Earnings Per Share - Additional Information (Detail) - $ / shares shares in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock outstanding	4	6		5
Number of weighted average outstanding diluted shares	1,237	1,189		1,238	1,137
Number of common stock shares issued in a part of acquisition				90
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares, option exercised			89
Common stock outstanding		89	89		89
Number of weighted average outstanding shares included in both basic and diluted shares					56
Common stock outstanding					89
Number of weighted average outstanding diluted shares					33
Mandatory Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	77			77
Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities					33
Shares that would have been included in diluted earnings per share calculation					33
Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities					10
Shares that would have been included in diluted earnings per share calculation					19
Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities					6
Shares that would have been included in diluted earnings per share calculation					31
Weighted average exercise price of options				$ 14.78	$ 16.24
Equity Unit Purchase Agreements [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities				13	3