Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Parenthetical) (Detail)
$ in Millions
 6 Months Ended
Jun. 30, 2016
USD ($)
Transactions
Financing Receivable, Recorded Investment [Line Items]  
Number of transactions | Transactions 84
Financial receivable outstanding, Average Remaining Balance $ 12
Total aggregate remaining balance 30
Investment Grade By Independent Rating Agency [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable 10
U.S. Federal Government [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable 268
State, Local, Institutions [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable 179
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 9
Commercial Investment Grade [Member] | Residential Solar Loan [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Total financing receivable $ 177