Share-Based Compensation - Stock Options (Details) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Options outstanding and exercisable under the Company's 1991 Equity and Performance Incentive Plan
Outstanding, Shares, Beginning balance | shares	1.7
Outstanding, Weighted average exercise price, Beginning balance | $ / shares	$ 31.98
Expired or forfeited, Shares | shares	(0.2)
Expired or forfeited, Weighted average exercise price | $ / shares	$ 39.41
Granted, Shares | shares	0.8
Granted, Weighted average exercise price | $ / shares	$ 26.57
Outstanding, Shares, Ending balance | shares	2.3
Outstanding, Weighted average exercise price, Ending balance | $ / shares	$ 29.68
Outstanding, Weighted Average Remaining Contractual Term	8 years
Outstanding, Aggregate Intrinsic Value | $	$ 0.0
Options exercisable, Shares | shares	1.1
Options exercisable, Weighted average exercise price | $ / shares	$ 32.15
Option exercisable, Weighted average remaining contractual term	6 years
Option exercisable, Aggregate Intrinsic Value | $	$ 0.0
Options vested and expected to vest, Shares | shares	2.2
Options vested and expected to vest, Weighted average exercise price | $ / shares	$ 29.80
Options vested and expected to vest, Weighted average remaining contractual term	8 years
Options vested and expected to vest, aggregate intrinsic value | $	$ 0.0