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Variable Interest Entities and Noncontrolling Interests - Redeemable noncontrolling interests (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2014
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, beginning of period			$ 58,548
Redeemable noncontrolling interests, end of period	$ 10,237		10,237
Watford Holdings Ltd
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, beginning of period	57,533	$ 55,986	58,548	$ 55,404
Impact of deconsolidation of Watford	(48,919)	0	(48,919)	0
Accretion of preference share issuance costs	0	23	0	70
Other	1,623	1,826	608	2,361
Redeemable noncontrolling interests, end of period	$ 10,237	$ 57,835	$ 10,237	$ 57,835
Cumulative redeemable preference shares | Watford Holdings Ltd
Redeemable Noncontrolling Interest [Line Items]
Par value per share					$ 0.01
Liquidation preference per share					25.00
Issue price per share					$ 24.50

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The amount of the reduction or elimination during the period of a redeemable noncontrolling interest resulting from the parent's loss of control and deconsolidation of the entity in which one or more outside parties had a redeemable noncontrolling interest.

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The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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As of the reporting date, the carrying amount of noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. The noncontrolling interest holder's ownership (or holders' ownership) may be in the form of preferred shares (regardless of class), preferred partnership units (regardless of class), preferential membership interests, or any other form of preferred equity regardless of investee entity legal form.

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