SHAREHOLDERS' EQUITY AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in Accumulated Other Comprehensive Income by component (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (63,595)
Other comprehensive income before reclassifications	(5,016)
Amounts reclassified from accumulated other comprehensive income (loss)	1,091
Balance at end of period	(67,520)
Defined benefit plans adjustment | Pension
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(12,255)
Other comprehensive income before reclassifications	(172)
Amounts reclassified from accumulated other comprehensive income (loss)	1,078
Balance at end of period	(11,349)
Defined benefit plans adjustment | Postretirement Medical Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(20,292)
Amounts reclassified from accumulated other comprehensive income (loss)	13
Balance at end of period	(20,279)
Available for sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	0
Other comprehensive income before reclassifications	1,231
Balance at end of period	1,231
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	0
Other comprehensive income before reclassifications	(5,364)
Balance at end of period	(5,364)
Tax effect of other comprehensive income gains
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(31,048)
Other comprehensive income before reclassifications	(711)
Balance at end of period	$ (31,759)