Earnings (Loss) Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 18, 2013
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares	700,000	100,000
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018
Earnings Per Share Disclosure [Line Items]
Debt instrument, interest rate, stated percentage	1.50%	1.50%	1.50%	1.50%
Performance Shares
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares	1,100,000
Performance Shares | Maximum
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares		100,000