Income Taxes - Narrative and Unrecognised Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Increase (decrease) in valuation allowance	$ 159,700	$ (66,500)	$ 2,200
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at beginning of period	24,251	22,395
Additions related to prior periods tax positions	3,953	726
Reductions related to prior periods tax positions	(216)	(82)
Additions related to current period tax positions	4,119	1,835
Settlements	(201)
Reductions due to lapse of applicable statute of limitations	(397)	(557)
Currency translation adjustment	88
Currency translation adjustment		(66)
Balance at end of period	$ 31,597	24,251	22,395
Interest and penalties as a component of income tax expense		$ 200	$ 100

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Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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