Commitments and Contingencies - Components of Lease Costs and Other Information Related to Leases (Details) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 11.9
Variable lease cost	3.1
Total lease cost	15.0
Operating cash outflows from operating leases	11.6
ROU assets obtained in exchange for new operating lease liabilities	$ 0.6
Weighted average remaining lease term (years)	6 years
Weighted average discount rate	4.40%

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Amount of lease cost recognized by lessee for lease contract.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

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Weighted average discount rate for operating lease calculated at point in time.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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