Quarterly report pursuant to Section 13 or 15(d)

Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Parenthetical) (Detail)

v3.4.0.3
Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Parenthetical) (Detail)
$ in Millions
 3 Months Ended
Mar. 31, 2016
USD ($)
Transactions
Financing Receivable, Recorded Investment [Line Items]  
Number of transactions | Transactions 79
Financial receivable outstanding, Average Remaining Balance $ 12
Total aggregate remaining balance 28
Investment Grade By Independent Rating Agency [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable 11
U.S. Federal Government [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable 260
State, Local, Institutions [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable 177
Maximum [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Financial receivable outstanding, Average Remaining Balance 1
Commercial Investment Grade [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Financial receivable outstanding, Average Remaining Balance 10
Commercial Investment Grade [Member] | Residential Solar Loan [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable $ 174