Stock-Based Compensation and Directors Stock Purchase Plan Stock-Based Compensation and Directors Stock Purchase Plan (Additional Information About Stock Options and SARs Exercises) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation [Abstract]
Intrinsic value of options and SARs exercised	$ 7,769	$ 6,722	$ 7,005
Cash received from options and SARs exercised	14,820	14,604	10,563
Tax benefit realized from options and SARs exercised	$ 1,269	$ 847	$ 1,042