CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 853,241	$ 770,560
Accounts receivable, net of allowance of $1,519 and $1,557, respectively	339,112	297,685
Unbilled revenues	142,949	104,652
Prepaid expenses and other current assets	29,390	26,171
Total current assets	1,364,692	1,199,068
Property and equipment, net	115,321	102,646
Operating lease right-of-use assets	207,145	0
Intangible assets, net	56,537	57,065
Goodwill	186,299	166,832
Deferred tax assets	75,071	69,983
Other noncurrent assets	35,098	16,208
Total assets	2,040,163	1,611,802
Current liabilities
Accounts payable	6,896	7,444
Accrued expenses and other current liabilities	128,639	127,937
Due to employees	63,536	49,683
Deferred compensation due to employees	13,427	9,920
Taxes payable, current	47,548	67,845
Operating lease liabilities, current	51,424	0
Total current liabilities	311,470	262,829
Long-term debt	25,000	25,031
Taxes payable, noncurrent	43,738	43,685
Operating lease liabilities, noncurrent	153,980	0
Other noncurrent liabilities	13,858	17,661
Total liabilities	548,046	349,206
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.001 par value; 160,000,000 authorized; 54,968,833 and 54,099,927 shares issued, 54,949,098 and 54,080,192 shares outstanding at September 30, 2019 and December 31, 2018, respectively	55	54
Additional paid-in capital	589,764	544,700
Retained earnings	946,066	759,533
Treasury stock	(177)	(177)
Accumulated other comprehensive loss	(43,591)	(41,514)
Total stockholders’ equity	1,492,117	1,262,596
Total liabilities and stockholders’ equity	$ 2,040,163	$ 1,611,802