CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 567,223	$ 421,818
Accounts receivable, net of allowance for doubtful accounts of approximately $7,478 and $6,344 as of December 31, 2015 and 2016, respectively	48,537	40,276
Income tax receivable	129	430
Prepaid expenses and other current assets	11,602	10,209
Total current assets	627,491	472,733
Long-term investments	9,952	15,507
Deferred income taxes, net	7,273	9,107
Property and equipment, net	87,568	88,311
Goodwill	1,254,866	1,252,945
Intangible assets, net	195,965	238,318
Deposits and other assets	1,948	2,650
Total assets	2,185,063	2,079,571
Current liabilities:
Current portion of long-term debt	31,866	16,746
Accounts payable	11,478	9,673
Accrued wages and commissions	33,803	31,045
Accrued expenses	31,092	31,423
Deferred gain on the sale of building	2,523	2,523
Income taxes payable	3,814	46
Deferred rent	1,206	1,687
Deferred revenue	39,164	42,138
Total current liabilities	154,946	135,281
Long-term debt, less current portion	306,473	338,366
Deferred gain on the sale of building	18,715	21,239
Deferred rent	31,589	29,628
Deferred income taxes, net	18,386	4,585
Income taxes payable	741	6,692
Total liabilities	530,850	535,791
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.01 par value; 2,000 shares authorized; none outstanding	0	0
Common stock, $0.01 par value; 60,000 shares authorized; 32,509 and 32,606 issued and outstanding as of December 31, 2015 and 2016, respectively	326	325
Additional paid-in capital	1,471,127	1,440,321
Accumulated other comprehensive loss	(13,039)	(7,594)
Retained earnings	195,799	110,728
Total stockholders’ equity	1,654,213	1,543,780
Total liabilities and stockholders’ equity	$ 2,185,063	$ 2,079,571