Earnings (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Twelve months ended December 31,
	2017	2016	2015
Shares used in basic loss per share (weighted-average common shares outstanding)	33,734	32,708	34,104
Effect of potentially dilutive shares issuable from stock options, RSUs and Convertible Senior Notes	—	—	—
Shares used in diluted loss per share calculation	33,734	32,708	34,104
Potentially dilutive shares excluded from calculation due to anti-dilutive effect	37	2,770	1,902