Other Material Contingencies - Total Guarantees (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 1,331	$ 859
Energy Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	841
Solar Energy Projects [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	459
Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	31
0 - 3 years [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,229
0 - 3 years [Member] | Energy Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	753
0 - 3 years [Member] | Solar Energy Projects [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	445
0 - 3 years [Member] | Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	31
4 - 10 years [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	44
4 - 10 years [Member] | Energy Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	30
4 - 10 years [Member] | Solar Energy Projects [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	14
4 - 10 years [Member] | Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term
Greater than 10 years [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	58
Greater than 10 years [Member] | Energy Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	58
Greater than 10 years [Member] | Solar Energy Projects [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term
Greater than 10 years [Member] | Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term