Commitments, Contingencies and Other Items - Purchase Commitments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Long-term Purchase Commitment
Total	$ 1,152
Less than 1 Year	557
2 - 3 Years	446
4 - 5 Years	62
After 5 Years	87
Cost of Access Services
Long-term Purchase Commitment
Total	930
Less than 1 Year	497
2 - 3 Years	402
4 - 5 Years	24
After 5 Years	7
Third Party Maintenance Services
Long-term Purchase Commitment
Total	222
Less than 1 Year	60
2 - 3 Years	44
4 - 5 Years	38
After 5 Years	$ 80