CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 159,795	$ 114,034
Short-term investments	584,088	614,130
Accounts receivable (net of allowances of $1,460 and $1,022 at June 30, 2016 and December 31, 2015, respectively)	94,772	81,305
Prepaid expenses and other current assets	17,124	16,162
Income tax receivable	9,879	18,377
Total current assets	865,658	844,008
Non-current assets:
Property, equipment and capitalized software, net	68,456	65,031
Goodwill	137,733	137,733
Intangible assets, net	58,201	61,855
Other assets	3,962	4,250
Total assets	1,134,010	1,112,877
Current liabilities:
Accounts payable	11,699	21,136
Accrued compensation	14,103	13,538
Other current liabilities	16,802	11,444
Deferred revenue	6,456	5,507
Deferred rent	931	797
Credit facilities	22,500	15,000
Capital lease obligation	110	109
Total current liabilities	72,601	67,531
Non-current liabilities:
Credit facilities, less current portion	251,250	266,250
Capital lease obligation, less current portion	270	296
Deferred rent	1,960	2,446
Deferred income taxes	38,116	37,198
Total liabilities	364,197	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 June 30, 2016 and December 31, 2015, respectively
Additional paid-in-capital	502,717	493,197
Retained earnings	266,156	247,540
Other comprehensive income (loss)	939	(1,582)
Total stockholders' equity	769,813	739,156
Total liabilities and stockholders' equity	1,134,010	1,112,877
Class A Common
Stockholders' equity:
Common stock
Class B Common
Stockholders' equity:
Common stock	$ 1	$ 1