Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Operating activities:
Net income	$ 16,557	$ 8,523	$ 25,528	$ 12,485
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	3,188	2,740	6,452	5,604
Amortization of content database costs	2,279	1,830	4,415	3,664
Amortization of acquired intangible assets	4,297	3,679	8,567	7,358
Amortization of deferred financing costs	69	614	138	829
Deferred income taxes	(2,021)	(1,487)	(2,989)	(2,637)
Stock-based compensation expense	2,201	1,262	3,926	2,266
Changes in operating assets and liabilities:
Accounts receivable	999	283	1,308	935
Restricted cash	44	(99)	536	(170)
Other assets	(581)	403	(233)	1,970
Income tax receivable	(8,672)		(7,268)	1,544
Accounts payable and other liabilities	24,563	4,200	23,148	8,188
Excess tax benefits from stock-based compensation	(16,393)	(3,570)	(20,449)	(3,570)
Deferred revenues	5,054	4,654	24,906	19,088
Net cash provided by operating activities	31,584	23,032	67,985	57,554
Investing activities:
Capitalization of content database costs	(4,204)	(2,349)	(9,951)	(5,141)
Purchases of property and equipment	(3,693)	(2,221)	(4,418)	(3,628)
Purchases of short-term investments		(5,193)		(7,193)
Proceeds from sale and maturity of short-term investments		4,991		10,037
Net cash used in investing activities	(7,897)	(4,772)	(14,369)	(5,925)
Financing activities:
Proceeds from exercise of stock options	7,290	4,858	10,022	5,072
Taxes paid related to net share settlement of stock-based awards	(515)		(515)
Principal payments on debt		(20,937)		(23,795)
Excess tax benefits from stock-based compensation	16,393	3,570	20,449	3,570
Repurchases of common stock	(78,095)		(78,095)
Net cash used in financing activities	(54,927)	(12,509)	(48,139)	(15,153)
Effect of changes in foreign currency exchange rates on cash and cash equivalents	(4)		23
Net increase (decrease) in cash and cash equivalents	(31,244)	5,751	5,500	36,476
Cash and cash equivalents at beginning of period	102,263	97,666	65,519	66,941
Cash and cash equivalents at end of period	71,019	103,417	71,019	103,417
Supplemental disclosures of cash flow information:
Cash paid for interest	111	476	226	1,477
Cash paid for income taxes	3,282	5,778	3,557	6,181
Supplemental disclosures of noncash investing and financing activities:
Capitalization of stock-based compensation	$ 9	$ 2	$ 18	$ 3