Earnings Per Share (Reconciliation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Oct. 31, 2012
Basic EPS
Net income attributable to common stockholders	$ (9,930)	$ 23,003
Weighted Average Shares (Denominator) (in shares)	121,071	120,521
Net income attributable to common stockholders (in usd per share)	$ (0.08)	$ 0.19
Effect of Dilutive Securities
Convertible debentures, net of tax		$ 4,424
Stock options (in shares)		3
Nonvested shares (in shares)		31
Contingently issuable shares (in shares)		154
Diluted EPS
Net income attributable to common stockholders and assumed conversions		$ 27,427
Weighted Average Shares (Denominator) (in shares)	121,071	156,807
Net income attributable to common stockholders and assumed conversions (in usd per share)	$ (0.08)	$ 0.17
1.875% Convertible Debentures [Member]
Effect of Dilutive Securities
Convertible debentures, net of tax (in shares)		95
Diluted EPS
Stated interest rate	1.875%	1.875%	1.875%
1.75% Convertible Debentures [Member]
Effect of Dilutive Securities
Convertible debentures, net of tax (in shares)		36,003
Diluted EPS
Stated interest rate	1.75%	1.75%	1.75%	1.75%