Loan Receivables (Schedule of Allowance for Loan Losses and Recorded Investment in its Loan Portfolio by Impairment Methodology) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Allowance for loan losses, collectively evaluated for impairment in accordance with ASC 450-20 $ 1,554 $ 1,525    
Allowance for loan losses, evaluated for impairment in accordance with ASC 310-10-35 194 [1],[2] 193 [1],[2]    
Allowance for loan losses, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 28 28    
Total allowance for loan losses 1,776 1,746 1,591 1,648
Recorded investment in loans, collectively evaluated for impairment in accordance with ASC 450-20 62,765 64,997    
Recorded investment in loans, evaluated for impairment in accordance with ASC 310-10-35 1,184 [1],[2] 1,190 [1],[2]    
Recorded investment in loans, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 3,519 3,660    
Total recorded investment 67,468 69,847    
Credit Card Receivable [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Allowance for loan losses, collectively evaluated for impairment in accordance with ASC 450-20 1,334 1,314    
Allowance for loan losses, evaluated for impairment in accordance with ASC 310-10-35 158 [1],[2] 160 [1],[2]    
Allowance for loan losses, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 0 0    
Total allowance for loan losses 1,492 1,474 1,342 1,406
Recorded investment in loans, collectively evaluated for impairment in accordance with ASC 450-20 52,475 55,091    
Recorded investment in loans, evaluated for impairment in accordance with ASC 310-10-35 1,024 [1],[2] 1,037 [1],[2]    
Recorded investment in loans, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 0 0    
Total recorded investment 53,499 56,128    
Unpaid principal balance of modified loans accounted for as troubled debt restructurings 868 878    
Total Other Loans [Member] | Personal Loans [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Allowance for loan losses, collectively evaluated for impairment in accordance with ASC 450-20 118 114    
Allowance for loan losses, evaluated for impairment in accordance with ASC 310-10-35 5 [1],[2] 6 [1],[2]    
Allowance for loan losses, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 0 0    
Total allowance for loan losses 123 120 109 112
Recorded investment in loans, collectively evaluated for impairment in accordance with ASC 450-20 5,007 4,952    
Recorded investment in loans, evaluated for impairment in accordance with ASC 310-10-35 58 [1],[2] 55 [1],[2]    
Recorded investment in loans, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 0 0    
Total recorded investment 5,065 5,007    
Unpaid principal balance of modified loans accounted for as troubled debt restructurings 58 54    
Total Other Loans [Member] | Private Student Loans (Excluding PCI) [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Allowance for loan losses, collectively evaluated for impairment in accordance with ASC 450-20 101 [3] 96 [3]    
Allowance for loan losses, evaluated for impairment in accordance with ASC 310-10-35 13 [1],[2],[3] 11 [1],[2],[3]    
Recorded investment in loans, collectively evaluated for impairment in accordance with ASC 450-20 5,136 [3] 4,812 [3]    
Recorded investment in loans, evaluated for impairment in accordance with ASC 310-10-35 41 [1],[2],[3] 38 [1],[2],[3]    
Unpaid principal balance of modified loans accounted for as troubled debt restructurings 40 37    
Total Other Loans [Member] | Other Loans [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Allowance for loan losses, collectively evaluated for impairment in accordance with ASC 450-20 1 [4] 1 [4]    
Allowance for loan losses, evaluated for impairment in accordance with ASC 310-10-35 18 [1],[2],[4] 16 [1],[2],[4]    
Allowance for loan losses, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 0 [4] 0 [4]    
Total allowance for loan losses 19 [4] 17 [4] 18 17
Recorded investment in loans, collectively evaluated for impairment in accordance with ASC 450-20 147 [4] 142 [4]    
Recorded investment in loans, evaluated for impairment in accordance with ASC 310-10-35 61 [1],[2],[4] 60 [1],[2],[4]    
Recorded investment in loans, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 0 [4] 0 [4]    
Total recorded investment 208 [4] 202 [4]    
PCI Student Loans [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Allowance for loan losses, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 28 [3] 28 [3]    
Total allowance for loan losses 28 28    
Recorded investment in loans, acquired with deteriorated credit quality, evaluated in accordance with ASC 310-30 3,519 [3] 3,660 [3]    
Student Loans [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Total allowance for loan losses 142 [3] 135 [3] 122 [3] 113 [3]
Total recorded investment $ 8,696 [3] $ 8,510 [3]    
[1] The unpaid principal balance of credit card loans was $868 million and $878 million at March 31, 2015 and December 31, 2014, respectively. The unpaid principal balance of personal loans was $58 million and $54 million at March 31, 2015 and December 31, 2014, respectively. The unpaid principal balance of student loans was $40 million and $37 million at March 31, 2015 and December 31, 2014, respectively. All loans accounted for as troubled debt restructurings have a related allowance for loan losses.
[2] Loan receivables evaluated for impairment in accordance with Accounting Standards Codification ("ASC") 310-10-35 include credit card loans, personal loans and student loans collectively evaluated for impairment in accordance with ASC Subtopic 310-40, Receivables, which consists of modified loans accounted for as troubled debt restructurings. Other loans are individually evaluated for impairment and generally do not represent troubled debt restructurings.
[3] Includes both PCI and non-PCI private student loans.
[4] Excludes mortgage loans held for sale. Certain other loans, including non-performing Diners Club licensee loans, are individually evaluated for impairment.