Bank Loans and Related Allowance for Loan Losses (Narrative) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) loan	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commitments to extend credit related to unused HELOCs, PALs, and other lines of credit	$ 8,800		$ 8,400
Commitments to purchase First Mortgage loans	$ 453		$ 466
Number of loans accruing interest contractually 90 days or more past due | loan	0		0
Nonperforming assets, including nonaccrual loans and other real estate owned	$ 33		$ 31
Impaired assets, which include nonaccrual loans, other real estate owned and troubled debt restructurings	46		45
First Mortgage and Home Equity Loans and Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized premiums and discounts and direct origination costs	$ 78		$ 78
Loan term	30 years
Initial draw period	10 years
Converting to amortizing loans period	20 years
First Mortgage and Home Equity Loans and Lines of Credit [Member] | California [Member] | Loans, Geographic Area [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk percentage	48.00%		48.00%
First Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased first mortgages and HELOCs	$ 665	$ 557
Bank loans	$ 8,500
Percent of loans with interest-only payments	35.00%
Interest rate	56.00%
First Mortgage [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate interest rate period	3 years
Interest-only reset period	3 years
First Mortgage [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate interest rate period	10 years
Home equity loans and lines of credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased first mortgages and HELOCs	$ 118	$ 110
Percent of minimum interest paid	36.00%
Home equity loans and lines of credit [Member] | Second Lien [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured financings	$ 1,800