ACQUISITIONS (Estimated Fair Values) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2015	Jun. 30, 2015	Dec. 31, 2015	Jul. 10, 2015	Dec. 31, 2014	Oct. 31, 2014	Jun. 06, 2014	Apr. 30, 2014	Mar. 05, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill			$ 115,930		$ 57,417					$ 22,268
2015 Acquisitions | NavigationArts
Business Acquisition [Line Items]
Adjustment to net assets acquired			0
2015 Acquisitions | As Originally Reported | Total
Business Acquisition [Line Items]
Cash and cash equivalents			3,044
Trade receivables and other current assets			14,520
Property and equipment and other long-term assets			1,895
Deferred tax asset			4,996
Acquired intangible assets			11,500
Goodwill			57,637
Total assets acquired			93,592
Accounts payable and accrued expenses			3,958
Deferred revenue			1,099
Due to employees			3,606
Deferred tax liability			4,325
Total liabilities assumed			12,988
Net assets acquired			80,604
2015 Acquisitions | Current | NavigationArts
Business Acquisition [Line Items]
Cash and cash equivalents			1,317
Trade receivables and other current assets			3,920
Property and equipment and other long-term assets			230
Deferred tax asset			233
Acquired intangible assets			2,800
Goodwill			21,764
Total assets acquired			30,264
Accounts payable and accrued expenses			871
Deferred revenue			50
Due to employees			596
Deferred tax liability			0
Total liabilities assumed			1,517
Net assets acquired			28,747
2015 Acquisitions | Current | AGS
Business Acquisition [Line Items]
Cash and cash equivalents			1,727
Trade receivables and other current assets			10,600
Property and equipment and other long-term assets			1,665
Deferred tax asset			4,996
Acquired intangible assets			10,000
Goodwill			33,815
Total assets acquired			62,803
Accounts payable and accrued expenses			3,087
Deferred revenue			1,049
Due to employees			3,010
Deferred tax liability			3,800
Total liabilities assumed			10,946
Net assets acquired			51,857
2015 Acquisitions | Current | Total
Business Acquisition [Line Items]
Cash and cash equivalents			3,044
Trade receivables and other current assets			14,520
Property and equipment and other long-term assets			1,895
Deferred tax asset			5,229
Acquired intangible assets			12,800
Goodwill			55,579
Total assets acquired			93,067
Accounts payable and accrued expenses			3,958
Deferred revenue			1,099
Due to employees			3,606
Deferred tax liability			3,800
Total liabilities assumed			12,463
Net assets acquired			80,604
2014 Acquisition | Netsoft
Business Acquisition [Line Items]
Adjustment to net assets acquired	$ (348)
2014 Acquisition | Jointech
Business Acquisition [Line Items]
Adjustment to net assets acquired		$ 0
2014 Acquisition | GGA
Business Acquisition [Line Items]
Adjustment to net assets acquired		(1,366)
2014 Acquisition | Great Fridays
Business Acquisition [Line Items]
Adjustment to net assets acquired			(77)
2014 Acquisition | As Originally Reported | NavigationArts
Business Acquisition [Line Items]
Cash and cash equivalents				$ 1,317
Trade receivables and other current assets				3,920
Property and equipment and other long-term assets				230
Deferred tax asset				0
Acquired intangible assets				1,500
Goodwill				23,822
Total assets acquired				30,789
Accounts payable and accrued expenses				871
Deferred revenue				50
Due to employees				596
Deferred tax liability				525
Total liabilities assumed				2,042
Net assets acquired				$ 28,747
2014 Acquisition | As Originally Reported | Netsoft
Business Acquisition [Line Items]
Cash and cash equivalents									$ 0
Trade receivables and other current assets									788
Property and equipment and other long-term assets									52
Deferred tax asset									351
Acquired intangible assets									1,700
Goodwill									2,776
Total assets acquired									5,667
Accounts payable and accrued expenses									69
Deferred revenue									0
Due to employees									0
Deferred tax liability									0
Total liabilities assumed									69
Net assets acquired									$ 5,598
2014 Acquisition | As Originally Reported | Jointech
Business Acquisition [Line Items]
Cash and cash equivalents								$ 871
Trade receivables and other current assets								784
Property and equipment and other long-term assets								338
Deferred tax asset								0
Acquired intangible assets								25,744
Goodwill								11,033
Total assets acquired								38,770
Accounts payable and accrued expenses								728
Deferred revenue								0
Due to employees								1,254
Deferred tax liability								0
Total liabilities assumed								1,982
Net assets acquired								$ 36,788
2014 Acquisition | As Originally Reported | GGA
Business Acquisition [Line Items]
Cash and cash equivalents							$ 0
Trade receivables and other current assets							5,157
Property and equipment and other long-term assets							444
Deferred tax asset							4,463
Acquired intangible assets							10,959
Goodwill							6,496
Total assets acquired							27,519
Accounts payable and accrued expenses							2,593
Deferred revenue							0
Due to employees							0
Deferred tax liability							0
Total liabilities assumed							2,593
Net assets acquired							$ 24,926
2014 Acquisition | As Originally Reported | Great Fridays
Business Acquisition [Line Items]
Cash and cash equivalents						$ 259
Trade receivables and other current assets						1,825
Property and equipment and other long-term assets						262
Deferred tax asset						0
Acquired intangible assets						5,747
Goodwill						6,947
Total assets acquired						15,040
Accounts payable and accrued expenses						872
Deferred revenue						317
Due to employees						624
Deferred tax liability						1,200
Total liabilities assumed						3,013
Net assets acquired						$ 12,027
2014 Acquisition | As Originally Reported | Total
Business Acquisition [Line Items]
Cash and cash equivalents			1,130
Trade receivables and other current assets			8,554
Property and equipment and other long-term assets			1,096
Deferred tax asset			4,814
Acquired intangible assets			44,150
Goodwill			27,252
Total assets acquired			86,996
Accounts payable and accrued expenses			4,262
Deferred revenue			317
Due to employees			1,878
Deferred tax liability			1,200
Total liabilities assumed			7,657
Net assets acquired			79,339
2014 Acquisition | Final | Netsoft
Business Acquisition [Line Items]
Cash and cash equivalents	0
Trade receivables and other current assets	788
Property and equipment and other long-term assets	52
Deferred tax asset	0
Acquired intangible assets	1,700
Goodwill	2,779
Total assets acquired	5,319
Accounts payable and accrued expenses	69
Deferred revenue	0
Due to employees	0
Deferred tax liability	0
Total liabilities assumed	69
Net assets acquired	$ 5,250
2014 Acquisition | Final | Jointech
Business Acquisition [Line Items]
Cash and cash equivalents		871
Trade receivables and other current assets		784
Property and equipment and other long-term assets		338
Deferred tax asset		0
Acquired intangible assets		15,312
Goodwill		23,758
Total assets acquired		41,063
Accounts payable and accrued expenses		728
Deferred revenue		0
Due to employees		1,254
Deferred tax liability		2,293
Total liabilities assumed		4,275
Net assets acquired		36,788
2014 Acquisition | Final | GGA
Business Acquisition [Line Items]
Cash and cash equivalents		0
Trade receivables and other current assets		5,377
Property and equipment and other long-term assets		306
Deferred tax asset		0
Acquired intangible assets		16,000
Goodwill		7,306
Total assets acquired		28,989
Accounts payable and accrued expenses		2,593
Deferred revenue		104
Due to employees		0
Deferred tax liability		0
Total liabilities assumed		2,697
Net assets acquired		$ 26,292
2014 Acquisition | Final | Great Fridays
Business Acquisition [Line Items]
Cash and cash equivalents			259
Trade receivables and other current assets			1,825
Property and equipment and other long-term assets			262
Deferred tax asset			0
Acquired intangible assets			200
Goodwill			11,262
Total assets acquired			13,808
Accounts payable and accrued expenses			807
Deferred revenue			317
Due to employees			624
Deferred tax liability			110
Total liabilities assumed			1,858
Net assets acquired			11,950
2014 Acquisition | Final | Total
Business Acquisition [Line Items]
Cash and cash equivalents			1,130
Trade receivables and other current assets			8,774
Property and equipment and other long-term assets			958
Deferred tax asset			0
Acquired intangible assets			33,212
Goodwill			45,105
Total assets acquired			89,179
Accounts payable and accrued expenses			4,197
Deferred revenue			421
Due to employees			1,878
Deferred tax liability			2,403
Total liabilities assumed			8,899
Net assets acquired			$ 80,280