SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset	$ 170,550
Total current and noncurrent lease liabilities	$ 172,547
Cumulative effect of change in accounting principle			$ (1,564)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset		$ 185,500
Total current and noncurrent lease liabilities		$ 188,500
Accumulated Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle			$ (1,564)
Real Estate Leases | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	5 years
Real Estate Leases | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	10 years
Non-Real Estate Leases | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	2 years
Non-Real Estate Leases | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	7 years
Short Term Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	1 year