Summary of Significant Accounting Policies - Aggregate Fair Values of Outstanding and Unearned Contingent Consideration Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Contingent consideration liabilities, current portion	$ 77,618	$ 0
Level 3
Business Acquisition [Line Items]
Contingent consideration liabilities	84,200	70,800
Level 3 \| Recurring
Business Acquisition [Line Items]
Contingent consideration liabilities	84,160	70,756
Accounts payable and accrued expenses \| Level 3 \| Recurring
Business Acquisition [Line Items]
Contingent consideration liabilities, current portion	77,618	0
Insurance and other non-current liabilities \| Level 3 \| Recurring
Business Acquisition [Line Items]
Contingent consideration liabilities, noncurrent	$ 6,542	$ 70,756

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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
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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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