Annual report pursuant to Section 13 and 15(d)

Goodwill and Intangible Assets, net - Additional Information (Details)

v3.8.0.1
Goodwill and Intangible Assets, net - Additional Information (Details)
12 Months Ended
Dec. 31, 2017
USD ($)
reporting_unit
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]      
Number of reporting units | reporting_unit 1    
Percentage of estimated fair value in excess of carrying amount 4.00%    
Impairment of goodwill $ 0    
Amortization of intangible assets $ 4,204,000 $ 4,206,000 $ 3,695,000