CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 126,885	$ 114,034
Short-term investments	611,598	614,130
Accounts receivable (net of allowances of $1,320 and $1,022 at March 31, 2016 and December 31, 2015, respectively)	73,177	81,305
Prepaid expenses and other current assets	21,217	16,162
Income tax receivable	17,251	18,377
Total current assets	850,128	844,008
Noncurrent assets:
Property, equipment and capitalized software, net	65,278	65,031
Goodwill	137,733	137,733
Intangible assets, net	60,028	61,855
Other assets	3,940	4,250
Total assets	1,117,107	1,112,877
Current liabilities:
Accounts payable	17,716	21,136
Accrued compensation	10,281	13,538
Other current liabilities	14,168	11,444
Deferred revenue	7,044	5,507
Deferred rent	843	797
Credit facilities	18,750	15,000
Capital lease obligation	109	109
Total current liabilities	68,911	67,531
Noncurrent liabilities:
Credit facilities, less current portion	258,750	266,250
Capital lease obligation, less current portion	309	296
Deferred rent	2,251	2,446
Deferred income taxes	36,275	37,198
Total liabilities	$ 366,496	$ 373,721
Commitments and contingencies (Note 5)
Stockholders' equity:
Common stock
Preferred stock, $0.0001 par value, 100,000,000 shares authorized, zero shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively
Additional paid-in-capital	$ 499,899	$ 493,197
Retained earnings	249,905	247,540
Other comprehensive loss (loss)	806	(1,582)
Total stockholders' equity	750,611	739,156
Total liabilities and stockholders' equity	$ 1,117,107	$ 1,112,877
Class A Common
Stockholders' equity:
Common stock
Class B Common
Stockholders' equity:
Common stock	$ 1	$ 1