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Acquisitions and Dispositions of Businesses - Dispositions (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 USD ($) disposal | Jun. 30, 2016 USD ($) disposal | Jun. 30, 2017 USD ($) disposal | Jun. 30, 2016 USD ($) disposal
Dispositions |  |  |  |
Gain (loss) on disposal of business | $ | $ 0 | $ 6,000,000 | $ (2,000,000) | $ 41,000,000
Disposal Group, Not Discontinued Operations [Member] |  |  |  |
Dispositions |  |  |  |
Number of dispositions | disposal | 1 | 2 | 4 | 4

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- Definition Amount before tax of gain (loss) recognized on the sale or disposal of a disposal group. Excludes discontinued operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2443-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2941-110230 + Details
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