CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Total revenue	$ 633,906	$ 630,854	$ 611,991
Operating expenses
Selling, general and administrative	112,540	113,222	165,937
Acquisition, integration and migration expenses	0	0	11,030
Depreciation and amortization	159,653	166,405	177,007
Total operating expenses	536,860	537,608	565,481
Operating income	97,046	93,246	46,510
Other income (expense):
Interest expense	(29,468)	(34,847)	(38,237)
Other	3,461	3,713	4,984
Income before income taxes	71,039	62,112	13,257
Income tax expense (benefit)	16,104	15,517	(53,133)
Net income	54,935	46,595	66,390
Other comprehensive income:
Unrealized (loss) gain on interest rate hedge, net of tax	(7,972)
Unrealized (loss) gain on interest rate hedge, net of tax		50	1,442
Comprehensive income	$ 46,963	$ 46,645	$ 67,832
Net income per share, basic and diluted:
Basic net income per share (in dollars per share)	$ 1.10	$ 0.94	$ 1.35
Diluted net income per share (in dollars per share)	$ 1.10	$ 0.93	$ 1.33
Weighted average shares outstanding, basic (in shares)	49,811	49,542	49,150
Weighted average shares outstanding, diluted (in shares)	50,101	50,063	50,026
Cash dividend declared per share (in dollars per share)	$ 0.29	$ 0.27	$ 0.26
Service revenue and other
Revenue:
Total revenue	$ 565,063	$ 562,456	$ 601,673
Equipment revenue
Revenue:
Total revenue	68,843	68,398	10,318
Services
Operating expenses
Cost of services and cost of goods sold	198,753	194,022	188,721
Products
Operating expenses
Cost of services and cost of goods sold	$ 65,914	$ 63,959	$ 22,786