Guarantor and Non-Guarantor Statements (Notes To Consolidated Statement Of Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 511.7	$ 509.5	$ 486.9	$ 652.9
Short-term investments	6.1	116.2
Receivables, net	417.5	383.4
Inventories	729.9	608.8
Short-term intercompany receivables	0	0
Other current assets	140.6	89.3
Total current assets	1,805.8	1,707.2
Property, plant and equipment, net	1,203.9	1,074.2	1,103.3
Goodwill	264.7	184.6
Intangible assets, net	457.6	223.4
Long-term intercompany receivables	0	0
Other assets	91.0	104.4
Total assets	3,823.0	3,293.8
Accounts payable	378.2	276.8
Accrued expenses	287.9	220.3
Deferred income on sales to distributors	165.1	140.5
Current portion of long-term debt	209.6	181.6
Short-term intercompany payables	0	0
Total current liabilities	1,040.8	819.2
Long-term debt	983.0	760.6
Other long-term liabilities	151.8	190.4
Long-term intercompany payables	0	0
Total liabilities	2,175.6	1,770.2
Total ON Semiconductor Corporation stockholders’ equity	1,626.5	1,490.8
Non-controlling interest in consolidated subsidiary	20.9	32.8	29.6
Total stockholders' equity	1,647.4	1,523.6	1,427.9	1,537.3
Total liabilities and equity	3,823.0	3,293.8
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Short-term investments	0	0
Receivables, net	0	0
Inventories	0	0
Short-term intercompany receivables	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Long-term intercompany receivables	0	0
Other assets	1,969.1	1,827.0
Total assets	1,969.1	1,827.0
Accounts payable	0	0
Accrued expenses	0.4	1.0
Deferred income on sales to distributors	0	0
Current portion of long-term debt	0	0
Short-term intercompany payables	0	0
Total current liabilities	0.4	1.0
Long-term debt	342.2	335.2
Other long-term liabilities	0	0
Long-term intercompany payables	0	0
Total liabilities	342.6	336.2
Total ON Semiconductor Corporation stockholders’ equity	1,626.5	1,490.8
Non-controlling interest in consolidated subsidiary	0	0
Total stockholders' equity	1,626.5	1,490.8
Total liabilities and equity	1,969.1	1,827.0
SCI LLC [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	199.9	267.9	212.1	304.5
Short-term investments	2.0	116.2
Receivables, net	56.6	49.8
Inventories	60.5	46.7
Short-term intercompany receivables	0	0
Other current assets	14.0	17.8
Total current assets	333.0	498.4
Property, plant and equipment, net	262.1	252.3
Goodwill	111.6	111.5
Intangible assets, net	98.2	113.0
Long-term intercompany receivables	204.2	0
Other assets	2,002.3	1,637.4
Total assets	3,011.4	2,612.6
Accounts payable	37.8	39.1
Accrued expenses	71.6	50.8
Deferred income on sales to distributors	36.4	32.3
Current portion of long-term debt	57.6	79.3
Short-term intercompany payables	2.3	11.7
Total current liabilities	205.7	213.2
Long-term debt	609.5	396.1
Other long-term liabilities	21.1	42.2
Long-term intercompany payables	0	3.3
Total liabilities	836.3	654.8
Total ON Semiconductor Corporation stockholders’ equity	2,175.1	1,957.8
Non-controlling interest in consolidated subsidiary	0	0
Total stockholders' equity	2,175.1	1,957.8
Total liabilities and equity	3,011.4	2,612.6
Other Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	(0.2)
Short-term investments	0	0
Receivables, net	0	0
Inventories	0	0
Short-term intercompany receivables	4.9	4.1
Other current assets	0	0
Total current assets	4.9	4.1
Property, plant and equipment, net	3.1	3.1
Goodwill	37.3	37.3
Intangible assets, net	0	0
Long-term intercompany receivables	0	0
Other assets	143.5	136.1
Total assets	188.8	180.6
Accounts payable	0.1	0.5
Accrued expenses	0.5	0.2
Deferred income on sales to distributors	0	0
Current portion of long-term debt	0	0
Short-term intercompany payables	0	0
Total current liabilities	0.6	0.7
Long-term debt	0	0
Other long-term liabilities	0	0.1
Long-term intercompany payables	0	0
Total liabilities	0.6	0.8
Total ON Semiconductor Corporation stockholders’ equity	188.2	179.8
Non-controlling interest in consolidated subsidiary	0	0
Total stockholders' equity	188.2	179.8
Total liabilities and equity	188.8	180.6
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	311.8	241.6	274.8	348.6
Short-term investments	4.1	0
Receivables, net	360.9	333.6
Inventories	652.9	559.1
Short-term intercompany receivables	0	7.6
Other current assets	126.6	71.5
Total current assets	1,456.3	1,213.4
Property, plant and equipment, net	940.1	820.6
Goodwill	115.8	35.8
Intangible assets, net	377.0	132.2
Long-term intercompany receivables	0	3.3
Other assets	858.2	877.1
Total assets	3,747.4	3,082.4
Accounts payable	340.3	237.2
Accrued expenses	215.4	168.3
Deferred income on sales to distributors	128.7	108.2
Current portion of long-term debt	152.0	102.3
Short-term intercompany payables	2.6	0
Total current liabilities	839.0	616.0
Long-term debt	31.3	29.3
Other long-term liabilities	130.7	148.1
Long-term intercompany payables	204.2	0
Total liabilities	1,205.2	793.4
Total ON Semiconductor Corporation stockholders’ equity	2,542.2	2,289.0
Non-controlling interest in consolidated subsidiary	0	0
Total stockholders' equity	2,542.2	2,289.0
Total liabilities and equity	3,747.4	3,082.4
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Short-term investments	0	0
Receivables, net	0	0
Inventories	16.5	3.0
Short-term intercompany receivables	(4.9)	(11.7)
Other current assets	0	0
Total current assets	11.6	(8.7)
Property, plant and equipment, net	(1.4)	(1.8)
Goodwill	0	0
Intangible assets, net	(17.6)	(21.8)
Long-term intercompany receivables	(204.2)	(3.3)
Other assets	(4,882.1)	(4,373.2)
Total assets	(5,093.7)	(4,408.8)
Accounts payable	0	0
Accrued expenses	0	0
Deferred income on sales to distributors	0	0
Current portion of long-term debt	0	0
Short-term intercompany payables	(4.9)	(11.7)
Total current liabilities	(4.9)	(11.7)
Long-term debt	0	0
Other long-term liabilities	0	0
Long-term intercompany payables	(204.2)	(3.3)
Total liabilities	(209.1)	(15.0)
Total ON Semiconductor Corporation stockholders’ equity	(4,905.5)	(4,426.6)
Non-controlling interest in consolidated subsidiary	20.9	32.8
Total stockholders' equity	(4,884.6)	(4,393.8)
Total liabilities and equity	$ (5,093.7)	$ (4,408.8)