Income Taxes - Tax Reform (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Statutory tax rate		21.00%	21.00%	35.00%
Percentage of tax reform enacted		15.50%
Percentage of tax reform enacted remaining earnings		8.00%
Income tax expense on foreign earnings deemed repatriated				$ 18.2
Tax liability for repatriation tax			$ 10.1
Repatriation tax, period for payment			8 years
Deferred tax expense for foreign taxes on distributions from foreign subsidiaries deemed repatriated	$ 7.3		$ 0.0
Provisional tax expense for remeasurement of net deferred tax assets			2.3
Reduction of provisional taxes payable		$ 0.5	$ 2.5