Net Loss Per Share and Shareholders' Equity - Additional Information (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the diluted EPS calculation (in shares)				600,000.0
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the diluted EPS calculation (in shares)				200,000.0
Performance-based Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the diluted EPS calculation (in shares)	200,000.0	100,000.0	200,000.0	100,000.0
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the diluted EPS calculation (in shares)	900,000.0	1,500,000.0	900,000.0	5,000,000