Capital Transactions (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2011 Y
$10 to $15
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 10
Exercise price range, high end of range (in dollars per share)	$ 15
Options Outstanding
Number of options outstanding (in shares)	1,148,921
Options outstanding, Weighted Average Remaining Contractual Life (in years)	3.9
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.01
Options Exercisable
Number of options Exercisable (in shares)	282,391
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 10.66
$16 to $21
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 16
Exercise price range, high end of range (in dollars per share)	$ 21
Options Outstanding
Number of options outstanding (in shares)	1,698,224
Options outstanding, Weighted Average Remaining Contractual Life (in years)	2.8
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 17.70
Options Exercisable
Number of options Exercisable (in shares)	1,698,224
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 17.70
$22 to $28
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 22
Exercise price range, high end of range (in dollars per share)	$ 28
Options Outstanding
Number of options outstanding (in shares)	1,329,528
Options outstanding, Weighted Average Remaining Contractual Life (in years)	1.5
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 25.79
Options Exercisable
Number of options Exercisable (in shares)	1,329,528
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 25.79
$10 to $28
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 10
Exercise price range, high end of range (in dollars per share)	$ 28
Options Outstanding
Number of options outstanding (in shares)	4,176,673
Options outstanding, Weighted Average Remaining Contractual Life (in years)	2.7
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 19.26
Options Exercisable
Number of options Exercisable (in shares)	3,310,143
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 20.35