Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of Residual Interests Securitized Receivables and Derivatives Carried at Fair Value (Detail)

v2.4.0.8
Fair Value Measurements - Schedule of Residual Interests Securitized Receivables and Derivatives Carried at Fair Value (Detail) (Fair Value, Measurements, Recurring [Member], Level 3 [Member], USD $)
In Millions, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
Fair Value [Member] | Credit Facility [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities $ 166.2 $ 77.1
Fair Value [Member] | Nonrecourse Debt [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 153.1 167.1
Fair Value [Member] | Asset-Backed Nonrecourse Notes [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 97.6 99.8
Fair Value [Member] | Financing Receivable [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 475.2 346.4
Fair Value [Member] | Investments Available-for-sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 67.6 3.2
Fair Value [Member] | Residual Assets [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 5.1 4.9
Fair Value [Member] | Investments [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets   92.0
Fair Value [Member] | Financing Receivables Held For Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets   24.8
Carrying Value [Member] | Credit Facility [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 166.2 77.1
Carrying Value [Member] | Nonrecourse Debt [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 145.0 159.8
Carrying Value [Member] | Asset-Backed Nonrecourse Notes [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 97.4 100.0
Carrying Value [Member] | Financing Receivable [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 456.1 347.9
Carrying Value [Member] | Investments Available-for-sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 67.6 3.2
Carrying Value [Member] | Residual Assets [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 5.1 4.9
Carrying Value [Member] | Investments [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets   92.0
Carrying Value [Member] | Financing Receivables Held For Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets   $ 24.8