RESTATEMENT OF PREVIOUSLY ISSUED CONSOLIDATED FINANCIAL STATEMENTS - Statement of 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
Net loss	$ (18,607)	$ (29,397)	$ 26,909	$ (52,876)	$ (39,415)	$ (16,024)	$ (2,488)	$ (55,438)	$ (21,095)	$ (108,314)	$ (28,872)	$ (219,095)	$ (176,746)
Amortization of accumulated actuarial gains, pension	1,294	1,772	573	996	1,157	1,110	2,345	2,267	3,639	2,929	4,361	1,886	1,508
Adjustments to accumulated actuarial gains (losses) and transition obligations, pension	813	(199)	172	(253)	(822)	203	(27)	(619)	786	(538)	3,010	160	(24,793)
Amortization of accumulated actuarial gains, transition obligations, and prior service costs, postretirement medical benefits	368	323	200	327	327	327	523	654	891	981	1,259	1,308	18
Adjustments to accumulated actuarial gains (losses), postretirement medical benefits	0	1,672	(688)	0	0	0	984	0	984	0	(22,066)	7,322	(19,442)
Tax effect of other comprehensive income gains	(1,039)	(1,314)	(281)	(558)	312	325	(1,371)	(263)	(2,410)	(821)	0	(3,335)	161
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)
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
Other comprehensive loss, net of income taxes	(461)	1,640	19,094	(20,013)	4,092	(25,669)	20,734	(21,577)	20,273	(41,590)	(4,798)	(46,263)	(60,325)
Comprehensive loss	(19,068)	(27,757)	46,003	(72,889)	(35,323)	(41,693)	18,246	(77,015)	(822)	(149,904)	(33,670)	(265,358)	(237,071)
Less: Comprehensive loss attributable to noncontrolling interest	(240)	(792)	(500)	(1,458)	(1,246)	(2,146)	(1,292)	(3,392)	(1,532)	(4,850)	(1,767)	(5,453)	(921)
Comprehensive loss attributable to common shareholders	(18,828)	(26,965)	46,503	(71,431)	(34,077)	(39,547)	19,538	(73,623)	710	(145,054)	$ (31,903)	(259,905)	(236,150)
As Reported [Member]
Net loss	(8,760)	(26,175)	30,086	(48,020)	(37,851)	(13,878)	3,911	(51,729)	(4,849)	(99,749)		(208,767)	(173,180)
Amortization of accumulated actuarial gains, pension	1,294	1,772	818	996	1,157	1,110	2,590	2,267	3,884	3,263		1,347	983
Adjustments to accumulated actuarial gains (losses) and transition obligations, pension	813	(199)	172	(253)	(488)	203	(27)	(285)	786	(538)		160	(24,793)
Amortization of accumulated actuarial gains, transition obligations, and prior service costs, postretirement medical benefits	368	323	200	327	327	327	523	654	891	981		1,308	18
Adjustments to accumulated actuarial gains (losses), postretirement medical benefits	0	1,672	(688)	0	0	0	984	0	984	0		7,322	(19,442)
Tax effect of other comprehensive income gains	(1,039)	(1,314)	(281)	(558)	225	325	(1,371)	(350)	(2,410)	(908)		(3,382)	0
Change in foreign currency translation adjustment	(2,438)	(617)	(57)	(20,802)	4,924	(575)	18,622	(22,216)	16,184	(43,018)		(52,021)	(17,880)
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)		(1,738)	413
Other comprehensive loss, net of income taxes	(467)	1,638	19,403	(20,125)	4,360	(25,750)	21,041	(21,390)	20,574	(41,515)		(47,004)	(60,701)
Comprehensive loss	(9,227)	(24,537)	49,489	(68,145)	(33,491)	(39,628)	24,952	(73,119)	15,725	(141,264)		(255,771)	(233,881)
Less: Comprehensive loss attributable to noncontrolling interest	(240)	(792)	(500)	(1,458)	(1,246)	(2,146)	(1,292)	(3,392)	(1,532)	(4,850)		(5,453)	(921)
Comprehensive loss attributable to common shareholders	(8,987)	(23,745)	49,989	(66,687)	(32,245)	(37,482)	26,244	(69,727)	17,257	(136,414)		(250,318)	(232,960)
Adjustments [Member]
Net loss	(9,847)	(3,222)	(3,177)	(4,856)	(1,564)	(2,146)	(6,399)	(3,709)	(16,246)	(8,565)		(10,328)	(3,566)
Amortization of accumulated actuarial gains, pension	0	0	(245)	0	0	0	(245)	0	(245)	(334)		539	525
Adjustments to accumulated actuarial gains (losses) and transition obligations, pension	0	0	0	0	(334)	0	0	(334)	0	0		0	0
Amortization of accumulated actuarial gains, transition obligations, and prior service costs, postretirement medical benefits	0	0	0	0	0	0	0	0	0	0		0	0
Adjustments to accumulated actuarial gains (losses), postretirement medical benefits	0	0	0	0	0	0	0	0	0	0		0	0
Tax effect of other comprehensive income gains	0	0	0	0	87	0	0	87	0	87		47	161
Change in foreign currency translation adjustment	6	2	(64)	112	(21)	81	(62)	60	(56)	172		155	(310)
Unrealized and realized gains (losses) on available-for-sale securities	0	0	0	0	0	0	0	0	0	0		0	0
Other comprehensive loss, net of income taxes	6	2	(309)	112	(268)	81	(307)	(187)	(301)	(75)		741	376
Comprehensive loss	(9,841)	(3,220)	(3,486)	(4,744)	(1,832)	(2,065)	(6,706)	(3,896)	(16,547)	(8,640)		(9,587)	(3,190)
Less: Comprehensive loss attributable to noncontrolling interest	0	0	0	0	0	0	0	0	0	0		0	0
Comprehensive loss attributable to common shareholders	$ (9,841)	$ (3,220)	$ (3,486)	$ (4,744)	$ (1,832)	$ (2,065)	$ (6,706)	$ (3,896)	$ (16,547)	$ (8,640)		$ (9,587)	$ (3,190)