Dividend Restrictions and Statutory Financial Information - Subsidiary Statutory Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Bermuda
Statutory Accounting Practices [Line Items]
Required	$ 2,138,395	$ 1,591,991
Actual	4,016,663	3,701,825
Statutory Income	643,683	29,486	$ 390,752
U.K.
Statutory Accounting Practices [Line Items]
Required	837,104	654,721
Actual	1,532,751	715,448
Statutory Income	154,644	(52,936)	77,900
U.S.
Statutory Accounting Practices [Line Items]
Required	364,507	392,394
Actual	861,379	660,470
Statutory Income	121,406	(75,005)	(5,065)
Europe
Statutory Accounting Practices [Line Items]
Required	94,334	239,582
Actual	229,344	431,863
Statutory Income	11,816	(17,611)	(4,245)
Australia
Statutory Accounting Practices [Line Items]
Required	18,110	22,535
Actual	37,815	26,882
Statutory Income	$ 4,847	$ 1,761	$ (874)

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No definition available.

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- Definition

The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(c))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

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- Definition

Amount of statutory capital required to be maintained as of the balance sheet date under prescribed or permitted statutory accounting practices.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

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- Definition

Amount of net income for the period determined using accounting principles prescribed or permitted by insurance regulators.

+ References

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