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Variable Interests and Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Variable Interest Entities And Equity Investments [Abstract]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 0.0
Payments made to Pure Air	$ 16.0	$ 16.5

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- References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	duration

X

- Definition

Variable Interest Entities and Equity Investments.

+ References

No definition available.

+ Details

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- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

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