Commitments and Contingencies (Details)				3 Months Ended	24 Months Ended
	Apr. 30, 2016	Jul. 17, 2013 USD ($)	Oct. 14, 2011 plaintiff	Mar. 31, 2016 USD ($) plaintiff	Dec. 31, 2007 USD ($)
Loss Contingencies
Patents allegedly infringed, minimum number				1
William Douglas Fulghum, et al. v. Embarq Corporation
Loss Contingencies
Effect of modifications made to Embarq's benefits program, greater than | $					$ 300,000,000
Breach of fiduciary duty claims | plaintiff				15
Abbott et al. v. Sprint Nextel et al.
Loss Contingencies
Number of plaintiffs have alleged breach of fiduciary duty (plaintiffs) | plaintiff			1,500
Number of plaintiffs, limited discovery (plaintiffs) | plaintiff				80
Unfavorable regulatory action
Loss Contingencies
Estimate of possible loss per proceeding | $				$ 100,000
Qwest Communications International Inc. | Comcast
Loss Contingencies
Damages sought by plaintiff | $		$ 80,000,000
Subsequent event | Missouri municipalities
Loss Contingencies
Opinion of counsel on ruling on one pending case	In an April 2016 ruling in connection with one of these pending cases, the court made findings which, if not overturned, will result in tax liability to us well in excess of the contingent liability we have established. Following further proceedings at the district court, we plan to file an appeal and continue to vigorously defend against these claims. For a variety of reasons, we expect the outcome of our appeal to significantly reduce our ultimate exposure, although we can provide no assurances to this effect.