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	Jun. 30, 2018	Dec. 31, 2017
Separate Accounts Disclosure [Abstract]
Variable annuity	$ 73,155	$ 75,174
VUL insurance	7,204	7,352
Other insurance	32	34
Threadneedle investment liabilities	4,867	4,808
Total	$ 85,258	$ 87,368