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Affiliate Equity - Additional Information (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Affiliate Equity |  |  |
Distributions paid to affiliate partners | $ 352.2 | $ 354.1 | $ 431.4
Payments to acquire interest in affiliates | 174.7 | 115.8 | 130.8
Issuance of interest in affiliates | 9.0 | 11.8 | $ 6.1
Other Assets |  |  |
Affiliate Equity |  |  |
Due from affiliates | 12.4 | 22.9 |
Other Liabilities |  |  |
Affiliate Equity |  |  |
Due to affiliates | $ 49.2 | $ 12.1 |
Minimum |  |  |
Affiliate Equity |  |  |
Affiliate equity, conditional right to put interest, period | 5 years |  |
Maximum |  |  |
Affiliate Equity |  |  |
Affiliate equity, conditional right to put interest, period | 15 years |  |

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- Definition For an unclassified balance sheet, amount of receivables due from an entity that is affiliated with the reporting entity by means of direct or indirect ownership. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.3) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39599-107864 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 + Details
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