Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities:
Net income (loss)	$ (40,074)	$ (35,547)	$ 24,399
Less: Discontinued operations, net of income taxes	(27,348)	(30,003)	50,060
Net loss from continuing operations	(12,726)	(5,544)	(25,661)
Adjustments to reconcile net loss from continuing operations to cash from operating activities:
Stock-based compensation	8,694	8,694	8,499
Depreciation and amortization of acquired intangible assets	22,590	22,164	21,973
Excess tax benefits from stock-based award activity	(7,967)	(6,398)	(4,313)
Deferred income taxes	(12,607)	(9,858)	(11,601)
Amortization of premium on investments, net	1,589	3,772	3,007
Amortization of debt issuance costs	1,133	1,059	1,099
Accretion of debt discounts	3,866	3,594	2,826
Loss on debt extinguishment and modification expense	398	0	1,593
Loss on derivative instrument	0	0	11,652
Impairment loss on equity investment in privately-held company	0	0	3,711
Other	203	77	622
Cash provided (used) by changes in operating assets and liabilities:
Accounts receivable	(1,862)	47	(47)
Other receivables	651	367	1,671
Prepaid expenses and other current assets	(493)	(3,457)	2,407
Other long-term assets	(15)	191	247
Accounts payable	369	(258)	16
Deferred revenue	1,875	1,130	2,609
Accrued expenses and other current and long-term liabilities	10,643	4,548	7,701
Net cash provided by operating activities from continuing operations	16,341	20,128	28,011
Investing Activities:
Business acquisitions, net of cash acquired	(573,366)	0	(4,892)
Equity investment in privately-held company	0	0	(4,000)
Purchases of property and equipment	(1,512)	(2,037)	(2,352)
Change in restricted cash	150	0	2,491
Proceeds from sales of investments	156,506	28,535	25,812
Proceeds from maturities of investments	296,455	255,994	213,616
Purchases of investments	(214,257)	(336,495)	(351,883)
Net cash used by investing activities from continuing operations	(336,024)	(54,003)	(121,208)
Financing Activities:
Proceeds from issuance of convertible notes, net of debt issuance costs of $6,432	0	0	194,818
Proceeds from credit facility, net of debt issuance costs and debt discount of $9,730 and $12,000 in 2015	378,270	36,556	6,000
Repayment of credit facility	(51,940)	(56,000)	(10,000)
Debt issuance costs on credit facility	0	0	(28)
Stock repurchases	(7,735)	(38,650)	(10,006)
Excess tax benefits from stock-based award activity	7,967	6,398	4,313
Proceeds from stock option exercises	2,409	6,730	2,826
Proceeds from issuance of stock through employee stock purchase plan	1,193	1,376	1,065
Proceeds from issuance of stock upon warrant exercise	0	0	9,620
Tax payments from shares withheld upon vesting of restricted stock units	(1,545)	(2,875)	(2,405)
Net cash provided (used) by financing activities from continuing operations	328,619	(46,465)	196,203
Net cash provided (used) by continuing operations	8,936	(80,340)	103,006
Net cash provided by operating activities from discontinued operations	14,108	41,406	56,741
Net cash used by investing activities from discontinued operations	(540)	(47,933)	(182,483)
Net cash provided (used) by financing activities from discontinued operations	(8,982)	8,886	74,401
Net cash provided (used) by discontinued operations	4,586	2,359	(51,341)
Effect of exchange rate changes on cash and cash equivalents	(17)	0	0
Net increase (decrease) in cash and cash equivalents	13,505	(77,981)	51,665
Cash and cash equivalents, beginning of period	41,968	119,949	68,284
Cash and cash equivalents, end of period	55,473	41,968	119,949
Non-cash investing and financing activities from continuing operations:
Purchases of property and equipment through leasehold incentives (investing)	0	120	1,006
Cash paid for income taxes from continuing operations	614	684	343
Cash paid for interest from continuing operations	$ 8,994	$ 9,469	$ 6,944