Pledged Assets Repurchase Agreements with Counterparties Greater than or Equal to 5% of Equity at Risk (Details) $ in Millions	Jun. 30, 2017 USD ($) days	Dec. 31, 2016 USD ($) days month
Repurchase Agreements with Counterparties Greater than or equal to 5% of Equity at Risk [Line Items]
Securities Sold under Agreements to Repurchase	$ 39,058	$ 37,858
Weighted Average Days to Maturity | days	154	186
J.P. Morgan Securities, LLC [Member]
Repurchase Agreements with Counterparties Greater than or equal to 5% of Equity at Risk [Line Items]
Securities Sold under Agreements to Repurchase		$ 4,875
Risk Of Repurchase Agreement To Stockholders Equity		5.50%
Counterparty Exposure, Net		$ 405
Repurchase Agreements Weighted Average Months To Maturity | month		34.1