Derivative Instruments Level 4 Derivative Collateral Arrangements (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	$ 27	$ 81
Derivative Asset, Collateral, Obligation to Return Cash, Offset	366	333
Security Owned and Pledged as Collateral, Fair Value	26	134
Securities Received as Collateral	$ 26	$ 0
Information about Sources and Uses of Collateral that is Received Through Resale Agreements and Securities Borrowing Agreements	As of March 31,2017, and December 31, 2016, the Company had no repledged securities and did not sell any securities. In addition, as of March 31,2017, and December 31, 2016, non-cash collateral accepted was held in separate custodial accounts and was not included in the Company’s Condensed Consolidated Balance Sheets.	As of March 31, 2017, and December 31, 2016, the Company had no repledged securities and did not sell any securities. In addition, as of March 31, 2017, and December 31, 2016, non-cash collateral accepted was held in separate custodial accounts and was not included in the Company’s Condensed Consolidated Balance Sheets.
Collateral Pledged [Member]
Derivative [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 751	$ 830
Liability [Member]
Derivative [Line Items]
Securities Received as Collateral	$ 74	$ 107