Debt and Capital Lease Obligations (Debt) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Solar Energy [Member]	Dec. 31, 2013 Solar Energy [Member]	Sep. 30, 2013 Solar Energy [Member]	Mar. 31, 2014 Semiconductor Materials [Member]	Dec. 31, 2013 Semiconductor Materials [Member]	Mar. 31, 2014 Construction and Term Debt [Member] Solar Energy [Member]	Dec. 31, 2013 Construction and Term Debt [Member] Solar Energy [Member]	Mar. 31, 2014 SunEdison [Member] Solar Energy [Member]	Dec. 31, 2013 SunEdison [Member] Solar Energy [Member]	Mar. 31, 2014 SunEdison [Member] Construction and Term Debt [Member] Solar Energy [Member]	Dec. 31, 2013 SunEdison [Member] Construction and Term Debt [Member] Solar Energy [Member]	Mar. 31, 2014 SunEdison [Member] Construction and Term Debt [Member] Semiconductor Materials [Member]	Dec. 31, 2013 SunEdison [Member] Construction and Term Debt [Member] Semiconductor Materials [Member]	Mar. 31, 2014 2018 Senior Notes [Member]	Dec. 31, 2013 2018 Senior Notes [Member]	Dec. 20, 2013 2018 Senior Notes [Member]	Sep. 28, 2012 Second Lien Credit Agreement [Member]	Mar. 31, 2014 Yieldco Bridge Facility [Member]	Dec. 31, 2013 Yieldco Bridge Facility [Member]	Mar. 31, 2014 Yieldco Bridge Facility [Member] Credit facility [Member]	Mar. 31, 2014 Yieldco Bridge Facility [Member] Line of Credit [Member]
Debt Instrument [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (451.8)
Debt Instrument, Face Amount		3,576.2																600.0	200.0
Senior Notes	413.3															466.4
Senior Notes, Current	0	0														0	0
Senior Notes, Noncurrent		408.2															460.0
Loans Payable	879.7	868.2
Loans Payable, Current	0	0
Loans Payable, Noncurrent	879.7	868.2
Notes Payable	413.3	10.6														466.4
Notes Payable, Noncurrent		408.2															460.0
Current portion of Semiconductor Materials debt	2.8	2.8
Long-term debt and capital lease obligations, less current portion	879.7	868.2
Short-term Debt			0	68.9				99.3	68.9
Short-term Debt, Weighted Average Interest Rate				6.50%	8.00%
Long-term Debt									1,012.5				1,028.0	10.6	10.4
Long-term Debt, Current Maturities												322.7	305.0	2.8	2.8
Long-term Debt, Excluding Current Maturities									0			689.8	723.0	7.8	7.6
Capital Lease Obligations										84.7	94.0
Capital Lease Obligations, Current			3.9	4.5
Capital Lease Obligations, Noncurrent			80.8	89.5
Sale Leaseback Transaction, Amount Due under Financing Arrangement			1,382.1	1,384.8
Financing Obligations, Current			13.1	16.2
Long-term Finance Obligations			1,369.0	1,368.6
Line of Credit Facility, Amount Outstanding																				250.0	0	247.5	2.5
Other System Financing transactions			223.9	121.9
Other system financing transactions, current			7.5	0.1
Other system financing transactions, noncurrent			216.4	121.8
Non-Recourse Debt		23.1	3,052.5						212.5
Long Term Solar Energy Systems Financing And Capital Leases				2,697.6
Short Term Solar Energy System Financing And Current Portion Of Long Term Solar Energy System Financing And Capital Lease Obligations	449.0	394.7	449.0	394.7
Long Term Solar Energy Systems Financing And Capital Leases Less Current Portion	2,603.5	2,302.9	2,603.5	2,302.9		7.8	7.6
Debt And Capital Lease Obligations Including Solar Energy Systems Financing	3,942.8	3,576.2
Debt And Capital Lease Obligations Including Solar Energy Systems Financing, Current	451.8	397.5
Long Term Debt And Capital Lease Obligations Including Solar Energy Systems Financing	$ 3,491.0	$ 3,178.7