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Earnings Per Share - Additional Information (Detail) - $ / shares | 1 Months Ended | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Jul. 31, 2015 | Mar. 31, 2015 | Sep. 30, 2015 | Sep. 30, 2014 | Mar. 31, 2014 | Sep. 30, 2015 | Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Common stock outstanding |  |  | 1,000,000 | 8,000,000 |  | 4,000,000 | 6,000,000
Number of weighted average outstanding diluted shares |  |  | 1,294,000,000 | 1,205,000,000 |  | 1,257,000,000 | 1,170,000,000
Basic average number of share |  |  | 58,000,000 |  |  | 20,000,000 |
Weighted average number of shares outstanding |  |  | 1,281,000,000 | 1,177,000,000 |  | 1,241,000,000 | 1,150,000,000
RTI [Member] |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Number of common stock shares issued in a part of acquisition | 87,000,000 | 87,397,414 |  |  |  |  |
Weighted average number of shares outstanding |  |  | 87,000,000 |  |  | 87,000,000 |
Convertible Debt Securities [Member] |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Number of shares, option exercised |  |  |  |  | 89,000,000 |  |
Common stock outstanding |  |  |  | 89,000,000 |  |  | 89,000,000
Number of weighted average outstanding shares included in both basic and diluted shares |  |  |  |  |  |  | 67,000,000
Common stock outstanding |  |  |  |  |  |  | 89,000,000
Number of weighted average outstanding diluted shares |  |  |  |  |  |  | 22,000,000
Equity Unit Purchase Agreements [Member] |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Number of anti-dilutive securities |  |  |  |  |  | 26,000,000 | 3,000,000
Stock options [Member] |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Weighted average exercise price of options |  |  |  |  |  | $ 12.76 | $ 16.24
Mandatory Convertible Notes [Member] |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Number of anti-dilutive securities |  |  | 77,000,000 |  |  | 77,000,000 |
Convertible Notes [Member] |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Number of anti-dilutive securities |  |  | 25,000,000 |  |  | 8,000,000 |

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