Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 505,867,000	$ 189,961,000
Accounts receivable:
Billed receivables	477,408,000	390,996,000
Unbilled receivables	366,997,000	312,569,000
Allowance for doubtful accounts and unbilled services	(221,008,000)	(180,687,000)
Accounts receivable, net	623,397,000	522,878,000
Current portion of notes receivable	31,318,000	25,691,000
Prepaid expenses and other current assets	45,931,000	55,649,000
Total current assets	1,206,513,000	794,179,000
Property and equipment, net	82,476,000	75,075,000
Goodwill	1,175,929,000	1,204,803,000
Other intangible assets, net	36,729,000	44,150,000
Notes receivable, net	89,342,000	98,105,000
Other assets	37,849,000	40,929,000
Total assets	2,628,838,000	2,257,241,000
Current liabilities
Accounts payable, accrued expenses and other	116,222,000	94,873,000
Accrued compensation	286,149,000	268,513,000
Billings in excess of services provided	38,178,000	46,942,000
Current portion of long-term debt, net	296,851,000	0
Total current liabilities	737,400,000	410,328,000
Long-term debt, net	263,317,000	396,284,000
Deferred income taxes	153,045,000	124,471,000
Other liabilities	123,601,000	134,187,000
Total liabilities	1,277,363,000	1,065,270,000
Commitments and contingent liabilities (Note 11)
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 — 38,356 (2018) and 37,729 (2017)	384,000	377,000
Additional paid-in capital	315,720,000	266,035,000
Retained earnings	1,173,003,000	1,045,774,000
Accumulated other comprehensive loss	(137,632,000)	(120,215,000)
Total stockholders' equity	1,351,475,000	1,191,971,000
Total liabilities and stockholders' equity	$ 2,628,838,000	$ 2,257,241,000

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business.