Annual report pursuant to Section 13 and 15(d)

Goodwill and Other Identifiable Intangible Assets - Additional Information (Details)

v3.8.0.1
Goodwill and Other Identifiable Intangible Assets - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]      
Impairment of finite lived intangible assets $ 0 $ 0  
Amortization of intangible assets $ 507,000 $ 101,000 $ 86,000