Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

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

Schedule of Stock Options Roll Forward

A summary of award activity by type for the six months ended June 30, 2018 is presented below.

Stock Options	Awards/Units (in millions)		Weighted- Average Exercise Price		Aggregate Intrinsic Value  (in millions)		Weighted Average Remaining Contractual Life (years)
Outstanding at January 1, 2018	8.1		$	16.54
Granted	0.8		29.84
Exercised	(0.9	)	11.58
Forfeited	(0.1	)	28.92
Outstanding at June 30, 2018	7.9		$	18.35
Vested and expected to vest at June 30, 2018	7.9		$	18.35	$	96.1	6.39
Exercisable at June 30, 2018	6.2		$	15.66	$	93.2	5.73

Schedule of Restricted Stock Units and Restricted Stock Awards Roll Forward

Restricted Stock Awards and Restricted Stock Units	Awards (millions)		Weighted-Average Fair Value
Outstanding at January 1, 2018	1.9		$	29.32
Granted	0.6		30.13
Vested	(1.1	)	30.17
Forfeited	—		—
Outstanding at June 30, 2018	1.4		$	29.04

Schedule of Performance Stock Roll Forward

Performance Stock Awards and Performance Share Units	Awards (millions)	Weighted-Average Fair Value
Outstanding at January 1, 2018	0.6	$	31.17
Granted	0.3	33.77
Vested	—	—
Forfeited	—	—
Outstanding at June 30, 2018	0.9	$	32.08