Fair Value of Financial Assets and Liabilities - Changes in Level 3 Liabilities Measured at Fair Value on Recurring Basis (Detail) - Level 3 [Member] - Accounts Payable Accrued and Other Liabilities [Member] - Contingent Consideration [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Opening Balance, Liabilities	$ 42,152	$ 29,784	$ 45,984	$ 41,386
Total realized and unrealized gains (losses) included in Net income (loss), Liabilities	(533)	(437)	(4,242)	(761)
Unrealized gains (losses) included in Other comprehensive income (loss), Liabilities	7	15	14	12
Purchases/ Issuances, Liabilities				22
Sales/ Settlements, Liabilities	(1,652)		(9,186)	(11,951)
Closing Balance, Liabilities	41,026	30,206	41,026	30,206
Unrealized gains (losses) for the period on Level 3 Liabilities Outstanding	$ (533)	$ (437)	$ (4,242)	$ (761)