Note 13. Common Stock and Stock-based Compensation

12 Months Ended

Dec. 31, 2024

Share-Based Payment Arrangement [Abstract]

Share-based Payment Arrangement [Text Block]

Stockholders' Equity

Share Repurchase Authorization

In December 2022, our Board of Directors authorized a share repurchase program effective December 9, 2022 with no expiration. The share repurchase program authorizes the Company to repurchase up to $250.0 million of its common stock. During the year ended December 31, 2024, share repurchases totaled 0.6 million shares, at a cost of approximately $21.0 million, resulting in a remaining authorization to repurchase up to $229.0 million of our common stock under the share repurchase program as of December 31, 2024. Certain shares of stock repurchased during December 2024, totaling $0.3 million, were cash settled in January 2025 in accordance with normal settlement practices. There were no shares repurchased under this share repurchase program during the year ended December 31, 2023.

Previous Share Repurchase Authorization

In September 2021, our Board of Directors authorized a share repurchase program effective September 9, 2021 through December 31, 2022. The share repurchase program authorized the Company to repurchase up to $250.0 million of its common stock. In December 2021, we entered into an accelerated share repurchase agreement (the "ASR") to repurchase $125.0 million of our common stock. Approximately 3.3 million shares totaling $100.0 million that were repurchased as part of the ASR on December 31, 2021 were delivered to the Company in January 2022 in accordance with normal settlement practices, representing approximately 80% of the total notional value of the ASR. The ASR was completed in April 2022. During the year ended December 31, 2022, share repurchases totaled 2.8 million shares, at a cost of approximately $76.8 million. Share repurchases during the year ended December 31, 2022 included 0.8 million shares, at a cost of $25.0 million, representing the final settlement of the ASR, which was funded in December 2021 but a portion of which remained outstanding as of December 31, 2021. Our Board of Directors terminated this share repurchase program effective December 8, 2022, and the remaining authorization of $21.3 million under this program expired unused.

Shareholders' Equity and Share-based Payments [Text Block]

Stock-Based Compensation

Stock Award Plans

Our Fifth Amended and Restated Stock Option and Incentive Plan (the "Plan”) provides for awarding 22,050,000 (adjusted for stock splits) shares of common stock plus (i) shares covered by forfeited, expired, and canceled options granted under prior plans; and (ii) shares tendered as full or partial payment for the purchase price of an award or to satisfy tax withholding obligations. At December 31, 2024, a total of 2,978,308 shares were available for issuance. The Plan provides for the granting of nonqualified and incentive stock options having maximum ten-year terms to purchase common stock at its market value on the award date; stock appreciation rights based on common stock fair market values with settlement in common stock or cash; restricted stock awards; restricted stock units; and performance awards with settlement in common stock or cash on achievement of specific business objectives. Our stock options have contractual terms of ten years and become exercisable over a three-year period.

Stock-Based Compensation Expense

The cost of employee services received in exchange for awards of equity instruments is referred to as stock-based compensation and is recognized over the applicable vesting periods based on the grant date fair-value of those awards. Stock-based compensation expense totaled $23.6 million, $22.7 million, and $22.5 million for the years ended December 31, 2024, 2023, and 2022, respectively.

The income tax benefit related to stock-based compensation expense was $6.8 million, $2.8 million, and $2.6 million for the years ended December 31, 2024, 2023, and 2022, respectively.

Stock Options

Expense related to stock options is recognized on a straight-line basis over the vesting period.

	Number of Shares	Weighted Average Grant-Date Fair Value per Award		Weighted Average Remaining Contractual Terms (Years)	Aggregate Intrinsic Value (in millions)
Options outstanding at December 31, 2023	300,000	$	5.26
Granted	—	$	—
Exercised	—	$	—
Cancelled	—	$	—
Options outstanding and exercisable at December 31, 2024	300,000	$	5.26	5.1	$	4.0

At December 31, 2024, there was no unrecognized compensation expense related to stock options. The weighted average exercise price of stock options outstanding as of December 31, 2024 was $21.61. There were no options exercised during the years ended December 31, 2024, 2023, and 2022.

Restricted Stock Units

Expense related to restricted stock units ("RSUs") issued to eligible employees under the Plan is recognized over the vesting period, generally between three years and four years. Beginning in 2020, certain RSU grants provide for full vesting when the award recipients retire having reached 60 years of age and having provided at least ten years of service to the Company, provided that the awards remain outstanding for a period of six months from the date of grant. The expense for these awards is recognized over the applicable service period for each of the eligible award recipients. Expense related to RSUs granted to non-employee directors under the Plan is recognized on a straight-line basis over the vesting period, generally one year. The fair value of RSUs granted is based on the Company's closing stock price on the date of grant. Forfeitures are recognized as a reduction to expense in the period in which they occur.

	Number of Restricted Stock Units	Weighted Average Grant-Date Fair Value per Award		Aggregate Intrinsic Value (in millions)
Restricted stock units outstanding at December 31, 2023	1,646,571	$	22.60	$	43.8
Granted	455,673	$	30.70
Vested	(671,979)	$	23.52
Forfeited	(133,403)	$	25.21
Restricted stock units outstanding at December 31, 2024	1,296,862	$	24.71	$	45.5

Additional information related to RSUs is as follows:

	Year Ended December 31,
	2024		2023		2022
	(in millions, except weighted average fair value)
Weighted average grant-date fair value of RSUs granted	$	30.70	$	21.63	$	25.65
Total grant-date fair value of RSUs vested and released	$	15.8	$	14.9	$	14.2
Total intrinsic value of RSUs vested and released	$	20.6	$	13.9	$	16.5

At December 31, 2024, unrecognized compensation expense related to RSUs totaled $15.0 million, which will be recognized over a weighted average period of 1.5 years.

Performance Units

Performance units are granted to employees based upon a target level; however, depending upon the achievement of certain specified goals during the performance period, performance units may be adjusted to a level ranging between 0% and 200% of the target level. The performance units vest upon certification by the Human Resources Committee of the Board of Directors of the achievement of the specified performance goals. Expense related to performance units is recognized on a straight-line basis from their award date to the end of the performance period, generally three years. For the performance units granted for which the payout is based on relative total shareholder return, the fair value was estimated at the date of grant using a Monte Carlo simulation with assumptions that reflect market conditions at the date of grant, including stock price, risk-free interest rate, expected term, expected volatility, and dividend yield. For the performance units granted for which the payout is based on return on equity, the fair value is based on the Company's closing stock price on the date of grant, adjusted to exclude the cumulative value of dividends over the three-year vesting period as these units do not earn dividend equivalents. Forfeitures are recognized as a reduction to expense in the period in which they occur.

	Number of Performance Units	Weighted Average Grant-Date Fair Value per Award		Aggregate Intrinsic Value (in millions)
Performance units outstanding at December 31, 2023	747,214	$	29.41	$	19.9
Granted	241,212	$	29.54
Performance adjustment (1)	40,179	$	20.27
Vested (2)	(273,078)	$	29.39
Forfeited	(31,905)	$	27.84
Performance units outstanding at December 31, 2024	723,622	$	29.15	$	25.4

(1) For the 2021-2023 performance period, performance adjustment includes 63,954 additional performance units for return on equity, for which actual performance resulted in a payout of 170% of target, and is net of 23,775 performance units for relative total shareholder return, for which actual performance resulted in a payout of 91% of target.

(2) Includes 63,954 performance units for the 2021-2023 performance period for return on equity that were paid out at 170% of target based on actual performance achieved.

Additional information related to performance units is as follows:

	Year Ended December 31,
	2024		2023		2022
	(in millions, except weighted average fair value)
Weighted average grant-date fair value of performance units granted	$	29.54	$	27.72	$	29.80
Total grant-date fair value of performance units vested and released	$	8.0	$	10.2	$	4.7
Total intrinsic value of performance units vested and released	$	8.4	$	8.6	$	4.8

At December 31, 2024, unrecognized compensation expense related to performance units totaled $10.3 million, which will be recognized over a weighted average period of 1.4 years.

Restricted Stock Awards

Expense related to restricted stock awards ("RSAs") granted to non-employee directors under the Plan is recognized on a straight-line basis over the vesting period, generally one year. Certain RSAs vest in their entirety upon an employee's retirement from the Company, taking into consideration the employee's age and years of service to the Company, as defined more specifically in our benefit plans. The fair value of RSAs granted is based on the Company's closing stock price on the date of grant. Forfeitures are recognized as a reduction to expense in the period in which they occur.

	Number of Restricted Stock Awards	Weighted Average Grant-Date Fair Value per Award		Aggregate Intrinsic Value (in millions)
Restricted stock awards outstanding at December 31, 2023	552,240	$	20.84	$	14.7
Granted	15,903	$	30.75
Vested	(99,038)	$	20.11
Forfeited	(50,159)	$	21.19
Restricted stock awards outstanding at December 31, 2024 (1)	418,946	$	21.34	$	14.7

(1) The balance of RSAs outstanding at December 31, 2024 includes approximately 0.1 million RSAs for Arcosa Inc. ("Arcosa") employees that were converted under the shareholder method at the time of the Arcosa spin-off. These RSAs will be released to Arcosa employees upon vesting, but as of the spin-off date, Trinity no longer records the compensation expense associated with these shares.

Additional information related to RSAs is as follows:

	Year Ended December 31,
	2024		2023		2022
	(in millions, except weighted average fair value)
Weighted average grant-date fair value of RSAs granted	$	30.75	$	21.32	$	25.43
Total grant-date fair value of RSAs vested and released	$	2.0	$	2.0	$	1.7
Total intrinsic value of RSAs vested and released	$	3.1	$	2.1	$	2.4

At December 31, 2024, unrecognized compensation expense related to RSAs totaled $1.4 million, which will be recognized over a weighted average period of 3.6 years.