Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Treasury stock, shares | 6,083,098 | 6,056,719 |
| Preferred stock, par value (USD per share) | $ 0.001 | $ 0.001 |
| Preferred stock, shares authorized | 100,000,000 | 100,000,000 |
| Preferred stock, shares outstanding | 0 | 0 |
| Class A Common Stock [Member] | ||
| Common stock, par value (USD per share) | $ 0.001 | $ 0.001 |
| Common stock, shares authorized | 1,000,000,000 | 1,000,000,000 |
| Common stock, shares outstanding | 97,825,148 | 97,781,933 |
| Class B common stock [Member] | ||
| Common stock, par value (USD per share) | $ 0.001 | $ 0.001 |
| Common stock, shares authorized | 1,000,000 | 1,000,000 |
| Common stock, shares outstanding | 28 | 28 |