Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period		$ 823,007
Amounts attributable to noncontrolling interests		36,697	$ (233,944)
Other comprehensive (income) loss attributable to noncontrolling interests		(4,570)	(33,058)
Non-redeemable noncontrolling interests, end of period		876,864	492,785
Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period		823,007	762,777
Additional paid in capital attributable to noncontrolling interests		21,730	(123)
Repurchases attributable to non-redeemable noncontrolling interests	[1]	0	(2,867)
Amounts attributable to noncontrolling interests		36,697	(233,944)
Other comprehensive (income) loss attributable to noncontrolling interests		(4,570)	(33,058)
Non-redeemable noncontrolling interests, end of period		$ 876,864	$ 492,785
Noncontrolling shareholders | Common shares | Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners		90.00%

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