CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Service revenue	$ 142,302	$ 136,942	$ 424,205	$ 405,866
Operating expenses:
Network operations	54,519	55,253	164,326	163,811
Selling, general, and administrative	39,722	35,971	119,232	110,396
Depreciation and amortization	21,619	20,006	61,022	60,246
Total operating expenses	115,860	111,230	344,580	334,453
Loss on finance lease amendment	(505)		(423)
Gains on equipment transactions	99	87	343	808
Operating income	26,036	25,799	79,545	72,221
Interest expense	(15,760)	(15,191)	(46,481)	(42,243)
Realized foreign exchange gain on issuance on 2024 Euro Notes			2,547
Unrealized foreign exchange (loss) gain on 2024 Euro Notes	(17,315)	6,162	(17,827)	6,339
Interest income and other, net	484	2,185	430	5,588
Loss on debt extinguishment and redemption- 2021 Notes			(638)
(Loss) Income before income taxes	(6,555)	18,955	17,576	41,905
Income tax benefit (provision)	1,600	(5,254)	(4,740)	(11,851)
Net (loss) income	(4,955)	13,701	12,836	30,054
Comprehensive income:
Net (loss) income	(4,955)	13,701	12,836	30,054
Foreign currency translation adjustment	5,408	(4,709)	4,828	(4,748)
Comprehensive income	$ 453	$ 8,992	$ 17,664	$ 25,306
Net (loss) income per common share:
Basic net (loss) income per common share (in dollars per share)	$ (0.11)	$ 0.30	$ 0.28	$ 0.66
Diluted net (loss) income per common share (in dollars per share)	(0.11)	0.30	0.28	0.65
Dividends declared per common share (in dollars per share)	$ 0.705	$ 0.620	$ 2.045	$ 1.800
Weighted-average common shares - basic (in shares)	45,815,718	45,438,656	45,818,677	45,428,305
Weighted-average common shares - diluted (in shares)	45,815,718	46,019,691	46,598,870	45,948,331