Summary of Significant Accounting Policies (Net Income Per Share) (Details) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weighted Average Number of Shares Outstanding, Basic	72,000	71,543	70,374
Weighted Average Number of Shares Outstanding, Diluted	72,854	72,703	72,236
Employee Stock Options [Member]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	225	286	783
Restricted Stock Units (RSUs) [Member]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	629	874	1,079

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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