Note 1. Principal Accounting Policies Earnings per share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 21,792us-gaap_NetIncomeLoss	$ 12,893us-gaap_NetIncomeLoss
Weighted average common shares outstanding - Basic	57,634,382	56,957,433
Stock options and nonvested stock	587,784	582,635
Weighted average common shares outstanding - Diluted	58,222,166	57,540,068
Diluted EPS	$ 0.37us-gaap_EarningsPerShareDiluted	$ 0.22us-gaap_EarningsPerShareDiluted
Anti-dilutive securities excluded from computation of diluted EPS	287,050	899,241

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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