Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share
Net income for basic and diluted earnings per share	$ 12,926	$ 5,086	$ 26,546	$ 13,708
Shares of common stock and common stock equivalents:
Average common shares used in basic computation	35,720	36,956	35,900	37,166
Effect of dilutive securities (in shares)	921	1,044	1,033	1,205
Average common shares used in diluted computation	36,641	38,000	36,933	38,371
Earnings per share:
Basic (in dollars per share)	$ 0.36	$ 0.14	$ 0.74	$ 0.37
Diluted (in dollars per share)	$ 0.35	$ 0.13	$ 0.72	$ 0.36
Anti-dilutive equity awards not included in the detailed earnings per share computation
Equity awards not included in the diluted earnings per share computation	83	385	220	450

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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