Business Segment Data - Operating Revenues and Operating Assets Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 4,657,340	$ 4,441,784	$ 3,454,436
Total assets	7,833,159	9,660,781	8,910,435
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	4,720,713	4,505,706	3,515,695
Total assets	7,685,794	7,205,711	6,535,988
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	7,941	5,840	4,606
Total assets	726,600	3,639,582	3,366,531
Intersegment eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(71,314)	(69,762)	(65,865)
Total assets	$ (579,235)	$ (1,184,512)	$ (992,084)