Summary of significant accounting policies Summary of Significant Accounting Policies (Tables)
|12 Months Ended|
Dec. 31, 2018
|Accounting Policies [Abstract]|
|Disaggregation of Revenue||
The following table further disaggregates our revenue by major source by segment for the year ended December 31, 2018.
Tabular disclosure of disaggregation of revenue into categories depicting how nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factor.
Reference 1: http://www.xbrl.org/2003/role/presentationRef