Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Fair value assumptions of stock options
Dividend yield	2.00%	3.00%
Risk-free interest rate	2.30%	2.70%
Expected volatility	47.20%	45.38%
Weighted average expected life	6	6
Weighted average per share fair value of stock options	$ 5.59	$ 4.60
Summary of Company's Stock Option Activities
Stock Options Shares Outstanding, Beginning balance	7,301,458	6,708,618	6,708,618
Granted, Shares	1,560,238		1,348,474
Exercised, Shares	(23,437)		(14,868)
Forfeited or expired, Shares	(1,306,848)		(740,766)
Stock Options Shares Outstanding, Ending balance	7,531,411		7,301,458
Options exercisable, shares	4,958,251		5,275,738
Stock Options Outstanding, Weighted Average Exercise Price, Beginning balance	$ 24.33	$ 26.16	$ 26.16
Granted, Weighted Average Exercise Price	$ 14.26		$ 13.24
Exercised, Weighted Average Exercise Price	$ 12.66		$ 12.71
Forfeited or expired, Weighted Average Exercise Price	$ 24.53		$ 20.95
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance	$ 22.24		$ 24.33
Options Exercisable, Weighted Average Exercise Price	$ 26.38		$ 27.60
Stock Options Outstanding, Weighted Average Remaining Contractual Term	6.09		5.01
Options exercisable, Weighted Average Remaining Contractual Term	4.54		3.63
Stock Options Outstanding, Aggregate Intrinsic Value	$ 827		$ 2,460
Options exercisable, Aggregate Intrinsic Value	$ 278		$ 63

Per share fair value of stock options.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of vested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The weighted average period between the balance sheet date and expiration for all vested portions of options outstanding and currently exercisable (or convertible) under the plan, which may be expressed in a decimal value for number of years.

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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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Net number of share options (or share units) granted during the period.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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