Number of new stock issued during the period.

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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Common Stock (Controlled Equity Offering) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	May 10, 2019	Apr. 30, 2019	Feb. 29, 2016
Components Of Common Stock [Line Items]
Percentage of commission			3.00%
Controlled Equity Offering Agreement
Components Of Common Stock [Line Items]
Issuance of common stock (Shares)	0	0
Percentage of commission				3.00%	3.00%
Maximum aggregate offering price of equity securities				$ 24,650	$ 25,000