Long-Term Debt Guantor and Non-Guarantor Balance Sheet (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Oct. 01, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 659.3	$ 623.3	$ 562.9	$ 525.7
Short-term Investments	178.4	0
Receivables, Net, Current	539.0	294.6
Inventories	706.6	360.8
Other current assets	90.3	63.6
Deferred income taxes, net of allowances	14.6	15.7
Total current assets	2,188.2	1,358.0
Restricted cash	0	142.1
Property, plant and equipment, net	1,130.8	864.3
Deferred income taxes, net of allowances	72.2	0
Goodwill	199.2	191.2
Intangible assets, net	348.3	303.0
Investments and other assets	73.2	60.6
Total assets	4,011.9	2,919.2
Accounts payable	472.6	256.9
Accrued expenses	218.6	162.6
Income taxes payable	13.8	5.1
Accrued interest	4.0	0.8
Deferred income on sales to distributors	188.4	149.5
Deferred income taxes, net of allowances	69.7	0
Current portion of long-term debt	288.2	136.0
Total current liabilities	1,255.3	710.9
Long-term debt	948.8	752.8
Other long-term liabilities	261.0	49.3
Deferred income tax	21.1	18.2
Intercompany	0	0
Total liabilities	2,486.2	1,531.2
Common stock	5.0	4.9
Additional paid in capital	3,102.5	3,016.1
Accumulated other comprehensive loss	(48.5)	(59.1)
Accumulated deficit	(1,159.8)	(1,213.9)
Less: treasury stock, at cost	(397.4)	(382.0)
Total ON Semiconductor Corporation stockholders' equity	1,501.8	1,366.0
Minority interest in consolidated subsidiaries	23.9	22.0	21.8	19.6
Total equity	1,525.7	1,388.0
Total liabilities and equity	4,011.9	2,919.2
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Short-term Investments	0
Receivables, Net, Current	0	0
Inventories	0	0
Other current assets	0	0
Deferred income taxes, net of allowances	0	0
Total current assets	0	0
Restricted cash	0	0
Property, plant and equipment, net	0	0
Deferred income taxes, net of allowances	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investments and other assets	2,065.5	1,946.6
Total assets	2,065.5	1,946.6
Accounts payable	0	0
Accrued expenses	0	0
Income taxes payable	0	0
Accrued interest	3.9	0.6
Deferred income on sales to distributors	0	0
Deferred income taxes, net of allowances	0	0
Current portion of long-term debt	92.4	0
Total current liabilities	96.3	0.6
Long-term debt	467.1	579.7
Other long-term liabilities	0	0
Deferred income tax	0	0
Intercompany	0.3	0.3
Total liabilities	563.7	580.6
Common stock	5.0	4.9
Additional paid in capital	3,102.5	3,016.1
Accumulated other comprehensive loss	(48.5)	(59.1)
Accumulated deficit	(1,159.8)	(1,213.9)
Less: treasury stock, at cost	(397.4)	(382.0)
Total ON Semiconductor Corporation stockholders' equity	1,501.8	1,366.0
Minority interest in consolidated subsidiaries	0	0
Total equity	1,501.8	1,366.0
Total liabilities and equity	2,065.5	1,946.6
SCILLC [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	407.1	392.3	366.3	286.0
Short-term Investments	178.4
Receivables, Net, Current	57.3	47.4
Inventories	44.8	48.0
Other current assets	8.7	14.9
Deferred income taxes, net of allowances	3.0	5.6
Total current assets	699.3	508.2
Restricted cash	0	142.1
Property, plant and equipment, net	268.0	221.0
Deferred income taxes, net of allowances	(6.1)	0
Goodwill	125.7	125.7
Intangible assets, net	156.8	165.4
Investments and other assets	1,376.9	1,131.2
Total assets	2,620.6	2,293.6
Accounts payable	36.0	43.4
Accrued expenses	64.1	82.1
Income taxes payable	9.6	0.9
Accrued interest	0	0
Deferred income on sales to distributors	46.2	33.7
Deferred income taxes, net of allowances	0.9	0
Current portion of long-term debt	78.6	33.0
Total current liabilities	235.4	193.1
Long-term debt	411.3	103.0
Other long-term liabilities	25.2	21.1
Deferred income tax	0	5.6
Intercompany	(265.9)	(123.8)
Total liabilities	406.0	199.0
Common stock	0.3	0.3
Additional paid in capital	2,727.6	2,502.2
Accumulated other comprehensive loss	(48.5)	(59.1)
Accumulated deficit	(464.8)	(348.8)
Less: treasury stock, at cost	0	0
Total ON Semiconductor Corporation stockholders' equity	2,214.6	2,094.6
Minority interest in consolidated subsidiaries	0	0
Total equity	2,214.6	2,094.6
Total liabilities and equity	2,620.6	2,293.6
Other Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0.1	0
Short-term Investments	0
Receivables, Net, Current	0	0
Inventories	0	0
Other current assets	0	0
Deferred income taxes, net of allowances	0	0
Total current assets	0	0
Restricted cash	0	0
Property, plant and equipment, net	2.3	2.6
Deferred income taxes, net of allowances	0	0
Goodwill	37.2	37.2
Intangible assets, net	0	0
Investments and other assets	55.8	51.4
Total assets	95.3	91.2
Accounts payable	0.1	0.1
Accrued expenses	0.8	0.8
Income taxes payable	0	0
Accrued interest	0	0
Deferred income on sales to distributors	0	0
Deferred income taxes, net of allowances	0	0
Current portion of long-term debt	0	0
Total current liabilities	0.9	0.9
Long-term debt	0	0
Other long-term liabilities	0.4	0.4
Deferred income tax	0	0
Intercompany	(54.2)	(53.4)
Total liabilities	(52.9)	(52.1)
Common stock	50.9	50.9
Additional paid in capital	238.3	178.5
Accumulated other comprehensive loss	0	0
Accumulated deficit	(141.0)	(86.1)
Less: treasury stock, at cost	0	0
Total ON Semiconductor Corporation stockholders' equity	148.2	143.3
Minority interest in consolidated subsidiaries	0	0
Total equity	148.2	143.3
Total liabilities and equity	95.3	91.2
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	252.2	231.0	196.5	239.7
Short-term Investments	0
Receivables, Net, Current	481.7	247.2
Inventories	656.6	299.9
Other current assets	81.6	48.7
Deferred income taxes, net of allowances	11.6	10.1
Total current assets	1,483.7	836.9
Restricted cash	0	0
Property, plant and equipment, net	863.7	644.1
Deferred income taxes, net of allowances	78.3	0
Goodwill	36.3	28.3
Intangible assets, net	222.6	172.0
Investments and other assets	845.3	830.0
Total assets	3,529.9	2,511.3
Accounts payable	436.5	213.4
Accrued expenses	152.0	78.0
Income taxes payable	4.2	4.2
Accrued interest	0.1	0.2
Deferred income on sales to distributors	142.2	115.8
Deferred income taxes, net of allowances	68.8	0
Current portion of long-term debt	117.2	103.0
Total current liabilities	921.0	514.6
Long-term debt	70.4	70.1
Other long-term liabilities	235.4	27.8
Deferred income tax	21.1	12.6
Intercompany	114.3	(28.6)
Total liabilities	1,362.2	596.5
Common stock	146.9	146.9
Additional paid in capital	1,377.5	1,110.7
Accumulated other comprehensive loss	(40.8)	(52.3)
Accumulated deficit	684.1	709.5
Less: treasury stock, at cost	0	0
Total ON Semiconductor Corporation stockholders' equity	2,167.7	1,914.8
Minority interest in consolidated subsidiaries	0	0
Total equity	2,167.7	1,914.8
Total liabilities and equity	3,529.9	2,511.3
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Short-term Investments	0
Receivables, Net, Current	0	0
Inventories	5.2	12.9
Other current assets	0	0
Deferred income taxes, net of allowances	0	0
Total current assets	5.2	12.9
Restricted cash	0	0
Property, plant and equipment, net	(3.2)	(3.4)
Deferred income taxes, net of allowances	0	0
Goodwill	0	0
Intangible assets, net	(31.1)	(34.4)
Investments and other assets	(4,270.3)	(3,898.6)
Total assets	(4,299.4)	(3,923.5)
Accounts payable	0	0
Accrued expenses	1.7	1.7
Income taxes payable	0	0
Accrued interest	0	0
Deferred income on sales to distributors	0	0
Deferred income taxes, net of allowances	0	0
Current portion of long-term debt	0	0
Total current liabilities	1.7	1.7
Long-term debt	0	0
Other long-term liabilities	0	0
Deferred income tax	0	0
Intercompany	205.5	205.5
Total liabilities	207.2	207.2
Common stock	(198.1)	(198.1)
Additional paid in capital	(4,343.4)	(3,791.4)
Accumulated other comprehensive loss	89.3	111.4
Accumulated deficit	(78.3)	(274.6)
Less: treasury stock, at cost	0	0
Total ON Semiconductor Corporation stockholders' equity	(4,530.5)	(4,152.7)
Minority interest in consolidated subsidiaries	23.9	22.0
Total equity	(4,506.6)	(4,130.7)
Total liabilities and equity	$ (4,299.4)	$ (3,923.5)