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Investment Securities (Mortgage-backed Asset Securities) (Details) - USD ($) $ in Millions | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
--- | --- | --- | ---
Investment securities |  |  |
Fair value investments | $ 4,050.9 | $ 3,343.6 | $ 3,889.0
GNMA |  |  |
Investment securities |  |  |
Fair value investments | 265.5 | 308.7 |
FNMA |  |  |
Investment securities |  |  |
Fair value investments | 42.2 | 33.4 |
FHLMC |  |  |
Investment securities |  |  |
Fair value investments | 22.8 | 28.9 |
Total Agency |  |  |
Investment securities |  |  |
Fair value investments | 330.5 | 371.0 |
Residential |  |  |
Investment securities |  |  |
Fair value investments | 133.2 | 71.0 |
Commercial |  |  |
Investment securities |  |  |
Fair value investments | 140.4 | 109.3 |
Total Non-agency |  |  |
Investment securities |  |  |
Fair value investments | 273.6 | 180.3 |
Total mortgage-backed securities |  |  |
Investment securities |  |  |
Fair value investments | 604.1 | 551.3 |
Credit card receivables |  |  |
Investment securities |  |  |
Fair value investments | 217.7 | 218.1 |
Vehicle receivables |  |  |
Investment securities |  |  |
Fair value investments | 269.7 | 152.8 |
Other |  |  |
Investment securities |  |  |
Fair value investments | 75.5 | 45.7 |
Total asset-backed securities |  |  |
Investment securities |  |  |
Fair value investments | 562.9 | 416.6 |
Total mortgage and asset- backed securities |  |  |
Investment securities |  |  |
Fair value investments | 1,167.0 | 967.9 |
Non-Agency Residential Mortgage |  |  |
Investment securities |  |  |
Fair value investments | 39.6 |  |
Level 2 Inputs |  |  |
Investment securities |  |  |
Fair value investments | 2,531.4 | 2,372.9 | $ 2,575.4
Level 2 Inputs | GNMA |  |  |
Investment securities |  |  |
Fair value investments | 265.5 | 308.7 |
Level 2 Inputs | FNMA |  |  |
Investment securities |  |  |
Fair value investments | 42.2 | 33.4 |
Level 2 Inputs | FHLMC |  |  |
Investment securities |  |  |
Fair value investments | 22.8 | 28.9 |
Level 2 Inputs | Total Agency |  |  |
Investment securities |  |  |
Fair value investments | 330.5 | 371.0 |
Level 2 Inputs | Residential |  |  |
Investment securities |  |  |
Fair value investments | 133.2 | 71.0 |
Level 2 Inputs | Commercial |  |  |
Investment securities |  |  |
Fair value investments | 140.4 | 109.3 |
Level 2 Inputs | Total Non-agency |  |  |
Investment securities |  |  |
Fair value investments | 273.6 | 180.3 |
Level 2 Inputs | Total mortgage-backed securities |  |  |
Investment securities |  |  |
Fair value investments | 604.1 | 551.3 |
Level 2 Inputs | Credit card receivables |  |  |
Investment securities |  |  |
Fair value investments | 217.7 | 218.1 |
Level 2 Inputs | Vehicle receivables |  |  |
Investment securities |  |  |
Fair value investments | 269.7 | 152.8 |
Level 2 Inputs | Other |  |  |
Investment securities |  |  |
Fair value investments | 75.5 | 45.7 |
Level 2 Inputs | Total asset-backed securities |  |  |
Investment securities |  |  |
Fair value investments | 562.9 | 416.6 |
Level 2 Inputs | Total mortgage and asset- backed securities |  |  |
Investment securities |  |  |
Fair value investments | 1,167.0 | 967.9 |
Level 3 Inputs | GNMA |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | FNMA |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | FHLMC |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Total Agency |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Residential |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Commercial |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Total Non-agency |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Total mortgage-backed securities |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Credit card receivables |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Vehicle receivables |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Other |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Total asset-backed securities |  |  |
Investment securities |  |  |
Fair value investments | 0.0 | 0.0 |
Level 3 Inputs | Total mortgage and asset- backed securities |  |  |
Investment securities |  |  |
Fair value investments | $ 0.0 | $ 0.0 |

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- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph a, f, g -Article 7 + Details
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