Amount projected for the current year to complete work specified in work plans for source control work.

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Amount spent to complete work specified in work plans for source control work.

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- Definition

Estimated cost of EPA selected remedy.

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Estimated time to complete selected EPA remedy.

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- Definition

Number of potentially responsible parties for Portland Harbor Superfund site.

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No definition available.

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 30

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

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-Name Accounting Standards Codification

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-Paragraph 1

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The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

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

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No definition available.

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- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

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No definition available.

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- Definition

Amount of loss contingency liability expected to be resolved within one year or the normal operating cycle, if longer.

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-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

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Amount of payments made reducing loss contingency liability.

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Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended			3 Months Ended	1 Months Ended
	Jan. 31, 2015	Jun. 30, 2007	Jul. 31, 2014	Mar. 31, 2015	Apr. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Other Commitments [Line Items]
Company made payment to Lower Willamette Group as interim settlement		$ 0.2us-gaap_LitigationSettlementAmount
Amount spent for Source Control work						0.1
Amount projected for the current year to complete work specified in work plans				0.1
Number of potentially responsible parties				100
Insurance settlement received from its insurance carriers	2.6us-gaap_InsuranceRecoveries
Total stand-by letters of credit				2.1
Portland Harbor Natural Resources Trustee Council [Member]
Other Commitments [Line Items]
Injury assessment process, payment	0.2		0.2
Injury assessment process, outstanding							0.4
Voluntary Cleanup Program [Member] \| Estimated [Member]
Other Commitments [Line Items]
Accrual based environmental cleanup costs				0.4
Minimum [Member]
Other Commitments [Line Items]
Estimated cost				169
Estimated years to implement				2 years
Minimum [Member] \| Voluntary Cleanup Program [Member] \| Subsequent Event [Member]
Other Commitments [Line Items]
Environmental cleanup costs					0.3
Maximum [Member]
Other Commitments [Line Items]
Estimated cost				1,760
Estimated years to implement				28 years
Maximum [Member] \| Voluntary Cleanup Program [Member] \| Subsequent Event [Member]
Other Commitments [Line Items]
Environmental cleanup costs					$ 2.5