Net Income (Loss) Per Share - Narrative (Detail) - $ / shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share of common stock excluded from diluted net loss per share calculation (in shares)	0.7	1.1	0.7	1.1
Shares of common stock at prices ranging, lower limit (in dollars per share)	$ 9.83	$ 7.14	$ 9.83	$ 7.14
Shares of common stock at prices ranging, upper limit (in dollars per share)	$ 19.95	$ 19.95	$ 19.95	$ 19.95
Deferred stock units, performance-based stock units and restricted stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share of common stock excluded from diluted net loss per share calculation (in shares)	0.6	0.4	0.6	0.4
Convertible Senior Debentures due 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share of common stock excluded from diluted net loss per share calculation (in shares)	3.0	3.0	3.0	3.0