Related Party Transactions (Related Party Transactions) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Liabilities	$ 191,163		$ 195,177
Broker Dealer Activities [Member]
Related Party Transaction [Line Items]
Due from Related Parties	19		19
Revenue from Related Parties	56	$ 54
Related Party Transaction, Expenses from Transactions with Related Party	164	126
All Services and Transactions Except Broker Dealer Activities [Member]
Related Party Transaction [Line Items]
Due from Related Parties	2,952		2,839
Due to Related Parties	2,583		$ 2,675
Revenue from Related Parties	49	(206)
Related Party Transaction, Expenses from Transactions with Related Party	$ 181	$ 200

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

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-Name Accounting Standards Codification
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