Fair Value Measurements (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Fair Value Measurements [Line Items]
Estimated fair value of performance targets	$ 2.5		$ 2.5		$ 5.5
Performance targets, maximum potential obligation	5.6		5.6
Impairment recognized, related to long-lived assets	0.6	0.3	1.0	0.3
Certificate of deposits	4.8		4.8		5.6
Held-to-maturity investments, carrying value	1.4		1.4		1.6
Held-to-maturity investments, fair value	$ 1.4		$ 1.4		$ 1.6
Changes in credit risk, percentage			1.875%
London Interbank Offered Rate [Member]
Fair Value Measurements [Line Items]
Changes in credit risk, percentage			3.50%

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

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+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

- Definition

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

+ References

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

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+ Details