Commitments, Contingencies and Other Items - Purchase Commitments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Long-term Purchase Commitment
Total	$ 660
Less than 1 Year	337
2 - 3 Years	200
4 - 5 Years	51
After 5 Years	72
Cost of Access Services
Long-term Purchase Commitment
Total	425
Less than 1 Year	278
2 - 3 Years	131
4 - 5 Years	11
After 5 Years	5
Third Party Maintenance Services
Long-term Purchase Commitment
Total	235
Less than 1 Year	59
2 - 3 Years	69
4 - 5 Years	40
After 5 Years	$ 67