Consolidated Statements of Changes in Common Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance, beginning of period at Dec. 31, 2022		$ 176	$ (930,643)	$ 1,519,641	$ 3,786,952	$ (456,799)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under incentive and benefit plans		2		4,173
Share-based compensation				41,129
Shares repurchased under share repurchase program, net of excise tax (Note 14)		(5)		(134,349)
Repurchases of common stock under incentive plans			(15,227)
Net income	$ 603,119				603,119
Dividends and dividend equivalents declared					(146,312)
Net unrealized gains (losses) on investments, net of tax	125,641					125,769	[1]
Other adjustments to other comprehensive income (loss)						179
Balance, end of period at Dec. 31, 2023	4,397,805	173	(945,870)	1,430,594	4,243,759	(330,851)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under incentive and benefit plans		2		3,592
Share-based compensation				38,473
Shares repurchased under share repurchase program, net of excise tax (Note 14)		(7)		(225,833)
Repurchases of common stock under incentive plans			(22,376)
Net income	604,440				604,440
Dividends and dividend equivalents declared					(152,851)
Net unrealized gains (losses) on investments, net of tax	(19,472)					(19,319)	[1]
Other adjustments to other comprehensive income (loss)						(68)
Balance, end of period at Dec. 31, 2024	4,623,858	168	(968,246)	1,246,826	4,695,348	(350,238)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under incentive and benefit plans		2		3,628
Share-based compensation				44,704
Shares repurchased under share repurchase program, net of excise tax (Note 14)		(13)		(433,947)
Repurchases of common stock under incentive plans			(21,499)
Net income	582,640				582,640
Dividends and dividend equivalents declared					(145,938)
Net unrealized gains (losses) on investments, net of tax	127,746					128,034	[1]
Other adjustments to other comprehensive income (loss)						45
Balance, end of period at Dec. 31, 2025	$ 4,781,514	$ 157	$ (989,745)	$ 861,211	$ 5,132,050	$ (222,159)

[1] Includes net unrealized gains (losses) from investments recorded as assets held for sale.