Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Basic earnings per share [Abstract]
Net income	$ 133,076us-gaap_NetIncomeLoss	$ 59,982us-gaap_NetIncomeLoss
Weighted average common shares outstanding (in shares)	339,107,000	338,213,000
Basic income per share (in dollars per share)	$ 0.39us-gaap_EarningsPerShareBasic	$ 0.18us-gaap_EarningsPerShareBasic
Diluted earnings per share [Abstract]
Net income	133,076us-gaap_NetIncomeLoss	59,982us-gaap_NetIncomeLoss
Diluted income available to common shareholders	149,582	63,031
Weighted-average shares - Basic (in shares)	339,107,000	338,213,000
Effect of dilutive securities [Abstract]
Weighted-average shares - Diluted (in shares)	468,141,000	413,180,000
Diluted income per share (in dollars per share)	$ 0.32us-gaap_EarningsPerShareDiluted	$ 0.15us-gaap_EarningsPerShareDiluted
Antidilutive securities (in shares)	0	54,500,000
5% Convertible Senior Notes due 2017 [Member]
Effect of dilutive securities [Abstract]
Dilutive securities	4,692	0
Dilutive securities (in shares)	25,670,000	0
2% Convertible Senior Notes due 2020 [Member]
Effect of dilutive securities [Abstract]
Dilutive securities	3,049	3,049
Dilutive securities (in shares)	71,942,000	71,942,000
9% Convertible Junior Subordinated Debentures due 2063 [Member]
Effect of dilutive securities [Abstract]
Dilutive securities	$ 8,765	$ 0
Dilutive securities (in shares)	28,853,000	0
Restricted stock units [Member] \| Unvested restricted stock units [Member]
Effect of dilutive securities [Abstract]
Dilutive securities (in shares)	2,569,000	3,025,000

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Amount of increase (decrease) to net income used for calculating diluted earnings per share (EPS), resulting from the assumed exercise stock options, restrictive stock units (RSUs), convertible preferred stock of an employee stock ownership plan (ESOP), and other dilutive convertible securities.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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