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Income Taxes - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended | 24 Months Ended
--- | --- | --- | ---
Sep. 30, 2019 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2018
Income Tax Contingency [Line Items] |  |  |  |  |  |
Accrued liabilities for interest and penalties |  | $ 0.3 | $ 0.2 |  |  |
Total gross unrecognized tax benefits |  | 10.4 | 5.0 | $ 3.9 |  | $ 3.9
Estimated increase (decrease) in the liability for unrecognized tax benefits |  | (0.3) |  |  |  |
Tax benefit from impact of tax law changes enacted | $ (1.0) | 0.5 | 0.3 | 2.5 |  |
Tax benefit from stock-based compensation |  | $ 20.8 | $ 10.3 | $ 14.3 |  |
U.S. federal corporate tax rate |  | 21.00% | 21.00% | 21.00% | 35.00% |
Transition toll tax |  |  |  | $ (7.5) | $ 27.9 | $ 20.4
Measurement period adjustment, Tax Cuts and Jobs Act of 2017 |  |  |  | $ 4.0 |  |
Net impact to the 2018 effective tax rate, Tax Cuts and Jobs Act of 2017 |  |  |  | 0.0145 |  |
Operating loss carryforwards, state and local |  | $ 14.0 |  |  |  |
Operating loss carryforwards, foreign |  | 7.4 |  |  |  |
Undistributed earnings of foreign subsidiaries |  | 345.6 |  |  |  |
State and Local Jurisdiction |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Operating loss carryforwards |  | 204.1 |  |  |  |
Foreign Tax Authority |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Operating loss carryforwards |  | 56.7 |  |  |  |
Operating loss carryforwards, not subject to expiration |  | 54.1 |  |  |  |
Year 2021 | State and Local Jurisdiction |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Operating loss carryforwards |  | 25.7 |  |  |  |
Year After 2021 | State and Local Jurisdiction |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Operating loss carryforwards |  | 178.4 |  |  |  |
Research Tax Credit Carryforward | State and Local Jurisdiction |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax credit carryforward |  | $ 0.9 |  |  |  |

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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e32059-109318 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
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