Investments and Derivative Instruments Level 4 Repurchase Agreements, Dollar Roll Transactions and Other Collateral Transactions (Details) - USD ($)	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned	$ 67,000,000		$ 0
Securities Held as Collateral, at Fair Value	68,000,000
Secured Debt, Repurchase Agreements	0
Securities Reserve Deposit Required and Made	$ 2,500,000,000		$ 2,500,000,000
Other Liabilities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability		$ 445,000,000