Annual report pursuant to Section 13 and 15(d)

Revenue (Major Customers) (Details)

v3.10.0.1
Revenue (Major Customers) (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Revenues | Customer concentration risk | Fidelity      
Major Customers      
Revenue as a percentage of the company's total 17.00% 17.00% 15.00%