Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
REVENUE	$ 648,578,000	$ 632,492,000	$ 1,281,802,000	$ 1,243,404,000
Cost of services	552,868,000	539,473,000	1,095,585,000	1,059,764,000
General and administrative expenses	47,048,000	53,433,000	95,134,000	105,156,000
OPERATING INCOME	48,662,000	39,586,000	91,083,000	78,484,000
Interest expense	(366,000)	(632,000)	(720,000)	(1,287,000)
Interest income	39,000	137,000	79,000	187,000
Other expense, net	(12,000)	0	(133,000)	(22,000)
INCOME FROM OPERATIONS BEFORE INCOME TAXES AND EQUITY METHOD INVESTMENTS	48,323,000	39,091,000	90,309,000	77,362,000
Provision for income taxes	(11,714,000)	(9,143,000)	(21,371,000)	(18,734,000)
Equity in losses of unconsolidated subsidiaries	0	0	(1,000)	(1,000)
NET INCOME	$ 36,609,000	$ 29,948,000	$ 68,937,000	$ 58,627,000
Class A common stock
BASIC EARNINGS PER SHARE:
Basic earnings per share	$ 0.90	$ 0.74	$ 1.70	$ 1.46
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	0.89	0.74	1.68	1.44
Class B common stock
BASIC EARNINGS PER SHARE:
Basic earnings per share	0.90	0.74	1.70	1.46
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	$ 0.89	$ 0.74	$ 1.68	$ 1.44