Share-Based Compensation Schedule of Stock Option Transactions (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock options outstanding, beginning of year | shares	2,354,277
Options exercised | shares	(23,337)
Options Cancelled | shares	(232,007)
Stock options outstanding, end of year | shares	2,098,933
Options exercisable, shares | shares	1,732,827
Unvested options, shares | shares	366,106
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]
Weighted average exercise price, beginning of year | $ / shares	$ 23.62
Weighted average exercise price, granted in period | $ / shares	10.12
Weighted average exercise price, cancelled in period | $ / shares	37.16
Weighted average exercise price, end of year | $ / shares	22.27
Options exercisable, weighted average exercise price | $ / shares	23.90
Unvested options, weighted average exercise price | $ / shares	$ 14.57
Weighted average remaining contractual term, options outstanding	2 years 10 months 14 days
Weighted average remaining contractual term, options exercisable	2 years 5 months 16 days
Weighted average remaining contractual term, options unvested	4 years 9 months 22 days
Aggregate intrinsic value, options outstanding | $	$ 0.0
Aggregate intrinsic value, options exercisable | $	0.0
Aggregate intrinsic value, options unvested | $	$ 0.0