Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Balance, beginning of period at Dec. 31, 2021		$ 1,641	$ 1,428,952	$ 50,707	$ 2,754,814	$ 0
Changes in Stockholders' Equity
Issuance of management incentive shares		9	(9)
Cancellation of treasury stock		(35)	(97,717)			97,752
Dividends and dividend equivalents declared			419		(44,453)
Stock-based compensation expense			9,005
Other comprehensive income (loss)	$ (337,274)			(337,274)
Net income	505,936				505,936
Treasury stock acquired						(97,752)
Balance, end of period at Jun. 30, 2022	4,271,995	1,615	1,340,650	(286,567)	3,216,297	0
Balance, beginning of period at Mar. 31, 2022		1,622	1,358,583	(152,299)	3,007,162	0
Changes in Stockholders' Equity
Issuance of management incentive shares		2	(2)
Cancellation of treasury stock		(9)	(22,321)			22,330
Dividends and dividend equivalents declared			192		(22,634)
Stock-based compensation expense			4,198
Other comprehensive income (loss)	(134,268)			(134,268)
Net income	231,769				231,769
Treasury stock acquired						(22,330)
Balance, end of period at Jun. 30, 2022	4,271,995	1,615	1,340,650	(286,567)	3,216,297	0
Balance, beginning of period at Dec. 31, 2022	4,462,309	1,615	1,350,377	(382,790)	3,493,107	0
Changes in Stockholders' Equity
Issuance of management incentive shares		8	(8)
Cancellation of treasury stock		(18)	(50,813)			50,831
Dividends and dividend equivalents declared			818		(54,119)
Stock-based compensation expense			9,460
Other comprehensive income (loss)	22,655			22,655
Net income	343,060				343,060
Treasury stock acquired						(50,831)
Balance, end of period at Jun. 30, 2023	4,733,352	1,605	1,309,834	(360,135)	3,782,048	0
Balance, beginning of period at Mar. 31, 2023		1,615	1,334,607	(324,037)	3,636,756	0
Changes in Stockholders' Equity
Issuance of management incentive shares		0	0
Cancellation of treasury stock		(10)	(29,542)			29,552
Dividends and dividend equivalents declared			415		(26,941)
Stock-based compensation expense			4,354
Other comprehensive income (loss)	(36,098)			(36,098)
Net income	172,233				172,233
Treasury stock acquired						(29,552)
Balance, end of period at Jun. 30, 2023	$ 4,733,352	$ 1,605	$ 1,309,834	$ (360,135)	$ 3,782,048	$ 0