UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Service revenues and other	$ 134,153	$ 150,521
Equipment revenues	17,579	3,359
Total operating revenues	151,732	153,880
Operating expenses:
Cost of services	49,342	48,776
Cost of goods sold	15,805	4,985
Selling, general and administrative	28,750	40,153
Acquisition, integration and migration expenses	0	4,489
Depreciation and amortization	43,487	44,804
Total operating expenses	137,384	143,207
Operating income (loss)	14,348	10,673
Other income (expense):
Interest expense	(9,332)	(9,100)
Gain (loss) on investments, net	(32)	120
Non-operating income (loss), net	1,021	1,255
Income (loss) before income taxes	6,005	2,948
Income tax expense (benefit)	1,176	607
Net income (loss)	4,829	2,341
Other comprehensive income (loss):
Unrealized gain (loss) on interest rate hedge, net of tax	3,062	599
Comprehensive income (loss)	$ 7,891	$ 2,940
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.10	$ 0.05
Diluted (in dollars per share)	$ 0.10	$ 0.05
Weighted average shares outstanding, basic (in shares)	49,474	49,050
Weighted average shares outstanding, diluted (in shares)	50,024	49,834