Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 189,106	$ 312,069
Accounts receivable:
Billed receivables	557,412	437,797
Unbilled receivables	429,285	319,205
Allowance for doubtful accounts and unbilled services	(243,295)	(202,394)
Accounts receivable, net	743,402	554,608
Current portion of notes receivable	29,606	29,228
Prepaid expenses and other current assets	57,141	69,448
Total current assets	1,019,255	965,353
Property and equipment, net	87,376	84,577
Operating lease assets	155,100
Goodwill	1,172,557	1,172,316
Other intangible assets, net	30,920	34,633
Notes receivable, net	76,150	84,471
Other assets	30,005	37,771
Total assets	2,571,363	2,379,121
Current liabilities
Accounts payable, accrued expenses and other	138,344	104,600
Accrued compensation	280,512	333,536
Billings in excess of services provided	45,022	44,434
Total current liabilities	463,878	482,570
Long-term debt, net	290,531	265,571
Noncurrent operating lease liabilities	177,110
Deferred income taxes	155,799	155,088
Other liabilities	65,033	127,067
Total liabilities	1,152,351	1,030,296
Commitments and contingent liabilities
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 — 37,612 (2019) and 38,147 (2018)	376	381
Additional paid-in capital	242,075	299,534
Retained earnings	1,323,970	1,196,727
Accumulated other comprehensive loss	(147,409)	(147,817)
Total stockholders' equity	1,419,012	1,348,825
Total liabilities and stockholders' equity	$ 2,571,363	$ 2,379,121