Condensed Consolidating Statement of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$ (307.6)	$ (283.4)
Cash flows from investing activities:
Capital expenditures	(101.2)	(100.3)
Construction of solar energy systems	(261.3)	(193.2)
Purchases of cost and equity method investments	(46.6)	(35.2)
Net proceeds from equity method investments	68.4	3.0
Change in Restricted cash	(16.8)	(1.3)
Payments to Acquire Businesses, Net of Cash Acquired	(7.3)	0
Proceeds from Other Deposits	0.6	4.8
Equity Infusions or investments in subsidiaries	0	0
Other	4.9	(0.1)
Net cash used in investing activities	(359.3)	(322.3)
Cash flows from financing activities:
Cash paid for SunEdison acquisition contingent consideration	(0.8)	(58.0)
Proceeds from solar energy system financing and capital lease obligations	626.4	720.3
Repayments of solar energy system financing and capital lease obligations	(64.4)	(184.0)
Net repayments of customer deposits related to long-term supply agreements	(51.7)	(23.6)
Principal payments on long-term debt	(1.4)	(1.8)
Common stock repurchased	239.6	(0.1)
Dividends to noncontrolling interest	25.9	16.4
(Repayment of) collection of intercompany debt	0	0
Second lien term loan	0	196.0
Debt financing fees	(25.6)	(35.2)
Proceeds from (Payments for) Other Financing Activities	(1.4)	0
Net cash provided by financing activities	746.6	630.0
Effect of exchange rate changes on cash and cash equivalents	(12.0)	(0.3)
Net increase in cash and cash equivalents	67.7	24.0
Cash and cash equivalents at beginning of period	572.6	585.8
Cash and cash equivalents at end of period	640.3	609.8
MEMC, Inc. [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(48.6)	(100.2)
Cash flows from investing activities:
Capital expenditures	(11.4)	(14.7)
Construction of solar energy systems	0	0
Purchases of cost and equity method investments	0	(3.8)
Net proceeds from equity method investments	68.5	7.2
Change in Restricted cash	0	0
Payments to Acquire Businesses, Net of Cash Acquired	0
Proceeds from Other Deposits	0	0
Equity Infusions or investments in subsidiaries	(66.8)	(44.0)
Other	0.7	1.9
Net cash used in investing activities	(9.0)	(53.4)
Cash flows from financing activities:
Cash paid for SunEdison acquisition contingent consideration	0	0
Proceeds from solar energy system financing and capital lease obligations	0	0
Repayments of solar energy system financing and capital lease obligations	0	0
Net repayments of customer deposits related to long-term supply agreements	0	0
Principal payments on long-term debt	0	0
Common stock repurchased	239.6	(0.1)
Dividends to noncontrolling interest	0	0
(Repayment of) collection of intercompany debt	(115.0)	(33.8)
Second lien term loan		196.0
Debt financing fees	0	(12.7)
Proceeds from (Payments for) Other Financing Activities	(0.6)
Net cash provided by financing activities	124.0	149.4
Effect of exchange rate changes on cash and cash equivalents	0	(0.2)
Net increase in cash and cash equivalents	66.4	(4.4)
Cash and cash equivalents at beginning of period	65.1	228.9
Cash and cash equivalents at end of period	131.5	224.5
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	5.5	28.9
Cash flows from investing activities:
Capital expenditures	(8.2)	(16.3)
Construction of solar energy systems	0	0
Purchases of cost and equity method investments	(1.5)	0
Net proceeds from equity method investments	0	0
Change in Restricted cash	(0.5)	(2.1)
Payments to Acquire Businesses, Net of Cash Acquired	0
Proceeds from Other Deposits	0	0
Equity Infusions or investments in subsidiaries	(24.2)	(6.7)
Other	(1.3)	0
Net cash used in investing activities	(35.7)	(25.1)
Cash flows from financing activities:
Cash paid for SunEdison acquisition contingent consideration	(0.8)	(3.8)
Proceeds from solar energy system financing and capital lease obligations	0	8.4
Repayments of solar energy system financing and capital lease obligations	(0.1)	(0.5)
Net repayments of customer deposits related to long-term supply agreements	0	0
Principal payments on long-term debt	0	0
Common stock repurchased	0	0
Dividends to noncontrolling interest	0	0
(Repayment of) collection of intercompany debt	70.4	9.5
Second lien term loan		0
Debt financing fees	0	0
Proceeds from (Payments for) Other Financing Activities	0
Net cash provided by financing activities	69.5	13.6
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	39.3	17.4
Cash and cash equivalents at beginning of period	60.0	58.3
Cash and cash equivalents at end of period	99.3	75.7
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(431.7)	(152.5)
Cash flows from investing activities:
Capital expenditures	(81.6)	(69.3)
Construction of solar energy systems	(97.1)	(243.3)
Purchases of cost and equity method investments	(45.1)	(31.4)
Net proceeds from equity method investments	(0.1)	(4.2)
Change in Restricted cash	(16.3)	0.8
Payments to Acquire Businesses, Net of Cash Acquired	(7.3)
Proceeds from Other Deposits	0.6	4.8
Equity Infusions or investments in subsidiaries	91.0	50.7
Other	8.5	(11.5)
Net cash used in investing activities	(147.4)	(303.4)
Cash flows from financing activities:
Cash paid for SunEdison acquisition contingent consideration	0	(54.2)
Proceeds from solar energy system financing and capital lease obligations	626.4	711.9
Repayments of solar energy system financing and capital lease obligations	(64.3)	(183.5)
Net repayments of customer deposits related to long-term supply agreements	(51.7)	(23.6)
Principal payments on long-term debt	(1.4)	(1.8)
Common stock repurchased	0	0
Dividends to noncontrolling interest	25.9	16.4
(Repayment of) collection of intercompany debt	44.6	24.3
Second lien term loan		0
Debt financing fees	(25.6)	(22.5)
Proceeds from (Payments for) Other Financing Activities	(0.8)
Net cash provided by financing activities	553.1	467.0
Effect of exchange rate changes on cash and cash equivalents	(12.0)	(0.1)
Net increase in cash and cash equivalents	(38.0)	11.0
Cash and cash equivalents at beginning of period	447.5	298.6
Cash and cash equivalents at end of period	409.5	309.6
Consolidating Adjustments [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	167.2	(59.6)
Cash flows from investing activities:
Capital expenditures	0	0
Construction of solar energy systems	(164.2)	50.1
Purchases of cost and equity method investments	0	0
Net proceeds from equity method investments	0	0
Change in Restricted cash	0	0
Payments to Acquire Businesses, Net of Cash Acquired	0
Proceeds from Other Deposits	0	0
Equity Infusions or investments in subsidiaries	0	0
Other	(3.0)	9.5
Net cash used in investing activities	(167.2)	59.6
Cash flows from financing activities:
Cash paid for SunEdison acquisition contingent consideration	0	0
Proceeds from solar energy system financing and capital lease obligations	0	0
Repayments of solar energy system financing and capital lease obligations	0	0
Net repayments of customer deposits related to long-term supply agreements	0	0
Principal payments on long-term debt	0	0
Common stock repurchased	0	0
Dividends to noncontrolling interest	0	0
(Repayment of) collection of intercompany debt	0	0
Second lien term loan		0
Debt financing fees	0	0
Proceeds from (Payments for) Other Financing Activities	0
Net cash provided by financing activities	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0