Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain on fair value adjustment	$ 500	$ 21,900
Foreign exchange gains (losses)	1,700	(500)
Acquisition-related contingent consideration accrual	9,490	16,851
Payment of contingent consideration	5,180	0	$ 0
Acquisition related contingent consideration	9,490	4,963
Additional obligations	4,637	3,721
Senior Notes 5.50 Percent Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long term notes	$ 312,200	311,900
Convertible Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long term notes		$ 305,700

Amount of asset retirement obligations incurred during the period.

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Amount of liability recognized arising from contingent consideration in a business combination.

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Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

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Amount before tax of foreign currency transaction unrealized gain (loss) recognized in the income statement.

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Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Amount of cash outflow, not made soon after acquisition date of business combination, to settle contingent consideration liability up to amount recognized at acquisition date, including, but not limited to, measurement period adjustment and less amount paid soon after acquisition date.

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