Policyholder Account Balances, Future Policy Benefits and Claims and Separate Account Liabilities Policyholder Account Balances, Future Policy Benefits and Claims and Separate Account Liabilities (Separate Account Liabilities) (Details 2) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Separate Accounts Disclosure [Abstract]
Variable annuity	$ 74,317	$ 75,174
VUL insurance	7,338	7,352
Other insurance	33	34
Threadneedle investment liabilities	4,904	4,808
Total	$ 86,592	$ 87,368