Employee Benefit Arrangements - Defined Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Annual credit earned by participants, percentage of eligible compensation	4.00%
30-year U.S. Treasury Securities Bond Rate Period	30 years
Deferred compensation commitment	$ 305	$ 284

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer).

No definition available.

Name:	us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant