Share-Based Compensation Schedule Of Stock Option Transactions (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period | shares	2,354,277
Options exercised | shares	23,337
Options canceled | shares	(232,007)
Outstanding at end of period | shares	2,098,933
Options exercisable, shares | shares	1,707,915
Unvested options, shares | shares	391,018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average exercise price, beginning of year | $ / shares	$ 23.62
Weighted average exercise price, exercised in period | $ / shares	10.12
Weighted average exercise price, canceled in period | $ / shares	37.16
Weighted average exercise price, end of year | $ / shares	22.27
Options exercisable, weighted average exercise price | $ / shares	24.04
Unvested options, weighted average exercise price | $ / shares	$ 14.56
Weighted average remaining contractual term, options outstanding	3 years 1 month 13 days
Weighted average remaining contractual term, options exercisable	2 years 8 months 5 days
Weighted average remaining contractual term, options unvested	5 years 18 days
Aggregate intrinsic value, options outstanding | $	$ 0.5
Aggregate intrinsic value, options exercisable | $	0.3
Aggregate intrinsic value, options unvested | $	$ 0.2