Acquisitions and Divestitures - Reconciliation of Changes in Contingent Earn-Out Obligations (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($)
Business Combinations [Abstract]
Beginning balance January 1, 2017	$ 2,950
Contingent earn-out obligations associated with acquisitions	2,692
Remeasurement of fair value	746
Ending balance	$ 6,388

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Name:	us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant