XML 83 R67.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stockholders' Equity - Share Repurchases (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended 23 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items]        
Shares repurchased in association with tax withholdings on the vesting of RSUs (in shares) 32,457 94,826 77,649  
Class A common stock        
Equity, Class of Treasury Stock [Line Items]        
Shares repurchased pursuant to repurchase authorizations (in shares) 329,000 1,312,848 228,737 1,042,725
Total purchase price (in thousands) $ 30,527 $ 104,370 $ 24,676  
Average purchase price per share (in dollars per share) $ 92.79 $ 79.50 $ 107.88 $ 83.86