Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Corporate income tax rate		21.00%	21.00%	35.00%
Deferred tax asset Impairment expense	$ 4.8
Unrecognized tax benefits impairment expenses				$ 1.4

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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