Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated Other Comprehensive Income (Loss)	Unrealized investment gain	Currency Translation Adjustments	Treasury stock	Noncontrolling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles		$ 105,803	$ 977,215	$ 8,348,381	$ (62,172)	$ 289,714	$ (351,886)	$ (3,058,425)	$ 14,995
Beginning of period at Dec. 31, 2020		105,803	977,215	8,348,381	(62,172)	289,714	(351,886)	(3,058,425)	14,995
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(28,669)
Restricted stock units expensed			34,486
Net income before noncontrolling interests	$ 736,712			728,060					8,652
Dividends ($0.10, $0.09, $0.79 and $0.59 per share, respectively)				(156,107)
Change in unrealized losses on securities without an allowance for expected credit losses	(102,454)					(112,852)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						10,397
Net change in period	(26,235)						(26,235)
Stock exercised/vested								10,985
Stock repurchased								(122,426)
(Contributions) distributions									(8,376)
Other comprehensive loss, net of tax	$ (128,689)				(128,689)		(26,235)		(1)
End of period at Sep. 30, 2021			983,032	8,920,334	(190,862)	187,259	(378,121)	(3,169,866)	15,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.59
Cumulative effect adjustment resulting from changes in accounting principles		105,803	999,898	8,682,088	(122,444)	222,855	(345,299)	(3,087,069)	9,678
Beginning of period at Jun. 30, 2021		105,803	999,898	8,682,088	(122,444)	222,855	(345,299)	(3,087,069)	9,678
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(28,741)
Restricted stock units expensed			11,875
Net income before noncontrolling interests	$ 267,318			261,297					6,021
Dividends ($0.10, $0.09, $0.79 and $0.59 per share, respectively)				(23,051)
Change in unrealized losses on securities without an allowance for expected credit losses	(35,596)					(35,707)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						111
Net change in period	(32,822)						(32,822)
Stock exercised/vested								9,946
Stock repurchased								(92,743)
(Contributions) distributions									(429)
Other comprehensive loss, net of tax	$ (68,418)				(68,418)		(32,822)		0
End of period at Sep. 30, 2021			983,032	8,920,334	(190,862)	187,259	(378,121)	(3,169,866)	15,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.09
Cumulative effect adjustment resulting from changes in accounting principles			983,032	8,920,334	(190,862)	187,259	(378,121)	(3,169,866)	15,270
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,667,730	105,803	981,104	9,015,135	(281,955)	90,900	(372,855)	(3,167,076)	14,719
Beginning of period at Dec. 31, 2021	6,667,730	105,803	981,104	9,015,135	(281,955)	90,900	(372,855)	(3,167,076)	14,719
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(30,751)
Restricted stock units expensed			34,450
Net income before noncontrolling interests	1,002,970			998,839					4,131
Dividends ($0.10, $0.09, $0.79 and $0.59 per share, respectively)				(208,737)
Change in unrealized losses on securities without an allowance for expected credit losses	(1,076,217)					(1,055,628)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(20,590)
Net change in period	(27,637)						(27,637)
Stock exercised/vested								9,679
Stock repurchased								(6,570)
(Contributions) distributions									5,061
Other comprehensive loss, net of tax	(1,103,854)				(1,103,854)		(27,637)		(1)
End of period at Sep. 30, 2022	$ 6,369,976		984,803	9,805,237	(1,385,810)	(985,318)	(400,492)	(3,163,967)	23,910
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.79
Cumulative effect adjustment resulting from changes in accounting principles		105,803	1,001,093	9,602,948	(1,029,630)	(669,654)	(359,976)	(3,165,729)	22,388
Beginning of period at Jun. 30, 2022		$ 105,803	1,001,093	9,602,948	(1,029,630)	(669,654)	(359,976)	(3,165,729)	22,388
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(28,381)
Restricted stock units expensed			12,091
Net income before noncontrolling interests	$ 230,474			228,879					1,595
Dividends ($0.10, $0.09, $0.79 and $0.59 per share, respectively)				(26,590)
Change in unrealized losses on securities without an allowance for expected credit losses	(315,664)					(311,659)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(4,005)
Net change in period	(40,516)						(40,516)
Stock exercised/vested								8,332
Stock repurchased								(6,570)
(Contributions) distributions									(73)
Other comprehensive loss, net of tax	(356,180)				(356,180)		(40,516)		0
End of period at Sep. 30, 2022	$ 6,369,976		984,803	9,805,237	(1,385,810)	(985,318)	(400,492)	(3,163,967)	23,910
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.10
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,369,976		$ 984,803	$ 9,805,237	$ (1,385,810)	$ (985,318)	$ (400,492)	$ (3,163,967)	$ 23,910