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Guarantees and Long Term Standby Purchase Commitments - Long-Term Standby Purchase Commitments (Details) - Long-Term Standby Purchase Commitments [Member] - USD ($) $ in Millions | 6 Months Ended |
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Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017
Guarantor Obligations [Line Items] |  |  |
Weighted average remaining maturity, Loans underlying guarantees not held by transferor | 15 years 5 months 20 days | 15 years 3 months 10 days |
Guarantor Obligations, Maximum Exposure, Undiscounted | $ 3,000.0 |  | $ 3,100.0
Guarantee obligations issued after January 1, 2003 [Member] |  |  |
Guarantor Obligations [Line Items] |  |  |
Guarantor Obligations, Current Carrying Value | $ 35.2 |  | $ 34.8

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- Definition Weighted average remaining maturity, Loans underlying guarantees not held by transferor + References No definition available. + Details
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- Definition The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248 + Details
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- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248 + Details
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- Details
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- Details
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