Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stocks	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Unrealized investment gains (losses	Currency Translation Adjustments	Treasury Stock	Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles				$ 215,939		$ (214,539)
Beginning of period at Dec. 31, 2017		$ 70,535	$ 1,024,772	6,956,882		375,421	$ (306,880)	$ (2,709,386)	$ 39,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(19,547)
Restricted stock units expensed			34,408
Change in controlling financial interest of a subsidiary			0
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	$ (252,327)					(252,241)
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						(132)
Net change in period	(112,099)						(112,099)
Stock exercised/vested								12,981
Stock issued								689
Stock repurchased								(24,750)
Distributions									(6,143)
Net income	649,066			640,749					8,317
Dividends ($0.47, $1.68, and $1.39 per share, respectively)				(254,951)
Other comprehensive (loss) income, net of tax	(364,426)								(46)
End of period at Dec. 31, 2018		70,535	1,039,633	7,558,619	$ (510,470)	(91,491)	(418,979)	(2,720,466)	41,947
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles				0		0
Restricted stock units issued			(32,370)
Restricted stock units expensed			48,779
Change in controlling financial interest of a subsidiary			0
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	215,902					215,636
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						369
Net change in period	37,166						37,166
Stock exercised/vested								11,431
Stock issued								549
Stock repurchased								(18,225)
Distributions									(688)
Net income	683,985			681,944					2,041
Dividends ($0.47, $1.68, and $1.39 per share, respectively)				(308,191)
Other comprehensive (loss) income, net of tax	253,068				253,068		37,166		103
End of period at Dec. 31, 2019	6,118,342	$ 70,535	1,056,042	7,932,372	(257,299)	124,514	(381,813)	(2,726,711)	43,403
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles				(30,514)		24,952
Restricted stock units issued			(38,491)
Restricted stock units expensed			48,567
Change in controlling financial interest of a subsidiary			(53,635)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	140,250					108,244
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						32,004
Net change in period	29,927						29,927
Stock exercised/vested								13,917
Stock issued								726
Stock repurchased								(346,357)
Distributions									(30,721)
Net income	532,985			530,670					2,315
Dividends ($0.47, $1.68, and $1.39 per share, respectively)				(84,147)
Other comprehensive (loss) income, net of tax	170,177				170,177		29,927		(2)
End of period at Dec. 31, 2020	$ 6,325,797		$ 1,012,483	$ 8,348,381	$ (62,172)	$ 289,714	$ (351,886)	$ (3,058,425)	$ 14,995