Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period			$ 791,560
Amounts attributable to noncontrolling interests	$ 136	$ 16,759	54,819	$ 36,251
Other comprehensive (income) loss attributable to noncontrolling interests	(764)	(1,158)	6,266	(2,908)
Non-redeemable noncontrolling interests, end of period	854,924	876,754	854,924	876,754
Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period	855,347	861,153	791,560	843,411
Additional paid in capital attributable to noncontrolling interests	205	0	2,279	0
Amounts attributable to noncontrolling interests	136	16,759	54,819	36,251
Other comprehensive (income) loss attributable to noncontrolling interests	(764)	(1,158)	6,266	(2,908)
Non-redeemable noncontrolling interests, end of period	$ 854,924	$ 876,754	$ 854,924	$ 876,754
Common shares \| Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	89.00%		89.00%

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

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