Annual report pursuant to Section 13 and 15(d)

Share Repurchase Program (Details)

v3.8.0.1
Share Repurchase Program (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Feb. 28, 2017
Dec. 31, 2016
Jul. 05, 2017
Feb. 24, 2017
Number of shares repurchased (in shares) 2,365,836   673,626    
Share repurchase cost $ 139,286   $ 22,296    
2016 Repurchase program          
Number of shares repurchased (in shares)   788,399      
Share repurchase cost   $ 26,600      
Average price per share (in dollars per share)   $ 33.72      
2017 Repurchase program          
Share repurchase program, authorized amount         $ 200,000
2017 ASR Agreement          
Payment under ASR agreement       $ 100,000  
Initial number of shares delivered under ASR agreement (in shares)       1,500,000  
Initial percentage of shares delivered under ASR agreement       80.00%