|12 Months Ended|
Dec. 31, 2017
|Equity Method Investments and Joint Ventures [Abstract]|
|Schedule of investments||
Investments accounted for under the equity method of accounting consisted of the following as of December 31, 2017 and 2016:
Tabular disclosure of equity method investments including, but not limited to, name of each investee or group of investments, percentage ownership, difference between recorded amount of an investment and the value of the underlying equity in the net assets, and summarized financial information.
Reference 1: http://www.xbrl.org/2003/role/presentationRef