Fair Value Measurements - Schedule of Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Municipal notes and bonds	$ 67,892	$ 62,684
Total assets	67,892	62,684
Contingent consideration - acquisitions	939	2,060
Foreign currency forward contracts	38	32
Total liabilities	977	2,092
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
Total assets	0	0
Contingent consideration - acquisitions	0	0
Foreign currency forward contracts	0	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	67,892	62,684
Total assets	67,892	62,684
Contingent consideration - acquisitions	0	0
Foreign currency forward contracts	38	32
Total liabilities	38	32
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
Total assets	0	0
Contingent consideration - acquisitions	939	2,060
Foreign currency forward contracts	0	0
Total liabilities	$ 939	$ 2,060