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Income Taxes - TCJA and Net operating loss carryforwards (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017
Federal |  |
Income Taxes [Line Items] |  |
Income tax receivable | $ 1.6 | $ 1.6
Cumulative net operating loss carryforwards | 191.1 |
Tax credit carryforwards | 14.9 |
State |  |
Income Taxes [Line Items] |  |
Cumulative net operating loss carryforwards | 138.9 |
Tax credit carryforwards | 8.2 |
Years Prior to 2018 | Federal |  |
Income Taxes [Line Items] |  |
Cumulative net operating loss carryforwards | $ 102.6 |
Percentage of net operating losses which can offset future taxable income | 100.00% |
Tax Year 2018 | Federal |  |
Income Taxes [Line Items] |  |
Cumulative net operating loss carryforwards | $ 88.6 |
Percentage of net operating losses which can offset future taxable income | 80.00% |

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- Definition Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable. + References Reference 1: 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(8)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(10)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319 + Details
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- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319 + Details
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