| **Fair Value Measurements (Details 2) - USD ($) $ in Millions**                     | Dec. 31, 2018 | Dec. 31, 2017 |
|-------------------------------------------------------------------------------------|---------------|---------------|
| Level 3                                                                             |          |          |
| **Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis** |          |          |
| Fair value of impaired loans                                                        | $ 469         | $ 341         |

| X                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The fair value of impaired loans.
+ References
No definition available.
+ Details**Name:**cfsc_FairValueOfImpairedLoans**Namespace Prefix:**cfsc_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |