Debt (First Lien Notes) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term Debt	$ 10,777	$ 10,750
First Lien Notes 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt	1,080	1,080
First Lien Notes 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt	360	360
First Lien Notes 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt	984	983
First Lien Notes 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt	1,800	1,800
First Lien Notes 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt	1,080	1,080
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 5,304	$ 5,303