Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents (Note 9)	$ 162,675	$ 6,158
Accounts receivable	126,853	143,827
Inventories	7,095	7,462
Prepaid income taxes	6,603	10,074
Prepaid expenses	26,177	23,150
Total current assets	329,403	190,671
Investments of deferred compensation plans held in trust (Notes 14 and 16)	88,811	77,446
Properties and equipment, at cost, less accumulated depreciation (Note 12)	187,820	175,763
Lease right of use asset (Note 13)	123,448	111,652
Identifiable intangible assets less accumulated amortization (Note 6)	118,085	126,370
Goodwill	578,585	577,367
Other assets	8,759	9,048
Total Assets	1,434,911	1,268,317
Current liabilities
Accounts payable	54,234	51,101
Income taxes	9,464	131
Accrued insurance	54,703	50,328
Accrued compensation	91,282	70,814
Accrued legal	10,632	6,941
Short-term lease liability (Note 13)	36,200	39,280
Other current liabilities	42,593	43,625
Total current liabilities	299,108	262,220
Deferred income taxes (Note 11)	20,664	18,504
Long-term debt (Note 3)		90,000
Deferred compensation liabilities (Note 14)	88,456	76,446
Long-term lease liability (Note 13)	99,210	86,656
Other liabilities	26,273	7,883
Total Liabilities	533,711	541,709
Commitments and contingencies (Note 17)
STOCKHOLDERS' EQUITY
Capital stock - authorized 80,000,000 shares $1 par; issued 36,258,638 shares (2019 - 35,810,528 shares)	36,259	35,811
Paid-in capital	961,404	860,671
Retained earnings	1,723,777	1,425,752
Treasury stock - 20,351,562 shares (2019 - 19,867,220 shares), at cost	(1,822,579)	(1,597,940)
Deferred compensation payable in Company stock (Note 14)	2,339	2,314
Total Stockholders' Equity	901,200	726,608
Total Liabilities and Stockholders' Equity	$ 1,434,911	$ 1,268,317