Leasing Activities (Cross-Border Energy Lease Investments) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Scheduled lease payments to PHI, net of non-recourse debt	$ 1,852		$ 2,120
Less: Unearned and deferred income	(615)		(771)
Investment in finance leases held in trust	1,237	[1]	1,349	[1]
Less: Deferred income tax liabilities	(756)		(793)
Net investment in finance leases held in trust	$ 481		$ 556

[1] Excludes the credit ratings of collateral posted by the lessees in these transactions.