Stock Compensation Plans (RSU, PRS And Cash RSU Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Weighted Average Grant Date Fair Value Per Share	$ 11.47	$ 10.41	$ 7.08
RSU's [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at December 31, 2010, Number of Shares	867,000
Granted, Number of Shares	219,000
Vested, Number of Shares	(267,000)
Forfeited/Cancelled, Number of Shares	(37,000)
Balance at December 31, 2011, Number of Shares	782,000
Balance at December 31, 2010, Weighted Average Grant Date Fair Value Per Share	$ 37.43
Granted, Weighted Average Grant Date Fair Value Per Share	$ 59.80
Vested, Weighted Average Grant Date Fair Value Per Share	$ 42.58
Forfeited/Cancelled, Weighted Average Grant Date Fair Value Per Share	$ 42.39
Balance at December 31, 2011, Weighted Average Grant Date Fair Value Per Share	$ 44.91
PRS [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at December 31, 2010, Number of Shares	525,000
Granted, Number of Shares	174,212	213,714	218,134
Vested, Number of Shares	(202,000)
Balance at December 31, 2011, Number of Shares	497,000	525,000
Balance at December 31, 2010, Weighted Average Grant Date Fair Value Per Share	$ 19.32
Granted, Weighted Average Grant Date Fair Value Per Share	$ 31.07
Vested, Weighted Average Grant Date Fair Value Per Share	$ 20.28
Balance at December 31, 2011, Weighted Average Grant Date Fair Value Per Share	$ 23.03	$ 19.32
Cash RSU's [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at December 31, 2010, Number of Shares	162,000
Granted, Number of Shares	40,000
Vested, Number of Shares	(45,000)
Forfeited/Cancelled, Number of Shares	(3,000)
Balance at December 31, 2011, Number of Shares	154,000
Balance at December 31, 2010, Weighted Average Grant Date Fair Value Per Share	$ 55.59
Granted, Weighted Average Grant Date Fair Value Per Share	$ 52.42
Vested, Weighted Average Grant Date Fair Value Per Share	$ 62.74
Forfeited/Cancelled, Weighted Average Grant Date Fair Value Per Share	$ 56.91
Balance at December 31, 2011, Weighted Average Grant Date Fair Value Per Share	$ 52.42