Income Taxes (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Non-Variable Interest Entities [Line Items]
Federal statutory tax rate	35.00%	35.00%	35.00%
Net deferred tax asset	$ 1,200,000,000
Maximum taxable income projections, years	20 years
Total deferred tax assets	1,200,000,000
Increase in deferred tax asset	61,000,000
Decrease accumulated other comprehensive income taxes	5,000,000
Decrease in current tax receivable	6,000,000
Increase in net income (loss)	60,000,000	1,000,000	22,000,000
Cumulative amounts of untaxed earnings	139,000,000	15,000,000	3,000,000
Estimated tax liability on disposition of foreign subsidiary	17,000,000
Capital loss carryforward	162,000,000
NOL carryforward	1,400,000,000
Minimum tax credit carryforward	19,000,000
Non Variable Interest Entities [Member]
Non-Variable Interest Entities [Line Items]
Net deferred tax asset	1,199,000,000	1,745,000,000
Valuation allowance	146,000,000	236,000,000
Valuation allowance decrease	$ 90,000,000