Note 14. Debt (Details) $ in Thousands, AUD in Millions, ₨ in Billions, ¥ in Billions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 INR (₨)	Nov. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2017 JPY (¥)	Mar. 31, 2017 USD ($)	Mar. 31, 2017 AUD	Dec. 31, 2016 INR (₨)	Dec. 31, 2016 JPY (¥)	Nov. 30, 2016 USD ($)	Nov. 30, 2016 INR (₨)	Mar. 31, 2016 USD ($)	Mar. 31, 2016 INR (₨)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 JPY (¥)	Mar. 31, 2015 USD ($)	Mar. 31, 2015 INR (₨)
Long-term Debt [Abstract]
Long-term debt, gross	$ 406,544	$ 197,253
Less: unamortized discount discount and issuance costs	(13,004)	(8,865)
Total long-term debt	393,540	188,388
Less: current portion	(13,075)	(27,966)
Noncurrent portion	380,465	160,422
Interest Paid	10,200	4,300	$ 15,200
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	13,062
Long-term Debt, Maturities, Repayments of Principal in Year Two	11,137
Long-term Debt, Maturities, Repayments of Principal in Year Three	19,639
Long-term Debt, Maturities, Repayments of Principal in Year Four	10,179
Long-term Debt, Maturities, Repayments of Principal in Year Five	58,898
Long-term Debt, Maturities, Repayments of Principal after Year Five	293,473
Total long-term debt future principal payments	$ 406,388
Revolving Credit Facility [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	USD
Revolving credit facility	$ 0	0
Line of Credit Facility, Current Borrowing Capacity	500,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 750,000
Debt Instrument, Description of Variable Rate Basis	Borrowings under the amended and restated facility bear interest at (i) London Interbank Offered Rate (“LIBOR”), adjusted for Eurocurrency reserve requirements, plus a margin of 2.00% or (ii) a base rate as defined in the credit agreement plus a margin of 1.00% depending on the type of borrowing requested
Letters of Credit Outstanding, Amount	$ 57,500	125,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.30%
Fronting fee	0.125%
Line of Credit Facility, Letter of Credit Sub-Limit	$ 400,000
Debt Instrument, Interest Rate, Stated Percentage	3.56%			3.56%
Revolving Credit Facility [Member] | Minimum [Member]
Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Revolving Credit Facility [Member] | Maximum [Member]
Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Luz del Norte Credit Facilities [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	USD
Long-term debt, gross	$ 185,675	180,939
Luz del Norte Credit Facilities [Member] | OPIC [Member] | Parque Solar Fotovoltaico Luz del Norte SpA [Member]
Long-term Debt [Abstract]
Long-term debt, gross	139,000	125,100
Luz del Norte Credit Facilities [Member] | IFC [Member] | Parque Solar Fotovoltaico Luz del Norte SpA [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 46,600	42,200
Luz del Norte Credit Facilities [Member] | OPIC and IFC [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	Variable rate loans at 91-Day U.S. Treasury Bill Yield or LIBOR plus 3.50%
Debt Instrument, Description of Fixed Rate Basis	Fixed rate loans at bank rate plus 3.50%
Debt Instrument, Basis Spread on Fixed Rate	3.50%
Debt Instrument, Basis Spread on Variable Rate	3.50%
Luz del Norte Credit Facilities [Member] | OPIC and IFC [Member] | Parque Solar Fotovoltaico Luz del Norte SpA [Member]
Long-term Debt [Abstract]
Debt Instrument, Collateral Amount	$ 330,500
Luz del Norte Credit Facilities [Member] | Banco de Crédito e Inversiones [Member] | Parque Solar Fotovoltaico Luz del Norte SpA [Member]
Long-term Debt [Abstract]
Long-term debt, gross		13,700
Luz del Norte Credit Facilities [Member] | Fixed Rate Term Loan [Member] | OPIC and IFC [Member]
Long-term Debt [Abstract]
Long-term debt, gross	165,400
Luz del Norte Credit Facilities [Member] | Variable Rate Term Loan [Member] | OPIC and IFC [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 20,300
Ishikawa Credit Agreement [Domain]
Long-term Debt [Abstract]
Debt Instrument, Currency	JPY
Long-term debt, gross	$ 121,446	0
Ishikawa Credit Agreement [Domain] | Mizuho Bank [Member] | FS Japan Project 12 GK [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 121,400	0
Line of Credit Facility, Current Borrowing Capacity		242,600									¥ 27.3
Line of Credit Facility, Senior Loan Sub-Limit		213,300									24.0
Line of Credit Facility, Consumption Tax Sub-Limit		18,700									2.1
Line of Credit Facility, Letter of Credit Sub-Limit		10,700									¥ 1.2
Japan Credit Facility [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	JPY
Long-term debt, gross	$ 10,710	9,477
Japan Credit Facility [Member] | Mizuho Bank [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	1-month TIBOR plus 0.5%
Debt Instrument, Basis Spread on Variable Rate	0.50%
Japan Credit Facility [Member] | Mizuho Bank [Member] | First Solar Japan GK [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 10,700	9,500
Line of Credit Facility, Current Borrowing Capacity																$ 35,600	¥ 4.0
Tochigi Credit Facility [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	JPY
Long-term debt, gross	$ 0	0
Tochigi Credit Facility [Member] | Mizuho Bank [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	3-month TIBOR plus 1.0%
Debt Instrument, Basis Spread on Variable Rate	1.00%
Tochigi Credit Facility [Member] | Mizuho Bank [Member] | First Solar Japan GK [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 0
Line of Credit Facility, Current Borrowing Capacity						$ 62,200	¥ 7.0
Mahabubnagar Credit Facility [Member] | Axis Bank [Member] | Mahabubnagar Solar Parks Private Limited [Member]
Long-term Debt [Abstract]
Long-term debt, gross					$ 7,400
Marikal and Mahabubnagar Credit Facilities [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	INR
Long-term debt, gross	$ 7,384	4,067
Marikal and Mahabubnagar Credit Facilities [Member] | Axis Bank [Member] | Marikal Solar Parks Private Limited and Mahabubnagar Solar Parks Private Limited [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 7,400	4,100
Line of Credit Facility, Current Borrowing Capacity																		$ 17,200	₨ 1.1
Letters of Credit Outstanding, Amount		11,200		₨ 0.0						₨ 0.8
Line of Credit Facility, Letter of Credit Sub-Limit																		$ 12,500	₨ 0.8
Marikal Credit Facility [Member] | Axis Bank [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	Bank rate plus 2.35%
Debt Instrument, Basis Spread on Variable Rate	2.35%
Marikal Credit Facility [Member] | Axis Bank [Member] | Marikal Solar Parks Private Limited [Member]
Long-term Debt [Abstract]
Debt Instrument, Collateral Amount	$ 89,700
Polepally Credit Facility [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	INR
Long-term debt, gross	$ 0	2,208
Polepally Credit Facility [Member] | Axis Bank [Member] | Polepally Solar Parks Private Limited [Member]
Long-term Debt [Abstract]
Long-term debt, gross		2,200			$ 1,500
Line of Credit Facility, Current Borrowing Capacity														$ 20,400	₨ 1.3
Letters of Credit Outstanding, Amount		15,300								1.0
Line of Credit Facility, Letter of Credit Sub-Limit														$ 17,200	₨ 1.1
Hindupur Credit Facility [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	INR
Long-term debt, gross	$ 18,722	0
Hindupur Credit Facility [Member] | Yes Bank Limited [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	Bank rate plus 1.0%
Debt Instrument, Basis Spread on Variable Rate	1.00%
Hindupur Credit Facility [Member] | Yes Bank Limited [Member] | Hindupur Solar Parks Limited [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 18,700	0
Line of Credit Facility, Current Borrowing Capacity												$ 67,300	₨ 4.3
Letters of Credit Outstanding, Amount	45,400			₨ 2.9						₨ 0.0
Debt Instrument, Collateral Amount	$ 101,400
Line of Credit Facility, Letter of Credit Sub-Limit												$ 50,100	₨ 3.2
Manildra Credit Facility [Domain]
Long-term Debt [Abstract]
Debt Instrument, Currency	AUD
Long-term debt, gross	$ 62,451	0
Manildra Credit Facility [Domain] | Société Générale S.A. and The Bank of Tokyo-Mitsubishi UFJ, Ltd. [Member] | Manildra Finco Pty Ltd [Member]
Long-term Debt [Abstract]
Long-term debt, gross	$ 62,500
Line of Credit Facility, Current Borrowing Capacity								$ 63,800	AUD 81.7
Line of Credit Facility, Construction Loan Sub-Limit								59,100	75.7
Line of Credit Facility, Goods and Service Tax Sub-Limit								$ 4,700	AUD 6.0
Capital Lease Obligations [Member]
Long-term Debt [Abstract]
Debt Instrument, Currency	Various
Long-term debt, gross	$ 156	$ 562
Senior Loan Facility [Member] | Ishikawa Credit Agreement [Domain] | Mizuho Bank [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	Senior loan facility at 6-month TIBOR plus 0.75% (2)
Debt Instrument, Basis Spread on Variable Rate	0.75%
Consumption Tax Facility [Member] | Ishikawa Credit Agreement [Domain] | Mizuho Bank [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	Consumption tax facility at 3-month TIBOR plus 0.5%
Debt Instrument, Basis Spread on Variable Rate	0.50%
Construction Loans [Member] | Manildra Credit Facility [Domain] | Société Générale S.A. and The Bank of Tokyo-Mitsubishi UFJ, Ltd. [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	Construction loan facility at 1-month BBSY plus 1.70% (2)
Debt Instrument, Basis Spread on Variable Rate	1.70%
Goods and Service Tax Facility [Member] | Manildra Credit Facility [Domain] | Société Générale S.A. and The Bank of Tokyo-Mitsubishi UFJ, Ltd. [Member]
Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	GST facility at 1-month BBSY plus 1.60%
Debt Instrument, Basis Spread on Variable Rate	1.60%