Business, Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($) Segment	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of segments | Segment	6
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premiums and Other Receivables, Net	$ 26,487		$ 26,081
Payables For Collateral Under Securities Loaned And Other Transactions	33,725		33,264
Derivative assets	12,178		15,761
Derivative liabilities	8,217		10,804
Accrued Investment Income Receivable	3,970		3,988
Other Liabilities	$ 27,060		$ 28,818
CME update impact [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premiums and Other Receivables, Net		$ 991
Payables For Collateral Under Securities Loaned And Other Transactions		816
Derivative assets		1,800
Derivative liabilities		2,000
Accrued Investment Income Receivable		101
Other Liabilities		$ 14