Segment And Geographic Information (Information Concerning Principal Geographic Areas) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	$ 1,358	$ 1,127	$ 2,685	$ 2,220
Income (loss) from continuing operations before income tax expense	413	263	810	545
Net income (loss)	360	182	610	758
Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	24	28	45	53
Income (loss) from continuing operations before income tax expense	12	13	22	28
Net income (loss)	8	30	15	501
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	24	28	45	52
Income (loss) from continuing operations before income tax expense	12	13	22	24
Net income (loss)	10	13	18	21
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue (loss)	0	0	0	1
Income (loss) from continuing operations before income tax expense	0	0	0	4
Net income (loss)	(2)	17	(3)	28
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)	1,334	1,099	2,640	2,167
Income (loss) from continuing operations before income tax expense	401	250	788	517
Net income (loss)	$ 352	$ 152	$ 595	$ 257