CONDENSED CONSOLIDATING FINANCIAL INFORMATION - STATEMENTS OF CASH FLOWS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Net loss	$ (3,508)	$ (13,151)
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization	28,155	35,518
Amortization of financing costs	1,672	1,672
Loss (gain) on sale or disposal of assets	436	611
Accretion of contract rights	2,002	2,097
Provision for bad debts	2,817	2,444
Reserve for obsolescence	408	119
Stock-based compensation	1,412	1,061
Changes in operating assets and liabilities:
Net settlement receivables and liabilities	(25,098)	(12,969)
Other changes in operating assets and liabilities	23,062	7,302
Net cash provided by operating activities	31,358	24,704
Cash flows from investing activities
Capital expenditures	(17,184)	(23,613)
Proceeds from sale of fixed assets		10
Placement fee agreements	(3,044)	(1,000)
Changes in restricted cash and cash equivalents	(125)	44
Net cash used in investing activities	(20,353)	(24,559)
Cash flows from financing activities
Repayments of credit facility	(2,500)	(2,500)
Debt issuance costs		(480)
Proceeds from exercise of stock options	5
Purchase of treasury stock	(7)	(9)
Net cash used in financing activities	(2,502)	(2,989)
Effect of exchange rates on cash	307	148
Cash and cash equivalents
Net (decrease) increase for the period	8,810	(2,696)
Balance, beginning of the period	119,051	102,030
Balance, end of the period	127,861	99,334
Reportable Legal Entities | Parent
Cash flows from operating activities
Net loss	(3,508)	(13,151)
Adjustments to reconcile net loss to cash provided by operating activities:
Equity in loss (income) of subsidiaries	3,508	13,151
Changes in operating assets and liabilities:
Other changes in operating assets and liabilities	4	1
Net cash provided by operating activities	4	1
Cash flows from investing activities
Intercompany investing activities	(2)	2
Net cash used in investing activities	(2)	2
Cash flows from financing activities
Proceeds from exercise of stock options	5
Purchase of treasury stock	(7)	(9)
Net cash used in financing activities	(2)	(9)
Cash and cash equivalents
Net (decrease) increase for the period		(6)
Balance, beginning of the period		6
Reportable Legal Entities | Subsidiary Issuer
Cash flows from operating activities
Net loss	14,632	3,026
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization	4,643	5,619
Amortization of financing costs	1,672	1,672
Loss (gain) on sale or disposal of assets	27	21
Provision for bad debts	27
Reserve for obsolescence	140	60
Equity in loss (income) of subsidiaries	(4,181)	(3,294)
Stock-based compensation	998	699
Changes in operating assets and liabilities:
Net settlement receivables and liabilities	(20,802)	(17,373)
Other changes in operating assets and liabilities	19,002	3,788
Net cash provided by operating activities	16,158	(5,782)
Cash flows from investing activities
Capital expenditures	(1,227)	(3,150)
Proceeds from sale of fixed assets		10
Changes in restricted cash and cash equivalents	25	44
Intercompany investing activities	179	148
Net cash used in investing activities	(1,023)	(2,948)
Cash flows from financing activities
Repayments of credit facility	(2,500)	(2,500)
Debt issuance costs		(480)
Intercompany financing activities	36	54
Net cash used in financing activities	(2,464)	(2,926)
Cash and cash equivalents
Net (decrease) increase for the period	12,671	(11,656)
Balance, beginning of the period	88,648	87,078
Balance, end of the period	101,319	75,422
Reportable Legal Entities | Guarantor Subsidiaries
Cash flows from operating activities
Net loss	(14,926)	(13,389)
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization	22,913	29,289
Loss (gain) on sale or disposal of assets	409	590
Accretion of contract rights	2,002	2,097
Provision for bad debts	2,790	2,444
Reserve for obsolescence	268	59
Equity in loss (income) of subsidiaries	(103)
Stock-based compensation	414	362
Changes in operating assets and liabilities:
Net settlement receivables and liabilities	(164)	39
Other changes in operating assets and liabilities	4,878	3,408
Net cash provided by operating activities	18,481	24,899
Cash flows from investing activities
Capital expenditures	(15,938)	(20,362)
Placement fee agreements	(3,044)	(1,000)
Changes in restricted cash and cash equivalents	(150)
Intercompany investing activities	145	(8)
Net cash used in investing activities	(18,987)	(21,370)
Cash and cash equivalents
Net (decrease) increase for the period	(506)	3,529
Balance, beginning of the period	9,103	3,900
Balance, end of the period	8,597	7,429
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash flows from operating activities
Net loss	1,070	506
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization	599	610
Changes in operating assets and liabilities:
Net settlement receivables and liabilities	(4,132)	4,365
Other changes in operating assets and liabilities	(822)	105
Net cash provided by operating activities	(3,285)	5,586
Cash flows from investing activities
Capital expenditures	(19)	(101)
Intercompany investing activities	(26)	(52)
Net cash used in investing activities	(45)	(153)
Cash flows from financing activities
Intercompany financing activities	(332)	(144)
Net cash used in financing activities	(332)	(144)
Effect of exchange rates on cash	307	148
Cash and cash equivalents
Net (decrease) increase for the period	(3,355)	5,437
Balance, beginning of the period	21,300	11,046
Balance, end of the period	17,945	16,483
Eliminations
Cash flows from operating activities
Net loss	(776)	9,857
Adjustments to reconcile net loss to cash provided by operating activities:
Equity in loss (income) of subsidiaries	776	(9,857)
Cash flows from investing activities
Intercompany investing activities	(296)	(90)
Net cash used in investing activities	(296)	(90)
Cash flows from financing activities
Intercompany financing activities	296	90
Net cash used in financing activities	$ 296	$ 90