Pensions and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Republic of China (Taiwan) [Member]
Defined Benefit Plan Disclosure [Line Items]
Company pension contributions			$ 4,409
Defined Benefit Pension Plan [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	$ 0	$ 0	0	$ 0
Interest cost	411	2,945	1,232	8,834
Expected return on plan assets	0	(2,825)	0	(8,476)
Amortization of prior service cost (credit)	36	36	108	108
Amortization of losses (gains)	82	1,650	247	4,951
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	529	1,806	1,587	5,417
Defined Benefit Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	948	790	2,776	2,355
Interest cost	1,247	1,361	3,613	4,097
Expected return on plan assets	(519)	(529)	(1,543)	(1,605)
Amortization of prior service cost (credit)	19	12	55	37
Amortization of losses (gains)	1,595	1,196	4,596	3,568
Curtailments and settlements	331	205	983	601
Net periodic benefit cost	3,621	3,035	10,480	9,053
Other Postretirement Benefits [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	33	31	99	94
Interest cost	77	85	232	255
Amortization of prior service cost (credit)	(209)	(209)	(627)	(627)
Amortization of losses (gains)	(24)	(8)	(70)	(23)
Net periodic benefit cost	(123)	(101)	(366)	(301)
Other Postretirement Benefits [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	71	67	202	202
Interest cost	26	36	76	108
Amortization of prior service cost (credit)	0	0	0	0
Amortization of losses (gains)	16	17	45	51
Net periodic benefit cost	$ 113	$ 120	$ 323	$ 361