SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES – Adoption of ASU 2017-07 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales	$ 435,379	$ 407,781	$ 1,355,445	$ 1,192,129
Selling, research & development and administrative	103,574	95,536	323,146	292,274
Total Operating Expenses	604,662	543,404	1,849,726	1,599,063
Operating Income	61,113	80,922	230,007	244,325
Miscellaneous, net	(2,928)	(2,712)	(4,372)	(1,996)
Total Other (Expense) Income	(10,171)	(11,404)	(22,950)	(25,759)
Income before Income Taxes	$ 50,942	69,518	$ 207,057	218,566
Original Balance | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		408,081		1,192,967
Selling, research & development and administrative		95,748		292,923
Total Operating Expenses		543,916		1,600,550
Operating Income		80,410		242,838
Miscellaneous, net		(2,200)		(509)
Total Other (Expense) Income		(10,892)		(24,272)
Income before Income Taxes		69,518		218,566
Adjustment | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		(300)		(838)
Selling, research & development and administrative		(212)		(649)
Total Operating Expenses		(512)		(1,487)
Operating Income		512		1,487
Miscellaneous, net		(512)		(1,487)
Total Other (Expense) Income		$ (512)		$ (1,487)