Stock-Based and Other Compensation Plans - Stock Option Activity (Details) - Stock Option $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Options
Outstanding, beginning balance (in shares) | shares	15,549,222
Granted (in shares) | shares	551,888
Exercised (in shares) | shares	(576,617)
Forfeited (in shares) | shares	(1,672,473)
Outstanding, ending balance (in shares) | shares	13,852,020
Exercisable (in shares) | shares	11,866,188
Weighted Average Exercise Price
Weighted average exercise price per share outstanding, beginning balance (in dollars per share) | $ / shares	$ 43.42
Weighted average exercise price per share granted (in dollars per share) | $ / shares	30.20
Weighted average exercise price per share exercised (in dollars per share) | $ / shares	34.55
Weighted average exercise price per share forfeited (in dollars per share) | $ / shares	40.04
Weighted average exercise price per share outstanding, ending balance (in dollars per share) | $ / shares	44.04
Weighted average exercise price per exercisable share (in dollars per share) | $ / shares	$ 45.58
Weighted average remaining contractual term of shares outstanding (in years)	5 years
Weighted average remaining contractual term, exercisable shares (in years)	4 years
Aggregate intrinsic value of shares outstanding | $	$ 0
Aggregate intrinsic value, exercisable shares | $	$ 0