Comprehensive Income Reclassification out of Accumulated other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications	$ 3,936	$ (10,758)	$ 4,273	$ (4,347)	$ 221	$ (11,139)
Revenues	410,955			419,977			$ 1,198,279	$ 1,254,617
Other - net	(241)			(1,326)			113	(1,436)
Total before tax	10,628			8,055			(44,586)	30,145
Provision for income taxes	(1,617)			(1,770)			790	(8,381)
Net income (loss)	9,011			6,285			(43,796)	21,764
Amounts reclassified from AOCI to net income (loss)	(1,239)	(593)	(941)	(299)	(271)	1,988
Other Comprehensive Income (Loss), Net of Tax	2,697	(11,351)	3,332	(4,646)	(50)	(9,151)	(5,322)	(13,847)
Accumulated other comprehensive income (loss)	(24,175)	(26,872)	(15,521)	(3,473)	1,173	1,223	(24,175)	(3,473)	$ (18,853)	$ 10,374
Currency translation gain (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications	2,811	(11,566)	1,740	(7,685)	2,214	(10,923)
Amounts reclassified from AOCI to net income (loss)	0	0	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	2,811	(11,566)	1,740	(7,685)	2,214	(10,923)
Accumulated other comprehensive income (loss)	(26,508)	(29,319)	(17,753)	(4,843)	2,842	628	(26,508)	(4,843)	(19,493)	11,551
Net unrealized gain (loss) on investments (net of tax)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications	18	(7)	18	(30)	11	(1)
Amounts reclassified from AOCI to net income (loss)	0	0	1	0	1	1
Other Comprehensive Income (Loss), Net of Tax	18	(7)	19	(30)	(12)	0
Accumulated other comprehensive income (loss)	(14)	(32)	(25)	(40)	(10)	(22)	(14)	(40)	(44)	(22)
Net unrealized gain (loss) on derivative instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications	1,132	778	2,576	3,337	(2,004)	(215)
Amounts reclassified from AOCI to net income (loss)	(1,247)	(651)	(1,003)	(359)	(338)	1,916
Other Comprehensive Income (Loss), Net of Tax	(115)	127	1,573	2,978	(2,342)	1,701
Accumulated other comprehensive income (loss)	3,371	3,486	3,359	2,214	(764)	1,578	3,371	2,214	1,786	(123)
Net unrealized gain (loss) on derivative instruments | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues	1,940			407			4,524	429
Cost of Goods Sold	24			53			57	151
Other - net	(445)			14			(1,065)	(18)
Total before tax	1,519			474			3,516	562
Provision for income taxes	272			115			615	120
Net income (loss)	1,247			359			2,901	442
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods Sold	(15)			(1,139)			294	(1,339)
Provision for income taxes	(7)			(1,048)			421	(1,128)
Net income (loss)	(8)			(91)			(127)	(211)
Realized Gain Loss On Sale Of Investment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other - net	0			0			(1)	(3)
Provision for income taxes	0			0			0	(1)
Net income (loss)	0			0			(1)	(2)
Net unrecognized gain (loss) related to benefit plans (net of tax)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss) before reclassifications	(25)	37	(61)	31	0	0
Amounts reclassified from AOCI to net income (loss)	8	58	61	60	66	71
Other Comprehensive Income (Loss), Net of Tax	(17)	95	0	91	66	71
Accumulated other comprehensive income (loss)	$ (1,024)	$ (1,007)	$ (1,102)	$ (804)	$ (895)	$ (961)	$ (1,024)	$ (804)	$ (1,102)	$ (1,032)