Property and equipment: Purchase and installment payment agreements (Details) - Network equipment $ in Millions	1 Months Ended
	Mar. 31, 2015 USD ($) payment installment	Jan. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Equipment purchase agreement
Purchase agreement		$ 28.9
Term of purchase agreement		18 months
Required purchases remaining under purchase agreement			$ 3.0
Note obligations
Installment payment agreement
Amount of installment payment agreement	$ 25.0
Term of debt	24 months
Number of payments during the first six months | payment	0
Number of equal payments | installment	18
Remaining term	18 months
Aggregate principal amount of debt issued			21.2
Unamortized discount			$ 0.8