CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 1,161,065	$ 936,552
Short-term investments	60,089	9
Trade receivables and contract assets, net of allowance of $5,371 and $2,920, respectively	493,225	497,716
Prepaid and other current assets	37,843	39,934
Total current assets	1,752,222	1,474,211
Property and equipment, net	163,689	165,259
Operating lease right-of-use assets, net	232,780	238,991
Intangible assets, net	54,321	56,258
Goodwill	207,764	195,043
Deferred tax assets	90,071	75,013
Other noncurrent assets	54,578	39,433
Total assets	2,555,425	2,244,208
Current liabilities
Accounts payable	10,785	7,831
Accrued compensation and benefits expenses	263,918	230,035
Accrued expenses and other current liabilities	65,242	82,476
Income taxes payable, current	13,779	9,064
Operating lease liabilities, current	61,107	57,542
Total current liabilities	414,831	386,948
Long-term debt	25,039	25,074
Income taxes payable, noncurrent	43,259	45,878
Operating lease liabilities, noncurrent	183,935	180,848
Other noncurrent liabilities	28,127	9,315
Total liabilities	695,191	648,063
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.001 par value; 160,000,000 authorized; 56,001,270 and 55,207,446 shares issued, 55,981,535 and 55,187,711 shares outstanding at September 30, 2020 and December 31, 2019, respectively	56	55
Additional paid-in capital	648,686	607,051
Retained earnings	1,262,341	1,020,590
Treasury stock	(177)	(177)
Accumulated other comprehensive loss	(50,672)	(31,374)
Total stockholders’ equity	1,860,234	1,596,145
Total liabilities and stockholders’ equity	$ 2,555,425	$ 2,244,208