Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Common Share (Details) [Abstract]
Number of anti-dilutive stock options	1,507,355	1,115,245	744,640
Earnings Per Common Share (Table Details) [Abstract]
Net earnings	$ 128,238	$ 181,703	$ 163,464
Basic weighted average shares	54,804,000	58,913,000	61,188,000
Effect of dilutive stock options	358,000	492,000	701,000
Diluted weighted average shares	55,162,000	59,405,000	61,889,000
Basic earnings per common share	$ 2.34	$ 3.08	$ 2.67
Diluted earnings per common share	$ 2.32	$ 3.06	$ 2.64