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Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2019 USD ($) yr | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Mortgage Banking [Abstract] |  |  |
Mortgage servicing rights | $ 376.4 | $ 193.8 |
Mortgage-backed Securities Held-to-maturity, Fair Value Disclosure | $ 423.7 | 246.8 |
Real Estate Investments, Net [Abstract] |  |  |
Minimum ownership percentage in real estate ventures (in hundredths) | 1.00% |  |
Maximum ownership percentage in real estate ventures (in hundredths) | 10.00% |  |
Foreign Currency Translation [Abstract] |  |  |
Net foreign currency gains (losses) | $ (2.4) | (4.1) | $ (4.8)
Bank Servicing Fees. | 63.0 | 49.6 | $ 43.3
Operating Lease, Right-of-Use Asset | 804.4 | 0.0 |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | $ 404.2 | $ 356.9 |
Share-based Payment Arrangement [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award Sum Of Age Plus Years Of Service Minimum | yr | 65 |  |

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- Definition The maximum percentage ownership of common stock or equity participation in the investee under the equity method of accounting. + References No definition available. + Details
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- Definition Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method. + References No definition available. + Details
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- Definition This element represent the minimum sum of age plus years of service with the company to be eligible for receipt of retirement benefits upon departure from the company. + References No definition available. + Details
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- Definition Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30700-110894 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30690-110894 + Details
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- Definition Amount of investment in equity method investee and investment in and advance to affiliate. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Fair value of securitized, pay-through debt securities collateralized by real estate mortgage loans classified as held-to-maturity. + References No definition available. + Details
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- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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