Fair Value Measurements - Schedule of Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Municipal notes and bonds	$ 62,684	$ 109,589
Foreign currency forward contracts		45
Total assets	62,684	109,634
Contingent consideration - acquisitions	2,060	2,593
Foreign currency forward contracts	32
Total liabilities	2,092	2,593
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Municipal notes and bonds	0	0
Foreign currency forward contracts		0
Total assets	0	0
Contingent consideration - acquisitions	0	0
Foreign currency forward contracts	0
Total liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Municipal notes and bonds	62,684	109,589
Foreign currency forward contracts		45
Total assets	62,684	109,634
Contingent consideration - acquisitions	0	0
Foreign currency forward contracts	32
Total liabilities	32	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Municipal notes and bonds	0	0
Foreign currency forward contracts		0
Total assets	0	0
Contingent consideration - acquisitions	2,060	2,593
Foreign currency forward contracts	0
Total liabilities	$ 2,060	$ 2,593