Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Shareholders' Equity [Abstract]
Common stock, shares authorized (in shares)	680,000,000	460,000,000
Shareholder Rights Agreement [Abstract]
Shareholder rights accompanying each outstanding share of the company's common stock (in number of Rights)	1
Distribution date, description	The earlier of ten days after a public announcement that a person has become an Acquiring Person, or ten business days after a person announces or begins a tender offer in which consummation of such offer would result in a person becoming an Acquiring Person.
Common stock, beneficial ownership threshold to be considered an Acquiring Person (in hundredths)	5.00%
Common shares purchaseable per Right (in shares)	0.5
Purchase price (in dollars per share)	$ 14
Purchase price (in dollars per one-half share)	$ 7.00
Redemption price (in dollars per Right)	$ 0.001
Sale of common stock (in shares)			74,883,720
Sale of common stock, price per share (in dollars per share)			$ 10.75
Sale of common stock, net proceeds	$ 0	$ 0	$ 772,376
Convertible Debentures [Member]
Debt Instrument [Line Items]
Shares reserved for conversion under convertible debt (in shares)	35,900,000
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Shares reserved for conversion under convertible debt (in shares)	25,700,000