Consolidated Financial Statements (Details) (USD $) In Thousands, except Per Share data	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Income (numerator)
Net (loss) income	$ (4,124)	$ 8,704	$ (4,037)	$ 9,248
Shares (denominator)
Weighted-average basic common shares outstanding (in shares)	92,125	91,844	92,027	93,122
Effect of dilutive securities-stock rights (in shares)		396		526
Weighted-average diluted common shares outstanding (in shares)	92,125	92,240	92,027	93,648
Basic and diluted net (loss) income per share:
Basic net (loss) income per share (in dollars per share)	$ (0.04)	$ 0.09	$ (0.04)	$ 0.10
Diluted net (loss) income per share (in dollars per share)	$ (0.04)	$ 0.09	$ (0.04)	$ 0.10
Anti-dilutive weighted-average stock rights outstanding (in shares)		6,917		6,496

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