Segment Reporting - Reconciliation of Net Income To Adjusted Segment Earnings before Interest, Taxes, Depreciation and Amortization (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net income	$ 64,496	$ 56,747
Income tax provision	20,247	16,465
Interest income and other	(1,034)	(5,017)
Interest expense	4,797	4,861
Adjusted Segment EBITDA	125,446	106,124
Segment Reconciling Items
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net income	64,496	56,747
Income tax provision	20,247	16,465
Interest income and other	(1,034)	(5,017)
Interest expense	4,797	4,861
Unallocated corporate expenses	26,710	23,591
Segment depreciation expense	7,430	7,146
Amortization of intangible assets	2,800	2,331
Adjusted Segment EBITDA	$ 125,446	$ 106,124