Business Dispositions and Discontinued Operations - Major Classes of Assets and Liabilities Transferred by the Company to the Buyer in Connection with Sale (Details) - USD ($) $ in Millions	Sep. 30, 2018	May 31, 2018	Dec. 31, 2017
Assets
Total assets held for sale	$ 0		$ 164,936
Liabilities
Total liabilities held for sale	$ 0		162,442
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Assets
Cash and investments		$ 27,058	30,135
Reinsurance recoverables		20,718	20,785
Loss accrual [1]		(3,044)	(3,257)
Other assets		2,907	1,439
Separate account assets		110,773	115,834
Total assets held for sale		158,412	164,936
Liabilities
Reserve for future policy benefits and unpaid loss and loss adjustment expenses		14,308	14,482
Other policyholder funds and benefits payable		28,680	29,228
Long-term debt		142	142
Other liabilities		2,222	2,756
Separate account liabilities		110,773	115,834
Total liabilities held for sale		$ 156,125	$ 162,442