Treasury Stock Activity (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2011
Share Repurchases [Line Items]
Shares repurchased, shares	1,213
Shares repurchased, value	$ 57,009
Repurchase of Equity
Share Repurchases [Line Items]
Shares repurchased, shares	408
Shares repurchased, value	19,439
2016 Convertible Senior Notes
Share Repurchases [Line Items]
Shares repurchased, shares	805
Shares repurchased, value	$ 37,570

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

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-Section 45

-Paragraph 1

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section B

-Paragraph 7

-Subparagraph b

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

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