Stockholders' Equity - Summary of Cash Dividends Declared on Class A Common Stock (Detail) - $ / shares |
3 Months Ended | ||
|---|---|---|---|
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
|
| Equity [Abstract] | |||
| Dividends Per Share (in dollars per share) | $ 0.4200 | $ 0.4180 | $ 0.4138 |
| Dividends Payable, Date Declared | Aug. 03, 2017 | May 04, 2017 | Feb. 24, 2017 |
| Record date for dividends declared | Sep. 29, 2017 | Jun. 30, 2017 | Mar. 31, 2017 |
| Dividends payment date | Oct. 31, 2017 | Jul. 31, 2017 | Apr. 28, 2017 |