Segment And Geographic Information (Information Concerning Principal Geographic Areas) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	$ 1,327	$ 1,093
Income (loss) from continuing operations before income tax expense	397	282
Net income (loss)	250	576
Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	21	25
Income (loss) from continuing operations before income tax expense	10	15
Net income (loss)	7	471
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	21	24
Income (loss) from continuing operations before income tax expense	10	11
Net income (loss)	8	8
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	0	1
Income (loss) from continuing operations before income tax expense	0	4
Net income (loss)	(1)	11
Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)		0
Income (loss) from continuing operations before income tax expense		0
Net income (loss)		452
Domestic [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	1,306	1,068
Income (loss) from continuing operations before income tax expense	387	267
Net income (loss)	$ 243	$ 105