|12 Months Ended|
Dec. 31, 2017
|Goodwill and Intangible Assets Disclosure [Abstract]|
|Schedule of changes in goodwill||
The following table presents the changes in goodwill including business acquisitions as described in Note 4 Acquisitions and Recent Transactions.
Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.
Reference 1: http://www.xbrl.org/2003/role/presentationRef