Debt - Schedule of Cash and Non-Cash Interest Expense (Parenthetical) (Detail)	Dec. 31, 2011	Dec. 31, 2012 0.375% Convertible Senior Notes [Member]	Dec. 31, 2012 1.875% Convertible Senior Notes due 2013 [Member]	Dec. 31, 2012 4.0% Convertible Senior Notes due 2014 [Member]	Dec. 31, 2012 8.0% Senior Notes due 2016 [Member]	Dec. 31, 2012 8.25% Senior Notes due 2019 [Member]	Dec. 31, 2012 5.625% Senior Notes due 2019 [Member]	Dec. 31, 2012 5.75% Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Interest rates for senior notes	1.875%	0.375%	1.875%	4.00%	8.00%	8.25%	5.625%	5.75%

Interest rate stated in the contractual debt agreement.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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