Commitments and Contingencies, Legal Proceedings (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Loss Contingencies [Line Items]
Estimated Incremental Tax Liability Excluding Interest And Penalties Related to PNOD	$ 92
Estimated incremental tax liability excluding interest and penalties related to NOPA	$ 807
2011 California State Derivative Lawsuits [Member]
Loss Contingencies [Line Items]
Number of purported shareholder derivative actions	4
2011 Federal Derivative Lawsuit [Member]
Loss Contingencies [Line Items]
Number of purported shareholder derivative actions	2