RETIREMENT AND DEFERRED COMPENSATION PLANS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
United States
Change in benefit obligation:
Benefit obligation at beginning of year	$ 198,450	$ 175,879
Service cost	11,396	9,706	$ 9,041
Interest cost	6,878	7,010	6,776
Actuarial (gain) loss	(23,510)	21,085
Benefits paid	(12,411)	(15,230)
Benefit obligation at end of year	180,803	198,450	175,879
Change in plan assets:
Fair value of plan assets at beginning of year	169,600	126,246
Actual return on plan assets	(7,642)	18,372
Employer contribution	20,411	40,212
Benefits paid	(12,411)	(15,230)
Fair value of plan assets at end of year	169,958	169,600	126,246
Funded status at end of year				$ (10,845)	$ (28,850)
Funded status amounts recognized in Consolidated Balance Sheet
Non-current assets				207
Current liabilities				(430)	(423)
Non-current liabilities				(10,622)	(28,427)
Funded status amount				(10,845)	(28,850)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss				48,776	58,260
Tax effects				(17,876)	(20,057)
Net amount recognized				30,900	38,203
Changes in benefit obligations and plan assets recognized in other comprehensive income
Current year actuarial gain (loss)	4,611	(12,593)	(4,335)
Amortization of net loss	4,873	3,205	3,283
Net amount recognized	9,484	(9,388)	(1,052)
Amounts in accumulated other comprehensive loss expected to be recognized as components of periodic benefit cost in next fiscal year
Amortization of net loss				2,009
Amount expected to be recognized in next fiscal year				2,009
Components of net periodic benefit cost:
Service cost	11,396	9,706	9,041
Interest cost	6,878	7,010	6,776
Expected return on plan assets	(11,257)	(9,880)	(8,471)
Amortization of net loss	4,873	3,205	3,283
Net periodic benefit cost	$ 11,890	$ 10,041	$ 10,629
Accumulated benefit obligation				163,000	178,900
Projected benefit obligation ("PBO"), ABO, and fair value of plan assets for all pension plans with an ABO in excess of plan assets
Projected benefit obligation				11,052	11,478
Accumulated benefit obligation				9,216	9,291
Fair value of plan assets				0
PBO, ABO, and fair value of plan assets for all pension plans with a PBO in excess of plan assets
Projected benefit obligation				11,052	198,450
Accumulated benefit obligation				9,216	178,878
Fair value of plan assets				$ 0	$ 169,600
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)				4.20%	3.55%	4.05%
Rate of compensation increase (as a percent)				4.00%	4.00%	4.00%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	3.55%	4.05%	4.24%
Expected long-term return on plan assets (as a percent)	7.00%	7.00%	7.00%
Rate of compensation increase (as a percent)	4.00%	4.00%	4.00%
Plan Assets:
Weighted-average asset allocations (as a percent)				100.00%	100.00%
Total Investments in Fair Value Hierarchy				$ 107,943	$ 113,347
Total Investments	$ 169,600	$ 126,246	$ 126,246	169,958	169,600	$ 126,246
Minimum funding requirement	0
Expected contribution in next fiscal year				400
United States | Cash and Short Term Securities
Plan Assets:
Total Investments in Fair Value Hierarchy				$ 8,964	$ 21,644
United States | Equity Securities
Plan Assets:
Weighted-average asset allocations (as a percent)				44.00%	42.00%
Target allocation (as a percent)				60.00%
Total Investments in Fair Value Hierarchy				$ 66,707	$ 63,799
United States | Fixed Income Funds
Plan Assets:
Weighted-average asset allocations (as a percent)				29.00%	25.00%
Total Investments in Fair Value Hierarchy				$ 32,272	$ 27,904
United States | Hedge Fund
Plan Assets:
Weighted-average asset allocations (as a percent)				10.00%	9.00%
United States | Infrastructure
Plan Assets:
Weighted-average asset allocations (as a percent)				7.00%	6.00%
United States | Money market
Plan Assets:
Weighted-average asset allocations (as a percent)				5.00%	13.00%
United States | Fixed income securities and infrastructure
Plan Assets:
Target allocation (as a percent)				40.00%
United States | Real Estate Funds
Plan Assets:
Weighted-average asset allocations (as a percent)				5.00%	5.00%
United States | Level 1
Change in plan assets:
Fair value of plan assets at beginning of year	113,347
Fair value of plan assets at end of year	107,943	113,347
Plan Assets:
Total Investments in Fair Value Hierarchy				$ 107,943	$ 113,347
Total Investments	113,347	113,347		107,943	113,347
United States | Level 1 | Cash and Short Term Securities
Plan Assets:
Total Investments in Fair Value Hierarchy				8,964	21,644
United States | Level 1 | Cash and Short Term Securities | USD
Plan Assets:
Total Investments in Fair Value Hierarchy				8,964	21,644
United States | Level 1 | Equity Securities
Plan Assets:
Total Investments in Fair Value Hierarchy				66,707	63,799
United States | Level 1 | US Large Cap Equities
Plan Assets:
Total Investments in Fair Value Hierarchy				38,804	37,456
United States | Level 1 | US Small Cap Equities
Plan Assets:
Total Investments in Fair Value Hierarchy				7,747	7,569
United States | Level 1 | International Equities
Plan Assets:
Total Investments in Fair Value Hierarchy				20,156	18,774
United States | Level 1 | Fixed Income Funds
Plan Assets:
Total Investments in Fair Value Hierarchy				32,272	27,904
United States | Net Asset Value per Share
Plan Assets:
Investments at Net Asset Value per Share				62,015	56,253
Foreign Plans
Change in benefit obligation:
Benefit obligation at beginning of year	109,030	93,178
Service cost	5,954	5,526	4,556
Interest cost	1,828	1,747	1,892
Special termination benefit charge	62
Curtailment/Settlement	(1,751)
Business acquired	1,937
Prior service cost	35	1,419
Actuarial (gain) loss	(3,743)	(2,653)
Benefits paid	(3,288)	(3,489)
Foreign currency translation adjustment	(5,153)	13,302
Benefit obligation at end of year	104,911	109,030	93,178
Change in plan assets:
Fair value of plan assets at beginning of year	73,384	61,912
Actual return on plan assets	(487)	2,472
Employer contribution	2,780	3,824
Benefits paid	(3,288)	(3,489)
Foreign currency translation adjustment	(3,397)	8,665
Fair value of plan assets at end of year	68,992	73,384	61,912
Funded status at end of year				(35,919)	(35,646)
Funded status amounts recognized in Consolidated Balance Sheet
Non-current assets				500	297
Current liabilities				(8)	(9)
Non-current liabilities				(36,411)	(35,934)
Funded status amount				(35,919)	(35,646)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss				29,761	33,703
Net prior service cost				4,656	5,341
Tax effects				(4,855)	(12,651)
Net amount recognized				29,562	26,393
Changes in benefit obligations and plan assets recognized in other comprehensive income
Current year actuarial gain (loss)	534	2,952	(6,251)
Current year prior service cost	(35)	(1,399)	(656)
Recognition due to curtailment	1,692
Amortization of net loss	1,716	1,895	1,540
Amortization of prior service cost	720	400	350
Net amount recognized	4,627	3,848	(5,017)
Amounts in accumulated other comprehensive loss expected to be recognized as components of periodic benefit cost in next fiscal year
Amortization of net loss				1,465
Amortization of prior service cost				458
Amount expected to be recognized in next fiscal year				1,923
Components of net periodic benefit cost:
Service cost	5,954	5,526	4,556
Interest cost	1,828	1,747	1,892
Expected return on plan assets	(2,610)	(2,409)	(2,181)
Amortization of net loss	1,716	1,895	1,540
Amortization of prior service cost	720	400	350
Net periodic benefit cost	7,608	7,159	6,157
Curtailment	(59)
Special termination benefit charge	62
Total net periodic benefit cost	$ 7,611	$ 7,159	$ 6,157
Accumulated benefit obligation				80,900	84,700
Projected benefit obligation ("PBO"), ABO, and fair value of plan assets for all pension plans with an ABO in excess of plan assets
Projected benefit obligation				93,029	89,618
Accumulated benefit obligation				68,981	65,524
Fair value of plan assets				56,611	54,052
PBO, ABO, and fair value of plan assets for all pension plans with a PBO in excess of plan assets
Projected benefit obligation				92,555	84,799
Accumulated benefit obligation				68,506	59,383
Fair value of plan assets				$ 56,136	$ 49,233
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)				1.82%	1.62%	1.65%
Rate of compensation increase (as a percent)				3.01%	3.02%	3.00%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	1.62%	1.65%	2.10%
Expected long-term return on plan assets (as a percent)	3.66%	3.66%	3.66%
Rate of compensation increase (as a percent)	3.02%	3.00%	3.00%
Plan Assets:
Weighted-average asset allocations (as a percent)				100.00%	100.00%
Total Investments in Fair Value Hierarchy				$ 68,992	$ 73,384
Total Investments	$ 73,384	$ 61,912	$ 61,912	68,992	73,384	$ 61,912
Expected contribution in next fiscal year				4,300
Foreign Plans | Cash and Short Term Securities
Plan Assets:
Total Investments in Fair Value Hierarchy				$ 718	$ 432
Foreign Plans | Equity Securities
Plan Assets:
Weighted-average asset allocations (as a percent)				4.00%	4.00%
Total Investments in Fair Value Hierarchy				$ 2,591	$ 3,111
Foreign Plans | Fixed Income Funds
Plan Assets:
Weighted-average asset allocations (as a percent)				1.00%	1.00%
Total Investments in Fair Value Hierarchy				$ 717	$ 779
Foreign Plans | Corporate debts securities
Plan Assets:
Weighted-average asset allocations (as a percent)				3.00%	3.00%
Total Investments in Fair Value Hierarchy				$ 2,097	$ 2,256
Foreign Plans | Investment Funds
Plan Assets:
Weighted-average asset allocations (as a percent)				91.00%	91.00%
Target allocation (as a percent)				100.00%
Total Investments in Fair Value Hierarchy				$ 62,869	$ 66,807
Foreign Plans | Money market
Plan Assets:
Weighted-average asset allocations (as a percent)				1.00%	1.00%
Foreign Plans | Level 1
Change in plan assets:
Fair value of plan assets at beginning of year	31,387
Fair value of plan assets at end of year	28,245	31,387
Plan Assets:
Total Investments in Fair Value Hierarchy				$ 28,245	$ 31,387
Total Investments	31,387	31,387		28,245	31,387
Foreign Plans | Level 1 | Cash and Short Term Securities
Plan Assets:
Total Investments in Fair Value Hierarchy				718	432
Foreign Plans | Level 1 | Cash and Short Term Securities | EUR
Plan Assets:
Total Investments in Fair Value Hierarchy				718	432
Foreign Plans | Level 1 | Equity Securities
Plan Assets:
Total Investments in Fair Value Hierarchy				2,591	3,111
Foreign Plans | Level 1 | International Equities
Plan Assets:
Total Investments in Fair Value Hierarchy				2,591	3,111
Foreign Plans | Level 1 | Fixed Income Funds
Plan Assets:
Total Investments in Fair Value Hierarchy				717	779
Foreign Plans | Level 1 | Corporate debts securities
Plan Assets:
Total Investments in Fair Value Hierarchy				2,097	2,256
Foreign Plans | Level 1 | Euro Corporate Bonds
Plan Assets:
Total Investments in Fair Value Hierarchy				2,097	2,256
Foreign Plans | Level 1 | Investment Funds
Plan Assets:
Total Investments in Fair Value Hierarchy				22,122	24,810
Foreign Plans | Level 1 | Mutual Funds in Equities
Plan Assets:
Total Investments in Fair Value Hierarchy				3,339	4,356
Foreign Plans | Level 1 | Mutual Funds in Bonds
Plan Assets:
Total Investments in Fair Value Hierarchy				18,060	19,639
Foreign Plans | Level 1 | Mutual Funds Diversified
Plan Assets:
Total Investments in Fair Value Hierarchy				723	815
Foreign Plans | Level 2
Change in plan assets:
Fair value of plan assets at beginning of year	41,997
Fair value of plan assets at end of year	40,747	41,997
Plan Assets:
Total Investments in Fair Value Hierarchy				40,747	41,997
Total Investments	$ 41,997	$ 41,997		40,747	41,997
Foreign Plans | Level 2 | Investment Funds
Plan Assets:
Total Investments in Fair Value Hierarchy				40,747	41,997
Foreign Plans | Level 2 | Mutual Funds Diversified
Plan Assets:
Total Investments in Fair Value Hierarchy				40,747	41,997
Non-qualified supplemental pension plan | United States
Non-qualified supplemental pension plan information
Non funded liability				$ 11,100	$ 11,500