Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Summary of Nonvested Restricted Stock Awards Activity

The following table summarizes restricted stock awards activity for the nine months ended September 30, 2019:

	Time-Based					Market-Based
	Restricted Stock Awards					Restricted Stock Awards
	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Unvested shares of restricted stock outstanding at December 31, 2018		806.5		$	67.54		—		$	—
Granted		338.9			151.10		281.0			102.76
Vested		(318.5	)		64.06		(280.4	)		102.76
Forfeited		(77.8	)		85.82		(0.6	)		102.57
Unvested shares of restricted stock outstanding at September 30, 2019		749.1		$	104.92		—		$	—

Market-Based Shares [Member]

Summary of Market-Based Shares Vesting Activity

The following table summarizes vesting activity for Market-Based Shares during the nine months ended September 30, 2019, the associated compensation cost recognized in connection with each vesting event and the number of shares withheld to satisfy tax withholding obligations:

Vesting Condition

Date Vested

Number of Shares

Vested

Compensation

Cost Recognized

Upon Vesting

Shares Withheld

for Taxes¹

Market-based (TEV = $8.65 billion)

February 13, 2019

140.2

$14,900

54.5

Market-based (TEV = $9.35 billion)

February 22, 2019

140.2

$13,900

55.5

All shares withheld to satisfy tax withholding obligations are held as treasury stock.