Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Name:	us-gaap_ConcentrationRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Summary of Significant Accounting Policies (Concentration Risk) (Details) - customer	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Customer Concentration Risk, Revenue
Concentration Risk [Line Items]
Concentration risk, number of customers	0	0	0	0
Credit Concentration Risk, Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, number of customers			0	0