Income Taxes 2017 Tax Reform (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Federal income tax		35.00%	35.00%	35.00%
New Federal Income Tax Rate	21.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ 1,240	$ 0	$ 0
Impact of 2017 Tax Reform [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		1,240
Impact of 2017 Tax Reform [Member] \| Investee [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		219
Impact of 2017 Tax Reform [Member] \| after tax [Member] \| Investee [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ 144