Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 450,003	$ 461,443	$ 432,968
Adjustments to reconcile net income to net cash provided by operating activities:
Provisions for doubtful accounts on accounts receivable	3,656	2,256	3,265
Stock-based compensation expense	31,708	29,183	27,579
Deferred income taxes	169	(52,219)	(5,824)
Depreciation	38,165	37,422	36,531
Amortization of intangibles	41,530	31,409	29,856
Change in operating assets and liabilities, net of acquisitions:
Increase in accounts receivable	(35,233)	(39,836)	(12,528)
Increase in inventories	(11,389)	(10,930)	(8,707)
Decrease (increase) in other current assets	5,033	(7,136)	4,309
(Increase) decrease in other assets	(11,467)	1,473	(12,071)
(Decrease) increase in accounts payable and other current liabilities	(28,127)	563	(11,845)
Increase in deferred revenue and customer advances	8,512	11,005	2,630
(Decrease) increase in other liabilities	(7,684)	(15,353)	11,211
Net cash provided by operating activities	484,876	449,280	497,374
Cash flows from investing activities:
Additions to property, plant, equipment and software capitalization	(118,450)	(104,749)	(85,436)
Business acquisitions, net of cash acquired	(41,395)	(31,016)	(11,100)
Purchase of investments	(2,972,116)	(1,815,988)	(1,749,161)
Maturities and sales of investments	2,667,232	1,655,359	1,489,721
Net cash used in investing activities	(464,729)	(296,394)	(355,976)
Cash flows from financing activities:
Proceeds from debt issuances	1,032,209	218,324	598,528
Payments on debt	(886,644)	(32,107)	(373,751)
Payments of debt issuance costs	(2,039)	(497)	(4,523)
Proceeds from stock plans	68,958	28,869	60,153
Purchase of treasury shares	(301,580)	(295,878)	(370,835)
Excess tax benefit related to stock option plans	15,842	10,568	32,239
Proceeds from (payments for) derivative contracts	8,666	4,186	(2,233)
Net cash used in financing activities	(64,588)	(66,535)	(60,422)
Effect of exchange rate changes on cash and cash equivalents	4,202	10,694	(5,484)
(Decrease) increase in cash and cash equivalents	(40,239)	97,045	75,492
Cash and cash equivalents at beginning of period	481,035	383,990	308,498
Cash and cash equivalents at end of period	440,796	481,035	383,990
Supplemental cash flow information:
Income taxes paid	55,928	59,446	50,313
Interest paid	$ 29,563	$ 28,305	$ 19,658

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.