehensive (income) loss attributable to noncontrolling interests		10,820	(764)	(2,127)	6,266
Non-redeemable noncontrolling interests, end of period		$ 757,920	$ 854,924	$ 757,920	$ 854,924
Noncontrolling shareholders | Common shares | Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners		87.00%		87.00%

[1] During 2020, Watford’s board of directors authorized the investment in Watford’s common shares through a share repurchase program.