Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator [Abstract]
Net income (loss)	$ 26,996	$ 3,190	$ 7,866	$ 595	$ (11,867)	$ (18,644)	$ 10,903	$ 817	$ 38,647	$ (18,791)	$ 13,743
Denominator [Abstract]
Denominator for basic earnings per share - weighted-average common shares outstanding (in shares)									92,451,000	91,914,000	90,151,000
Effect of dilutive securities [Abstract]
Stock options, restricted shares and warrants (in shares)									1,087,000	0	2,093,000
Dilutive potential common shares [Abstract]
Denominator for diluted earnings per share - adjusted weighted-average shares and assumed exercise of options, restricted shares and warrants (in shares)									93,538,000	91,914,000	92,244,000
Net income (loss) per common share - basic (in dollars per share)	$ 0.29	$ 0.03	$ 0.09	$ 0.01	$ (0.13)	$ (0.20)	$ 0.12	$ 0.01	$ 0.42	$ (0.20)	$ 0.15
Net income (loss) per common share - diluted (in dollars per share)	$ 0.29	$ 0.03	$ 0.08	$ 0.01	$ (0.13)	$ (0.20)	$ 0.12	$ 0.01	$ 0.41	$ (0.20)	$ 0.15
Stock options excluded from the calculation of diluted income (loss) per share (in shares)									0	1,349	0