Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flow from operating activities:
Net income	$ 90,137	$ 94,072	$ 109,116
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	58,686	49,897	37,872
Stock-based compensation	27,796	23,219	18,795
Tax expense (benefit) from deferred income taxes	1,853	(8,581)	3,668
Tax benefit from stock option plans	(2,198)	(5,151)	(96)
Changes in operating assets and liabilities:
Accounts receivable	(26,007)	(21,957)	(22,923)
Inventories	(36,154)	(11,817)	(30,930)
Prepaid expenses and other assets	(7,037)	(1,350)	(20,411)
Accounts payable	23,419	5,573	9,630
Deferred revenue	21,050	16,953	14,408
Taxes, accrued expenses and other liabilities	(19,029)	29,041	25,929
Net cash provided by operating activities	132,516	169,899	145,058
Cash flow from investing activities:
Capital expenditures	(89,073)	(54,830)	(28,397)
Capitalization of internally developed software	(11,721)	(12,065)	(15,759)
Additions to other intangibles	(1,890)	(5,035)	(4,151)
Acquisitions, net of cash received	(25,481)	(73,558)	(4,218)
Purchases of short-term investments	(188,098)	(257,449)	(126,691)
Sales and maturities of short-term investments	238,436	166,104	82,672
Net cash used investing activities	(77,827)	(236,833)	(96,544)
Cash flow from financing activities:
Proceeds from issuance of common stock	30,902	32,905	51,852
Repurchase of common stock			(41,862)
Dividends paid	(68,401)	(47,961)	(40,618)
Tax benefit from stock option plans	2,198	5,151	96
Net cash used by financing activities	(35,301)	(9,905)	(30,532)
Net change in cash and cash equivalents	19,388	(76,839)	17,982
Cash and cash equivalents at beginning of period	142,608	219,447	201,465
Cash and cash equivalents at end of period	161,996	142,608	219,447
Cash paid for interest and income taxes:
Interest	68	14	82
Income taxes	$ 25,059	$ 2,393	$ 14,807