v3.8.0.1
Goodwill - Additional Information (Details)
12 Months Ended
Dec. 31, 2017
USD ($)
reporting_unit
Dec. 31, 2016
USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]    
Number of reporting units | reporting_unit 1  
Goodwill impairment | $ $ 0 $ 0