Restructuring-Related Liabilities: (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Current Liability
Restructuring Reserve
Liability at the beginning of the period	$ 30
Payments	(8)
Other Adjustments	7
Liability at the end of the period	29
Noncurrent Liability
Restructuring Reserve
Liability at the beginning of the period	430
Other Adjustments	(16)
Liability at the end of the period	414
Workforce | Current Liability
Restructuring Reserve
Liability at the beginning of the period	28
Payments	(7)
Other Adjustments	7
Liability at the end of the period	27
Workforce | Noncurrent Liability
Restructuring Reserve
Liability at the beginning of the period	430
Other Adjustments	(15)
Liability at the end of the period	414
Space | Current Liability
Restructuring Reserve
Liability at the beginning of the period	2
Payments	0
Other Adjustments	0
Liability at the end of the period	1
Space | Noncurrent Liability
Restructuring Reserve
Liability at the beginning of the period	0
Other Adjustments	0
Liability at the end of the period	$ 0