Fair Value Measurements - Fair Value of Financial Assets and Liabilities (Detail) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Quoted Price in Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets remeasured	$ 0	$ 0
Liabilities remeasured	0	0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	24,931,000	24,449,000
Fair value of financial assets, Total	27,032,000	26,864,000
Fair value of other current liabilities	34,313,000
Fair value of other non-current liabilities	52,782,000	80,092,000
Fair value of financial liabilities, Total	87,095,000	82,507,000
Fair Value, Measurements, Recurring \| NQDC Plan liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	2,101,000	2,415,000
Fair value of other non-current liabilities	22,022,000	19,962,000
Fair Value, Measurements, Recurring \| Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	32,212,000
Fair value of other non-current liabilities	30,760,000	60,130,000
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	24,931,000	24,449,000
Fair value of financial assets, Total	27,032,000	26,864,000
Fair value of other current liabilities	2,101,000
Fair value of other non-current liabilities	22,022,000	19,962,000
Fair value of financial liabilities, Total	24,123,000	22,377,000
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| NQDC Plan liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	2,101,000	2,415,000
Fair value of other non-current liabilities	22,022,000	19,962,000
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	0
Fair value of other non-current liabilities	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	0	0
Fair value of financial assets, Total	0	0
Fair value of other current liabilities	32,212,000
Fair value of other non-current liabilities	30,760,000	60,130,000
Fair value of financial liabilities, Total	62,972,000	60,130,000
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| NQDC Plan liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	0	0
Fair value of other non-current liabilities	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	32,212,000
Fair value of other non-current liabilities	30,760,000	60,130,000
Fair Value, Measurements, Recurring \| NQDC Plan assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	2,101,000	2,415,000
Fair value of other non-current assets	22,022,000	19,962,000
Fair Value, Measurements, Recurring \| NQDC Plan assets \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	2,101,000	2,415,000
Fair value of other non-current assets	22,022,000	19,962,000
Fair Value, Measurements, Recurring \| NQDC Plan assets \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	0	0
Fair value of other non-current assets	0	0
Fair Value, Measurements, Recurring \| Restricted Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	2,909,000	4,487,000
Fair Value, Measurements, Recurring \| Restricted Investments \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	2,909,000	4,487,000
Fair Value, Measurements, Recurring \| Restricted Investments \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	$ 0	$ 0

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Topic 820
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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial and nonfinancial obligations.

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