Summary of Significant Accounting Policies Deferred Offering Costs (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
Oct. 11, 2017	Oct. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs		$ 4.9	$ 0.0
Payments of Stock Issuance Costs	$ 4.9

Amount of decrease in additional paid in capital (APIC) resulting from direct costs associated with issuing stock. Includes, but is not limited to, legal and accounting fees and direct costs associated with stock issues under a shelf registration.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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Period Type:	duration