Borrowings and Contractual Commitments Borrowings and Contractual Commitments - Additional Information (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term Debt	[1]	$ 8,462	$ 13,022
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Long-term Debt		408	4,000
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	[2]	3,690	8,207
Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 4,772	$ 4,815

[1] Includes debt of consolidated VIEs of $259 million and $302 million at December 31, 2015 and December 31, 2014, respectively.

[2] 81% and 90% of total subsidiary debt was issued by the Bank as of December 31, 2015 and 2014, respectively.