Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 120,058	$ 126,363
Short-term investments, available for sale	99,100	103,300
Accounts receivable, net of allowances of $12.0 and $13.2 million, respectively	91,923	85,453
Inventories	44,788	46,216
Other current assets	20,792	24,317
Total current assets	376,661	385,649
Property and equipment, net	30,096	26,547
Restricted investments	56,850	56,850
Goodwill	164,323	139,517
Intangible assets, net	55,992	49,140
Deferred tax assets	53,675	47,137
Other assets	2,137	1,741
Total assets	739,734	706,581
Liabilities and Stockholders' Equity
Accounts payable	46,965	49,189
Accrued and other liabilities	56,236	45,730
Deferred revenue	26,053	24,298
Income taxes payable	2,583	1,182
Total current liabilities	131,837	120,399
Contingent and other liabilities	3,427	619
Deferred tax liabilities	4,090	1,292
Non-current income taxes payable	35,597	32,522
Total liabilities	174,951	154,832
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.01 par value; 5,000 shares authorized; none issued and outstanding
Common stock, $0.01 par value; 150,000 shares authorized; 76,565 and 74,456 shares issued and outstanding, respectively	766	745
Additional paid-in capital	725,801	692,904
Treasury stock, at cost, 30,964 and 28,031 shares, respectively	(534,400)	(488,559)
Accumulated other comprehensive income	1,447	2,955
Retained earnings	371,169	343,704
Total stockholders' equity	564,783	551,749
Total liabilities and stockholders' equity	$ 739,734	$ 706,581