Fair Value Of Financial Instruments (Changes In Fair Value Included In Company's Consolidated Statements Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loan Repurchase Commitments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Gains (Losses) on Financial Instruments at Fair Value and Foreign Exchange	$ 9	$ 242	$ 336
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	(55)	(484)	374
Residential Mortgage Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Gains (Losses) on Financial Instruments at Fair Value and Foreign Exchange	(107)	(143)	295
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Gains (Losses) on Financial Instruments at Fair Value and Foreign Exchange	(56)	(19)	(26)
Other Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Gains (Losses) on Financial Instruments at Fair Value and Foreign Exchange			26
Long-Term Debt [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Gains (Losses) on Financial Instruments at Fair Value and Foreign Exchange	$ 107	$ 594	$ (661)