Capital Stock - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Schedule of Capitalization, Equity [Line Items] | ||
| Common shares repurchased | 600,000 | |
| Common shares repurchased, value | $ 335 | $ 275 |
| Shares authorized to be repurchased | 5,800,000 | |
| Series C Nonvoting Participating Preferred Stock [Member] | PNC [Member] | ||
| Schedule of Capitalization, Equity [Line Items] | ||
| Surrender of share of series non- voting preferred stock | 103,064 | |
| X | ||||||||||
- Definition Surrender of share of series non- voting preferred stock. No definition available.
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. No definition available.
|
| X | ||||||||||
- Definition Number of shares that have been repurchased during the period and are being held in treasury. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|