Commitments, Contingencies and Other Items - Additional Information (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) lawsuit	Dec. 31, 2018 USD ($) patent lawsuit
Loss Contingencies [Line Items]
Estimated litigation liability | $	$ 17,000	$ 17,000
Number of patents allegedly Infringed, minimum | patent		1
Unfavorable regulatory action
Loss Contingencies [Line Items]
Maximum possible loss per proceeding | $	$ 100	$ 100
Interexchange Carriers
Loss Contingencies [Line Items]
Number of lawsuits (approximately) | lawsuit	100	100
Louisiana State Court
Loss Contingencies [Line Items]
New claims filed | lawsuit	2