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Income Taxes - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Operating Loss Carryforwards [Line Items] |  |  |
Income tax expense (benefit) from the Tax Act | $ 0.6 | $ 32.4 |
Valuation allowance, change in amount | (2.5) | $ (8.4) | $ 6.3
Unrecognized tax benefits that would impact effective tax rate | 28.2 |  |
Research Tax Credit Carryforward |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Tax credit carryforward | 23.0 |  |
California and New Jersey Research Tax Credit Carryforward |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Tax credit carryforward | 22.7 |  |
Internal Revenue Service (IRS) |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Operating loss carryforward | 229.9 |  |
State and Local Jurisdiction |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Operating loss carryforward | $ 125.3 |  |

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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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