Commitments, Contingent Liabilities and Litigation and Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended
	Feb. 29, 2012 state	Jan. 31, 2012 state	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments Guarantees Contingent Liabilities And Litigation [Line Items]
Commitments to fund commercial loans			$ 9	$ 5
Commitments to fund investments			121	$ 53
Number of States Needed for Agreement to Become Effective | state	20	20
Maximum
Commitments Guarantees Contingent Liabilities And Litigation [Line Items]
Estimate of possible losses in excess of accruals			$ 150