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Equity Incentive Plan (Tables)

9 Months Ended

Sep. 30, 2024

Equity Incentive Plan

Schedule of restricted share activity

Restricted share activity is summarized as follows:

​

​	​	​	​	​	​
​		Shares		Weighted Average
​	​	Outstanding	​	Grant Date
​	​	(in thousands)	​	Fair Value
Unvested restricted stock at December 31, 2023		194	​	$	68.85
​	​	​	​	​	​
Restricted stock granted		101	​	$	57.51
Restricted stock vested	​	(67)	​	$	69.37
Restricted stock forfeited		(5)	​	$	64.51
Unvested restricted stock at September 30, 2024		223	​	$	63.63

Schedule of valuation assumptions used

The following assumptions were used when determining the grant date fair value:

​	​	​	​	​	​	​	​	​	​	​
​	​	​	2024		​	2023		​	2022
Expected term (years)	​	​	2.9	​	​	2.9	​	​	2.9	​
Volatility	​	​	20.0	%	​	23.6	%	​	33.5	%
Risk-free rate	​	​	4.5	%	​	4.4	%	​	1.8	%

Schedule of performance share and unit activity

Performance units activity is summarized as follows:

​	​	​	​	​	​
​		Target Number		Weighted Average
​	​	of Awards	​	Grant Date
​	​	(in thousands)	​	Fair Value
Performance units at December 31, 2023 - three-year performance period to be completed	​	111	​	$	72.14
​	​	​	​	​	​
Performance units granted	​	77	​	$	59.16
Performance shares - three-year performance period completed	​	(31)	​	$	63.42
Performance units at September 30, 2024 - three-year performance period to be completed	​	157	​	$	67.50

​

​	​	​	​	​
​	Shares		Weighted Average
​	Outstanding	​	Grant Date
​	(in thousands)	​	Fair Value
Performance units and shares - three-year performance period completed but not yet vested at December 31, 2023	31	​	$	83.40
​	​	​	​	​
Shares earned at completion of three-year performance period (1)	23	​	$	63.42
Shares vested	(28)	​	$	75.18
Performance units and shares - three-year performance period completed but not yet vested at September 30, 2024	26	​	$	74.58
​	​	​	​	​

​

(1)Performance units granted in 2021 for which the three-year performance period was completed in 2024 were earned at the 76% performance level.

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Tabular disclosure of the changes in outstanding nonvested performance-based units.

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Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year.

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