Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2020		Dec. 31, 2019
Deferred tax assets
Loss carryforwards		$ 423,013	[1]	$ 343,614
Tax credits		88,433	[2]	98,098
Accrued expenses		47,569		46,846
Pension plan benefits expense		21,735		17,310
Warranty reserves		11,083		12,961
Depreciation and amortization		6,363		6,112
Equity compensation		4,701		4,685
Inventory valuation		1,799		1,069
Deferred revenue		9,705		8,951
Leases		10,872		13,876
Other deferred tax assets, net		10,817		9,777
Total deferred tax assets		636,090		563,299
Valuation allowance		(503,859)	[1]	(427,030)
Total deferred tax assets, net of valuation allowance		132,231		136,269
Deferred tax liabilities
Depreciation and amortization		(39,995)		(54,663)
Leases		(10,046)		(12,976)
Other deferred tax liabilities, net		(7,969)		(6,540)
Total deferred tax liabilities		(58,010)		(74,179)
Net deferred tax assets		74,221		$ 62,090
Deferred tax assets, tax credit carryforwards, general business	[2]	46,900
Deferred tax assets, tax credit carryforwards, foreign	[2]	50,800
Deferred tax assets, tax credit carryforwards, other	[2]	38,200
U.S. federal
Deferred tax liabilities
Loss carryforwards by Jurisdiction	[1]	125,300
LUXEMBOURG
Deferred tax liabilities
Loss carryforwards by Jurisdiction	[1]	$ 1,400,000

[1] For tax return purposes at December 31, 2020, we had U.S. federal loss carryforwards of $125.3 million, which begin to expire in the year 2021. At December 31, 2020, we have net operating loss carryforwards in Luxembourg of $1.4 billion, the majority of which can be carried forward indefinitely, offset by a full valuation allowance. The remaining portion of the loss carryforwards are composed primarily of losses in various other state and foreign jurisdictions. The majority of these losses can be carried forward indefinitely. At December 31, 2020, there was a valuation allowance of $503.9 million primarily associated with foreign loss carryforwards and foreign tax credit carryforwards (discussed below).

[2] For tax return purposes at December 31, 2020, we had: (1) U.S. general business credits of $46.9 million, which begin to expire in 2022; (2) U.S. foreign tax credits of $50.8 million, which begin to expire in 2024; and (3) state tax credits of $38.2 million, which begin to expire in 2021.