Stock Transactions (Summary of Options Outstanding) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
$15.23 to $23.56 [Member]
Options, Exercise Price, lower range limit	$ 15.23
Options, Exercise Price, upper range limit	$ 23.56
Outstanding, Shares	5,194
Outstanding, Average Exercise Price	$ 18.42
Outstanding, Average Remaining Life, in years	1
Exercisable, Shares	5,194
Exercisable, Average Exercise Price	$ 18.42
$23.56 to $31.26 [Member]
Options, Exercise Price, lower range limit	$ 23.57
Options, Exercise Price, upper range limit	$ 31.26
Outstanding, Shares	9,815
Outstanding, Average Exercise Price	$ 28.33
Outstanding, Average Remaining Life, in years	5
Exercisable, Shares	6,804
Exercisable, Average Exercise Price	$ 28.51
$31.27 to $38.81 [Member]
Options, Exercise Price, lower range limit	$ 31.27
Options, Exercise Price, upper range limit	$ 38.81
Outstanding, Shares	10,401
Outstanding, Average Exercise Price	$ 36.25
Outstanding, Average Remaining Life, in years	6
Exercisable, Shares	5,387
Exercisable, Average Exercise Price	$ 35.01
$38.82 to $46.81 [Member]
Options, Exercise Price, lower range limit	$ 38.82
Options, Exercise Price, upper range limit	$ 46.81
Outstanding, Shares	3,320
Outstanding, Average Exercise Price	$ 40.35
Outstanding, Average Remaining Life, in years	7
Exercisable, Shares	1,824
Exercisable, Average Exercise Price	$ 40.14
$46.82 to $55.07 [Member]
Options, Exercise Price, lower range limit	$ 46.82
Options, Exercise Price, upper range limit	$ 55.07
Outstanding, Shares	3,724
Outstanding, Average Exercise Price	$ 50.01
Outstanding, Average Remaining Life, in years	9
Exercisable, Shares	23
Exercisable, Average Exercise Price	$ 50.40