Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares |
Sep. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Class A | ||
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 400,000,000 | 400,000,000 |
| Common stock, shares issued | 17,806,125 | 15,280,833 |
| Common stock, shares outstanding | 16,413,700 | 14,424,558 |
| Treasury stock, shares | 1,392,425 | 856,275 |
| Class B | ||
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 200,000,000 | 200,000,000 |
| Common stock, shares issued | 53,684,006 | 55,284,408 |
| Common stock, shares outstanding | 51,283,669 | 53,137,428 |
| Treasury stock, shares | 2,400,337 | 2,146,980 |