Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

In thousands	2022		2021		2020
Operations and maintenance expense, for stock-based compensation	$	2,877	$	3,272	$	3,525
Income tax benefit	(762)		(866)		(933)
Net stock-based compensation effect on net income	2,115		2,406		2,592
Amounts capitalized for stock-based compensation	$	351	$	344	$	841

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Number of RSUs	Weighted - Average Price Per RSU
Nonvested, December 31, 2019	79,733	$	61.17
Granted	33,594	55.58
Vested	(29,273)	59.29
Forfeited	(1,590)	69.71
Nonvested, December 31, 2020	82,464	59.40
Granted	38,160	49.16
Vested	(31,733)	60.06
Forfeited	(1,164)	46.82
Nonvested, December 31, 2021	87,727	54.87
Granted	48,212	46.50
Vested	(33,054)	55.90
Forfeited	(3,037)	56.34
Nonvested, December 31, 2022	99,848	$	50.44

Share-based Payment Arrangement, Performance Shares, Outstanding Activity [Table Text Block]

The aggregate number of performance shares granted and outstanding at the target and maximum levels were as follows:

Dollars in thousands	Performance Share Awards Outstanding		2022
Performance Period	Target	Maximum	Expense
2020-22	31,160	62,320	$	888
2021-23	—	—	—
2022-24	—	—	—
Total	31,160	62,320	$	888

Long Term Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangements by Share-based Payment Award, Performance-Based Units, Vested and Expected to Vest [Table Text Block]

The following table summarizes performance share expense information:

Dollars in thousands	Shares(1)	Expense During Award Year(2)		Total Expense for Award
Estimated award:
2020-2022 grant(3)	29,472	$	888	$	888
Actual award:
2019-2021 grant	37,430	$	1,323	$	1,323
2018-2020 grant	31,600	$	2,137	$	2,137

(1)     In addition to common stock shares, a participant also receives a dividend equivalent cash payment equal to the number of shares of common stock received on the award payout multiplied by the aggregate cash dividends paid per share during the performance period.

(2)     Amount represents the expense recognized in the third year of the vesting period noted above. For the 2019-2021 and 2020-2022 grants, mutual understanding of the award's key terms was established in the third year of the vesting period, triggering full expense recognition in 2021 and 2022, respectively.

(3)    This represents the estimated number of shares to be awarded as of December 31, 2022 as certain performance share measures have been achieved. Amounts are subject to change with final payout amounts authorized by the Board of Directors in February 2023.