v3.26.3
Fair Value Measurements - Valuation of Financial Instruments that are Marked-to-Market on Recurring Basis (Detail) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets $ 0 $ 42
Derivative liabilities (101) (79)
Interest Rate Swaps [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 39
Derivative liabilities (6) 0
Cross-Currency Interest Rate Swaps [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 3
Derivative liabilities (95) (79)
Fair Value Measurements Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 247 42
Derivative liabilities (101) (79)
Fair Value Measurements Recurring [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value Measurements Recurring [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 39
Derivative liabilities (6) 0
Fair Value Measurements Recurring [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 247 3
Derivative liabilities (95) (79)
Fair Value Measurements Recurring [Member] | Interest Rate Swaps [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 39
Derivative liabilities (6) 0
Fair Value Measurements Recurring [Member] | Interest Rate Swaps [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value Measurements Recurring [Member] | Interest Rate Swaps [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 39
Derivative liabilities (6) 0
Fair Value Measurements Recurring [Member] | Interest Rate Swaps [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value Measurements Recurring [Member] | Cross-Currency Interest Rate Swaps [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 3
Derivative liabilities (95) (79)
Fair Value Measurements Recurring [Member] | Cross-Currency Interest Rate Swaps [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value Measurements Recurring [Member] | Cross-Currency Interest Rate Swaps [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value Measurements Recurring [Member] | Cross-Currency Interest Rate Swaps [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 3
Derivative liabilities (95) (79)
Fair Value Measurements Recurring [Member] | Private Education Loans At Fair Value [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 235 0
Fair Value Measurements Recurring [Member] | Private Education Loans At Fair Value [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Fair Value Measurements Recurring [Member] | Private Education Loans At Fair Value [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Fair Value Measurements Recurring [Member] | Private Education Loans At Fair Value [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 235 0
Fair Value Measurements Recurring [Member] | Private Education Loans Commitments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 12 0
Fair Value Measurements Recurring [Member] | Private Education Loans Commitments [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Fair Value Measurements Recurring [Member] | Private Education Loans Commitments [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 $ 0
Fair Value Measurements Recurring [Member] | Private Education Loans Commitments [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets $ 12