Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement, Noncash Expense [Abstract]

Stock-Based Compensation Cost and Associated Tax Benefit

Presented below is a summary of the stock-based compensation cost and associated tax benefit included in the accompanying consolidated statements of operations:

	Three Months Ended March 31,
	2020		2019
Stock-based compensation cost	$	37	$	36
Tax benefit	$	7	$	8

Weighted Average Assumptions used in Determining Fair Value for Options Granted

The following weighted average assumptions were used in determining the fair value for options granted in 2020:

Expected dividend yield	0.80	%
Expected stock volatility	22.43	%
Risk-free interest rate	1.45	%
Expected holding period	5.7 years

Stock Option Exercises and Restricted Stock Vesting

The following tables summarize information relating to stock option exercises and restricted stock vesting:

	Three Months Ended March 31,
	2020		2019
Exercise of stock options:
Proceeds from stock option exercises	$	13	$	12
Aggregate intrinsic value	$	46	$	36
Tax benefit realized upon exercise	$	11	$	9
Number of shares exercised	0.2		0.3
Vesting of restricted stock:
Fair value of shares vested	$	191	$	147
Tax benefit realized upon vesting	$	44	$	34
Number of shares vested	0.8		0.8
Vesting of performance-based restricted stock:
Fair value of shares vested	$	70	$	48
Tax benefit realized upon vesting	$	17	$	12
Number of shares vested	0.3		0.3