Income Taxes Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Current Federal Tax Expense (Benefit)	$ 999	$ 1,211	$ 1,190
Current State Tax Expense (Benefit)	127	168	169
Total Current Income Tax Expense (Benefit)	1,126	1,379	1,359
Deferred Federal Income Tax Expense (Benefit)	901	1,097	852
Deferred State Income Tax Expense (Benefit)	97	51	89
Total Deferred Income Tax Expense (Benefit)	998	1,148	941
Total Income Tax Expense (Benefit)	$ 2,124	$ 2,527	$ 2,300