Stockholders' Equity - Additional Information (Detail) - USD ($) |
Sep. 30, 2016 |
Sep. 20, 2016 |
Sep. 16, 2013 |
|---|---|---|---|
| Share Repurchases [Line Items] | |||
| Amount available for repurchase under the current share repurchase program approved by the company's Board of Directors | $ 40,000,000,000 | $ 40,000,000,000 | |
| Unused amount of share repurchase program | $ 3,500,000,000 |