Retirement Plans (Details 10) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Plan assets using the fair value hierarchy
Fair value of plan assets	$ 998	$ 989
U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	139	150
Global ex U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	104	115
Emerging Markets Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	36	35
Absolute Return Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	117	116
Equity Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	107	127
Private Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	47	41
Private Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	16	10
Public Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	20	24
Fixed Income [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	399	363
Cash Equivalents [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	13	8
Level 1 [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	452	410
Level 1 [Member] | U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	53	47
Level 1 [Member] | Global ex U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Emerging Markets Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Absolute Return Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Equity Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Private Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Private Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Public Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 1 [Member] | Fixed Income [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	399	363
Level 1 [Member] | Cash Equivalents [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 2 [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	278	293
Level 2 [Member] | U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	20	30
Level 2 [Member] | Global ex U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	104	115
Level 2 [Member] | Emerging Markets Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	36	35
Level 2 [Member] | Absolute Return Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	37	29
Level 2 [Member] | Equity Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	57	64
Level 2 [Member] | Private Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 2 [Member] | Private Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 2 [Member] | Public Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	11	12
Level 2 [Member] | Fixed Income [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 2 [Member] | Cash Equivalents [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	13	8
Level 3 [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	268	286
Level 3 [Member] | U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	66	73
Level 3 [Member] | Global ex U.S. Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 3 [Member] | Emerging Markets Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 3 [Member] | Absolute Return Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	80	87
Level 3 [Member] | Equity Hedge Funds [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	50	63
Level 3 [Member] | Private Equity [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	47	41
Level 3 [Member] | Private Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	16	10
Level 3 [Member] | Public Real Assets [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	9	12
Level 3 [Member] | Fixed Income [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	0	0
Level 3 [Member] | Cash Equivalents [Member]
Plan assets using the fair value hierarchy
Fair value of plan assets	$ 0	$ 0