Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($)	Total	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance, shares at Dec. 31, 2021		14,145,888
Common stock repurchased, shares	(1,261,457)	(1,261,457)
Restricted stock units converted to common stock, shares		3,980
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		36,300
Balance, shares at Sep. 30, 2022		12,924,711
Balance at Dec. 31, 2021	$ 1,824,200,000	$ 100,000	$ 197,200,000	$ 1,626,700,000	$ 200,000
Net income	408,500,000	0	0	408,500,000	0
Other comprehensive loss	(3,600,000)	0	0	0	(3,600,000)
Stock-based compensation	26,900,000	0	26,900,000	0	0
Common stock repurchased, value	(679,200,000)	0	(700,000)	(678,500,000)	0
Stock Issued During Period, Value, Stock Options Exercised	12,400,000		12,400,000
Balance at Sep. 30, 2022	1,589,200,000	$ 100,000	235,800,000	1,356,700,000	(3,400,000)
Balance, shares at Jun. 30, 2022		12,975,455
Common stock repurchased, shares		(53,769)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		3,025
Balance, shares at Sep. 30, 2022		12,924,711
Balance at Jun. 30, 2022	1,520,100,000	$ 100,000	225,800,000	1,296,400,000	(2,200,000)
Net income	86,800,000	0	0	86,800,000	0
Other comprehensive loss	(1,200,000)	0	0	0	(1,200,000)
Stock-based compensation	8,700,000	0	8,700,000	0	0
Common stock repurchased, value	(26,500,000)	0	0	(26,500,000)	0
Stock Issued During Period, Value, Stock Options Exercised	1,300,000		1,300,000
Balance at Sep. 30, 2022	$ 1,589,200,000	$ 100,000	235,800,000	1,356,700,000	(3,400,000)
Balance, shares at Dec. 31, 2022	12,756,885	12,756,885
Common stock repurchased, shares	(305,493)	(305,493)
Restricted stock units converted to common stock, shares		101,757
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		13,070
Balance, shares at Sep. 30, 2023	12,566,219	12,566,219
Balance at Dec. 31, 2022	$ 1,624,000,000	$ 100,000	245,700,000	1,381,100,000	(2,900,000)
Net income	192,500,000	0	0	192,500,000	0
Stock-based compensation	29,000,000.0	0	29,000,000.0	0	0
Common stock repurchased, value	(149,000,000.0)	0	(7,800,000)	(141,200,000)	0
Stock Issued During Period, Value, Stock Options Exercised	4,400,000		4,400,000
Balance at Sep. 30, 2023	$ 1,700,900,000	$ 100,000	271,300,000	1,432,400,000	(2,900,000)
Balance, shares at Jun. 30, 2023		12,821,681
Common stock repurchased, shares		(256,232)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		770
Balance, shares at Sep. 30, 2023	12,566,219	12,566,219
Balance at Jun. 30, 2023	$ 1,747,000,000	$ 100,000	261,700,000	1,487,900,000	(2,700,000)
Net income	70,800,000	0	0	70,800,000	0
Other comprehensive loss	(200,000)	0	0	0	(200,000)
Stock-based compensation	9,300,000	0	9,300,000	0	0
Common stock repurchased, value	(126,300,000)	0	0	(126,300,000)	0
Stock Issued During Period, Value, Stock Options Exercised	300,000		300,000
Balance at Sep. 30, 2023	$ 1,700,900,000	$ 100,000	$ 271,300,000	$ 1,432,400,000	$ (2,900,000)