Incentive Plans (Tables)

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

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

Assumptions used to value awards:
Dividend yield	—		%
Expected volatility	28.1		%
Risk-free interest rate	1.5		%
Expected life (years)	4.7
Stock price at valuation date	$	106.72

Share-based Payment Arrangement, Option, Activity

Changes in options outstanding for Company employees during the period from December 31, 2019 to September 30, 2020 are presented in the following table:

Options	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (Millions of Dollars)
Outstanding at 12/31/2019	392,300	$	68.52
Granted	79,200	105.57
Exercised	(148,800)	64.21
Outstanding at 9/30/2020	322,700	$	79.60	4.9	$	15.7
Exercisable at 9/30/2020	110,700	$	66.91	3.5	$	6.8

Share-based Payment Arrangement, Restricted Stock Unit, Activity

Changes in restricted stock units outstanding for Company employees during the period from December 31, 2019 to September 30, 2020 are presented in the following table:

Employee RSUs	Number of units	Weighted Average Grant Date Fair Value		Total Fair Value (Millions of Dollars)
Outstanding at 12/31/2019	198,915	$	70.58
Granted	55,395	$	90.64
Vested and issued	(59,324)	$	66.31	$	6.4
Forfeited	(8,680)	$	78.06
Outstanding at 9/30/2020	186,306	$	77.56	$	23.9

Changes in performance-based restricted stock units outstanding for Company employees during the period from December 31, 2019 to September 30, 2020 are presented in the following table:

Employee PSU's	Number of Units	Weighted Average Grant Date Fair Value		Total Fair Value (Millions of Dollars)
Outstanding at 12/31/2019	131,200	$	82.98
Granted	64,050	$	123.65
Vested and issued	(65,745)	$	85.04	$	7.0
Forfeited	(405)	$	65.75
Outstanding at 9/30/2020	129,100	$	97.19	$	16.6

Changes in restricted stock units outstanding for Company non-employee directors during the period from December 31, 2019 to September 30, 2020 are presented in the following table:

Director RSU's	Number of Units	Weighted Average Grant Date Fair Value		Total Fair Value (Millions of Dollars)
Outstanding at 12/31/2019	33,607	$	70.68
Granted	9,744	$	105.33
Vested and issued	(12,404)	$	66.01	$	1.3
Outstanding at 9/30/2020	30,947	$	83.46	$	4.0