Fair Value Of Financial Instruments (Changes In Fair Value Included In Company's Consolidated Statements Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Loan Repurchase Commitments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 90
Fixed-Maturity Securities Held At Fair Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	18	(1)
Residential Mortgage Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(74)	18
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	13	(39)
Long-Term Debt [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 81	$ (7)