Discontinued Operations and Dispositions (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2011	Jul. 31, 2011 Power [Member] MW	Mar. 31, 2011 Power [Member] MW	Dec. 31, 2011 Leveraged Leases [Member]
Gain (Loss) on Sale of Loans and Leases					$ 34
Proceeds from Sale of Loans and Leases Held-for-investment		215			175
Proceeds from Sale of Other Investments	41
Sale of gas-fired generation facilities			1,000	1,000
Total purchase price of plant sale			335	352
Gain on disposal of discontinued operations, after tax			25	54
Gain (Loss) on Sale of Other Investments	$ 6