Stockholders' Equity and Share-Based Awards (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

The following table summarizes the changes in the number of shares of common stock under option for 2018 (shares and aggregate intrinsic value in millions):


	Shares			Weighted- Average Exercise Price Per Share		Weighted Average Remaining Life (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2017		0.4		$	16
Exercised		(0.1	)	$	18

Outstanding at December 31, 2018 (a)		0.3		$	15		2.2	$	1.2

(a) All options outstanding are exercisable

Summary of Changes of Restricted Stock and Restricted Stock Units

The following table summarizes the changes in the number of outstanding restricted stock units for 2018 (shares in millions):


	Restricted Stock Units			Weighted- Average Average Grant Date Fair Value Per Share
Outstanding at December 31, 2017		4.4		$	50
Granted		2.8			29
Vested		(1.2	)		44
Forfeited		(1.3	)		43

Outstanding at December 31, 2018		4.7			41

Expected to vest at December 31, 2018		2.9			32

Summary of Total Unrecognized Compensation Cost Related to Stock-based Compensation

The following table summarizes the Company’s total unrecognized compensation cost related to stock-based compensation as of December 31, 2018 (in millions):


	Unrecognized Compensation Cost		Weighted- Average Period of Expense Recognition (in years)
Restricted stock units	$	65.3		1