Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Operating activities:
Net income	$ 41,767	$ 28,214	$ 36,014	$ 26,074	$ 108,953	$ 100,737
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					16,961	15,658
Amortization					1,538	1,575
Deferred income taxes					(5,570)	(734)
Provision for credit losses	83		1,734		(51)	4,385
Stock-based compensation costs					1,034	517
Unrealized gain on investments	(200)		0		(531)	0
Gain on sale of assets					(5,513)	(6,297)
Equity in earnings of unconsolidated affiliates, net of distributions					(4,788)	(4,718)
Changes in current assets and liabilities, net of acquisitions:
Receivables					(97,980)	(5,828)
Due from related-party					(763)	1,381
Costs and estimated earnings in excess of billings					(15,573)	(44,802)	$ (4,622)
Inventories					(4,214)	(8,984)
Other current assets					(2,303)	(2,512)
Accounts payable					44,265	(11,125)
Due to related-party					10	356
Billings in excess of costs and estimated earnings					23,431	12,566	32,042
Other current liabilities					32,760	6,540
Other noncurrent changes					(8,984)	2,647
Net cash provided by operating activities					82,682	61,362
Investing activities:
Capital expenditures					(34,506)	(28,134)
Net proceeds from sale or disposition of property					9,587	12,247
Investments					(570)	(535)
Net cash used in investing activities					(25,489)	(16,422)
Financing activities:
Repayment of related-party notes payable					0	(45,000)
Repayment of related-party short-term notes payable					0	(27,000)
Net amounts received from related-party cash management program					45,994	62,527
Transfers to Centennial					(104,201)	(37,026)
Net cash used in financing activities					(58,207)	(46,499)
Decrease in cash and cash equivalents					(1,014)	(1,559)
Cash and cash equivalents - beginning of period		$ 1,567		$ 2,112	1,567	2,112	2,112
Cash and cash equivalents - end of period	$ 553		$ 553		$ 553	$ 553	$ 1,567