Fair Value Of Financial Instruments (Reconciliation Of Assets And Liabilities Measured At Fair Value On Recurring Basis, Level 3) (Detail) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reversal of unrealized losses on redeemed or sold securities	$ 0	$ 0	$ (936,000)
Earn-out Arrangements [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	80,500,000	45,000,000
Additions from new business combinations	66,700,000	47,700,000
Payments of contingent consideration	(3,600,000)	(12,200,000)
Changes in fair value recorded in earnings	0
Ending balance	143,600,000	80,500,000
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	13,600,000	19,000,000
Redemption or sale of securities, cost basis		(4,600,000)
Reversal of unrealized losses on redeemed or sold securities		500,000
Changes in fair value recorded in earnings	0	(600,000)
Changes in unrealized (losses)/gains included in other comprehensive income	800,000	(700,000)
Ending balance	14,400,000	13,600,000
Auction Rate Securities [Member] \| Asset-backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	11,900,000	16,400,000
Redemption or sale of securities, cost basis		(4,600,000)
Reversal of unrealized losses on redeemed or sold securities		500,000
Changes in fair value recorded in earnings	0	0
Changes in unrealized (losses)/gains included in other comprehensive income	(200,000)	(400,000)
Ending balance	11,700,000	11,900,000
Auction Rate Securities [Member] \| Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,700,000	2,600,000
Redemption or sale of securities, cost basis		0
Reversal of unrealized losses on redeemed or sold securities		0
Changes in fair value recorded in earnings	0	(600,000)
Changes in unrealized (losses)/gains included in other comprehensive income	1,000,000	(300,000)
Ending balance	$ 2,700,000	$ 1,700,000

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Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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- Definition

Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Amount of gain (loss) recognized in earnings, arising from liabilities measured at fair value on a recurring basis using unobservable inputs (level 3).

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- Definition

Purchases that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

Settlements that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

This element represents a liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

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- Definition

Before tax amount of the income statement impact of the reclassification adjustment for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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