Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Narrative (Details)

v3.8.0.1
Stockholders' Equity - Narrative (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2017
Mar. 06, 2017
Equity [Abstract]    
Shares authorized to repurchase   $ 50.0
Repurchase of common stock (in shares) 2.5  
Repurchase of common stock $ 40.0  
Repurchase of common stock (in dollars per share) $ 16.29