The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Debt and Capital Lease Obligations Related to Continuing Operations (Parenthetical) (Detail) (USD $)			9 Months Ended			9 Months Ended
	Sep. 30, 2012	Jul. 25, 2011	Sep. 30, 2012 $925 Million Credit Facility [Member]	Sep. 30, 2012 3.75% Convertible Senior Notes [Member]	Dec. 31, 2011 3.75% Convertible Senior Notes [Member]	Sep. 30, 2012 6.75% Senior Notes [Member]
Debt Instrument [Line Items]
Total credit facility	$ 925,000,000	$ 1,000,000,000	$ 925,000,000
Spread rate added to LIBOR			2.25%
Spread rate added to bank's base rate			1.25%
Maturity date for credit facility			Aug. 01, 2015
Interest rate of Senior Notes				3.75%		6.75%
Maturity date for Notes				Oct. 01, 2014		Nov. 15, 2014
Debt discount on Convertible Senior Notes				$ 30,554,000	$ 40,754,000