Income Taxes - Balance Sheet Location (Details) - Foreign Tax Authority - Danish Tax Authority (SKAT) - Tax Years Post 2011 kr in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020 DKK (kr)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 DKK (kr)	Dec. 31, 2019 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Income Tax Examination [Line Items]
Income tax liability	kr 1,115.8	$ 164.8	kr 1,110.0	$ 166.7
Tax deposit	1,104.1		kr 970.1		$ 163.0	$ 145.6
Accrued expenses and other current liabilities
Income Tax Examination [Line Items]
Income tax liability	847.3	125.1
Tax deposit	847.3				125.1
Other non-current assets
Income Tax Examination [Line Items]
Income tax liability	268.5	$ 39.7
Tax deposit	kr 256.8				$ 37.9