Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flow from operating activities:
Net income	$ 80,513	$ 90,137	$ 94,072
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	67,974	58,686	49,897
Stock-based compensation	28,992	27,796	23,219
Tax expense (benefit) from deferred income taxes	(4,353)	1,853	(8,581)
Tax benefit from stock option plans	(2,407)	(2,198)	(5,151)
Changes in operating assets and liabilities:
Accounts receivable	6,820	(26,007)	(21,957)
Inventories	(1,563)	(36,154)	(11,817)
Prepaid expenses and other assets	(1,767)	(7,037)	(1,350)
Accounts payable	(8,604)	23,419	5,573
Deferred revenue	6,346	21,050	16,953
Taxes, accrued expenses and other liabilities	(2,472)	(19,029)	29,041
Net cash provided by operating activities	169,479	132,516	169,899
Cash flow from investing activities:
Capital expenditures	(47,796)	(89,073)	(54,830)
Capitalization of internally developed software	(14,883)	(11,721)	(12,065)
Additions to other intangibles	(5,182)	(1,890)	(5,035)
Acquisition, net of cash received		(25,481)	(73,558)
Purchases of short-term investments	(70,354)	(188,098)	(257,449)
Sales and maturities of short-term investments	80,371	238,436	166,104
Net cash used in investing activities	(57,844)	(77,827)	(236,833)
Cash flow from financing activities:
Proceeds from issuance of common stock	39,319	30,902	32,905
Deferred acquisition payments	(15,318)
Dividends paid	(69,776)	(68,401)	(47,961)
Tax benefit from stock option plans	2,407	2,198	5,151
Net cash used in financing activities	(43,368)	(35,301)	(9,905)
Net change in cash and cash equivalents	68,267	19,388	(76,839)
Cash and cash equivalents at beginning of period	161,996	142,608	219,447
Cash and cash equivalents at end of period	230,263	161,996	142,608
Interest	110	68	14
Income taxes	$ 10,510	$ 25,059	$ 2,393