Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of Assets and Liabilities at Fair Value on Recurring Basis (Parenthetical) (Detail)

v3.19.1
Fair Value Measurements - Schedule of Assets and Liabilities at Fair Value on Recurring Basis (Parenthetical) (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Recurring [Member] | Maximum [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Earn-out period for contingent consideration 7 years  
Recurring [Member] | Minimum [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Earn-out period for contingent consideration 3 years  
Contingent Consideration [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Beginning balance $ 2,875 $ 0
Contingent consideration in connection with acquisitions 0 2,674
Change in fair value of contingent consideration 48 201
Payments of contingent consideration 0 0
Ending balance $ 2,923 $ 2,875