Pension Plan and Postretirement Benefits Other Than Pension - Pension plan asset allocation (Details)	Dec. 31, 2016	Dec. 31, 2015
Pension Plan and Postretirement Benefits Other Than Pension
Cash (as a percent)	18.00%	24.00%
Equity securities:
Domestic (as a percent)	49.00%	53.00%
International (as a percent)	17.00%	15.00%
Fixed income securities (as a percent)	10.00%	5.00%
Gold bullion (as a percent)	6.00%	3.00%
Percentage of plan assets allocation	100.00%	100.00%

No definition available.

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

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- Definition

The percentage of the fair value of cash securities to the fair value of total plan assets held as of the measurement date.

+ References

No definition available.

+ Details

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- Definition

The percentage of the fair value of domestic equity securities to the fair value of total plan assets held as of the measurement date.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

The percentage of the fair value of fixed income securities to the fair value of total plan assets held as of the measurement date.

+ References

No definition available.

+ Details

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- Definition

The percentage of the fair value of foreign equity securities to the fair value of total plan assets held as of the measurement date.

+ References

No definition available.

+ Details

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- Definition

The percentage of the fair value of gold bullion to the fair value of total plan assets held as of the measurement date.

+ References

No definition available.

+ Details

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