Special Charges and Other, Net Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		45 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Employee separation costs	$ 90			$ 6,525	$ 1,477	$ 35,346
Contract exit costs	$ (97)			4,954	20,057	5,294
Supply commitment, period	10 years
Gain on sale of assets	$ 0			0	4,447	0
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 40,225		40,225
Charges					21,534
Payments					(11,845)
Non-cash - Other					582
Foreign exchange gains					272
Restructuring reserve, ending balance	$ 50,768				50,768		$ 50,768
Contract Termination
Restructuring Cost and Reserve [Line Items]
Incurred cost		$ 19,500
Contract termination fee, period	5 years
Employee Severance
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			5,474		5,474
Charges					1,477
Payments					(4,755)
Non-cash - Other					(287)
Foreign exchange gains					272
Restructuring reserve, ending balance	$ 2,181				2,181		2,181
Exit Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			34,751		34,751
Charges					20,057
Payments					(7,090)
Non-cash - Other					869
Foreign exchange gains					0
Restructuring reserve, ending balance	48,587				48,587		48,587
Accrued Liabilities
Restructuring Reserve [Roll Forward]
Current	14,042				14,042		14,042
Other Noncurrent Liabilities
Restructuring Reserve [Roll Forward]
Non-current	36,726				36,726		36,726
Semiconductor products
Restructuring Cost and Reserve [Line Items]
Employee separation costs	100			6,500	1,500	35,300	52,600
Contract exit costs	$ (100)			$ 5,000	$ 20,100	$ 5,300	$ 64,800
San Jose Facility | Micrel Incorporated
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of property, plant, and equipment			10,000
Gain on sale of assets			$ 4,400