Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of deferred compensation plan	$ 127,332	$ 106,851
Available-for-sale debt securities	25,708	60,659	$ 56,556
Deferred compensation plan liabilities	(127,332)	(106,851)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets of deferred compensation plan	127,332	106,851
Available-for-sale debt securities	25,708	60,659
Deferred compensation plan liabilities	(127,332)	(106,851)
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps, net	(2,565)	(525)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent purchase price liabilities	$ (54,391)	$ (32,089)