Revenue from contracts with customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Revenues	$ 1,203,717	$ 1,105,293	$ 2,390,948	$ 2,241,789
Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(272,754)	(276,899)	(475,688)	(488,532)
Operating Segments Excluding Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenues	1,203,553	1,105,230	2,390,478	2,241,341
West \| Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(76,705)	(72,336)	(162,163)	(156,359)
West \| Operating Segments Excluding Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenues	395,552	382,811	920,766	912,403
Mountain \| Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(45,020)	(65,281)	(77,082)	(106,021)
Mountain \| Operating Segments Excluding Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenues	229,670	261,118	471,785	514,713
Central \| Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(117,528)	(110,905)	(177,481)	(172,079)
Central \| Operating Segments Excluding Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenues	434,327	354,815	757,231	630,379
Energy Services \| Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(30,301)	(25,308)	(48,946)	(41,735)
Energy Services \| Operating Segments Excluding Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenues	144,004	106,486	240,696	183,846
Corporate Services and Eliminations \| Corporate, Non-Segment & Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	164	63	470	448
Corporate Services and Eliminations \| Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(3,200)	(3,069)	(10,016)	(12,338)
Aggregates
Disaggregation of Revenue [Line Items]
Revenues	218,044	193,480	465,391	436,154
Aggregates \| West
Disaggregation of Revenue [Line Items]
Revenues	91,252	90,680	222,339	233,947
Aggregates \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	34,823	40,115	72,216	80,708
Aggregates \| Central
Disaggregation of Revenue [Line Items]
Revenues	91,969	62,685	170,836	121,499
Aggregates \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Aggregates \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	261,375	213,460	575,814	492,834
Ready-mix concrete \| West
Disaggregation of Revenue [Line Items]
Revenues	98,581	87,427	258,313	232,751
Ready-mix concrete \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	42,121	40,559	90,915	89,361
Ready-mix concrete \| Central
Disaggregation of Revenue [Line Items]
Revenues	120,673	85,474	226,586	170,722
Ready-mix concrete \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Ready-mix concrete \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Asphalt
Disaggregation of Revenue [Line Items]
Revenues	200,436	215,049	327,403	350,801
Asphalt \| West
Disaggregation of Revenue [Line Items]
Revenues	61,674	59,029	109,085	110,765
Asphalt \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	42,210	60,022	71,500	93,712
Asphalt \| Central
Disaggregation of Revenue [Line Items]
Revenues	96,552	95,998	146,818	146,324
Asphalt \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Asphalt \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Liquid asphalt
Disaggregation of Revenue [Line Items]
Revenues	148,765	110,917	246,888	187,256
Liquid asphalt \| West
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Liquid asphalt \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Liquid asphalt \| Central
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Liquid asphalt \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	148,765	110,917	246,888	187,256
Liquid asphalt \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Other
Disaggregation of Revenue [Line Items]
Revenues	91,411	89,704	214,452	206,425
Other \| West
Disaggregation of Revenue [Line Items]
Revenues	50,311	53,444	133,993	130,277
Other \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	6	9	11	22
Other \| Central
Disaggregation of Revenue [Line Items]
Revenues	12,190	12,242	27,208	25,015
Other \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	25,540	20,877	42,754	38,325
Other \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	3,364	3,132	10,486	12,786
Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	481,559	479,413	851,423	852,679
Contracting services public-sector \| West
Disaggregation of Revenue [Line Items]
Revenues	141,893	137,706	269,125	271,237
Contracting services public-sector \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	123,245	142,864	240,349	258,746
Contracting services public-sector \| Central
Disaggregation of Revenue [Line Items]
Revenues	216,421	198,843	341,949	322,696
Contracting services public-sector \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Contracting services public-sector \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	74,881	80,169	185,265	204,172
Contracting services private-sector \| West
Disaggregation of Revenue [Line Items]
Revenues	28,546	26,861	90,074	89,785
Contracting services private-sector \| Mountain
Disaggregation of Revenue [Line Items]
Revenues	32,285	42,830	73,876	98,185
Contracting services private-sector \| Central
Disaggregation of Revenue [Line Items]
Revenues	14,050	10,478	21,315	16,202
Contracting services private-sector \| Energy Services
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Contracting services private-sector \| Corporate Services and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0

Knife River Corp 10-Q