Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions |
1 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Jan. 31, 2013 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Schedule of Capitalization, Equity [Line Items] | ||||
| Common stock, par value | $ 0.01 | $ 0.01 | ||
| Preferred stock, par value | 0.01 | 0.01 | ||
| Dividends, cash per common or preferred share | $ 8.72 | $ 7.72 | $ 6.72 | |
| Aggregate dividends | $ 1,476 | $ 1,338 | $ 1,168 | |
| Common shares repurchased | 3,100,000 | |||
| Common shares repurchased, value | $ 1,100 | $ 1,000 | $ 1,000 | |
| Shares authorized to be repurchased | 6,300,000 | |||
| Series C Non-voting Participating Preferred Stock [Member] | ||||
| Schedule of Capitalization, Equity [Line Items] | ||||
| Preferred stock, par value | $ 0.01 | $ 0.01 | ||
| Series C Non-voting Participating Preferred Stock [Member] | PNC [Member] | ||||
| Schedule of Capitalization, Equity [Line Items] | ||||
| Surrender of share of series non- voting preferred stock | 205,350 | |||