Earnings Per Share - Additional Information (Detail) - $ / shares shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Weighted Average [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	28
Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares that would have been included in diluted earnings per share calculation	28
Mandatory Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	77	77
Shares that would have been included in diluted earnings per share calculation	77
Equity Unit Purchase Agreements [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	26	13
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	42
Shares that would have been included in diluted earnings per share calculation	2
Weighted average exercise price of options	$ 12.74	$ 14.79
Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	24
Shares that would have been included in diluted earnings per share calculation	10