Segment Reporting - Reconciliation of Net Income to Adjusted Segment Earnings before Interest, Taxes, Depreciation and Amortization (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting [Abstract]
Net income	$ 48,174	$ 56,747	$ 64,598	$ 62,645	$ 104,921	$ 127,243
Add back:
Income tax provision	14,470		21,313		30,935	41,243
Interest income and other	(2,202)		(2,609)		(7,219)	(2,768)
Interest expense	5,157		4,793		10,018	9,539
Unallocated corporate expenses	30,276		28,892		53,867	50,995
Segment depreciation expense	7,191		6,556		14,337	12,920
Amortization of intangible assets	2,314		1,852		4,645	3,713
Total Adjusted Segment EBITDA	$ 105,380		$ 125,395		$ 211,504	$ 242,885