Consolidated Balance Sheets (Parenthetical) - $ / shares |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Common stock, par value | $ 0.01 | |
| Class A | ||
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 400,000,000 | 400,000,000 |
| Common stock, shares issued | 18,099,772 | 15,280,833 |
| Common stock, shares outstanding | 16,414,617 | 14,424,558 |
| Treasury stock, shares | 1,685,155 | 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 | 53,937,394 | 55,284,408 |
| Common stock, shares outstanding | 51,281,512 | 53,137,428 |
| Treasury stock, shares | 2,655,882 | 2,146,980 |