Business, Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2017 USD ($) Segment shares	Aug. 04, 2017 shares	Jun. 30, 2017	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 0	$ 0	$ 0
Derivative assets	2,244	2,244	2,244				$ 3,603
Derivative liabilities	3,129	3,129	3,129				3,883
Accrued investment income relating to variable interest entities	575	575	575				668
Premiums and Other Receivables, Net	12,918	12,918	12,918				13,853
Payables For Collateral Under Securities Loaned And Other Transactions	$ 4,158	$ 4,158	$ 4,158				$ 7,371
Number of segments		3	3
Restructuring Cost and Reserve [Line Items]
Common Stock, Shares, Issued | shares	3,000	3,000	3,000				3,000
AOCI Attributable to Parent [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 330	$ 330	$ 330
Spinoff [Member]
Restructuring Cost and Reserve [Line Items]
Common Stock, Shares, Issued | shares				119,773,106
Spinoff [Member] | Parent shareholders' percentage [Member]
Restructuring Cost and Reserve [Line Items]
Common Stock, Shares, Issued | shares				96,776,670
Common Stock Distribution by Parent					80.80%
Spinoff [Member] | Minimum
Restructuring Cost and Reserve [Line Items]
Common Stock Distribution by Parent					80.10%
Distribution Rights [Member] | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	40 years
Distribution Rights [Member] | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 19	19	19
CME update impact [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Derivative assets						$ 206
Derivative liabilities						927
Accrued investment income relating to variable interest entities						30
Premiums and Other Receivables, Net						765
Payables For Collateral Under Securities Loaned And Other Transactions						$ 74
Adjustments for New Accounting Principle, Early Adoption [Member] | AOCI Attributable to Parent [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 9	$ 9	$ 9