Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2012 Scenario, Forecast [Member]
Estimated payments to the third-party providers		$ 232
Long-term Purchase Commitment, Time Period	between 2012 and 2016
Significant purchase commitment termination fee			$ 34	$ 28

The minimum amount the entity agreed to spend under the long-term purchase commitment.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration