Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 304,206	$ 369,373
Accounts receivable:
Billed receivables	578,722	540,584
Unbilled receivables	435,234	418,288
Allowance for doubtful accounts and unbilled services	(299,038)	(265,500)
Accounts receivable, net	714,918	693,372
Current portion of notes receivable	32,279	35,106
Prepaid expenses and other current assets	75,938	80,810
Total current assets	1,127,341	1,178,661
Property and equipment, net	91,753	93,672
Operating lease assets	152,245	159,777
Goodwill	1,196,162	1,202,767
Other intangible assets, net	33,588	38,432
Notes receivable, net	64,646	69,033
Other assets	39,172	40,800
Total assets	2,704,907	2,783,142
Current liabilities
Accounts payable, accrued expenses and other	163,162	158,936
Accrued compensation	314,018	416,903
Billings in excess of services provided	40,288	36,698
Total current liabilities	517,468	612,537
Long-term debt, net	315,808	275,609
Noncurrent operating lease liabilities	161,753	176,378
Deferred income taxes	155,293	151,352
Other liabilities	75,482	78,124
Total liabilities	1,225,804	1,294,000
Commitments and contingent liabilities (Note 10)
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 — 36,710 (2020) and 37,390 (2019)	367	374
Additional paid-in capital	122,743	216,162
Retained earnings	1,518,374	1,413,453
Accumulated other comprehensive loss	(162,381)	(140,847)
Total stockholders' equity	1,479,103	1,489,142
Total liabilities and stockholders' equity	$ 2,704,907	$ 2,783,142