Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
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The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Expiration date of the tax credit carryforward, in CCYY-MM-DD format.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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-Name Accounting Standards Codification
-Topic 740
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Income Taxes (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Millions	Dec. 22, 2017	Dec. 31, 2017	Dec. 31, 2016
Increase (decrease) in valuation allowance	$ 21.6	$ 12.6	$ 10.5
Federal Statutory Income Tax Rate		34.00%	34.00%
Minimum [Member]
Federal Statutory Income Tax Rate		21.00%
Maximum [Member]
Federal Statutory Income Tax Rate		35.00%
Internal Revenue Service I R S [Member]
Net operating loss carryforwards		$ 166.0
Internal Revenue Service I R S [Member] \| Research [Member]
Tax credit carryforwards		$ 1.3
Internal Revenue Service I R S [Member] \| Minimum [Member]
Expiration year		Dec. 31, 2021
Internal Revenue Service I R S [Member] \| Minimum [Member] \| Research [Member]
Expiration year		Dec. 31, 2022
Internal Revenue Service I R S [Member] \| Maximum [Member]
Expiration year		Dec. 31, 2036
Internal Revenue Service I R S [Member] \| Maximum [Member] \| Research [Member]
Expiration year		Dec. 31, 2035
State And Local Jurisdiction [Member]
Net operating loss carryforwards		$ 156.0
State And Local Jurisdiction [Member] \| Research [Member]
Tax credit carryforwards		$ 2.2
State And Local Jurisdiction [Member] \| Minimum [Member]
Expiration year		Dec. 31, 2018
State And Local Jurisdiction [Member] \| Maximum [Member]
Expiration year		Dec. 31, 2037