Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Summary of Significant Accounting Policies - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Aug. 31, 2017
Summary Of Accounting Policies [Line Items]
Goodwill			$ 18,504
Goodwill impairment charge	$ 18,504	$ 18,504
Confluence
Summary Of Accounting Policies [Line Items]
Goodwill				$ 18,504