| **New Accounting Pronouncements (Details) $ in Millions**           | Jan. 01, 2019 USD ($) |
|---------------------------------------------------------------------|-----------------------|
| Accounting Standards Update 2018-02                                 |                  |
| **New Accounting Pronouncements or Change in Accounting Principle** |                  |
| Amount, Reclassification of certain tax effects from AOCI           | $ 97                  |

| X                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from U.S. tax reform legislation.
+ References
No definition available.
+ Details**Name:**cfsc_ExpectedAmountReclassificationofcertaintaxeffectsfromAOCI**Namespace Prefix:**cfsc_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**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_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=cfsc_AccountingStandardsUpdate201802Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |