CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Service revenue	$ 147,927	$ 142,302	$ 442,584	$ 424,205
Operating expenses:
Network operations (including $163 and $346 of equity-based compensation expense, respectively, exclusive of depreciation and amortization shown separately below)	56,645	54,519	169,920	164,326
Selling, general, and administrative (including $6,425 and $6,176 of equity-based compensation expense, respectively)	40,117	39,722	122,952	119,232
Depreciation and amortization	22,609	21,619	66,675	61,022
Total operating expenses	119,371	115,860	359,547	344,580
Loss on finance lease amendment		(505)		(423)
Gains on equipment transactions		99	18	343
Operating income	28,556	26,036	83,055	79,545
Interest expense	(17,349)	(15,760)	(47,421)	(46,481)
Realized foreign exchange gain on issuance on 2024 Euro Notes				2,547
Unrealized foreign exchange gain (loss) on 2024 Euro Notes	10,169	(17,315)	23,759	(17,827)
Interest income and other, net	648	484	1,460	430
Income (loss) before income taxes	22,024	(6,555)	46,155	17,576
Income tax (provision) benefit	(8,704)	1,600	(16,477)	(4,740)
Net income (loss)	13,320	(4,955)	29,678	12,836
Comprehensive income:
Net income (loss)	13,320	(4,955)	29,678	12,836
Foreign currency translation adjustment	(3,818)	5,408	(7,252)	4,828
Comprehensive income	$ 9,502	$ 453	$ 22,426	$ 17,664
Net income (loss) per common share:
Basic net income (loss) per common share (in dollars per share)	$ 0.29	$ (0.11)	$ 0.64	$ 0.28
Diluted net income (loss) per common share (in dollars per share)	0.28	(0.11)	0.63	0.28
Dividends declared per common share (in dollars per share)	$ 0.805	$ 0.705	$ 2.340	$ 2.045
Weighted-average common shares - basic (in shares)	46,293,524	45,815,718	46,290,452	45,818,677
Weighted-average common shares - diluted (in shares)	46,866,929	45,815,718	46,825,948	46,598,870
2021 Notes
Operating expenses:
Loss on debt extinguishment and redemption				$ (638)
2022 Notes
Operating expenses:
Loss on debt extinguishment and redemption			$ (14,698)