Investments (Details)	3 Months Ended
Mar. 31, 2019
Minimum
Debt Securities, Available-for-sale [Line Items]
Marketable securities maturity term	1 month
Maximum
Debt Securities, Available-for-sale [Line Items]
Marketable securities maturity term	78 months

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.

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration