Consolidated Statements Of Income Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Consolidated Statements Of Income [Abstract]
Service revenues and sales	$ 530,549	$ 527,360
Cost of services provided and goods sold (excluding depreciation)	336,552	340,473
Selling, general and administrative expenses	89,954	91,599
Depreciation	12,138	11,715
Amortization	2,518	2,510
Other operating expenses	13	622
Total costs and expenses	441,175	446,919
Income from operations	89,374	80,441
Interest expense	(810)	(381)
Other (expense)/income - net	(3,862)	3,602
Income before income taxes	84,702	83,662
Income taxes	(20,533)	(18,262)
Net income	$ 64,169	$ 65,400
Earnings Per Share:
Net income	$ 4.28	$ 4.08
Average number of shares outstanding	14,986	16,010
Diluted Earnings Per Share:
Net income	$ 4.22	$ 4.01
Average number of shares outstanding	15,192	16,310
Cash Dividends Per Share	$ 0.36	$ 0.34