Discontinued Operations - Cross-Border Energy Lease Investments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Discontinued Operations [Line Items]
Assets held for disposition		$ 1,237
Cross-Border Energy Lease Investments [Member]
Schedule of Discontinued Operations [Line Items]
Scheduled lease payments to PHI, net of non-recourse debt		1,852
Less: Unearned and deferred income		(615)
Assets held for disposition		1,237
Liabilities associated with assets held for disposition		$ 1