|12 Months Ended|
Dec. 31, 2017
|Goodwill and Intangible Assets Disclosure [Abstract]|
|Summary of Changes in Carrying Amount of Goodwill||
The following table summarizes the changes in the carrying amount of goodwill for 2017 and 2016:
Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.
Reference 1: http://www.xbrl.org/2003/role/presentationRef