SUPPLEMENTAL CONSOLIDATED BALANCE SHEETS AND STATEMENTS OF OPERATIONS INFORMATION - Schedule of Other Non-current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Supplemental Consolidated Balance Sheet & Statement of Operations Information [Abstract]
Contingent income tax liabilities	$ 46,073	$ 43,699
Deferred rent	31,860	29,032
Capital lease obligations	12,224	18,500
Deferred income taxes	2,776	811
Other	9,610	10,366
Total other non-current liabilities	$ 102,543	$ 102,408

Supplemental Consolidated Balance Sheet & Statement of Operations Information [Abstract]

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Carrying amount as of the balance sheet date of the unpaid sum of the known and estimated amounts payable to satisfy all domestic and foreign income tax obligations due beyond one year or the operating cycle, whichever is longer. Alternate captions include income taxes payable, noncurrent.

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date.

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Amount of deferred tax liability attributable to taxable temporary differences, after deferred tax asset, and other tax liabilities expected to be paid after one year or operating cycle, if longer.

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For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date.

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Amount of obligation due after one year or beyond the normal operating cycle, if longer.

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Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

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