Stock-Based Compensation (Summary of Options Outstanding and Options Exerciseable) (Details) (USD $) In Thousands, except Share data, unless otherwise specified					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2012 Range of Exercise Prices $1.43-$3.10 [Member] Stock Options [Member]	Dec. 31, 2012 Range of Exercise Prices $16.75-$29.69 [Member] Stock Options [Member]	Dec. 31, 2012 Range of Exercise Prices $30.23-$35.91 [Member] Stock Options [Member]	Dec. 31, 2012 Range of Exercise Prices $36.22-$39.68 [Member] Stock Options [Member]	Dec. 31, 2012 Range of Exercise Prices $40.15-$51.47 [Member] Stock Options [Member]
Stock options, Outstanding at January 1, Number of options	3,649,520	4,741,732	4,769,122	5,649,233
Stock options, Outstanding at December 31, Number of options	3,649,520	4,741,732	4,769,122	5,649,233	3,649,520	465,772	553,756	1,175,749	1,062,788	391,455
Stock options, Outstanding at December 31, Weighted average exercise price	$ 29.84	$ 21.24	$ 16.13	$ 11.59	$ 29.84	$ 2.64	$ 24.32	$ 33.04	$ 36.77	$ 41.60
Options Outstanding - Weighted Average Remaining Contractual Life (Years)					4 years 1 month 0 days	0 years 9 months 0 days	1 year 7 months 0 days	5 years 2 months 0 days	5 years 5 months 0 days	4 years 0 months 0 days
Options Outstanding - Aggregate Intrinsic Value (thousands)					$ 20,521
Stock options, Exercisable at December 31,					2,372,538	465,772	541,606	505,485	493,943	365,732
Stock options Exercisable at December 31, Weighted average exercise price					$ 26.77	$ 2.64	$ 24.24	$ 31.30	$ 36.75	$ 41.49
Options Exercisable - Weighted Average Remaining Contractual Life (Years)					2 years 9 months 0 days	0 years 9 months 0 days	1 year 6 months 0 days	3 years 1 month 0 days	5 years 3 months 0 days	3 years 9 months 0 days
Options Exercisable - Aggregate Intrinsic Value (thousands)					$ 20,437