CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating activities:
Net income	$ 4,240	$ 5,490
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	444	286
Amortization of intangibles	2,157
Stock-based compensation expense	765	711
Change in valuation of deferred acquisition consideration	136
Changes in operating assets and liabilities:
Accounts receivable	4,763
Income tax receivable	(1,329)	40
Prepaid expenses and other assets	112	(99)
Restricted cash		2,134
Accounts payable and other accrued liabilities	(1,988)	1,614
Deferred tax liability	(1,484)
Deferred revenue	(1,430)	(127)
Net cash provided by operating activities	6,386	10,049
Investing activities:
Purchases of marketable securities	(63,510)	(31,014)
Sales and maturities of marketable securities	62,204	20,602
Purchases of property and equipment	(668)	(398)
Payment of deferred consideration relating to acquisition of Astex Therapeutics Limited	(10,012)
Net cash used in investing activities	(11,986)	(10,810)
Financing activities:
Proceeds from issuances of common stock	62	24
Net cash provided by financing activities	62	24
Effect of foreign exchange rate changes on cash and cash equivalents	434
Net decrease in cash and cash equivalents	(5,104)	(737)
Cash and cash equivalents at beginning of period	39,788	25,554
Cash and cash equivalents at end of period	34,684	24,817
Supplemental Disclosure of Cash Flow Information:
Income taxes paid in cash during the period		$ 39