Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical) (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Income tax benefit on unrealized (loss) on marketable securities	$ 0	$ (1)
Income tax benefit on unrecognized prior service cost	0	3
Income tax benefit on unrealized gain (loss) on interest rate swaps	0
Accumulated Other Comprehensive Income
Income tax benefit on unrealized (loss) on marketable securities	0	(1)
Income tax benefit on unrecognized prior service cost	0	3
Income tax benefit on unrealized gain (loss) on interest rate swaps	$ 0