Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Surplus	Accumulated Other Comprehensive Income (Loss)	Undivided Profits	Spirit	Spirit Common Stock	Spirit Surplus
Beginning balance at Dec. 31, 2021	$ 3,248,841	$ 1,127	$ 2,164,989	$ (10,545)	$ 1,093,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	(250,603)			(507,015)	256,412
Stock issued for employee stock purchase plan	1,151	1	1,150
Stock-based compensation plans, net	10,284	3	10,281
Stock issued for acquisition						$ 464,918	$ 183	$ 464,735
Stock repurchases	(111,133)	(44)	(111,089)
Dividends on common stock	(94,096)				(94,096)
Ending balance at Dec. 31, 2022	3,269,362	1,270	2,530,066	(517,560)	1,255,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	288,242			113,185	175,057
Stock issued for employee stock purchase plan	833	0	833
Stock-based compensation plans, net	9,335	5	9,330
Stock repurchases	(40,322)	(23)	(40,299)
Dividends on common stock	(100,962)				(100,962)
Ending balance at Dec. 31, 2023	3,426,488	1,252	2,499,930	(404,375)	1,329,681
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	196,158			43,465	152,693
Stock issued for employee stock purchase plan	970	0	970
Stock-based compensation plans, net	10,695	5	10,690
Dividends on common stock	(105,439)				(105,439)
Ending balance at Dec. 31, 2024	$ 3,528,872	$ 1,257	$ 2,511,590	$ (360,910)	$ 1,376,935