Share Information - Earnings Per Share Calculation, Share Information (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Weighted average number of common shares used for basic EPS	36,468,374	37,893,170	36,886,777	37,928,548
Effect of dilutive stock options and restricted and deferred stock unit awards	314,797	357,028	266,394	378,099
Weighted average number of common shares and dilutive potential common stock used in dilutive EPS	36,783,171	38,250,198	37,153,171	38,306,647