Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Net Income (Numerator)
Basic earnings per share - net income (in dollars)	$ 30,761	$ 38,579
5.125% convertible senior notes, net of tax (in dollars)		2,358
Diluted earnings per share - net income (in dollars)	$ 30,761	$ 40,937
Weighted average common shares outstanding (in shares)
Weighted average common shares outstanding (in shares)	241,535,000	223,011,000
Dilutive common share equivalents (in shares)	1,332,000	1,608,000
5.125% convertible senior notes, net of tax (in shares)		16,775,000
Weighted average common shares outstanding - diluted (in shares)	242,867,000	241,394,000
Per Share Amount
Basic (in dollars per share)	$ 0.13us-gaap_EarningsPerShareBasic	$ 0.17us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 0.13us-gaap_EarningsPerShareDiluted	$ 0.17us-gaap_EarningsPerShareDiluted
Options
Antidilutive securities excluded from computation of earnings per share amount
Antidilutive securities excluded from computation of earnings per share amount (in shares)	0	0

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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