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, 2020		17,092,432
Restricted stock awards, net of forfeitures, shares		(18)
Common stock repurchased, shares	(393,408)	(393,408)
Restricted stock units converted to common stock, shares		11,416
Balance, shares at Mar. 31, 2021		16,710,422
Balance at Dec. 31, 2020	$ 2,302,500,000	$ 200,000	$ 161,900,000	$ 2,138,800,000	$ 1,600,000
Net income	202,100,000	0	0	202,100,000	0
Other comprehensive loss	(700,000)	0	0	0	(700,000)
Stock-based compensation	1,100,000	0	1,100,000	0	0
Common stock repurchased, value	(135,200,000)	0	(1,300,000)	(133,900,000)	0
Balance at Mar. 31, 2021	$ 2,369,800,000	$ 200,000	161,700,000	2,207,000,000	900,000
Balance, shares at Dec. 31, 2021	14,145,888	14,145,888
Restricted stock awards, net of forfeitures, shares		0
Common stock repurchased, shares	(803,735)	(803,735)
Restricted stock units converted to common stock, shares		3,980
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		17,650
Balance, shares at Mar. 31, 2022	13,363,783	13,363,783
Balance at Dec. 31, 2021	$ 1,824,200,000	$ 100,000	197,200,000	1,626,700,000	200,000
Net income	214,300,000	0	0	214,300,000	0
Other comprehensive loss	(1,700,000)	0	0	0	(1,700,000)
Stock-based compensation	9,100,000	0	9,100,000	0	0
Common stock repurchased, value	(423,000,000.0)	0	(700,000)	(422,300,000)	0
Stock Issued During Period, Value, Stock Options Exercised	5,900,000		5,900,000
Balance at Mar. 31, 2022	$ 1,628,800,000	$ 100,000	$ 211,500,000	$ 1,418,700,000	$ (1,500,000)