Earnings per Share (Schedule of Earnings per Share, Basic and Diluted) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Weighted average common shares outstanding, used in computing basic earnings per share	69,807	68,756	67,680
Effect of dilutive stock options and restricted stock units	874	678	584
Weighted-average common shares outstanding, used in computing diluted earnings per share	70,681	69,434	68,264
Basic	$ 1.97us-gaap_EarningsPerShareBasic	$ 1.37us-gaap_EarningsPerShareBasic	$ 1.48us-gaap_EarningsPerShareBasic
Diluted	$ 1.94us-gaap_EarningsPerShareDiluted	$ 1.36us-gaap_EarningsPerShareDiluted	$ 1.46us-gaap_EarningsPerShareDiluted

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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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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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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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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