SEGMENT INFORMATION (REVENUE GEOGRAPHY) (DETAILS) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	$ 341,816	$ 309,195	$ 310,223	$ 325,521	$ 338,170	$ 305,900	$ 295,490	$ 302,221	$ 1,286,755	$ 1,241,781	$ 1,193,157
Property, plant and equipment, gross	660,081				628,351				660,081	628,351	575,499
Other long-term assets	42,486				36,658				42,486	36,658	45,726
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net									679,959	603,297	556,239
Property, plant and equipment, gross	415,918				382,508				415,918	382,508	337,311
Other long-term assets	34,007				27,728				34,007	27,728	34,891
Philippines [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net									343,013	348,339	354,942
Property, plant and equipment, gross	140,712				119,482				140,712	119,482	101,123
Other long-term assets	5,220				5,202				5,220	5,202	4,408
Latin America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net									147,267	172,270	176,906
Property, plant and equipment, gross	49,464				67,193				49,464	67,193	75,618
Other long-term assets	1,161				1,456				1,161	1,456	5,299
Europe Middle East Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net									78,182	83,944	72,644
Property, plant and equipment, gross	14,567				13,367				14,567	13,367	12,311
Other long-term assets	811				692				811	692	311
Asia Pacific[ Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net									32,554	28,294	18,489
Property, plant and equipment, gross	23,181				26,502				23,181	26,502	28,195
Other long-term assets	165				1,309				165	1,309	779
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net									5,780	5,637	13,937
Property, plant and equipment, gross	16,239				19,299				16,239	19,299	20,941
Other long-term assets	$ 1,122				$ 271				$ 1,122	$ 271	$ 38