Number of new stock issued during the period.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: 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(28))
-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

Nature of Business and Significant Accounting Policies - Initial Public Offering and Secondary Offerings (Details) - Common stock - $ / shares	Jul. 20, 2017	May 01, 2017	Jul. 26, 2017
Over-Allotment Option for Underwriters
Subsidiary, Sale of Stock [Line Items]
Shares issued in public offering (shares)		1,500,000
Secondary Offering
Subsidiary, Sale of Stock [Line Items]
Offering price (in dollars per share)		$ 47.50	$ 51.63
Shares issued in public offering (shares)	5,437,502	10,000,000