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Debt and Credit Sources - Narrative (Details)				1 Months Ended		3 Months Ended	9 Months Ended
Debt and Credit Sources - Narrative (Details)	Sep. 01, 2020 $ / shares shares	Oct. 29, 2019 USD ($)	Jun. 28, 2018 USD ($)	Dec. 31, 2015 USD ($) $ / shares	Jun. 29, 2014	Sep. 27, 2020 USD ($)	Sep. 27, 2020 USD ($)	Sep. 29, 2019 USD ($)	Dec. 29, 2019 USD ($)	Sep. 27, 2019 MW	Mar. 29, 2019 USD ($)	Dec. 28, 2014	Jun. 30, 2014 USD ($) $ / shares	Sep. 30, 2011 USD ($)	Dec. 31, 2010 USD ($)
Debt Instrument [Line Items]
Debt face amount						$ 894,773,000	$ 894,773,000		$ 986,244,000
Cash paid for repurchase of convertible debt							95,178,000	$ 0
Non-recourse financing arrangements						15,700,000	15,700,000
Convertible Debt
Debt Instrument [Line Items]
Debt face amount						726,583,000	726,583,000		825,000,000
CEDA loan
Debt Instrument [Line Items]
Interest rate															8.50%
Revolving Credit Facility \| Credit Agricole
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 55,000,000.0
Fair market value limit		67.00%
Commitment fee		0.05%
Guaranty fee rate		0.25%
Revolving Credit Facility \| Credit Agricole \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread		0.25%
Revolving Credit Facility \| Credit Agricole \| Maximum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread		0.60%
Letter of Credit \| Credit Agricole
Debt Instrument [Line Items]
Long-term line of credit						$ 0	$ 0		0
0.875% debentures due 2021
Debt Instrument [Line Items]
Interest rate						0.875%	0.875%						0.875%
Debt face amount													$ 400,000,000.0
Conversion ratio	25.1388				20.5071
Debt instrument, convertible, conversion price (in dollars per share) \| $ / shares	$ 39.78												$ 48.76
Shares to be acquired \| shares	4,865,886
Convertible debt repurchased						$ 8,100,000	$ 98,400,000
Cash paid for repurchase of convertible debt							95,100,000
Gain on extinguishment of debt						$ 100,000
0.875% debentures due 2021 \| Total
Debt Instrument [Line Items]
Debt face amount													$ 250,000,000.0
Convertible debt repurchased							$ 56,400,000
0.875% debentures due 2021 \| Convertible Debt
Debt Instrument [Line Items]
Interest rate						0.875%	0.875%					0.875%
Debt face amount						$ 301,583,000	$ 301,583,000		400,000,000
4.00% debentures due 2023
Debt Instrument [Line Items]
Interest rate				4.00%		4.00%	4.00%
Debt face amount				$ 425,000,000.0
Conversion ratio	40.1552			32.7568
Debt instrument, convertible, conversion price (in dollars per share) \| $ / shares	$ 24.90			$ 30.53
Shares to be acquired \| shares	4,015,515
4.00% debentures due 2023 \| Total
Debt Instrument [Line Items]
Debt face amount				$ 100,000,000.0
4.00% debentures due 2023 \| Convertible Debt
Debt Instrument [Line Items]
Debt face amount						$ 425,000,000	$ 425,000,000		425,000,000
Safe Harbor Panels Inventory
Debt Instrument [Line Items]
Interest rate										7.50%
Inventory financed \| MW										200
Long-term line of credit						96,800,000	96,800,000
Repayments of debt						2,600,000	4,200,000
CEDA loan
Debt Instrument [Line Items]
Debt face amount						30,000,000	30,000,000		30,000,000						$ 30,000,000.0
Debt, fair value						30,600,000	30,600,000
September 2011 Letter of Credit \| Letter of Credit \| Deutsche Bank
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity														$ 200,000,000.0
Letters of credit outstanding, amount						2,600,000	2,600,000		$ 3,600,000
March 2019 Revolving Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term line of credit						25,200,000	25,200,000
Repayments of debt						28,100,000	40,400,000
Line of credit facility, maximum borrowing capacity											$ 60,000,000.0
Proceeds from lines of credit						25,300,000	46,400,000
June 2018 Facility Agreement With SunTrust Bank \| Line of Credit \| SunTrust Bank
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 75,000,000.0	$ 75,000,000.0
Current borrowing capacity			$ 75,000,000.0
June 2018 Facility Agreement With SunTrust Bank \| Line of Credit \| SunTrust Bank \| Maximum
Debt Instrument [Line Items]
Expiration period			3 years