Consolidated Balance Sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 294,953,000	$ 369,373,000
Accounts receivable, net	711,357,000	693,372,000
Current portion of notes receivable	35,253,000	35,106,000
Prepaid expenses and other current assets	88,144,000	80,810,000
Total current assets	1,129,707,000	1,178,661,000
Property and equipment, net	101,642,000	93,672,000
Operating lease assets	156,645,000	159,777,000
Goodwill	1,234,879,000	1,202,767,000
Intangible assets, net	41,550,000	38,432,000
Notes receivable, net	61,121,000	69,033,000
Other assets	51,819,000	40,800,000
Total assets	2,777,363,000	2,783,142,000
Current liabilities
Accounts payable, accrued expenses and other	170,066,000	158,936,000
Accrued compensation	455,933,000	416,903,000
Billings in excess of services provided	44,172,000	36,698,000
Total current liabilities	670,171,000	612,537,000
Long-term debt, net	286,131,000	275,609,000
Noncurrent operating lease liabilities	161,677,000	176,378,000
Deferred income taxes	158,342,000	151,352,000
Other liabilities	100,861,000	78,124,000
Total liabilities	1,377,182,000	1,294,000,000
Commitments and contingencies
Stockholders' equity
Preferred stock, $0.01 par value; shares authorized — 5,000; none    outstanding	0	0
Common stock, $0.01 par value; shares authorized — 75,000; shares issued and outstanding — 34,481 (2020) and 37,390 (2019)	345,000	374,000
Additional paid-in capital	0	216,162,000
Retained earnings	1,506,271,000	1,413,453,000
Accumulated other comprehensive loss	(106,435,000)	(140,847,000)
Total stockholders' equity	1,400,181,000	1,489,142,000
Total liabilities and stockholders' equity	$ 2,777,363,000	$ 2,783,142,000
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares outstanding (in shares)	0	0