Fair Value Measurements - Schedule of Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Municipal notes and bonds	$ 70,602	$ 62,684
Foreign currency forward contracts	13
Total assets	70,615	62,684
Contingent consideration - acquisitions	2,060	2,060
Foreign currency forward contracts		32
Total liabilities	2,060	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
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	70,602	62,684
Foreign currency forward contracts	13
Total assets	70,615	62,684
Contingent consideration - acquisitions	0	0
Foreign currency forward contracts		32
Total liabilities	0	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
Foreign currency forward contracts	0
Total assets	0	0
Contingent consideration - acquisitions	2,060	2,060
Foreign currency forward contracts		0
Total liabilities	$ 2,060	$ 2,060