Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Remaining estimated maximum potential amount of monetary payments subject to guaranty	$ 20.9
Outstanding letters of credit	1.3	$ 2.4
Surety Bond
Lessee, Lease, Description [Line Items]
Outstanding letters of credit	229.3	230.0
Letter of Credit
Lessee, Lease, Description [Line Items]
Restricted cash and certificates of deposit pledged as collateral	1.0	1.4
The San Francisco Venture
Lessee, Lease, Description [Line Items]
Guaranty of infrastructure obligations, maximum obligation	$ 198.3	$ 197.8

Monetary Payments Subject to Guaranty, Remaining Estimated Amount, Maximum

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

The carrying amount, as of the date of the latest financial statement presented, of other assets which are owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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