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Variable Interest Entity and Noncontrolling Interests - Non-redeemable noncontrolling interest (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interest, beginning of year		$ 762,777	$ 791,560
Amounts attributable to nonredeemable noncontrolling interests		(53,076)	(40,072)	$ 48,507
Other Amounts Attributable to Noncontrolling Interests		(375)	0
Non-redeemable noncontrolling interest, end of year		823,007	762,777	791,560
Watford Holdings Ltd | Noncontrolling Interest
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interest, beginning of year		762,777	791,560
Additional paid in capital attributable to noncontrolling interests		1,334	(2,929)
Repurchases attributable to non-redeemable noncontrolling interests (1)	[1]	(2,867)	(75,056)
Amounts attributable to nonredeemable noncontrolling interests		53,076	40,072
Other comprehensive (income) loss attributable to noncontrolling interests		9,062	9,130
Non-redeemable noncontrolling interest, end of year		$ 823,007	$ 762,777	$ 791,560
Common shares | Watford Holdings Ltd | Noncontrolling Interest | Noncontrolling Ownership [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners		87.00%
[1] During 2020 and 2019, Watford’s board of directors authorized the investment in Watford’s common shares through a share repurchase program

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