Earnings Per Share (Reconciliation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Mar. 31, 2013	Oct. 31, 2012
Basic EPS
Net income attributable to common stockholders	$ (11,878)	$ 18,148	$ (16,352)	$ 55,615
Weighted Average Shares (Denominator) (in shares)	120,960	120,067	120,746	119,849
Net income attributable to common stockholders (in usd per share)	$ (0.10)	$ 0.15	$ (0.14)	$ 0.46
Effect of Dilutive Securities
Convertible debentures, net of tax		$ 4,060		$ 12,229
Stock options (in shares)		6		31
Nonvested shares (in shares)		113		22
Contingently issuable shares (in shares)		107		45
Diluted EPS
Net income attributable to common stockholders and assumed conversions		$ 22,208		$ 67,844
Weighted Average Shares (Denominator) (in shares)	120,960	156,391	120,746	156,045
Net income attributable to common stockholders and assumed conversions (in usd per share)	$ (0.10)	$ 0.14	$ (0.14)	$ 0.43
1.875% Convertible Debentures [Member]
Effect of Dilutive Securities
Convertible debentures, net of tax (in shares)		95		95
Diluted EPS
Stated interest rate	1.875%	1.875%	1.875%	1.875%	1.875%	1.875%
1.75% Convertible Debentures [Member]
Effect of Dilutive Securities
Convertible debentures, net of tax (in shares)		36,003		36,003
Diluted EPS
Stated interest rate	1.75%	1.75%	1.75%	1.75%	1.75%		1.75%