ACQUISITIONS - Estimated Fair Values (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Nov. 16, 2015	Jul. 10, 2015
Business Acquisition [Line Items]
Goodwill	$ 111,722	$ 115,930
NavigationArts
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Adjustment to net assets acquired	1,797
NavigationArts | As Originally Reported
Business Acquisition [Line Items]
Cash and cash equivalents				$ 1,317
Accounts receivable and other current assets				3,920
Property and equipment and other long-term assets				230
Deferred tax assets				0
Acquired intangible assets				1,500
Goodwill				23,822
Total assets acquired				30,789
Accounts payable and accrued expenses				871
Bank loans and other long-term liabilities				0
Deferred revenue				50
Due to employees				596
Deferred tax liabilities				525
Total liabilities assumed				2,042
Net assets acquired				$ 28,747
NavigationArts | Final
Business Acquisition [Line Items]
Cash and cash equivalents	1,317
Accounts receivable and other current assets	3,920
Property and equipment and other long-term assets	230
Deferred tax assets	0
Acquired intangible assets	2,800
Goodwill	23,794
Total assets acquired	32,061
Accounts payable and accrued expenses	871
Bank loans and other long-term liabilities	0
Deferred revenue	50
Due to employees	596
Deferred tax liabilities	0
Total liabilities assumed	1,517
Net assets acquired	30,544
AGS
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Adjustment to net assets acquired	(140)
AGS | As Originally Reported
Business Acquisition [Line Items]
Cash and cash equivalents			$ 1,727
Accounts receivable and other current assets			10,600
Property and equipment and other long-term assets			1,665
Deferred tax assets			4,996
Acquired intangible assets			10,000
Goodwill			33,815
Total assets acquired			62,803
Accounts payable and accrued expenses			3,087
Bank loans and other long-term liabilities			0
Deferred revenue			1,049
Due to employees			3,010
Deferred tax liabilities			3,800
Total liabilities assumed			10,946
Net assets acquired			$ 51,857
AGS | Current
Business Acquisition [Line Items]
Cash and cash equivalents	1,727
Accounts receivable and other current assets	10,539
Property and equipment and other long-term assets	1,665
Deferred tax assets	4,996
Acquired intangible assets	22,700
Goodwill	25,078
Total assets acquired	66,705
Accounts payable and accrued expenses	2,676
Bank loans and other long-term liabilities	295
Deferred revenue	1,049
Due to employees	2,342
Deferred tax liabilities	8,626
Total liabilities assumed	14,988
Net assets acquired	51,717
Total
Business Acquisition [Line Items]
Cash and cash equivalents	3,044
Accounts receivable and other current assets	14,459
Property and equipment and other long-term assets	1,895
Deferred tax assets	4,996
Acquired intangible assets	25,500
Goodwill	48,872
Total assets acquired	98,766
Accounts payable and accrued expenses	3,547
Bank loans and other long-term liabilities	295
Deferred revenue	1,099
Due to employees	2,938
Deferred tax liabilities	8,626
Total liabilities assumed	16,505
Net assets acquired	82,261
Total | As Originally Reported
Business Acquisition [Line Items]
Cash and cash equivalents	3,044
Accounts receivable and other current assets	14,520
Property and equipment and other long-term assets	1,895
Deferred tax assets	4,996
Acquired intangible assets	11,500
Goodwill	57,637
Total assets acquired	93,592
Accounts payable and accrued expenses	3,958
Bank loans and other long-term liabilities	0
Deferred revenue	1,099
Due to employees	3,606
Deferred tax liabilities	4,325
Total liabilities assumed	12,988
Net assets acquired	$ 80,604