CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 777,365	$ 770,560
Accounts receivable, net of allowance of $1,882 and $1,557, respectively	343,864	297,685
Unbilled revenues	135,786	104,652
Prepaid expenses and other current assets	28,808	26,171
Total current assets	1,285,823	1,199,068
Property and equipment, net	111,175	102,646
Operating lease right-of-use assets	210,447	0
Intangible assets, net	53,821	57,065
Goodwill	179,214	166,832
Deferred tax assets	69,734	69,983
Other noncurrent assets	21,237	16,208
Total assets	1,931,451	1,611,802
Current liabilities
Accounts payable	6,043	7,444
Accrued expenses and other current liabilities	96,026	127,937
Due to employees	64,032	49,683
Deferred compensation due to employees	7,928	9,920
Taxes payable, current	50,156	67,845
Operating lease liabilities, current	48,429	0
Total current liabilities	272,614	262,829
Long-term debt	25,000	25,031
Taxes payable, noncurrent	43,650	43,685
Operating lease liabilities, noncurrent	158,137	0
Other noncurrent liabilities	9,803	17,661
Total liabilities	509,204	349,206
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.001 par value; 160,000,000 authorized; 54,799,024 and 54,099,927 shares issued, 54,779,289 and 54,080,192 shares outstanding at June 30, 2019 and December 31, 2018, respectively	55	54
Additional paid-in capital	574,619	544,700
Retained earnings	879,064	759,533
Treasury stock	(177)	(177)
Accumulated other comprehensive loss	(31,314)	(41,514)
Total stockholders’ equity	1,422,247	1,262,596
Total liabilities and stockholders’ equity	$ 1,931,451	$ 1,611,802