Fair Value of Financial Instruments - Additional Information (Details) - Discount Rate	Sep. 30, 2018	Dec. 31, 2017
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate (in percentage)	0.063	0.083
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate (in percentage)	0.097	0.105

Value of input used to measure contingent consideration liability from business combination.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Name:	us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant