Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions		12 Months Ended
Jun. 21, 2016	Dec. 31, 2016
Statement Of Cash Flows [Abstract]
Issuance of common stock, offering costs	$ 2.7	$ 2.7

The cash outflow for cost incurred directly with the issuance of an equity security.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

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Balance Type:	credit
Period Type:	duration