Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share (Details) [Abstract]
Number of anti-dilutive stock awards	1,183,826	691,491	1,340,372	1,059,078
Earnings Per Share (Table Details) [Abstract]
Net earnings	$ 27,622	$ 39,910	$ 116,083	$ 136,033
Basic weighted average shares	53,438,000	58,882,000	55,423,000	59,098,000
Effect of dilutive stock options	374,000	430,000	377,000	511,000
Diluted weighted average shares	53,812,000	59,312,000	55,800,000	59,609,000
Basic earnings per common share	$ 0.52	$ 0.68	$ 2.09	$ 2.30
Diluted earnings per common share	$ 0.51	$ 0.67	$ 2.08	$ 2.28