Summary of Significant Accounting Policies - Summary of Quantitative Information About Company's Level 3 Fair Value Measurements (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Note receivable	$ 3,768	$ 2,815
Valuation Technique	Discounted cash flow
Default Percentage [Member]
Unobservable input	15.00%
Discount Rate [Member]
Unobservable input	18.00%

Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_NotesReceivableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant