Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period			$ 6,325,797
Other comprehensive (loss) income	$ (68,418)	$ 78,467	(128,689)	$ 61,463
End of period	6,663,711		6,663,711
Net realized and unrealized gains (losses) on investments	17,187	(7,772)	89,407	(89,404)
Income before income taxes	332,281	206,414	928,289	305,395
Tax effect	(64,963)	(54,048)	(191,577)	(84,900)
Net income before noncontrolling interests	267,318	152,366	736,712	220,495
Total change in unrealized investment (losses) gains	(45,270)	48,980	(130,201)	111,756
Net change in period	(32,822)	40,194	(26,235)	(36,553)
Other comprehensive income (loss), pre-tax	(78,092)	89,174	(156,436)	75,203
Other comprehensive income (loss), tax effect	9,674	(10,707)	27,747	(13,740)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(122,444)	(249,350)	(62,172)	(257,299)
Other comprehensive income (loss) before reclassifications	(69,071)	79,682	(146,930)	39,921
Amounts reclassified from AOCI	653	(1,215)	18,241	21,542
Other comprehensive (loss) income	(68,418)	78,467	(128,689)	61,463
Unrealized investment gain related to noncontrolling interest	0	(3)	(1)	(2)
End of period	(190,862)	(170,886)	(190,862)	(170,886)
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	827	(1,538)	23,091	27,268
Tax effect	(174)	323	(4,850)	(5,726)
Net income before noncontrolling interests	653	(1,215)	18,241	21,542
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	222,855	209,210	289,714	124,514
Other comprehensive income (loss) before reclassifications	(36,249)	39,488	(120,695)	76,474
Amounts reclassified from AOCI	653	(1,215)	18,241	21,542
Other comprehensive (loss) income	(35,596)	38,273	(102,454)	98,016
Unrealized investment gain related to noncontrolling interest	0	(3)	(1)	(2)
End of period	187,259	247,480	187,259	247,480
Total change in unrealized investment (losses) gains	(45,270)	48,980	(130,201)	111,756
Unrealized investment gains, tax effect	9,674	(10,707)	27,747	(13,740)
Unrealized investment gains (losses), after-tax amounts	(35,596)	38,273	(102,454)	98,016
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized and unrealized gains (losses) on investments	827	(1,538)	23,091	27,268
Tax effect	(174)	323	(4,850)	(5,726)
Net income before noncontrolling interests	653	(1,215)	18,241	21,542
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(345,299)	(458,560)	(351,886)	(381,813)
Other comprehensive income (loss) before reclassifications	(32,822)	40,194	(26,235)	(36,553)
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive (loss) income	(32,822)	40,194	(26,235)	(36,553)
Unrealized investment gain related to noncontrolling interest	0	0	0	0
End of period	(378,121)	(418,366)	(378,121)	(418,366)
Currency translation adjustment, pre-tax	(32,822)	40,194	(26,235)	(36,553)
Currency translation adjustment, tax effect	0	0	0	0
Net change in period	(32,822)	40,194	(26,235)	(36,553)
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	0	0	0	0
Tax effect	0	0	0	0
Net income before noncontrolling interests	$ 0	$ 0	$ 0	0
Cumulative effect adjustment resulting from changes in accounting principles | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period				24,952
Cumulative effect adjustment resulting from changes in accounting principles | Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period				24,952
Cumulative effect adjustment resulting from changes in accounting principles | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period				0
Cumulative Effect, Period Of Adoption, Adjusted Balance | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period				(232,347)
Cumulative Effect, Period Of Adoption, Adjusted Balance | Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period				149,466
Cumulative Effect, Period Of Adoption, Adjusted Balance | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period				$ (381,813)