Income tax provision (Details)	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Reconciliation of effective tax rate
Income tax at federal statutory rate	21.00%	21.00%
Goodwill impairment charges	(18.80%)	(29.30%)
Change in valuation allowances	0.00%	(4.50%)
Net tax impact of share-based compensation	(0.90%)	(1.10%)
Foreign tax rate differences	3.90%	1.30%
State income tax, net of federal income tax benefit	2.20%	4.90%
Other	(2.30%)	0.00%
Effective tax rate	5.10%	(7.70%)

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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

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Percentage of the difference, between reported income tax expense (benefit) and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, that is attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority interest income (expense), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, change in enacted tax rate, prior year income taxes, change in deferred tax asset valuation allowance, and other adjustments.

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Percentage of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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