Common Stock and Stock-based Compensation (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Common Stock and Stock-based Compensation (Textual) [Abstract]
Serial preferred stock, shares authorized	5,000,000	5,000,000
Serial preferred stock, par value
Serial preferred stock, shares issued
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights vested period	4 years
Expire period of option rights granted to non employees	10 years
Allocated Share-based Compensation Expense	$ 0	$ 0	$ 0
Total cash received from the exercise of stock options	200,000	700,000	2,600,000
Tax benefit realized from tax deductions	100,000	500,000	800,000
Total intrinsic value of options exercised	300,000	1,400,000	2,300,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	2,700,000	2,500,000	2,300,000
Amortization period	3 years
Amount of Weighted average grant date fairvalue	$ 27.87	$ 39.18	$ 22.65
Unvested outstanding options	2,800,000
Expected amortization weighted average period	19 months
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights vested period	3 years
Allocated Share-based Compensation Expense	2,800,000	2,500,000	1,800,000
Amount of Weighted average grant date fairvalue	$ 12.87
Unvested outstanding options	3,800,000
Basis of risk-free rate of return	5 years
Duration of month-end Company share closing prices prior to granting of SARs used in calculating share price volatility	10 years
Stock Appreciation Rights (SARs) [Member] | Range of Exercise Prices One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	$ 15.01
Stock Appreciation Rights (SARs) [Member] | Range of Exercise Prices Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	$ 24.03
Stock Appreciation Rights (SARs) [Member] | Range of Exercise Prices Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	$ 27.78
Stock Appreciation Rights (SARs) [Member] | Range of Exercise Prices Six [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights granted	$ 44.72
Long Term Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	400,000	0	100,000
Period in which employees receive cash or stock awards	3 years
Compensation expense plan period	3 years
Deferred Directors Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expire period of option rights granted to non employees	10 years
Exercisable short term period of option rights granted to non employees	6 months
Amount of Weighted average grant date fairvalue	$ 23.10	$ 38.00	$ 25.13
Deferred compensation plan expense	$ 0	$ 0
Granted Prior To 2011 [Member] | Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expire period of option rights granted to non employees	10 years
Granted in 2011 and Later [Member] | Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expire period of option rights granted to non employees	7 years