Capital Transactions (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012 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)	1,167,959
Options outstanding, Weighted Average Remaining Contractual Life (in years)	3.9
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.38
Options Exercisable
Number of options Exercisable (in shares)	545,925
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 14.42
$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)	1,649,742
Options outstanding, Weighted Average Remaining Contractual Life (in years)	1.8
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 17.71
Options Exercisable
Number of options Exercisable (in shares)	1,649,742
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 17.71
$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)	836,158
Options outstanding, Weighted Average Remaining Contractual Life (in years)	1.3
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 25.56
Options Exercisable
Number of options Exercisable (in shares)	836,158
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 25.56
$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)	3,653,859
Options outstanding, Weighted Average Remaining Contractual Life (in years)	2.3
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 18.44
Options Exercisable
Number of options Exercisable (in shares)	3,031,825
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 19.28