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Additional Financial Information - Additional Information (Detail) (USD $)
Share data in Millions, unless otherwise specified |
12 Months Ended | 0 Months Ended | 1 Months Ended | |
|---|---|---|---|---|
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Dec. 31, 2014
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Dec. 31, 2013
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Feb. 10, 2015
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Feb. 23, 2015
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| Supplemental Cash Flow Information [Line Items] | ||||
| Common shares issued from treasury related to dividend payments | 18.2 | |||
| Aggregate value of common shares issued from treasury related to dividend payments | $ 700,000,000 | |||
| Payment for repurchase of common stock | 153,000,000 | |||
| February 2015 Accelerated Stock Repurchase | Subsequent Event | ||||
| Supplemental Cash Flow Information [Line Items] | ||||
| Accelerated Share Repurchase | 5,000,000,000 | |||
| Payment for repurchase of common stock | 4,250,000,000 | |||
| Number of shares repurchased | 86.2 | |||
| Expected Total Payment related to February 2015 Accelerated Stock Repurchase | Subsequent Event | ||||
| Supplemental Cash Flow Information [Line Items] | ||||
| Payment for repurchase of common stock | $ 5,000,000,000 | |||