Income Taxes Summary of Operating Loss Carryforwards (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 1,096
AMT net operating loss	51
Limited [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	64
AMT net operating loss	51
Annual Limitation [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	15
AMT net operating loss	$ 15