Consolidated Statements of Comprehensive (Loss) Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (19,300)	$ (18,607)	$ (107,124)	$ (21,095)
Other comprehensive income (loss)
Amortization of accumulated actuarial losses, pension	588	1,294	1,765	3,639
Adjustments to accumulated actuarial gains (losses) and transition obligations, pension	(112)	813	189	786
Amortization of accumulated actuarial losses, transition obligations, and prior service costs, postretirement medical benefit	964	368	2,893	891
Adjustments to accumulated actuarial gains and transition obligations, postretirement medical benefit	0	0	0	984
Tax effect of other comprehensive income losses	(684)	(1,039)	(2,503)	(2,410)
Change in foreign currency translation adjustment	9,426	(2,432)	17,455	16,128
Unrealized and realized gains and losses on available-for-sale securities	278	535	1,474	255
Other comprehensive income (loss), net of income taxes	10,460	(461)	21,273	20,273
Comprehensive loss	(8,840)	(19,068)	(85,851)	(822)
Less: Comprehensive loss attributable to noncontrolling interest	(78)	(240)	(715)	(1,532)
Comprehensive (loss) income attributable to common shareholders	$ (8,762)	$ (18,828)	$ (85,136)	$ 710