CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Service revenue	$ 147,879	$ 140,990	$ 294,656	$ 281,904
Operating expenses:
Network operations (including $136 and $305 of equity-based compensation expense, respectively, exclusive of depreciation and amortization shown separately below)	56,180	53,886	113,272	109,806
Selling, general, and administrative (including $6,738 and $5,778 of equity-based compensation expense, respectively)	41,392	39,839	82,834	79,513
Depreciation and amortization	22,096	19,896	44,065	39,402
Total operating expenses	119,668	113,621	240,171	228,721
Gains on equipment transactions		205	18	244
Operating income	28,211	27,574	54,503	53,427
Interest expense	(14,236)	(15,499)	(30,071)	(30,720)
Realized foreign exchange gain on issuance on 2024 Euro Notes		2,547		2,547
Unrealized gain (loss) on foreign exchange on 2024 Euro Notes	(5,280)	(3,420)	13,590	(512)
Interest income and other, net	64	735	807	28
(Loss) income before income taxes	(2,071)	11,299	24,131	24,132
Income tax provision	(422)	(2,735)	(7,773)	(6,341)
Net (loss) income	(2,493)	8,564	16,358	17,791
Comprehensive (loss) income:
Net (loss) income	(2,493)	8,564	16,358	17,791
Foreign currency translation adjustment	1,776	2,913	(3,434)	(580)
Comprehensive (loss) income	$ (717)	$ 11,477	$ 12,924	$ 17,211
Basic net (loss) income per common share (in dollars per share)	$ (0.05)	$ 0.19	$ 0.35	$ 0.39
Diluted net (loss) income per common share (in dollars per share)	(0.05)	0.18	0.35	0.38
Dividends declared per common share (in dollars per share)	$ 0.78	$ 0.68	$ 1.535	$ 1.340
Weighted-average common shares - basic (in shares)	46,229,603	45,754,880	46,227,528	45,760,302
Weighted-average common shares - diluted (in shares)	46,229,603	46,686,665	46,744,070	46,592,445
2021 Notes
Operating expenses:
Loss on debt extinguishment and redemption		$ (638)		$ (638)
2022 Notes
Operating expenses:
Loss on debt extinguishment and redemption	$ (10,830)		$ (14,698)