Condensed Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net income	$ 175.5	$ 157.1
Reconciliation of net income to net cash provided by operating activities:
Depreciation and amortization	23.5	17.7
Stock-based compensation expense	15.0	16.0
Excess tax benefits from stock-based compensation plans	(8.6)	(2.8)
Changes in assets and liabilities:
Accounts receivable	(96.0)	(2.0)
Other current assets	50.8	63.5
Other assets	(4.9)	16.4
Accounts payable and accrued liabilities	(105.7)	(108.1)
Restructuring		(0.1)
Deferred revenue	84.2	41.4
Unrecognized tax benefits	(83.0)	12.2
Other liabilities	11.2	(10.4)
Net cash provided by operating activities	62.0	200.9
Cash flows from investing activities
Capital additions	(15.3)	(19.6)
Purchases of short-term investments	(13.0)	(5.7)
Sales and maturities of short-term investments	14.7	12.0
Net cash used in investing activities	(13.6)	(13.3)
Cash flows from financing activities
Repayments of notes	(3.8)	(1.9)
Net proceeds from stock-based compensation plans	27.6	11.9
Cost of treasury shares repurchased		(127.6)
Excess tax benefits from stock-based compensation plans	8.6	2.8
Payment of dividends	(35.7)	(26.3)
Payment of dividends to noncontrolling interests	(3.7)	(4.0)
Net cash used in financing activities	(7.0)	(145.1)
Effect of exchange rate changes on cash and cash equivalents	13.3	17.4
Net increase in cash and cash equivalents	54.7	59.9
Cash and cash equivalents, beginning of the period	760.0	659.6
Cash and cash equivalents, end of the period	$ 814.7	$ 719.5

Name:	us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits are not generally reported as cash and cash equivalents. Includes cash and cash equivalents associated with the entity's continuing operations. Excludes cash and cash equivalents associated with the disposal group (and discontinued operation).