Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period				$ 823,007
Amounts attributable to noncontrolling interests		$ 41,617	$ 165,598	78,314	$ (68,346)
Other comprehensive (income) loss attributable to noncontrolling interests		10	20,111	(4,560)	(12,947)
Non-redeemable noncontrolling interests, end of period		918,874	679,089	918,874	679,089
Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period		876,864	492,785	823,007	762,777
Additional paid in capital attributable to noncontrolling interests		383	595	22,113	472
Repurchases attributable to non-redeemable noncontrolling interests	[1]			0	(2,867)
Amounts attributable to noncontrolling interests		41,617	165,598	78,314	(68,346)
Other comprehensive (income) loss attributable to noncontrolling interests		10	20,111	(4,560)	(12,947)
Non-redeemable noncontrolling interests, end of period		$ 918,874	$ 679,089	$ 918,874	$ 679,089
Noncontrolling shareholders | Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners		90.00%		90.00%

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