XML 71 R56.htm IDEA: XBRL DOCUMENT v3.20.4
Summary of significant accounting policies - Goodwill and other intangible assets, net; Advertising (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Goodwill      
Impairment losses on intangible assets $ 0 $ 0 $ 0
Advertising expense $ 462 $ 873 $ 720
Maximum      
Goodwill      
Finite useful life of intangible assets 10 years