Stockholders' Equity - Summary of Cash Dividends Declared on Class A Common Stock (Detail) - $ / shares |
3 Months Ended | |
|---|---|---|
Jun. 30, 2018 |
Mar. 31, 2018 |
|
| Equity [Abstract] | ||
| Dividends Per Share (in dollars per share) | $ 0.4220 | $ 0.4220 |
| Declaration Date | May 03, 2018 | Feb. 22, 2018 |
| Record Date | Jun. 29, 2018 | Mar. 30, 2018 |
| Payment Date | Jul. 31, 2018 | Apr. 30, 2018 |