Earnings Per Share - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Participating securities outstanding	0	0	2
Number of anti-dilutive securities		89
Stock and Performance Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Participating securities outstanding, nonforfeitable	16	12	8
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	89
Number of anti-dilutive securities	89
Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares that would have been included in diluted earnings per share calculation	16
Number of anti-dilutive securities	9
Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares that would have been included in diluted earnings per share calculation	12
Number of anti-dilutive securities	2
Weighted average exercise price of options	$ 15.81	$ 15.41	$ 24.00
Equity Unit Purchase Agreements [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	12	27	27