Commitments and Contingencies Lease Contractual obligation (Details)		3 Months Ended	9 Months Ended
	Mar. 01, 2019 USD ($) ft²	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Leases [Abstract]
Operating Lease Term	5 years
Finance lease right-of-use assets		$ 24,400,000	$ 24,400,000
Finance Lease, Right-of-Use Asset, Amortization		1,900,000	5,200,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months		14,900,000	14,900,000	$ 47,400,000
Capital Leases, Future Minimum Payments Due, Next Twelve Months		2,000,000.0	2,000,000.0	6,600,000
Operating Leases, Future Minimum Payments, Due in Two Years		55,300,000	55,300,000	38,400,000
Capital Leases, Future Minimum Payments Due in Two Years		7,100,000	7,100,000	5,400,000
Operating Leases, Future Minimum Payments, Due in Three Years		42,900,000	42,900,000	27,200,000
Capital Leases, Future Minimum Payments Due in Three Years		5,500,000	5,500,000	3,800,000
Operating Leases, Future Minimum Payments, Due in Four Years		30,300,000	30,300,000	17,900,000
Capital Leases, Future Minimum Payments Due in Four Years		3,600,000	3,600,000	2,100,000
Operating Leases, Future Minimum Payments, Due in Five Years		23,300,000	23,300,000	12,700,000
Capital Leases, Future Minimum Payments Due in Five Years		1,600,000	1,600,000	900,000
Operating Leases, Future Minimum Payments, Due Thereafter		22,500,000	22,500,000	16,100,000
Capital Leases, Future Minimum Payments Due Thereafter		11,900,000	11,900,000	12,800,000
Operating Leases, Future Minimum Payments Due		189,200,000	189,200,000	159,700,000
Capital Leases, Future Minimum Payments Due		31,700,000	31,700,000	31,600,000
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(14,600,000)	(14,600,000)
Finance Lease, Liability, Undiscounted Excess Amount		1,100,000	1,100,000
Capital Leases, Future Minimum Payments, Interest Included in Payments				(2,100,000)
Operating Lease, Liability		174,600,000	174,600,000
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments		30,600,000	30,600,000	29,500,000
Finance Lease, Interest Expense		200,000	500,000
Operating Lease, Cost		14,700,000	44,000,000.0
Short-term Lease, Cost		1,100,000	3,400,000
Variable Lease, Cost		5,000,000.0	15,100,000
Lease, Cost		22,900,000	68,200,000
Operating lease right-of-use assets		172,900,000	172,900,000	0
Finance lease liability, current		6,900,000	6,900,000
Finance lease liability, non-current		23,700,000	23,700,000
Operating lease liability, current		51,600,000	51,600,000	0
Operating lease liability, non-current		$ 123,000,000.0	$ 123,000,000.0	$ 0
Weighted-average remaining lease term - finance leases		5 years 2 months 12 days	5 years 2 months 12 days
Weighted-average remaining lease term - operating leases		4 years 2 months 12 days	4 years 2 months 12 days
Weighted-average discount rate - finance leases		2.10%	2.10%
Weighted-average discount rate – operating leases		3.81%	3.81%
Area of Leased Office Building | ft²	192,000
Purchase Price of Property at End of Lease Term	$ 41,200,000
Percentage of Lease Balance as Final Payment End of Lease Term	87.00%
debt instrument, Covenant for debt not paid	$ 75,000,000
Operating cash flows from operating leases		$ 15,000,000.0	$ 42,400,000
Financing cash flows from finance leases		2,000,000.0	5,800,000
Right-of-use assets obtained in exchange for new finance lease liabilities		2,500,000	8,500,000
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 10,300,000	$ 31,900,000