Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
REVENUE	$ 636,196,000	$ 579,179,000	$ 1,879,600,000	$ 1,618,146,000
Cost of services	538,000,000	487,914,000	1,597,764,000	1,378,263,000
General and administrative expenses	58,855,000	52,863,000	164,011,000	139,652,000
OPERATING INCOME	39,341,000	38,402,000	117,825,000	100,231,000
Interest expense	(310,000)	(659,000)	(1,597,000)	(2,088,000)
Interest income	40,000	90,000	227,000	401,000
Other (expense), net	(29,000)	(39,000)	(51,000)	(50,000)
INCOME FROM OPERATIONS BEFORE INCOME TAXES AND EQUITY METHOD INVESTMENTS	39,042,000	37,794,000	116,404,000	98,494,000
Provision for income taxes	(9,303,000)	(9,873,000)	(28,037,000)	(25,229,000)
Equity in earnings (losses) of unconsolidated subsidiaries	0	16,000	(1,000)	4,000
NET INCOME	$ 29,739,000	$ 27,937,000	$ 88,366,000	$ 73,269,000
Class A common stock
BASIC EARNINGS PER SHARE:
Basic earnings per share	$ 0.74	$ 0.70	$ 2.19	$ 1.84
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	0.73	0.69	2.18	1.82
Class B common stock
BASIC EARNINGS PER SHARE:
Basic earnings per share	0.74	0.70	2.19	1.84
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	$ 0.73	$ 0.69	$ 2.18	$ 1.82