Income Taxes Income Taxes - Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Examination [Line Items]
Deferred income tax asset	$ 223	$ 90
Deferred income tax liabilities	3,407	2,807
Deferred Tax Assets, Operating Loss Carryforwards, windfalls	24
Operating Loss Carryforwards	592
Operating Loss Carrying Forwards Alternative Minimum Tax Amt	51
AMT NOL Carryback		599
Deferred Tax Assets, Gross	1,621	1,726
Deferred Tax Assets, Valuation Allowance	148	160
Treasury Regulations Purchase of Stock	5.00%
Unrecognized Tax Benefits	644	599	369	34
Accrued liability for interest related to uncertain tax positions	13	6
Percentage Of Beneficial Interest Owned	50.00%
Federal Jurisdiction [Member]
Income Tax Examination [Line Items]
Operating Loss Carryforwards	592
State and Local Jurisdiction [Member]
Income Tax Examination [Line Items]
Deferred income tax asset	328
Operating Loss Carryforwards	7,000
Unrecognized Tax Benefits	4	1
Valuation Allowance Change [Member]
Income Tax Examination [Line Items]
Operating Loss Carryforwards, Valuation Allowance	$ 12