STOCKHOLDERS' EQUITY AND ACCUMULATED OTHER COMPREHENSIVE LOSS - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Unrealized and realized gains (losses) on available-for-sale securities		$ 535	$ 1	$ 19,239	$ 165	$ (1,785)	$ (27,140)	$ (280)	$ (1,460)	$ 255	$ (1,295)	$ (345)	$ (1,738)	$ 413
Change in foreign currency translation adjustment		$ (2,432)	$ (615)	$ (121)	$ (20,690)	$ 4,903	$ (494)	$ 18,560	$ (22,156)	$ 16,128	$ (42,846)	8,983	(51,866)	(18,190)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Unrealized and realized gains (losses) on available-for-sale securities												(349)	(1,738)	413
Postretirement Medical Benefits [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Prior service cost (credit)												(636)	$ (636)	$ (635)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Unrealized and realized gains (losses) on available-for-sale securities	[1]											228
Reclassification out of Accumulated Other Comprehensive Income [Member] | Other Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	[1]											228
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension Benefits [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Prior service cost (credit)												8
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Gain (Loss), before Tax	[1],[2]											4,353
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	[1]											4,361
Reclassification out of Accumulated Other Comprehensive Income [Member] | Postretirement Medical Benefits [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Prior Service Cost, before Tax	[1],[3]											(636)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Gain (Loss), before Tax	[1],[3]											1,895
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	[1]											$ 1,259

[1] Amounts in parenthesis indicate debits to income/loss.

[2] These accumulated other comprehensive income components are included in the computation of net periodic pension cost. (See Note 12 - Pension And Other Saving Plans to the consolidated financial statements for additional details)

[3] These accumulated other comprehensive income components are included in the computation of net periodic postretirement medical cost. (See Note 11 - Postretirement Medical Benefits to the consolidated financial statements for additional details)