Share-Based Compensation Plans (Schedule of Summary of Stock Options) (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Outstanding, beginning balance, in shares | shares	14,824
Granted, in shares | shares	6,785
Exercised, in shares | shares	0
Forfeited, in shares | shares	2,505
Expired, in shares | shares	1,939
Outstanding, ending balance, in shares | shares	17,165
Exercisable, ending balance, in shares | shares	8,518
Outstanding, beginning balance, weighted-average exercise price | $ / shares	$ 20.09
Granted, weighted-average exercise price | $ / shares	5.32
Exercised, weighted-average exercise price | $ / shares	0.00
Forfeited, weighted-average exercise price | $ / shares	5.52
Expired, weighted-average exercise price | $ / shares	34.50
Outstanding, ending balance, weighted-average exercise price | $ / shares	14.95
Exercisable, ending balance, weighted-average exercise price | $ / shares	$ 22.27
Outstanding, ending balance, weighted-average contractual term, years	5 years 7 months 6 days
Outstanding, exercisable, weighted-average contractual term, years	2 years 10 months 24 days
Outstanding, ending balance, aggregate intrinsic value | $	$ 0.0
Exercisable, ending balance, aggregate intrinsic value | $	$ 0.0