XML 67 R52.htm IDEA: XBRL DOCUMENT v3.8.0.1
Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accounting Policies [Abstract]      
Goodwill impairment $ 0 $ 0 $ 0