Pay vs Performance Disclosure - USD ($)

12 Months Ended

Dec. 31, 2024

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Pay vs Performance Disclosure

Pay vs Performance Disclosure, Table

Year	Summary Compensation Table Total for CEO ($)	Compensation Actually Paid to CEO ($)	Average Summary Compensation Table Total for Non-CEO NEO's ($)	Average Compensation Actually Paid to Non-CEO NEOs ($)	USLM Total Shareholder Return ($)	Peer Group Total Shareholder Return ($)	Net Income (Thousands of $)	EBITDA (Thousands of $)
	(a)	(b)	(c)	(d)	(e)	(f)	(g)	(h)
2024	7,745,413	15,582,727	381,125	569,095	753.94	224.41	108,839	160,844
2023	5,804,142	7,552,783	350,559	395,137	260.97	182.76	74,549	117,449
2022	4,149,736	4,293,399	300,169	306,538	158.81	129.82	45,429	78,999
2021	3,568,689	3,858,073	284,749	293,920	144.58	166.34	37,045	67,667
2020	3,078,464	3,195,964	267,293	281,261	127.17	102.26	28,223	55,356

(a)  Reflects compensation amounts reported in the Summary Compensation Table (“SCT”) for our CEO, Timothy W. Byrne, for the respective years shown.

(b)  “Compensation Actually Paid to CEO” in 2024 reflects the amount in (a) of the table above, adjusted as set forth in the table below, as determined in accordance with SEC rules:

	Covered Year
	2024
SCT Total Compensation	$	7,745,413
Less: Stock and Option Award Values Reported in SCT for the Covered Year		(6,305,150)
Plus: Fair Value for Outstanding Unvested Stock and Option Awards Granted in the Covered Year as of Year End		6,305,150
Change in Fair Value of Outstanding Unvested Stock and Option Awards from Prior Years		961,308
Change in Fair Value of Stock and Option Awards from Prior Years that Vested in the Covered Year		6,863,506
Plus: Dollar value of Dividends or Distributions Paid on Equity Awards during the Covered Year		12,500
Less: Fair Value of Stock and Option Awards Forfeited during the Covered Year		-
Less: Aggregate Change in Actuarial Present Value of Accumulated Benefit Under Pension Plans		-
Plus: Aggregate Service Cost and Prior Service Cost for Pension Plans		-
Compensation Actually Paid	$	15,582,727

(c)  The following non-CEO named executive officers are included in the average figures shown:

2024:  John J. Gagnon, Nathan M. O’Neill, Timothy W. Stone, and Michael L. Wiedemer

2023:  John J. Gagnon, Nathan M. O’Neill, Russell W. Riggs, Timothy W. Stone, and Michael L. Wiedemer

2022:  John J. Gagnon, Russell W. Riggs, Timothy W. Stone, and Michael L. Wiedemer

2021 and 2020:  Russell W. Riggs, Timothy W. Stone, and Michael L. Wiedemer

(d)  “Average Compensation Actually Paid to Non-CEO NEOs” in 2024 reflects the amount set forth in (c) of the table above, adjusted as set forth in the table below, as determined in accordance with SEC rules:

	Covered Year
	2024
SCT Total Compensation	$	381,125
Less: Stock and Option Award Values Reported in SCT for the Covered Year		(52,504)
Plus: Fair Value for Outstanding Unvested Stock and Option Awards Granted in the Covered Year as of Year End		139,377
Change in Fair Value of Outstanding Unvested Stock and Option Awards from Prior Years		96,745
Change in Fair Value of Stock and Option Awards from Prior Years that Vested in the Covered Year		3,919
Less: Fair Value of Stock and Option Awards Forfeited during the Covered Year		-
Plus: Dollar Value of Dividends or Distributions Paid on Equity Awards during the Covered Year		433
Less: Aggregate Change in Actuarial Present Value of Accumulated Benefit Under Pension Plans		-
Plus: Aggregate Service Cost and Prior Service Cost for Pension Plans		-
Compensation Actually Paid	$	569,095

(e)  For the relevant year, represents the cumulative total shareholder return (“TSR”) of the company for the measurement periods ending on December 31, of each of 2024, 2023, 2022, 2021 and 2020, respectively.  TSR assumes that the value of the investment in the company’s common stock was $100 on December 31, 2019, and that all cash dividends have been reinvested.

(f)  For the relevant year, represents the cumulative TSR of a peer group index consisting of Eagle Materials, Inc., Mineral Technologies, Inc., and Summit Materials Inc. for the measurement periods ending on December 31, of each of 2024, 2023, 2022, 2021, and 2020, respectively.  TSR assumes that the value of the investment in the peer group index was $100 on December 31, 2019, and that all cash dividends have been reinvested.

(g)  For the relevant year, represents “Net Income” in the company’s Consolidated Statements of Income included in the company’s Annual Reports on Form 10-K for each of the years ended December 31, 2024, 2023, 2022, 2021 and 2020.

(h)  For the relevant year, represents “EBITDA,” which is net income before interest expense, income tax expense, depreciation, depletion, and amortization.  EBITDA is a non-GAAP financial measure that the company’s management, investors and others use to measure a company’s operating performance and ability to incur and service debt, and forms of which are used to determine the EBITDA cash bonus for Mr. Byrne pursuant to his Employment Agreement and the compensation of other named executive officers and to determine the interest rate applicable under the company’s revolving credit facility.

Company Selected Measure Name

EBITDA

Named Executive Officers, Footnote

(a)  Reflects compensation amounts reported in the Summary Compensation Table (“SCT”) for our CEO, Timothy W. Byrne, for the respective years shown.

(c)  The following non-CEO named executive officers are included in the average figures shown:

2024:  John J. Gagnon, Nathan M. O’Neill, Timothy W. Stone, and Michael L. Wiedemer

2023:  John J. Gagnon, Nathan M. O’Neill, Russell W. Riggs, Timothy W. Stone, and Michael L. Wiedemer

2022:  John J. Gagnon, Russell W. Riggs, Timothy W. Stone, and Michael L. Wiedemer

2021 and 2020:  Russell W. Riggs, Timothy W. Stone, and Michael L. Wiedemer

Peer Group Issuers, Footnote

(f)  For the relevant year, represents the cumulative TSR of a peer group index consisting of Eagle Materials, Inc., Mineral Technologies, Inc., and Summit Materials Inc. for the measurement periods ending on December 31, of each of 2024, 2023, 2022, 2021, and 2020, respectively.  TSR assumes that the value of the investment in the peer group index was $100 on December 31, 2019, and that all cash dividends have been reinvested.

PEO Total Compensation Amount

$ 7,745,413

$ 5,804,142

$ 4,149,736

$ 3,568,689

$ 3,078,464

PEO Actually Paid Compensation Amount

$ 15,582,727

7,552,783

4,293,399

3,858,073

3,195,964

Adjustment To PEO Compensation, Footnote

(b)  “Compensation Actually Paid to CEO” in 2024 reflects the amount in (a) of the table above, adjusted as set forth in the table below, as determined in accordance with SEC rules:

	Covered Year
	2024
SCT Total Compensation	$	7,745,413
Less: Stock and Option Award Values Reported in SCT for the Covered Year		(6,305,150)
Plus: Fair Value for Outstanding Unvested Stock and Option Awards Granted in the Covered Year as of Year End		6,305,150
Change in Fair Value of Outstanding Unvested Stock and Option Awards from Prior Years		961,308
Change in Fair Value of Stock and Option Awards from Prior Years that Vested in the Covered Year		6,863,506
Plus: Dollar value of Dividends or Distributions Paid on Equity Awards during the Covered Year		12,500
Less: Fair Value of Stock and Option Awards Forfeited during the Covered Year		-
Less: Aggregate Change in Actuarial Present Value of Accumulated Benefit Under Pension Plans		-
Plus: Aggregate Service Cost and Prior Service Cost for Pension Plans		-
Compensation Actually Paid	$	15,582,727

Non-PEO NEO Average Total Compensation Amount

$ 381,125

350,559

300,169

284,749

267,293

Non-PEO NEO Average Compensation Actually Paid Amount

$ 569,095

395,137

306,538

293,920

281,261

Adjustment to Non-PEO NEO Compensation Footnote

(d)  “Average Compensation Actually Paid to Non-CEO NEOs” in 2024 reflects the amount set forth in (c) of the table above, adjusted as set forth in the table below, as determined in accordance with SEC rules:

	Covered Year
	2024
SCT Total Compensation	$	381,125
Less: Stock and Option Award Values Reported in SCT for the Covered Year		(52,504)
Plus: Fair Value for Outstanding Unvested Stock and Option Awards Granted in the Covered Year as of Year End		139,377
Change in Fair Value of Outstanding Unvested Stock and Option Awards from Prior Years		96,745
Change in Fair Value of Stock and Option Awards from Prior Years that Vested in the Covered Year		3,919
Less: Fair Value of Stock and Option Awards Forfeited during the Covered Year		-
Plus: Dollar Value of Dividends or Distributions Paid on Equity Awards during the Covered Year		433
Less: Aggregate Change in Actuarial Present Value of Accumulated Benefit Under Pension Plans		-
Plus: Aggregate Service Cost and Prior Service Cost for Pension Plans		-
Compensation Actually Paid	$	569,095

Compensation Actually Paid vs. Total Shareholder Return

Relationship Between Pay and Performance

Set forth below is a table showing the relationship of percentage changes over the prior year between various financial measures and compensation actually paid to our CEO and other named executive officers:

	Percentage Change from Prior Year
	2020	2021	2022	2023	2024
Compensation Actually Paid to CEO	17.3%	20.7%	11.1%	75.9%	106.3%
Average Compensation Actually Paid to Non-CEO NEOs	4.9%	4.5%	4.3%	28.9%	44.0%
USLM Total Shareholder Return	27.2%	13.7%	9.8%	64.3%	188.9%
Peer Group Total Shareholder Return	2.3%	62.7%	(22.0%)	40.8%	22.8%
Net Income	8.3%	31.3%	22.6%	64.1%	46.0%
EBITDA	11.4%	22.2%	16.7%	48.7%	36.9%

Compensation Actually Paid vs. Net Income

Relationship Between Pay and Performance

Set forth below is a table showing the relationship of percentage changes over the prior year between various financial measures and compensation actually paid to our CEO and other named executive officers:

	Percentage Change from Prior Year
	2020	2021	2022	2023	2024
Compensation Actually Paid to CEO	17.3%	20.7%	11.1%	75.9%	106.3%
Average Compensation Actually Paid to Non-CEO NEOs	4.9%	4.5%	4.3%	28.9%	44.0%
USLM Total Shareholder Return	27.2%	13.7%	9.8%	64.3%	188.9%
Peer Group Total Shareholder Return	2.3%	62.7%	(22.0%)	40.8%	22.8%
Net Income	8.3%	31.3%	22.6%	64.1%	46.0%
EBITDA	11.4%	22.2%	16.7%	48.7%	36.9%

Compensation Actually Paid vs. Company Selected Measure

Relationship Between Pay and Performance

Set forth below is a table showing the relationship of percentage changes over the prior year between various financial measures and compensation actually paid to our CEO and other named executive officers:

	Percentage Change from Prior Year
	2020	2021	2022	2023	2024
Compensation Actually Paid to CEO	17.3%	20.7%	11.1%	75.9%	106.3%
Average Compensation Actually Paid to Non-CEO NEOs	4.9%	4.5%	4.3%	28.9%	44.0%
USLM Total Shareholder Return	27.2%	13.7%	9.8%	64.3%	188.9%
Peer Group Total Shareholder Return	2.3%	62.7%	(22.0%)	40.8%	22.8%
Net Income	8.3%	31.3%	22.6%	64.1%	46.0%
EBITDA	11.4%	22.2%	16.7%	48.7%	36.9%

Total Shareholder Return Vs Peer Group

Relationship Between Pay and Performance

Set forth below is a table showing the relationship of percentage changes over the prior year between various financial measures and compensation actually paid to our CEO and other named executive officers:

	Percentage Change from Prior Year
	2020	2021	2022	2023	2024
Compensation Actually Paid to CEO	17.3%	20.7%	11.1%	75.9%	106.3%
Average Compensation Actually Paid to Non-CEO NEOs	4.9%	4.5%	4.3%	28.9%	44.0%
USLM Total Shareholder Return	27.2%	13.7%	9.8%	64.3%	188.9%
Peer Group Total Shareholder Return	2.3%	62.7%	(22.0%)	40.8%	22.8%
Net Income	8.3%	31.3%	22.6%	64.1%	46.0%
EBITDA	11.4%	22.2%	16.7%	48.7%	36.9%

Tabular List, Table

			Modernization,
		Human	Expansion and
	Succession	Capital	Development	Cost Savings		ESG and
Name	Planning	Development	Projects	and Efficiencies	Acquisitions	Sustainability
Timothy W. Byrne	ü	ü	ü	ü	ü	ü
John J. Gagnon		ü		ü	ü
Nathan M. O'Neill	ü	ü	ü	ü	ü
Timothy W. Stone		ü	ü		ü
Michael L. Wiedemer		ü		ü	ü	ü

Total Shareholder Return Amount

$ 753.94

260.97

158.81

144.58

127.17

Peer Group Total Shareholder Return Amount

224.41

182.76

129.82

166.34

102.26

Net Income (Loss)

$ 108,839,000

$ 74,549,000

$ 45,429,000

$ 37,045,000

$ 28,223,000

Company Selected Measure Amount

160,844,000

117,449,000

78,999,000

67,667,000

55,356,000

PEO Name

Timothy W. Byrne

Measure:: 1

Pay vs Performance Disclosure

Name

EBITDA

Non-GAAP Measure Description

(h)  For the relevant year, represents “EBITDA,” which is net income before interest expense, income tax expense, depreciation, depletion, and amortization.  EBITDA is a non-GAAP financial measure that the company’s management, investors and others use to measure a company’s operating performance and ability to incur and service debt, and forms of which are used to determine the EBITDA cash bonus for Mr. Byrne pursuant to his Employment Agreement and the compensation of other named executive officers and to determine the interest rate applicable under the company’s revolving credit facility.

Measure:: 2

Pay vs Performance Disclosure

Name

Succession Planning

Measure:: 3

Pay vs Performance Disclosure

Name

Human Capital Development

Measure:: 4

Pay vs Performance Disclosure

Name

Modernization, Expansion and Development Projects

Measure:: 5

Pay vs Performance Disclosure

Name

Cost Savings and Efficiencies

Measure:: 6

Pay vs Performance Disclosure

Name

Acquisitions  

Measure:: 7

Pay vs Performance Disclosure

Name

ESG and Sustainability

PEO | Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

$ (6,305,150)

PEO | Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

6,305,150

PEO | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

961,308

PEO | Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

6,863,506

PEO | Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

12,500

Non-PEO NEO | Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

(52,504)

Non-PEO NEO | Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

139,377

Non-PEO NEO | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

96,745

Non-PEO NEO | Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

3,919

Non-PEO NEO | Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

$ 433