Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Lease, renewal term			5 years
Sublease income	$ 1.7	$ 1.6	$ 3.5	$ 3.5
Minimum obligations	$ 815.9		815.9		$ 842.7
Tenant improvements					$ 75.0
Tenant improvement allowance reimbursement			(16.6)	$ (28.5)
Rent payments from sub-tenants			28.0
Operating leases, not yet commenced, value			$ 130.6
Minimum
Lessee, Lease, Description [Line Items]
Lease, remaining lease term			1 year
Operating sublease, term			1 year
Operating leases, not yet commenced, term of contract	5 years		5 years
Maximum
Lessee, Lease, Description [Line Items]
Lease, remaining lease term			16 years
Operating sublease, term			3 years
Operating leases, not yet commenced, term of contract	15 years		15 years
Corporate Headquarters Lease
Lessee, Lease, Description [Line Items]
Tenant improvement allowance reimbursement			$ 14.7
Line of Credit | Letter of Credit | Corporate Headquarters Lease
Lessee, Lease, Description [Line Items]
Letter of credit	$ 34.2		$ 34.2