Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flow from operating activities:
Net income	$ 45,083	$ 57,009
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	27,316	23,390
Stock-based compensation	13,285	10,296
Tax expense from deferred income taxes	6,695	2,770
Tax expense (benefit) from stock option plans	(2,094)	(5,035)
Changes in operating assets and liabilities:
Accounts receivable	(31,203)	(13,841)
Inventories	(16,994)	(21,393)
Prepaid expenses and other assets	(17,625)	2,186
Accounts payable	10,596	937
Deferred revenue	17,911	7,051
Taxes, accrued expenses and other liabilities	(11,169)	9,926
Net cash provided by operating activities	41,801	73,296
Cash flow from investing activities:
Capital expenditures	(28,934)	(23,053)
Capitalization of internally developed software	(9,664)	(9,391)
Additions to other intangibles	(1,085)	(1,756)
Acquisition, net of cash received		(73,558)
Purchases of short-term investments	(38,879)	(54,097)
Sales and maturities of short-term investments	183,058	73,915
Net cash provided/(used) by investing activities	104,496	(87,940)
Cash flow from financing activities:
Proceeds from issuance of common stock	14,422	21,389
Dividends paid	(34,019)	(23,860)
Tax benefit from stock option plans	2,094	5,035
Net cash (used)/provided by financing activities	(17,503)	2,564
Net change in cash and cash equivalents	128,794	(12,080)
Cash and cash equivalents at beginning of period	142,608	219,447
Cash and cash equivalents at end of period	$ 271,402	$ 207,367