Contingencies - Additional Information (Details)	3 Months Ended
Mar. 31, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Insurance recoveries	$ 91,000,000
Estimated insurance recoveries	0
Accrued litigation expense	1,300,000
Outstanding performance bonds	$ 96,300,000

Surety bond.

No definition available.

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- References

No definition available.

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- Definition

Carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts.

+ References

+ Details

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- Definition

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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- Definition

Carrying amount of reserve for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs, which is expected to be paid within one year of the date of the statement of financial position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 55
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6396582&loc=d3e15243-108350

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

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