Reinsurance - Effective Exit of GMDB and GMIB Business (Details) - Berkshire Hathway Life Insurance Company Of Nebraska [Member] - Variable Annuity [Member] $ in Billions	Sep. 30, 2019 USD ($)
Ceded Credit Risk [Line Items]
Percent of future claim payments reinsured	100.00%
Ceded Reinsurance Agreement, Coverage Limit, Amount Remaining	$ 3.3