Income Taxes Income Taxes (Schedule of Significant Components of Income Tax Expense) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)									$ (2)	$ (12)	$ (17)
Current Foreign Tax Expense (Benefit)									4	5	6
Current State and Local Tax Expense (Benefit)									65	35	53
Total current tax expense (benefit)									67	28	42
Deferred Federal Income Tax Expense (Benefit)									178	328	566
Deferred Foreign Income Tax Expense (Benefit)									2	0	0
Deferred State and Local Income Tax Expense (Benefit)									(1)	3	(27)
Deferred Income Tax Expense (Benefit)									179	331	539
Income tax expense from continuing operations	$ 106	$ 119	$ (90)	$ 111	$ 79	$ 91	$ 113	$ 76	$ 246	$ 359	$ 581