Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The following summarizes the significant assumptions used to determine the fair value of performance shares and related compensation expense as well as the resulting estimated fair value of performance shares granted:

	2021		2020
Risk-free interest rate	0.19	%	1.42	%
Expected life, in years	3		3
Expected volatility	28.2% to 38.5%		14.9% to 19.7%
Dividend yield	4.3	%	3.1	%

Schedule of Nonvested Share Activity

A summary of nonvested shares as of and changes during the year ended December 31, 2021, are as follows:

	Performance Unit Awards
	Shares	Weighted-Average Grant-Date Fair Value
Beginning nonvested grants	130,571	$	66.27
Granted	104,927	50.53
Vested	(69,867)	60.41
Forfeited	(3,108)	59.14
Remaining nonvested grants	162,523	$	58.76

Share-based Compensation Arrangement by Share-based Payment Award

Schedule of Nonvested Restricted Stock Units Activity

A summary of nonvested shares as of and changes during the year ended December 31, 2021, are as follows:

	Shares	Weighted-Average Grant-Date Fair Value
Beginning nonvested grants	77,967	$	50.86
Granted	24,385	43.29
Vested	(15,033)	45.78
Forfeited	—	—
Remaining nonvested grants	87,319	$	49.63

Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments

Following is a summary of the components of DSUs issued and compensation expense attributable to the DSUs (in millions, except DSU amounts):

	December 31,
	2021		2020		2019
DSUs Issued	18,741		21,434		19,027
Compensation expense	$	1.1	$	1.5	$	1.3
Change in value of shares	1.3		(2.9)		2.4
Total compensation (benefit) expense	$	2.4	$	(1.4)	$	3.7
DSUs withdrawn	186,137		613		3,708
Value of DSUs withdrawn	$	12.1	$	0.1	$	0.3