CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical)	Dec. 31, 2013 4.00% Convertible Notes due in November, 2013	Dec. 31, 2011 4.00% Convertible Notes due in November, 2013	Sep. 30, 2010 4.00% Convertible Notes due in November, 2013	Dec. 31, 2013 5.375% Convertible Notes due in August, 2014	Dec. 31, 2012 5.375% Convertible Notes due in August, 2014	Dec. 31, 2011 5.375% Convertible Notes due in August, 2014
Long-term debt [Line Items]
Interest rate on debt (as a percent)	4.00%	4.00%	4.00%	5.375%	5.375%	5.375%

Contractual interest rate for funds borrowed, under the 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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