Statutory Information - Summary of statutory capital, surplus and net income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Bermuda
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[1]	$ 17,528,510	$ 17,390,943
Required statutory capital and surplus	[1]	5,661,301	5,234,121
Statutory net income (loss)		2,370,746	1,579,889	$ 1,801,486
Ireland
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[1]	958,200	883,337
Required statutory capital and surplus	[1]	794,933	701,161
Statutory net income (loss)		25,191	18,397	26,367
United States
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[1]	5,600,652	4,904,840
Required statutory capital and surplus	[1]	1,717,646	1,644,324
Statutory net income (loss)		345,790	143,271	481,188
United Kingdom
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[1]	902,002	967,440
Required statutory capital and surplus	[1]	563,164	601,662
Statutory net income (loss)		35,286	4,078	(17,423)
Canada
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus	[1]	70,063	64,286
Required statutory capital and surplus	[1]	42,513	37,441
Statutory net income (loss)		6,985	(1,049)	(1,023)
Australia
Statutory Accounting Practices [Line Items]
Actual statutory capital and surplus		283,693	64,507
Required statutory capital and surplus		214,022	19,370
Statutory net income (loss)		$ 11,874	$ (8,601)	$ (6,199)

[1] Such amounts include ownership interests in affiliated insurance and reinsurance subsidiaries.